v3.15.0

fix corner case in inline (#5311 )
fixes #5222
2022-01-26 01:33:13 +08:00 · 2022-01-26 00:47:24 +08:00 · 2022-01-23 00:45:11 +08:00 · 2022-01-21 09:40:33 +08:00 · 2022-01-21 05:13:26 +08:00 · 2022-01-19 08:14:19 +08:00
90 changed files with 15387 additions and 3012 deletions
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -10,7 +10,7 @@ jobs:
      matrix:
        options:
          - '-mb braces'
-          - '--ie8 -c'
+          - '--ie -c'
          - '-mc'
          - '-p acorn --toplevel -mco spidermonkey'
          - '--toplevel -mc passes=3,pure_getters,unsafe'
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -7,14 +7,9 @@ jobs:
  test:
    strategy:
      matrix:
-        node: [ '0.8', '0.10', '0.12', '4', '6', '8', '10', '12', '14', latest ]
+        node: [ '0.10', '0.12', '4', '6', '8', '10', '12', '14', '16', latest ]
        os: [ ubuntu-latest, windows-latest ]
        script: [ compress, mocha, release/benchmark, release/jetstream ]
-        exclude:
-          - node: '0.8'
-            script: release/benchmark
-          - node: '0.8'
-            script: release/jetstream
    name: ${{ matrix.node }} ${{ matrix.os }} ${{ matrix.script }}
    runs-on: ${{ matrix.os }}
    env:
--- a/README.md
+++ b/README.md
@@ -111,10 +111,11 @@ a double dash to prevent input files being used as option arguments:
    -d, --define <expr>[=value] Global definitions.
    -e, --enclose [arg[:value]] Embed everything in a big function, with configurable
                                argument(s) & value(s).
-    --ie8                       Support non-standard Internet Explorer 8.
-                                Equivalent to setting `ie8: true` in `minify()`
+    --ie                        Support non-standard Internet Explorer.
+                                Equivalent to setting `ie: true` in `minify()`
                                for `compress`, `mangle` and `output` options.
                                By default UglifyJS will not try to be IE-proof.
+    --keep-fargs                Do not mangle/drop function arguments.
    --keep-fnames               Do not mangle/drop function names.  Useful for
                                code relying on Function.prototype.name.
    --name-cache <file>         File to hold mangled name mappings.
@@ -502,7 +503,10 @@ if (result.error) throw result.error;
 - `compress` (default: `{}`) — pass `false` to skip compressing entirely.
  Pass an object to specify custom [compress options](#compress-options).

- `ie8` (default: `false`) — set to `true` to support IE8.
+- `ie` (default: `false`) — enable workarounds for Internet Explorer bugs.
+
+- `keep_fargs` (default: `false`) — pass `true` to prevent discarding or mangling
+  of function arguments.

 - `keep_fnames` (default: `false`) — pass `true` to prevent discarding or mangling
  of function names.  Useful for code relying on `Function.prototype.name`.
@@ -566,7 +570,6 @@ if (result.error) throw result.error;
    },
    nameCache: null, // or specify a name cache object
    toplevel: false,
-    ie8: false,
    warnings: false,
 }
 ```
@@ -708,7 +711,8 @@ to be `false` and all symbol names will be omitted.
  - `1` — inline simple functions
  - `2` — inline functions with arguments
  - `3` — inline functions with arguments and variables
-  - `true` — same as `3`
+  - `4` — inline functions with arguments, variables and statements
+  - `true` — same as `4`

 - `join_vars` (default: `true`) — join consecutive `var` statements

@@ -795,9 +799,8 @@ to be `false` and all symbol names will be omitted.
  variables (`"vars"`) in the top level scope (`false` by default, `true` to drop
  both unreferenced functions and variables)

- `typeofs` (default: `true`) — Transforms `typeof foo == "undefined"` into
-  `foo === void 0`.  Note: recommend to set this value to `false` for IE10 and
-  earlier versions due to known issues.
+- `typeofs` (default: `true`) — compress `typeof` expressions, e.g.
+  `typeof foo == "undefined" → void 0 === foo`

 - `unsafe` (default: `false`) — apply "unsafe" transformations (discussion below)

@@ -869,6 +872,9 @@ UglifyJS.minify(code, { mangle: { toplevel: true } }).code;
 - `debug` (default: `false`) — Mangle names with the original name still present.
  Pass an empty string `""` to enable, or a non-empty string to set the debug suffix.

+- `keep_fargs` (default: `false`) — Use `true` to prevent mangling of function
+  arguments.
+
 - `keep_quoted` (default: `false`) — Only mangle unquoted property names.

 - `regex` (default: `null`) — Pass a RegExp literal to only mangle property
@@ -1201,6 +1207,17 @@ To allow for better optimizations, the compiler makes various assumptions:
 - Object properties can be added, removed and modified (not prevented with
  `Object.defineProperty()`, `Object.defineProperties()`, `Object.freeze()`,
  `Object.preventExtensions()` or `Object.seal()`).
+- If array destructuring is present, index-like properties in `Array.prototype`
+  have not been overridden:
+  ```javascript
+  Object.prototype[0] = 42;
+  var [ a ] = [];
+  var { 0: b } = {};
+  // 42 undefined
+  console.log([][0], a);
+  // 42 42
+  console.log({}[0], b);
+  ```
 - Earlier versions of JavaScript will throw `SyntaxError` with the following:
  ```javascript
  ({
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -10,7 +10,9 @@ var info = require("../package.json");
 var path = require("path");
 var UglifyJS = require("../tools/node");

-var skip_keys = [ "cname", "fixed", "inlined", "parent_scope", "scope", "uses_eval", "uses_with" ];
+var skip_keys = [ "cname", "fixed", "in_arg", "inlined", "length_read", "parent_scope", "redef", "scope", "unused" ];
+var truthy_keys = [ "optional", "pure", "terminal", "uses_arguments", "uses_eval", "uses_with" ];
+
 var files = {};
 var options = {};
 var short_forms = {
@@ -70,6 +72,7 @@ function process_option(name, no_value) {
                } else {
                    if (padding.length < name.length) padding = Array(name.length + 1).join(" ");
                    toplevels.push([ {
+                        keep_fargs: "keep-fargs",
                        keep_fnames: "keep-fnames",
                        nameCache: "name-cache",
                    }[name] || name, option ]);
@@ -101,7 +104,8 @@ function process_option(name, no_value) {
                "  --config-file <file>                     Read minify() options from JSON file.",
                "  -d, --define <expr>[=value]              Global definitions.",
                "  -e, --enclose [arg[,...][:value[,...]]]  Embed everything in a big function, with configurable argument(s) & value(s).",
-                "  --ie8                                    Support non-standard Internet Explorer 8.",
+                "  --ie                                     Support non-standard Internet Explorer.",
+                "  --keep-fargs                             Do not mangle/drop function arguments.",
                "  --keep-fnames                            Do not mangle/drop function names. Useful for code relying on Function.prototype.name.",
                "  --name-cache <file>                      File to hold mangled name mappings.",
                "  --rename                                 Force symbol expansion.",
@@ -110,6 +114,7 @@ function process_option(name, no_value) {
                "  --source-map [options]                   Enable source map/specify source map options.",
                "  --timings                                Display operations run time on STDERR.",
                "  --toplevel                               Compress and/or mangle variables in toplevel scope.",
+                "  --v8                                     Support non-standard Chrome & Node.js.",
                "  --validate                               Perform validation during AST manipulations.",
                "  --verbose                                Print diagnostic messages.",
                "  --warn                                   Print warning messages.",
@@ -145,9 +150,11 @@ function process_option(name, no_value) {
        options[name] = read_value();
        break;
      case "annotations":
+      case "ie":
      case "ie8":
      case "timings":
      case "toplevel":
+      case "v8":
      case "validate":
      case "webkit":
        options[name] = true;
@@ -155,6 +162,9 @@ function process_option(name, no_value) {
      case "no-annotations":
        options.annotations = false;
        break;
+      case "keep-fargs":
+        options.keep_fargs = true;
+        break;
      case "keep-fnames":
        options.keep_fnames = true;
        break;
@@ -344,9 +354,9 @@ function run() {
                    var list = annotations[node.start.file];
                    var pure = list[node.start.pos];
                    if (!pure) {
-                        var pos = node.start.parens;
-                        if (pos) for (var i = 0; !pure && i < pos.length; i++) {
-                            pure = list[pos[i]];
+                        var tokens = node.start.parens;
+                        if (tokens) for (var i = 0; !pure && i < tokens.length; i++) {
+                            pure = list[tokens[i].pos];
                        }
                    }
                    if (pure) node.pure = pure;
@@ -427,7 +437,7 @@ function run() {
              case "thedef":
                return symdef(value);
            }
-            if (skip_key(key)) return;
+            if (skip_property(key, value)) return;
            if (value instanceof UglifyJS.AST_Token) return;
            if (value instanceof UglifyJS.Dictionary) return;
            if (value instanceof UglifyJS.AST_Node) {
@@ -516,7 +526,7 @@ function read_file(path, default_value) {
 }

 function parse_js(value, options, flag) {
-    if (!options || typeof options != "object") options = {};
+    if (!options || typeof options != "object") options = Object.create(null);
    if (typeof value == "string") try {
        UglifyJS.parse(value, {
            expression: true
@@ -556,8 +566,10 @@ function parse_js(value, options, flag) {
    return options;
 }

-function skip_key(key) {
-    return skip_keys.indexOf(key) >= 0;
+function skip_property(key, value) {
+    return skip_keys.indexOf(key) >= 0
+        // only skip truthy_keys if their value is falsy
+        || truthy_keys.indexOf(key) >= 0 && !value;
 }

 function symdef(def) {
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -50,41 +50,39 @@ function DEFNODE(type, props, methods, base) {
    if (base && base.PROPS) props = props.concat(base.PROPS);
    var code = [
        "return function AST_", type, "(props){",
+        // not essential, but speeds up compress by a few percent
+        "this._bits=0;",
        "if(props){",
    ];
    props.forEach(function(prop) {
        code.push("this.", prop, "=props.", prop, ";");
    });
    code.push("}");
-    var proto = base && new base;
-    if (proto && proto.initialize || methods && methods.initialize) code.push("this.initialize();");
-    code.push("}");
+    var proto = Object.create(base && base.prototype);
+    if (methods.initialize || proto.initialize) code.push("this.initialize();");
+    code.push("};");
    var ctor = new Function(code.join(""))();
-    if (proto) {
    ctor.prototype = proto;
-        ctor.BASE = base;
-    }
-    if (base) base.SUBCLASSES.push(ctor);
    ctor.prototype.CTOR = ctor;
-    ctor.PROPS = props || null;
-    ctor.SELF_PROPS = self_props;
-    ctor.SUBCLASSES = [];
-    if (type) {
    ctor.prototype.TYPE = ctor.TYPE = type;
-    }
-    if (methods) for (var name in methods) if (HOP(methods, name)) {
-        if (/^\$/.test(name)) {
-            ctor[name.substr(1)] = methods[name];
-        } else {
-            ctor.prototype[name] = methods[name];
-        }
+    if (base) {
+        ctor.BASE = base;
+        base.SUBCLASSES.push(ctor);
    }
    ctor.DEFMETHOD = function(name, method) {
        this.prototype[name] = method;
    };
-    if (typeof exports !== "undefined") {
-        exports["AST_" + type] = ctor;
+    ctor.PROPS = props;
+    ctor.SELF_PROPS = self_props;
+    ctor.SUBCLASSES = [];
+    for (var name in methods) if (HOP(methods, name)) {
+        if (/^\$/.test(name)) {
+            ctor[name.substr(1)] = methods[name];
+        } else {
+            ctor.DEFMETHOD(name, methods[name]);
        }
+    }
+    if (typeof exports !== "undefined") exports["AST_" + type] = ctor;
    return ctor;
 }

@@ -139,6 +137,53 @@ var AST_Node = DEFNODE("Node", "start end", {
    },
 }, null);

+DEF_BITPROPS(AST_Node, [
+    "_optimized",
+    "_squeezed",
+    // AST_Call
+    "call_only",
+    // AST_Lambda
+    "collapse_scanning",
+    // AST_SymbolRef
+    "defined",
+    "evaluating",
+    "falsy",
+    // AST_SymbolRef
+    "in_arg",
+    // AST_Return
+    "in_bool",
+    // AST_SymbolRef
+    "is_undefined",
+    // AST_LambdaExpression
+    // AST_LambdaDefinition
+    "inlined",
+    // AST_Lambda
+    "length_read",
+    // AST_Yield
+    "nested",
+    // AST_Lambda
+    "new",
+    // AST_Call
+    // AST_PropAccess
+    "optional",
+    // AST_ClassProperty
+    "private",
+    // AST_Call
+    "pure",
+    // AST_Assign
+    "redundant",
+    // AST_ClassProperty
+    "static",
+    // AST_Call
+    // AST_PropAccess
+    "terminal",
+    "truthy",
+    // AST_Scope
+    "uses_eval",
+    // AST_Scope
+    "uses_with",
+]);
+
 (AST_Node.log_function = function(fn, verbose) {
    if (typeof fn != "function") {
        AST_Node.info = AST_Node.warn = noop;
@@ -257,7 +302,7 @@ var AST_SimpleStatement = DEFNODE("SimpleStatement", "body", {
    },
 }, AST_Statement);

-var AST_BlockScope = DEFNODE("BlockScope", "enclosed functions make_def parent_scope variables", {
+var AST_BlockScope = DEFNODE("BlockScope", "_var_names enclosed functions make_def parent_scope variables", {
    $documentation: "Base class for all statements introducing a lexical scope",
    $propdoc: {
        enclosed: "[SymbolDef*/S] a list of all symbol definitions that are accessed from this scope or any subscopes",
@@ -488,7 +533,7 @@ var AST_With = DEFNODE("With", "expression", {

 /* -----[ scope and functions ]----- */

-var AST_Scope = DEFNODE("Scope", "uses_eval uses_with", {
+var AST_Scope = DEFNODE("Scope", "fn_defs may_call_this uses_eval uses_with", {
    $documentation: "Base class for all statements introducing a lexical scope",
    $propdoc: {
        uses_eval: "[boolean/S] tells whether this scope contains a direct call to the global `eval`",
@@ -547,13 +592,13 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
    }
 }, AST_Scope);

-var AST_Lambda = DEFNODE("Lambda", "argnames length_read rest uses_arguments", {
+var AST_Lambda = DEFNODE("Lambda", "argnames length_read rest safe_ids uses_arguments", {
    $documentation: "Base class for functions",
    $propdoc: {
        argnames: "[(AST_DefaultValue|AST_Destructured|AST_SymbolFunarg)*] array of function arguments and/or destructured literals",
        length_read: "[boolean/S] whether length property of this function is accessed",
        rest: "[(AST_Destructured|AST_SymbolFunarg)?] rest parameter, or null if absent",
-        uses_arguments: "[boolean/S] whether this function accesses the arguments array",
+        uses_arguments: "[boolean|number/S] whether this function accesses the arguments array",
    },
    each_argname: function(visit) {
        var tw = new TreeWalker(function(node) {
@@ -1293,13 +1338,14 @@ function must_be_expressions(node, prop, allow_spread, allow_hole) {
    });
 }

-var AST_Call = DEFNODE("Call", "args expression optional pure", {
+var AST_Call = DEFNODE("Call", "args expression optional pure terminal", {
    $documentation: "A function call expression",
    $propdoc: {
        args: "[AST_Node*] array of arguments",
        expression: "[AST_Node] expression to invoke as function",
        optional: "[boolean] whether the expression is optional chaining",
-        pure: "[string/S] marker for side-effect-free call expression",
+        pure: "[boolean/S] marker for side-effect-free call expression",
+        terminal: "[boolean] whether the chain has ended",
    },
    walk: function(visitor) {
        var node = this;
@@ -1320,6 +1366,7 @@ var AST_New = DEFNODE("New", null, {
    $documentation: "An object instantiation.  Derives from a function call since it has exactly the same properties",
    _validate: function() {
        if (this.optional) throw new Error("optional must be false");
+        if (this.terminal) throw new Error("terminal must be false");
    },
 }, AST_Call);

@@ -1342,23 +1389,23 @@ var AST_Sequence = DEFNODE("Sequence", "expressions", {
    },
 });

-var AST_PropAccess = DEFNODE("PropAccess", "expression optional property", {
+function root_expr(prop) {
+    while (prop instanceof AST_PropAccess) prop = prop.expression;
+    return prop;
+}
+
+var AST_PropAccess = DEFNODE("PropAccess", "expression optional property terminal", {
    $documentation: "Base class for property access expressions, i.e. `a.foo` or `a[\"foo\"]`",
    $propdoc: {
        expression: "[AST_Node] the “container” expression",
        optional: "[boolean] whether the expression is optional chaining",
        property: "[AST_Node|string] the property to access.  For AST_Dot this is always a plain string, while for AST_Sub it's an arbitrary AST_Node",
+        terminal: "[boolean] whether the chain has ended",
    },
-    getProperty: function() {
+    get_property: function() {
        var p = this.property;
-        if (p instanceof AST_Constant) {
-            return p.value;
-        }
-        if (p instanceof AST_UnaryPrefix
-            && p.operator == "void"
-            && p.expression instanceof AST_Constant) {
-            return;
-        }
+        if (p instanceof AST_Constant) return p.value;
+        if (p instanceof AST_UnaryPrefix && p.operator == "void" && p.expression instanceof AST_Constant) return;
        return p;
    },
    _validate: function() {
@@ -1491,6 +1538,12 @@ var AST_Assign = DEFNODE("Assign", null, {
                    throw new Error("left must be assignable: " + node.TYPE);
                }
            });
+        } else if (!(this.left instanceof AST_Infinity
+            || this.left instanceof AST_NaN
+            || this.left instanceof AST_PropAccess && !this.left.optional
+            || this.left instanceof AST_SymbolRef
+            || this.left instanceof AST_Undefined)) {
+            throw new Error("left must be assignable");
        }
    },
 }, AST_Binary);
@@ -1749,7 +1802,7 @@ var AST_SymbolVar = DEFNODE("SymbolVar", null, {
    $documentation: "Symbol defining a variable",
 }, AST_SymbolDeclaration);

-var AST_SymbolFunarg = DEFNODE("SymbolFunarg", null, {
+var AST_SymbolFunarg = DEFNODE("SymbolFunarg", "unused", {
    $documentation: "Symbol naming a function argument",
 }, AST_SymbolVar);

@@ -1763,11 +1816,11 @@ var AST_SymbolLambda = DEFNODE("SymbolLambda", null, {

 var AST_SymbolDefClass = DEFNODE("SymbolDefClass", null, {
    $documentation: "Symbol defining a class",
-}, AST_SymbolLet);
+}, AST_SymbolConst);

 var AST_SymbolClass = DEFNODE("SymbolClass", null, {
    $documentation: "Symbol naming a class expression",
-}, AST_SymbolLet);
+}, AST_SymbolConst);

 var AST_SymbolCatch = DEFNODE("SymbolCatch", null, {
    $documentation: "Symbol naming the exception in catch",
@@ -1925,27 +1978,27 @@ var AST_Atom = DEFNODE("Atom", null, {

 var AST_Null = DEFNODE("Null", null, {
    $documentation: "The `null` atom",
-    value: null
+    value: null,
 }, AST_Atom);

 var AST_NaN = DEFNODE("NaN", null, {
    $documentation: "The impossible value",
-    value: 0/0
+    value: 0/0,
 }, AST_Atom);

 var AST_Undefined = DEFNODE("Undefined", null, {
    $documentation: "The `undefined` value",
-    value: function(){}()
+    value: function(){}(),
 }, AST_Atom);

 var AST_Hole = DEFNODE("Hole", null, {
    $documentation: "A hole in an array",
-    value: function(){}()
+    value: function(){}(),
 }, AST_Atom);

 var AST_Infinity = DEFNODE("Infinity", null, {
    $documentation: "The `Infinity` value",
-    value: 1/0
+    value: 1/0,
 }, AST_Atom);

 var AST_Boolean = DEFNODE("Boolean", null, {
@@ -1957,12 +2010,12 @@ var AST_Boolean = DEFNODE("Boolean", null, {

 var AST_False = DEFNODE("False", null, {
    $documentation: "The `false` atom",
-    value: false
+    value: false,
 }, AST_Boolean);

 var AST_True = DEFNODE("True", null, {
    $documentation: "The `true` atom",
-    value: true
+    value: true,
 }, AST_Boolean);

 /* -----[ TreeWalker ]----- */
@@ -2001,7 +2054,7 @@ TreeWalker.prototype = {
    },
    find_parent: function(type) {
        var stack = this.stack;
-        for (var i = stack.length; --i >= 0;) {
+        for (var i = stack.length - 1; --i >= 0;) {
            var x = stack[i];
            if (x instanceof type) return x;
        }
--- a/lib/compress.js
+++ b/lib/compress.js
--- a/lib/minify.js
+++ b/lib/minify.js
@@ -28,7 +28,7 @@ function read_source_map(name, toplevel) {
        var match = /^# ([^\s=]+)=(\S+)\s*$/.exec(comment.value);
        if (!match) break;
        if (match[1] == "sourceMappingURL") {
-            match = /^data:application\/json(;.*?)?;base64,(\S+)$/.exec(match[2]);
+            match = /^data:application\/json(;.*?)?;base64,([^,]+)$/.exec(match[2]);
            if (!match) break;
            return to_ascii(match[2]);
        }
@@ -76,7 +76,9 @@ function minify(files, options) {
            annotations: undefined,
            compress: {},
            enclose: false,
+            ie: false,
            ie8: false,
+            keep_fargs: false,
            keep_fnames: false,
            mangle: {},
            nameCache: null,
@@ -96,17 +98,20 @@ function minify(files, options) {
        var timings = options.timings && { start: Date.now() };
        if (options.rename === undefined) options.rename = options.compress && options.mangle;
        if (options.annotations !== undefined) set_shorthand("annotations", options, [ "compress", "output" ]);
-        if (options.ie8) set_shorthand("ie8", options, [ "compress", "mangle", "output" ]);
+        if (options.ie8) options.ie = options.ie || options.ie8;
+        if (options.ie) set_shorthand("ie", options, [ "compress", "mangle", "output" ]);
+        if (options.keep_fargs) set_shorthand("keep_fargs", options, [ "compress", "mangle" ]);
        if (options.keep_fnames) set_shorthand("keep_fnames", options, [ "compress", "mangle" ]);
        if (options.toplevel) set_shorthand("toplevel", options, [ "compress", "mangle" ]);
        if (options.v8) set_shorthand("v8", options, [ "mangle", "output" ]);
-        if (options.webkit) set_shorthand("webkit", options, [ "mangle", "output" ]);
+        if (options.webkit) set_shorthand("webkit", options, [ "compress", "mangle", "output" ]);
        var quoted_props;
        if (options.mangle) {
            options.mangle = defaults(options.mangle, {
                cache: options.nameCache && (options.nameCache.vars || {}),
                eval: false,
-                ie8: false,
+                ie: false,
+                keep_fargs: false,
                keep_fnames: false,
                properties: false,
                reserved: [],
--- a/lib/mozilla-ast.js
+++ b/lib/mozilla-ast.js
@@ -556,7 +556,9 @@
            return node;
        },
        ChainExpression: function(M) {
-            return from_moz(M.expression);
+            var node = from_moz(M.expression);
+            node.terminal = true;
+            return node;
        },
    };

@@ -868,7 +870,7 @@

    def_to_moz(AST_PropAccess, function To_Moz_MemberExpression(M) {
        var computed = M instanceof AST_Sub;
-        return {
+        var expr = {
            type: "MemberExpression",
            object: to_moz(M.expression),
            computed: computed,
@@ -878,6 +880,10 @@
                name: M.property,
            },
        };
+        return M.terminal ? {
+            type: "ChainExpression",
+            expression: expr,
+        } : expr;
    });

    def_to_moz(AST_Unary, function To_Moz_Unary(M) {
@@ -999,7 +1005,7 @@
    });

    def_to_moz(AST_RegExp, function To_Moz_RegExpLiteral(M) {
-        var flags = M.value.toString().match(/[gimuy]*$/)[0];
+        var flags = M.value.toString().match(/\/([gimuy]*)$/)[1];
        var value = "/" + M.value.raw_source + "/" + flags;
        return {
            type: "Literal",
@@ -1007,8 +1013,8 @@
            raw: value,
            regex: {
                pattern: M.value.raw_source,
-                flags: flags
-            }
+                flags: flags,
+            },
        };
    });

@@ -1134,58 +1140,54 @@
    }

    function map(moztype, mytype, propmap) {
-        var moz_to_me = "function From_Moz_" + moztype + "(M){\n";
-        moz_to_me += "return new U2." + mytype.name + "({\n" +
-            "start: my_start_token(M),\n" +
-            "end: my_end_token(M)";
-
-        var me_to_moz = "function To_Moz_" + moztype + "(M){\n";
-        me_to_moz += "return {\n" +
-            "type: " + JSON.stringify(moztype);
+        var moz_to_me = [
+            "start: my_start_token(M)",
+            "end: my_end_token(M)",
+        ];
+        var me_to_moz = [
+            "type: " + JSON.stringify(moztype),
+        ];

        if (propmap) propmap.split(/\s*,\s*/).forEach(function(prop) {
            var m = /([a-z0-9$_]+)(=|@|>|%)([a-z0-9$_]+)/i.exec(prop);
            if (!m) throw new Error("Can't understand property map: " + prop);
            var moz = m[1], how = m[2], my = m[3];
-            moz_to_me += ",\n" + my + ": ";
-            me_to_moz += ",\n" + moz + ": ";
            switch (how) {
              case "@":
-                moz_to_me += "M." + moz + ".map(from_moz)";
-                me_to_moz += "M." +  my + ".map(to_moz)";
+                moz_to_me.push(my + ": M." + moz + ".map(from_moz)");
+                me_to_moz.push(moz + ": M." +  my + ".map(to_moz)");
                break;
              case ">":
-                moz_to_me += "from_moz(M." + moz + ")";
-                me_to_moz += "to_moz(M." + my + ")";
+                moz_to_me.push(my + ": from_moz(M." + moz + ")");
+                me_to_moz.push(moz + ": to_moz(M." + my + ")");
                break;
              case "=":
-                moz_to_me += "M." + moz;
-                me_to_moz += "M." + my;
+                moz_to_me.push(my + ": M." + moz);
+                me_to_moz.push(moz + ": M." + my);
                break;
              case "%":
-                moz_to_me += "from_moz(M." + moz + ").body";
-                me_to_moz += "to_moz_block(M)";
+                moz_to_me.push(my + ": from_moz(M." + moz + ").body");
+                me_to_moz.push(moz + ": to_moz_block(M)");
                break;
              default:
                throw new Error("Can't understand operator in propmap: " + prop);
            }
        });

-        moz_to_me += "\n})\n}";
-        me_to_moz += "\n}\n}";
-
-        //moz_to_me = parse(moz_to_me).print_to_string({ beautify: true });
-        //me_to_moz = parse(me_to_moz).print_to_string({ beautify: true });
-        //console.log(moz_to_me);
-
-        moz_to_me = new Function("U2", "my_start_token", "my_end_token", "from_moz", "return(" + moz_to_me + ")")(
-            exports, my_start_token, my_end_token, from_moz
-        );
-        me_to_moz = new Function("to_moz", "to_moz_block", "to_moz_scope", "return(" + me_to_moz + ")")(
-            to_moz, to_moz_block, to_moz_scope
-        );
-        MOZ_TO_ME[moztype] = moz_to_me;
-        def_to_moz(mytype, me_to_moz);
+        MOZ_TO_ME[moztype] = new Function("U2", "my_start_token", "my_end_token", "from_moz", [
+            "return function From_Moz_" + moztype + "(M) {",
+            "    return new U2.AST_" + mytype.TYPE + "({",
+            moz_to_me.join(",\n"),
+            "    });",
+            "};",
+        ].join("\n"))(exports, my_start_token, my_end_token, from_moz);
+        def_to_moz(mytype, new Function("to_moz", "to_moz_block", "to_moz_scope", [
+            "return function To_Moz_" + moztype + "(M) {",
+            "    return {",
+            me_to_moz.join(",\n"),
+            "    };",
+            "};",
+        ].join("\n"))(to_moz, to_moz_block, to_moz_scope));
    }

    var FROM_MOZ_STACK = null;
--- a/lib/output.js
+++ b/lib/output.js
@@ -56,7 +56,7 @@ function OutputStream(options) {
        braces           : false,
        comments         : false,
        galio            : false,
-        ie8              : false,
+        ie               : false,
        indent_level     : 4,
        indent_start     : 0,
        inline_script    : true,
@@ -193,7 +193,7 @@ function OutputStream(options) {
              case "\t": return "\\t";
              case "\b": return "\\b";
              case "\f": return "\\f";
-              case "\x0B": return options.ie8 ? "\\x0B" : "\\v";
+              case "\x0B": return options.ie ? "\\x0B" : "\\v";
              case "\u2028": return "\\u2028";
              case "\u2029": return "\\u2029";
              case "\ufeff": return "\\ufeff";
@@ -521,9 +521,7 @@ function OutputStream(options) {
                indent();
            }
            var preamble = options.preamble;
-            if (preamble) {
-                print(preamble.replace(/\r\n?|[\n\u2028\u2029]|\s*$/g, "\n"));
-            }
+            if (preamble) print(preamble.replace(/\r\n?|\u2028|\u2029|(^|\S)\s*$/g, "$1\n"));
        }

        comments = comments.filter(comment_filter, node);
@@ -790,35 +788,26 @@ function OutputStream(options) {
        if (p instanceof AST_Unary) return true;
    });

-    function lhs_has_optional(node, output) {
-        var p = output.parent();
-        if (p instanceof AST_PropAccess && p.expression === node && is_lhs(p, output.parent(1))) {
-            // ++(foo?.bar).baz
-            // (foo?.()).bar = baz
-            do {
-                if (node.optional) return true;
-                node = node.expression;
-            } while (node.TYPE == "Call" || node instanceof AST_PropAccess);
-        }
+    function need_chain_parens(node, parent) {
+        if (!node.terminal) return false;
+        if (!(parent instanceof AST_Call || parent instanceof AST_PropAccess)) return false;
+        return parent.expression === node;
    }

    PARENS(AST_PropAccess, function(output) {
        var node = this;
        var p = output.parent();
-        if (p instanceof AST_New) {
-            if (p.expression !== node) return false;
        // i.e. new (foo().bar)
        //
        // if there's one call into this subtree, then we need
        // parens around it too, otherwise the call will be
        // interpreted as passing the arguments to the upper New
        // expression.
-            do {
-                node = node.expression;
-            } while (node instanceof AST_PropAccess);
-            return node.TYPE == "Call";
-        }
-        return lhs_has_optional(node, output);
+        if (p instanceof AST_New && p.expression === node && root_expr(node).TYPE == "Call") return true;
+        // (foo?.bar)()
+        // (foo?.bar).baz
+        // new (foo?.bar)()
+        return need_chain_parens(node, p);
    });

    PARENS(AST_Call, function(output) {
@@ -833,7 +822,10 @@ function OutputStream(options) {
            var g = output.parent(1);
            if (g instanceof AST_Assign && g.left === p) return true;
        }
-        return lhs_has_optional(node, output);
+        // (foo?.())()
+        // (foo?.()).bar
+        // new (foo?.())()
+        return need_chain_parens(node, p);
    });

    PARENS(AST_New, function(output) {
@@ -980,7 +972,6 @@ function OutputStream(options) {
    DEFPRINT(AST_Do, function(output) {
        var self = this;
        output.print("do");
-        output.space();
        make_block(self.body, output);
        output.space();
        output.print("while");
@@ -997,7 +988,6 @@ function OutputStream(options) {
        output.with_parens(function() {
            self.condition.print(output);
        });
-        output.space();
        force_statement(self.body, output);
    });
    DEFPRINT(AST_For, function(output) {
@@ -1027,7 +1017,6 @@ function OutputStream(options) {
                self.step.print(output);
            }
        });
-        output.space();
        force_statement(self.body, output);
    });
    function print_for_enum(prefix, infix) {
@@ -1042,7 +1031,6 @@ function OutputStream(options) {
                output.space();
                self.object.print(output);
            });
-            output.space();
            force_statement(self.body, output);
        };
    }
@@ -1056,7 +1044,6 @@ function OutputStream(options) {
        output.with_parens(function() {
            self.expression.print(output);
        });
-        output.space();
        force_statement(self.body, output);
    });
    DEFPRINT(AST_ExportDeclaration, function(output) {
@@ -1163,8 +1150,9 @@ function OutputStream(options) {
        });
    }
    function print_arrow(self, output) {
-        if (self.argnames.length == 1 && self.argnames[0] instanceof AST_SymbolFunarg && !self.rest) {
-            self.argnames[0].print(output);
+        var argname = self.argnames.length == 1 && !self.rest && self.argnames[0];
+        if (argname instanceof AST_SymbolFunarg && argname.name != "yield") {
+            argname.print(output);
        } else {
            print_funargs(self, output);
        }
@@ -1295,7 +1283,7 @@ function OutputStream(options) {
    function make_then(self, output) {
        var b = self.body;
        if (output.option("braces") && !(b instanceof AST_Const || b instanceof AST_Let)
-            || output.option("ie8") && b instanceof AST_Do)
+            || output.option("ie") && b instanceof AST_Do)
            return make_block(b, output);
        // The squeezer replaces "block"-s that contain only a single
        // statement with the statement itself; technically, the AST
@@ -1325,16 +1313,16 @@ function OutputStream(options) {
        output.with_parens(function() {
            self.condition.print(output);
        });
-        output.space();
        if (self.alternative) {
            make_then(self, output);
            output.space();
            output.print("else");
+            if (self.alternative instanceof AST_If) {
                output.space();
-            if (self.alternative instanceof AST_If)
                self.alternative.print(output);
-            else
+            } else {
                force_statement(self.alternative, output);
+            }
        } else {
            force_statement(self.body, output);
        }
@@ -1475,7 +1463,7 @@ function OutputStream(options) {
            parent = output.parent(level++);
            if (parent instanceof AST_Call && parent.expression === node) return;
        } while (parent instanceof AST_PropAccess && parent.expression === node);
-        output.print(typeof self.pure == "string" ? "/*" + self.pure + "*/" : "/*@__PURE__*/");
+        output.print("/*@__PURE__*/");
    }
    function print_call_args(self, output) {
        if (self.expression instanceof AST_Call || self.expression instanceof AST_Lambda) {
@@ -1520,7 +1508,7 @@ function OutputStream(options) {
        var expr = self.expression;
        expr.print(output);
        var prop = self.property;
-        if (output.option("ie8") && RESERVED_WORDS[prop]) {
+        if (output.option("ie") && RESERVED_WORDS[prop]) {
            output.print(self.optional ? "?.[" : "[");
            output.add_mapping(self.end);
            output.print_string(prop);
@@ -1634,7 +1622,19 @@ function OutputStream(options) {
        var self = this;
        var key = print_property_key(self, output);
        var value = self.value;
-        if (key && value instanceof AST_SymbolDeclaration && key == get_symbol_name(value)) return;
+        if (key) {
+            if (value instanceof AST_DefaultValue) {
+                if (value.name instanceof AST_Symbol && key == get_symbol_name(value.name)) {
+                    output.space();
+                    output.print("=");
+                    output.space();
+                    value.value.print(output);
+                    return;
+                }
+            } else if (value instanceof AST_Symbol) {
+                if (key == get_symbol_name(value)) return;
+            }
+        }
        output.colon();
        value.print(output);
    });
@@ -1683,30 +1683,23 @@ function OutputStream(options) {

    function print_property_key(self, output) {
        var key = self.key;
-        if (key instanceof AST_Node) {
-            output.with_square(function() {
+        if (key instanceof AST_Node) return output.with_square(function() {
            key.print(output);
        });
-        } else if (output.option("quote_keys")) {
-            output.print_string(key);
+        var quote = self.start && self.start.quote;
+        if (output.option("quote_keys") || quote && output.option("keep_quoted_props")) {
+            output.print_string(key, quote);
        } else if ("" + +key == key && key >= 0) {
            output.print(make_num(key));
-        } else {
-            var quote = self.start && self.start.quote;
-            if (self.private) {
+        } else if (self.private) {
            output.print_name(key);
-            } else if (RESERVED_WORDS[key] ? !output.option("ie8") : is_identifier_string(key)) {
-                if (quote && output.option("keep_quoted_props")) {
-                    output.print_string(key, quote);
-                } else {
+        } else if (RESERVED_WORDS[key] ? !output.option("ie") : is_identifier_string(key)) {
            output.print_name(key);
            return key;
-                }
        } else {
            output.print_string(key, quote);
        }
    }
-    }
    DEFPRINT(AST_ObjectKeyVal, function(output) {
        var self = this;
        print_property_key(self, output);
@@ -1836,6 +1829,7 @@ function OutputStream(options) {
        } else if (stat instanceof AST_EmptyStatement) {
            output.force_semicolon();
        } else {
+            output.space();
            stat.print(output);
        }
    }
@@ -1874,8 +1868,8 @@ function OutputStream(options) {
            len = match[0].length;
            digits = str.slice(len);
            candidates.push(digits + "e-" + (digits.length + len - 1));
-        } else if (match = /0+$/.exec(str)) {
-            len = match[0].length;
+        } else if (match = /[^0]0+$/.exec(str)) {
+            len = match[0].length - 1;
            candidates.push(str.slice(0, -len) + "e" + len);
        } else if (match = /^(\d)\.(\d+)e(-?\d+)$/.exec(str)) {
            candidates.push(match[1] + match[2] + "e" + (match[3] - match[2].length));
@@ -1884,6 +1878,7 @@ function OutputStream(options) {
    }

    function make_block(stmt, output) {
+        output.space();
        if (stmt instanceof AST_EmptyStatement) {
            print_braced_empty(stmt, output);
        } else if (stmt instanceof AST_BlockStatement) {
--- a/lib/parse.js
+++ b/lib/parse.js
@@ -44,10 +44,10 @@

 "use strict";

-var KEYWORDS = "break case catch class const continue debugger default delete do else extends finally for function if in instanceof let new return switch throw try typeof var void while with";
+var KEYWORDS = "break case catch class const continue debugger default delete do else extends finally for function if in instanceof new return switch throw try typeof var void while with";
 var KEYWORDS_ATOM = "false null true";
 var RESERVED_WORDS = [
-    "abstract async await boolean byte char double enum export final float goto implements import int interface long native package private protected public short static super synchronized this throws transient volatile yield",
+    "abstract async await boolean byte char double enum export final float goto implements import int interface let long native package private protected public short static super synchronized this throws transient volatile yield",
    KEYWORDS_ATOM,
    KEYWORDS,
 ].join(" ");
@@ -242,10 +242,10 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
        read_template   : with_eof_error("Unterminated template literal", function(strings) {
            var s = "";
            for (;;) {
-                var ch = next(true, true);
+                var ch = read();
                switch (ch) {
                  case "\\":
-                    ch += next(true, true);
+                    ch += read();
                    break;
                  case "`":
                    strings.push(s);
@@ -260,6 +260,11 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
                }
                s += ch;
            }
+
+            function read() {
+                var ch = next(true, true);
+                return ch == "\r" ? "\n" : ch;
+            }
        }),
    };
    var prev_was_dot = false;
@@ -862,6 +867,15 @@ function parse($TEXT, options) {
                    next();
                    return import_();
                }
+                break;
+              case "let":
+                if (is_vardefs()) {
+                    next();
+                    var node = let_();
+                    semicolon();
+                    return node;
+                }
+                break;
              case "yield":
                if (S.in_generator) return simple_statement();
                break;
@@ -947,12 +961,6 @@ function parse($TEXT, options) {
                next();
                return if_();

-              case "let":
-                next();
-                var node = let_();
-                semicolon();
-                return node;
-
              case "return":
                if (S.in_function == 0 && !options.bare_returns)
                    croak("'return' outside of function");
@@ -1192,7 +1200,7 @@ function parse($TEXT, options) {
        if (await || !is("punc", ";")) {
            init = is("keyword", "const")
                ? (next(), const_(true))
-                : is("keyword", "let")
+                : is("name", "let") && is_vardefs()
                ? (next(), let_(true))
                : is("keyword", "var")
                ? (next(), var_(true))
@@ -1308,6 +1316,11 @@ function parse($TEXT, options) {
        }
        if (node instanceof AST_SymbolFunarg) return node;
        if (node instanceof AST_SymbolRef) return new AST_SymbolFunarg(node);
+        if (node instanceof AST_Yield) return new AST_SymbolFunarg({
+            start: node.start,
+            name: "yield",
+            end: node.end,
+        });
        token_error(node.start, "Invalid arrow parameter");
    }

@@ -1334,21 +1347,19 @@ function parse($TEXT, options) {
        if (is("punc", "{")) {
            body = block_();
            value = null;
-            if (S.input.has_directive("use strict")) {
-                argnames.forEach(strict_verify_symbol);
-            }
        } else {
            body = [];
            handle_regexp();
            value = maybe_assign();
        }
+        var is_strict = S.input.has_directive("use strict");
        S.input.pop_directives_stack();
        --S.in_function;
        S.in_loop = loop;
        S.labels = labels;
        S.in_generator = was_gen;
        S.in_async = was_async;
-        return new (async ? AST_AsyncArrow : AST_Arrow)({
+        var node = new (async ? AST_AsyncArrow : AST_Arrow)({
            start: start,
            argnames: argnames,
            rest: rest,
@@ -1356,6 +1367,8 @@ function parse($TEXT, options) {
            value: value,
            end: prev(),
        });
+        if (is_strict) node.each_argname(strict_verify_symbol);
+        return node;
    }

    var function_ = function(ctor) {
@@ -1388,23 +1401,24 @@ function parse($TEXT, options) {
        S.in_loop = 0;
        S.labels = [];
        var body = block_();
-        if (S.input.has_directive("use strict")) {
-            if (name) strict_verify_symbol(name);
-            argnames.forEach(strict_verify_symbol);
-            if (argnames.rest) strict_verify_symbol(argnames.rest);
-        }
+        var is_strict = S.input.has_directive("use strict");
        S.input.pop_directives_stack();
        --S.in_function;
        S.in_loop = loop;
        S.labels = labels;
        S.in_generator = was_gen;
        S.in_async = was_async;
-        return new ctor({
+        var node = new ctor({
            name: name,
            argnames: argnames,
            rest: argnames.rest || null,
            body: body
        });
+        if (is_strict) {
+            if (name) strict_verify_symbol(name);
+            node.each_argname(strict_verify_symbol);
+        }
+        return node;
    };

    function if_() {
@@ -1534,12 +1548,18 @@ function parse($TEXT, options) {
    }

    var export_decl = embed_tokens(function() {
-        if (is("name", "async")) {
+        if (is("name")) switch (S.token.value) {
+          case "async":
            next();
            expect_token("keyword", "function");
            if (!is("operator", "*")) return function_(AST_AsyncDefun);
            next();
            return function_(AST_AsyncGeneratorDefun);
+          case "let":
+            next();
+            var node = let_();
+            semicolon();
+            return node;
        } else if (is("keyword")) switch (S.token.value) {
          case "class":
            next();
@@ -1554,11 +1574,6 @@ function parse($TEXT, options) {
            if (!is("operator", "*")) return function_(AST_Defun);
            next();
            return function_(AST_GeneratorDefun);
-          case "let":
-            next();
-            var node = let_();
-            semicolon();
-            return node;
          case "var":
            next();
            var node = var_();
@@ -1719,6 +1734,11 @@ function parse($TEXT, options) {
        return a;
    }

+    function is_vardefs() {
+        var token = peek();
+        return is_token(token, "name") || is_token(token, "punc", "[") || is_token(token, "punc", "{");
+    }
+
    var const_ = function(no_in) {
        return new AST_Const({
            start       : prev(),
@@ -1817,10 +1837,7 @@ function parse($TEXT, options) {
        if (is("punc")) {
            switch (start.value) {
              case "`":
-                var tmpl = template(null);
-                tmpl.start = start;
-                tmpl.end = prev();
-                return subscripts(tmpl, allow_calls);
+                return subscripts(template(null), allow_calls);
              case "(":
                next();
                if (is("punc", ")")) {
@@ -2132,7 +2149,7 @@ function parse($TEXT, options) {
    }

    function strict_verify_symbol(sym) {
-        if (sym.name == "arguments" || sym.name == "eval")
+        if (sym.name == "arguments" || sym.name == "eval" || sym.name == "let")
            token_error(sym.start, "Unexpected " + sym.name + " in strict mode");
    }

@@ -2229,6 +2246,7 @@ function parse($TEXT, options) {
    }

    function template(tag) {
+        var start = tag ? tag.start : S.token;
        var read = S.input.context().read_template;
        var strings = [];
        var expressions = [];
@@ -2239,72 +2257,73 @@ function parse($TEXT, options) {
        }
        next();
        return new AST_Template({
+            start: start,
            expressions: expressions,
            strings: strings,
            tag: tag,
+            end: prev(),
        });
    }

-    var subscripts = function(expr, allow_calls, optional) {
+    function subscripts(expr, allow_calls) {
        var start = expr.start;
+        var optional = null;
+        while (true) {
+            if (is("operator", "?") && is_token(peek(), "punc", ".")) {
+                next();
+                next();
+                optional = expr;
+            }
            if (is("punc", "[")) {
                next();
                var prop = expression();
                expect("]");
-            return subscripts(new AST_Sub({
+                expr = new AST_Sub({
                    start: start,
-                optional: optional,
+                    optional: optional === expr,
                    expression: expr,
                    property: prop,
                    end: prev(),
-            }), allow_calls);
-        }
-        if (allow_calls && is("punc", "(")) {
+                });
+            } else if (allow_calls && is("punc", "(")) {
                next();
-            var call = new AST_Call({
+                expr = new AST_Call({
                    start: start,
-                optional: optional,
+                    optional: optional === expr,
                    expression: expr,
                    args: expr_list(")", !options.strict),
                    end: prev(),
                });
-            return subscripts(call, true);
-        }
-        if (optional || is("punc", ".")) {
-            if (!optional) next();
-            return subscripts(new AST_Dot({
+            } else if (optional === expr || is("punc", ".")) {
+                if (optional !== expr) next();
+                expr = new AST_Dot({
                    start: start,
-                optional: optional,
+                    optional: optional === expr,
                    expression: expr,
                    property: as_name(),
                    end: prev(),
-            }), allow_calls);
+                });
+            } else if (is("punc", "`")) {
+                if (optional) croak("Invalid template on optional chain");
+                expr = template(expr);
+            } else {
+                break;
            }
-        if (is("punc", "`")) {
-            var tmpl = template(expr);
-            tmpl.start = expr.start;
-            tmpl.end = prev();
-            return subscripts(tmpl, allow_calls);
-        }
-        if (is("operator", "?") && is_token(peek(), "punc", ".")) {
-            next();
-            next();
-            return subscripts(expr, allow_calls, true);
        }
+        if (optional) expr.terminal = true;
        if (expr instanceof AST_Call && !expr.pure) {
            var start = expr.start;
            var comments = start.comments_before;
            var i = HOP(start, "comments_before_length") ? start.comments_before_length : comments.length;
            while (--i >= 0) {
-                var match = /[@#]__PURE__/.exec(comments[i].value);
-                if (match) {
-                    expr.pure = match[0];
+                if (/[@#]__PURE__/.test(comments[i].value)) {
+                    expr.pure = true;
                    break;
                }
            }
        }
        return expr;
-    };
+    }

    function maybe_unary(no_in) {
        var start = S.token;
--- a/lib/propmangle.js
+++ b/lib/propmangle.js
@@ -44,7 +44,7 @@
 "use strict";

 var builtins = function() {
-    var names = [];
+    var names = new Dictionary();
    // NaN will be included due to Number.NaN
    [
        "null",
@@ -72,10 +72,10 @@ var builtins = function() {
            Object.getOwnPropertyNames(ctor.prototype).map(add);
        }
    });
-    return makePredicate(names);
+    return names;

    function add(name) {
-        names.push(name);
+        names.set(name, true);
    }
 }();

@@ -116,9 +116,9 @@ function mangle_properties(ast, options) {
        reserved: null,
    }, true);

-    var reserved = Object.create(options.builtins ? null : builtins);
+    var reserved = options.builtins ? new Dictionary() : builtins.clone();
    if (Array.isArray(options.reserved)) options.reserved.forEach(function(name) {
-        reserved[name] = true;
+        reserved.set(name, true);
    });

    var cname = -1;
@@ -126,7 +126,7 @@ function mangle_properties(ast, options) {
    if (options.cache) {
        cache = options.cache.props;
        cache.each(function(name) {
-            reserved[name] = true;
+            reserved.set(name, true);
        });
    } else {
        cache = new Dictionary();
@@ -141,8 +141,8 @@ function mangle_properties(ast, options) {
    var debug_suffix;
    if (debug) debug_suffix = options.debug === true ? "" : options.debug;

-    var names_to_mangle = Object.create(null);
-    var unmangleable = Object.create(reserved);
+    var names_to_mangle = new Dictionary();
+    var unmangleable = reserved.clone();

    // step 1: find candidates to mangle
    ast.walk(new TreeWalker(function(node) {
@@ -211,20 +211,20 @@ function mangle_properties(ast, options) {
    // only function declarations after this line

    function can_mangle(name) {
-        if (unmangleable[name]) return false;
+        if (unmangleable.has(name)) return false;
        if (/^-?[0-9]+(\.[0-9]+)?(e[+-][0-9]+)?$/.test(name)) return false;
        return true;
    }

    function should_mangle(name) {
-        if (reserved[name]) return false;
+        if (reserved.has(name)) return false;
        if (regex && !regex.test(name)) return false;
-        return cache.has(name) || names_to_mangle[name];
+        return cache.has(name) || names_to_mangle.has(name);
    }

    function add(name) {
-        if (can_mangle(name)) names_to_mangle[name] = true;
-        if (!should_mangle(name)) unmangleable[name] = true;
+        if (can_mangle(name)) names_to_mangle.set(name, true);
+        if (!should_mangle(name)) unmangleable.set(name, true);
    }

    function mangle(name) {
--- a/lib/scope.js
+++ b/lib/scope.js
@@ -44,9 +44,9 @@
 "use strict";

 function SymbolDef(id, scope, orig, init) {
+    this._bits = 0;
+    this.defun = undefined;
    this.eliminated = 0;
-    this.exported = false;
-    this.global = false;
    this.id = id;
    this.init = init;
    this.mangled_name = null;
@@ -54,8 +54,8 @@ function SymbolDef(id, scope, orig, init) {
    this.orig = [ orig ];
    this.references = [];
    this.replaced = 0;
+    this.safe_ids = undefined;
    this.scope = scope;
-    this.undeclared = false;
 }

 SymbolDef.prototype = {
@@ -92,18 +92,35 @@ SymbolDef.prototype = {
        if (def && def !== self) return def.redefined() || def;
    },
    unmangleable: function(options) {
-        return this.global && !options.toplevel
-            || this.exported
-            || this.undeclared
-            || !options.eval && this.scope.pinned()
-            || options.keep_fnames
-                && (this.orig[0] instanceof AST_SymbolClass
-                    || this.orig[0] instanceof AST_SymbolDefClass
-                    || this.orig[0] instanceof AST_SymbolDefun
-                    || this.orig[0] instanceof AST_SymbolLambda);
+        if (this.exported) return true;
+        if (this.undeclared) return true;
+        if (!options.eval && this.scope.pinned()) return true;
+        if (options.keep_fargs && is_funarg(this)) return true;
+        if (options.keep_fnames) {
+            var sym = this.orig[0];
+            if (sym instanceof AST_SymbolClass) return true;
+            if (sym instanceof AST_SymbolDefClass) return true;
+            if (sym instanceof AST_SymbolDefun) return true;
+            if (sym instanceof AST_SymbolLambda) return true;
+        }
+        if (!options.toplevel && this.global) return true;
+        return false;
    },
 };

+DEF_BITPROPS(SymbolDef, [
+    "const_redefs",
+    "cross_loop",
+    "direct_access",
+    "exported",
+    "global",
+    "undeclared",
+]);
+
+function is_funarg(def) {
+    return def.orig[0] instanceof AST_SymbolFunarg || def.orig[1] instanceof AST_SymbolFunarg;
+}
+
 var unary_side_effects = makePredicate("delete ++ --");

 function is_lhs(node, parent) {
@@ -118,7 +135,7 @@ function is_lhs(node, parent) {
 AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
    options = defaults(options, {
        cache: null,
-        ie8: false,
+        ie: false,
    });

    // pass 1: setup scope chaining and handle definitions
@@ -205,20 +222,17 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
        } else if (node instanceof AST_SymbolDefun) {
            var def = defun.def_function(node, tw.parent());
            if (exported) def.exported = true;
-            entangle(defun, scope);
        } else if (node instanceof AST_SymbolFunarg) {
            defun.def_variable(node);
-            entangle(defun, scope);
        } else if (node instanceof AST_SymbolLambda) {
            var def = defun.def_function(node, node.name == "arguments" ? undefined : defun);
-            if (options.ie8) def.defun = defun.parent_scope.resolve();
+            if (options.ie) def.defun = defun.parent_scope.resolve();
        } else if (node instanceof AST_SymbolLet) {
            var def = scope.def_variable(node);
            if (exported) def.exported = true;
        } else if (node instanceof AST_SymbolVar) {
            var def = defun.def_variable(node, node instanceof AST_SymbolImport ? undefined : null);
            if (exported) def.exported = true;
-            entangle(defun, scope);
        }

        function walk_scope(descend) {
@@ -231,16 +245,6 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
            scope = save_scope;
            defun = save_defun;
        }
-
-        function entangle(defun, scope) {
-            if (defun === scope) return;
-            node.mark_enclosed(options);
-            var def = scope.find_variable(node.name);
-            if (node.thedef === def) return;
-            node.thedef = def;
-            def.orig.push(node);
-            node.mark_enclosed(options);
-        }
    });
    self.make_def = function(orig, init) {
        return new SymbolDef(++next_def_id, this, orig, init);
@@ -261,6 +265,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
        }
        if (node instanceof AST_Lambda) {
            in_arg.push(node);
+            if (node.name) node.name.walk(tw);
            node.argnames.forEach(function(argname) {
                argname.walk(tw);
            });
@@ -287,6 +292,16 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
                // ensure compression works if `const` reuses a scope variable
                var redef = def.redefined();
                if (redef) redef.const_redefs = true;
+            } else if (def.scope !== node.scope && (node instanceof AST_SymbolDefun
+                || node instanceof AST_SymbolFunarg
+                || node instanceof AST_SymbolVar)) {
+                node.mark_enclosed(options);
+                var redef = node.scope.find_variable(node.name);
+                if (node.thedef !== redef) {
+                    node.thedef = redef;
+                    redef.orig.push(node);
+                    node.mark_enclosed(options);
+                }
            }
            if (node.name != "arguments") return true;
            var parent = node instanceof AST_SymbolVar && tw.parent();
@@ -351,7 +366,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
    self.walk(tw);

    // pass 3: fix up any scoping issue with IE8
-    if (options.ie8) self.walk(new TreeWalker(function(node) {
+    if (options.ie) self.walk(new TreeWalker(function(node) {
        if (node instanceof AST_SymbolCatch) {
            var scope = node.thedef.defun;
            if (scope.name instanceof AST_SymbolLambda && scope.name.name == node.name) {
@@ -363,7 +378,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
        if (node instanceof AST_SymbolLambda) {
            var def = node.thedef;
            if (!redefine(node, node.scope.parent_scope.resolve())) {
-                delete def.defun;
+                def.defun = undefined;
            } else if (typeof node.thedef.init !== "undefined") {
                node.thedef.init = false;
            } else if (def.init) {
@@ -465,9 +480,12 @@ AST_Symbol.DEFMETHOD("mark_enclosed", function(options) {
    for (var s = this.scope; s; s = s.parent_scope) {
        push_uniq(s.enclosed, def);
        if (!options) {
-            delete s._var_names;
-        } else if (options.keep_fnames) {
-            s.functions.each(function(d) {
+            s._var_names = undefined;
+        } else {
+            if (options.keep_fargs && s instanceof AST_Lambda) s.each_argname(function(arg) {
+                push_uniq(def.scope.enclosed, arg.definition());
+            });
+            if (options.keep_fnames) s.functions.each(function(d) {
                push_uniq(def.scope.enclosed, d);
            });
        }
@@ -510,12 +528,12 @@ function names_in_use(scope, options) {
    if (!names) {
        scope.cname = -1;
        scope.cname_holes = [];
-        scope.names_in_use = names = Object.create(null);
+        scope.names_in_use = names = new Dictionary();
        var cache = options.cache && options.cache.props;
        scope.enclosed.forEach(function(def) {
-            if (def.unmangleable(options)) names[def.name] = true;
+            if (def.unmangleable(options)) names.set(def.name, true);
            if (def.global && cache && cache.has(def.name)) {
-                names[cache.get(def.name)] = true;
+                names.set(cache.get(def.name), true);
            }
        });
    }
@@ -526,34 +544,33 @@ function next_mangled_name(def, options) {
    var scope = def.scope;
    var in_use = names_in_use(scope, options);
    var holes = scope.cname_holes;
-    var names = Object.create(null);
+    var names = new Dictionary();
    var scopes = [ scope ];
    def.forEach(function(sym) {
        var scope = sym.scope;
        do {
-            if (scopes.indexOf(scope) < 0) {
-                for (var name in names_in_use(scope, options)) {
-                    names[name] = true;
-                }
+            if (member(scope, scopes)) break;
+            names_in_use(scope, options).each(function(marker, name) {
+                names.set(name, marker);
+            });
            scopes.push(scope);
-            } else break;
        } while (scope = scope.parent_scope);
    });
    var name;
    for (var i = 0; i < holes.length; i++) {
        name = base54(holes[i]);
-        if (names[name]) continue;
+        if (names.has(name)) continue;
        holes.splice(i, 1);
-        in_use[name] = true;
+        in_use.set(name, true);
        return name;
    }
    while (true) {
        name = base54(++scope.cname);
-        if (in_use[name] || RESERVED_WORDS[name] || options.reserved.has[name]) continue;
-        if (!names[name]) break;
+        if (in_use.has(name) || RESERVED_WORDS[name] || options.reserved.has[name]) continue;
+        if (!names.has(name)) break;
        holes.push(scope.cname);
    }
-    in_use[name] = true;
+    in_use.set(name, true);
    return name;
 }

@@ -572,7 +589,8 @@ AST_Symbol.DEFMETHOD("definition", function() {
 function _default_mangler_options(options) {
    options = defaults(options, {
        eval        : false,
-        ie8         : false,
+        ie          : false,
+        keep_fargs  : false,
        keep_fnames : false,
        reserved    : [],
        toplevel    : false,
@@ -580,32 +598,30 @@ function _default_mangler_options(options) {
        webkit      : false,
    });
    if (!Array.isArray(options.reserved)) options.reserved = [];
-    // Never mangle arguments
+    // Never mangle `arguments`
    push_uniq(options.reserved, "arguments");
    options.reserved.has = makePredicate(options.reserved);
    return options;
 }

+// We only need to mangle declaration nodes. Special logic wired into the code
+// generator will display the mangled name if it is present (and for
+// `AST_SymbolRef`s it will use the mangled name of the `AST_SymbolDeclaration`
+// that it points to).
 AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
    options = _default_mangler_options(options);
-
-    // We only need to mangle declaration nodes.  Special logic wired
-    // into the code generator will display the mangled name if it's
-    // present (and for AST_SymbolRef-s it'll use the mangled name of
-    // the AST_SymbolDeclaration that it points to).
-    var lname = -1;
-
    if (options.cache && options.cache.props) {
        var mangled_names = names_in_use(this, options);
        options.cache.props.each(function(mangled_name) {
-            mangled_names[mangled_name] = true;
+            mangled_names.set(mangled_name, true);
        });
    }
-
+    var cutoff = 10;
+    var lname = -1;
    var redefined = [];
    var tw = new TreeWalker(function(node, descend) {
        if (node instanceof AST_LabeledStatement) {
-            // lname is incremented when we get to the AST_Label
+            // `lname` is incremented when we get to the `AST_Label`
            var save_nesting = lname;
            descend();
            if (!options.v8 || !in_label(tw)) lname = save_nesting;
@@ -627,9 +643,9 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
                    });
                }, true);
            }
-            node.to_mangle = [];
+            var to_mangle = node.to_mangle = [];
            node.variables.each(function(def) {
-                if (!defer_redef(def)) node.to_mangle.push(def);
+                if (!defer_redef(def)) to_mangle.push(def);
            });
            descend();
            if (options.cache && node instanceof AST_Toplevel) {
@@ -640,7 +656,23 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
                sym.scope = node;
                sym.reference(options);
            }
-            node.to_mangle.forEach(mangle);
+            if (to_mangle.length > cutoff) {
+                var indices = to_mangle.map(function(def, index) {
+                    return index;
+                }).sort(function(i, j) {
+                    return to_mangle[j].references.length - to_mangle[i].references.length || i - j;
+                });
+                to_mangle = indices.slice(0, cutoff).sort(function(i, j) {
+                    return i - j;
+                }).map(function(index) {
+                    return to_mangle[index];
+                }).concat(indices.slice(cutoff).sort(function(i, j) {
+                    return i - j;
+                }).map(function(index) {
+                    return to_mangle[index];
+                }));
+            }
+            to_mangle.forEach(mangle);
            return true;
        }
        if (node instanceof AST_Label) {
--- a/lib/sourcemap.js
+++ b/lib/sourcemap.js
@@ -77,21 +77,23 @@ function vlq_encode(num) {
 }

 function create_array_map() {
-    var map = Object.create(null);
+    var map = new Dictionary();
    var array = [];
    array.index = function(name) {
-        if (!HOP(map, name)) {
-            map[name] = array.length;
+        var index = map.get(name);
+        if (!(index >= 0)) {
+            index = array.length;
            array.push(name);
+            map.set(name, index);
        }
-        return map[name];
+        return index;
    };
    return array;
 }

 function SourceMap(options) {
    var sources = create_array_map();
-    var sources_content = options.includeSources && Object.create(null);
+    var sources_content = options.includeSources && new Dictionary();
    var names = create_array_map();
    var mappings = "";
    if (options.orig) Object.keys(options.orig).forEach(function(name) {
@@ -110,7 +112,7 @@ function SourceMap(options) {
        if (!sources_content || !map.sourcesContent) return;
        for (var i = 0; i < map.sources.length; i++) {
            var content = map.sourcesContent[i];
-            if (content) sources_content[map.sources[i]] = content;
+            if (content) sources_content.set(map.sources[i], content);
        }
    });
    var prev_source;
@@ -144,8 +146,8 @@ function SourceMap(options) {
            add(source, gen_line, gen_col, orig_line, orig_col, name);
        } : add,
        setSourceContent: sources_content ? function(source, content) {
-            if (!(source in sources_content)) {
-                sources_content[source] = content;
+            if (!sources_content.has(source)) {
+                sources_content.set(source, content);
            }
        } : noop,
        toString: function() {
@@ -155,7 +157,7 @@ function SourceMap(options) {
                sourceRoot: options.root || undefined,
                sources: sources,
                sourcesContent: sources_content ? sources.map(function(source) {
-                    return sources_content[source] || null;
+                    return sources_content.get(source) || null;
                }) : undefined,
                names: names,
                mappings: mappings,
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -96,15 +96,6 @@ function defaults(args, defs, croak) {
    return defs;
 }

-function merge(obj, ext) {
-    var count = 0;
-    for (var i in ext) if (HOP(ext, i)) {
-        obj[i] = ext[i];
-        count++;
-    }
-    return count;
-}
-
 function noop() {}
 function return_false() { return false; }
 function return_true() { return true; }
@@ -143,7 +134,7 @@ function push_uniq(array, el) {
 }

 function string_template(text, props) {
-    return text.replace(/\{([^}]+)\}/g, function(str, p) {
+    return text.replace(/\{([^{}]+)\}/g, function(str, p) {
        var value = props[p];
        return value instanceof AST_Node ? value.print_to_string() : value;
    });
@@ -171,63 +162,80 @@ function all(array, predicate) {
 }

 function Dictionary() {
-    this._values = Object.create(null);
-    this._size = 0;
+    this.values = Object.create(null);
 }
 Dictionary.prototype = {
    set: function(key, val) {
-        if (!this.has(key)) ++this._size;
-        this._values["$" + key] = val;
+        if (key == "__proto__") {
+            this.proto_value = val;
+        } else {
+            this.values[key] = val;
+        }
        return this;
    },
    add: function(key, val) {
-        if (this.has(key)) {
-            this.get(key).push(val);
+        var list = this.get(key);
+        if (list) {
+            list.push(val);
        } else {
            this.set(key, [ val ]);
        }
        return this;
    },
-    get: function(key) { return this._values["$" + key] },
+    get: function(key) {
+        return key == "__proto__" ? this.proto_value : this.values[key];
+    },
    del: function(key) {
-        if (this.has(key)) {
-            --this._size;
-            delete this._values["$" + key];
+        if (key == "__proto__") {
+            delete this.proto_value;
+        } else {
+            delete this.values[key];
        }
        return this;
    },
-    has: function(key) { return ("$" + key) in this._values },
+    has: function(key) {
+        return key == "__proto__" ? "proto_value" in this : key in this.values;
+    },
    all: function(predicate) {
-        for (var i in this._values)
-            if (!predicate(this._values[i], i.substr(1)))
-                return false;
+        for (var i in this.values)
+            if (!predicate(this.values[i], i)) return false;
+        if ("proto_value" in this && !predicate(this.proto_value, "__proto__")) return false;
        return true;
    },
    each: function(f) {
-        for (var i in this._values)
-            f(this._values[i], i.substr(1));
+        for (var i in this.values)
+            f(this.values[i], i);
+        if ("proto_value" in this) f(this.proto_value, "__proto__");
    },
    size: function() {
-        return this._size;
+        return Object.keys(this.values).length + ("proto_value" in this);
    },
    map: function(f) {
        var ret = [];
-        for (var i in this._values)
-            ret.push(f(this._values[i], i.substr(1)));
+        for (var i in this.values)
+            ret.push(f(this.values[i], i));
+        if ("proto_value" in this) ret.push(f(this.proto_value, "__proto__"));
        return ret;
    },
    clone: function() {
        var ret = new Dictionary();
-        for (var i in this._values)
-            ret._values[i] = this._values[i];
-        ret._size = this._size;
+        this.each(function(value, i) {
+            ret.set(i, value);
+        });
        return ret;
    },
-    toObject: function() { return this._values }
+    toObject: function() {
+        var obj = {};
+        this.each(function(value, i) {
+            obj["$" + i] = value;
+        });
+        return obj;
+    },
 };
 Dictionary.fromObject = function(obj) {
    var dict = new Dictionary();
-    dict._size = merge(dict._values, obj);
+    for (var i in obj)
+        if (HOP(obj, i)) dict.set(i.slice(1), obj[i]);
    return dict;
 };

@@ -265,3 +273,21 @@ function first_in_statement(stack, arrow, export_default) {
        return false;
    }
 }
+
+function DEF_BITPROPS(ctor, props) {
+    if (props.length > 31) throw new Error("Too many properties: " + props.length + "\n" + props.join(", "));
+    props.forEach(function(name, pos) {
+        var mask = 1 << pos;
+        Object.defineProperty(ctor.prototype, name, {
+            get: function() {
+                return !!(this._bits & mask);
+            },
+            set: function(val) {
+                if (val)
+                    this._bits |= mask;
+                else
+                    this._bits &= ~mask;
+            },
+        });
+    });
+}
--- a/package.json
+++ b/package.json
@@ -3,7 +3,7 @@
  "description": "JavaScript parser, mangler/compressor and beautifier toolkit",
  "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
  "license": "BSD-2-Clause",
-  "version": "3.13.9",
+  "version": "3.15.0",
  "engines": {
    "node": ">=0.8.0"
  },
--- a/test/benchmark.js
+++ b/test/benchmark.js
@@ -16,7 +16,7 @@ var urls = [
    "https://code.angularjs.org/1.7.8/angular.js",
    "https://unpkg.com/mathjs@6.2.3/dist/math.js",
    "https://unpkg.com/react@15.3.2/dist/react.js",
-    "https://cdnjs.cloudflare.com/ajax/libs/d3/5.12.0/d3.js",
+    "https://cdnjs.cloudflare.com/ajax/libs/d3/6.7.0/d3.js",
    "https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.js",
    "https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js",
    "https://cdnjs.cloudflare.com/ajax/libs/ember.js/2.12.2/ember.prod.js",
--- a/test/compress/annotations.js
+++ b/test/compress/annotations.js
@@ -442,9 +442,9 @@ compress_annotations_disabled_output_annotations_enabled: {
    }
    expect_exact: [
        "/*@__PURE__*/a(3),",
-        "/*#__PURE__*/b(5),",
+        "/*@__PURE__*/b(5),",
        "c(side_effect),",
-        "/*#__PURE__*/d(effect());",
+        "/*@__PURE__*/d(effect());",
    ]
 }

--- a/test/compress/arrows.js
+++ b/test/compress/arrows.js
@@ -363,6 +363,28 @@ negate: {
 }

 inline_this: {
+    options = {
+        inline: true,
+    }
+    input: {
+        var p = "PASS";
+        console.log({
+            p: "FAIL",
+            q: (() => this.p)(),
+        }.q);
+    }
+    expect: {
+        var p = "PASS";
+        console.log({
+            p: "FAIL",
+            q: this.p,
+        }.q);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+dont_inline_this: {
    options = {
        inline: true,
    }
@@ -486,7 +508,7 @@ drop_value: {
        ((a, b) => a + b)(console.log(42));
    }
    expect: {
-        ((a, b) => {})(console.log(42));
+        void console.log(42);
    }
    expect_stdout: "42"
    node_version: ">=4"
@@ -556,6 +578,75 @@ reduce_iife_3: {
    node_version: ">=4"
 }

+reduce_lambda_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var f = () => {
+            console.log(a, b);
+        };
+        var a = "foo", b = 42;
+        f();
+        b = "bar";
+        f();
+    }
+    expect: {
+        var f = () => {
+            console.log("foo", b);
+        };
+        var b = 42;
+        f();
+        b = "bar";
+        f();
+    }
+    expect_stdout: [
+        "foo 42",
+        "foo bar",
+    ]
+    node_version: ">=4"
+}
+
+reduce_lambda_2: {
+    options = {
+        evaluate: true,
+        passes: 2,
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function(f, a, b) {
+            f = () => {
+                console.log(a, b);
+            };
+            a = "foo", b = 42;
+            f();
+            b = "bar";
+            f();
+        })();
+    }
+    expect: {
+        (function(f, a, b) {
+            f = () => {
+                console.log("foo", b);
+            };
+            b = 42;
+            f();
+            b = "bar";
+            f();
+        })();
+    }
+    expect_stdout: [
+        "foo 42",
+        "foo bar",
+    ]
+    node_version: ">=4"
+}
+
 single_use_recursive: {
    options = {
        reduce_vars: true,
@@ -815,3 +906,24 @@ issue_4772: {
    expect_stdout: "PASS"
    node_version: ">=4"
 }
+
+issue_5251: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        (() => {
+            while (console.log(arguments))
+                var arguments = "FAIL";
+        })();
+    }
+    expect: {
+        (() => {
+            while (console.log(arguments))
+                var arguments = "FAIL";
+        })();
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}
--- a/test/compress/assignments.js
+++ b/test/compress/assignments.js
@@ -489,7 +489,7 @@ logical_assignments: {
    node_version: ">=15"
 }

-logical_collapse_vars: {
+logical_collapse_vars_1: {
    options = {
        collapse_vars: true,
    }
@@ -509,6 +509,46 @@ logical_collapse_vars: {
    node_version: ">=15"
 }

+logical_collapse_vars_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "PASS";
+        (function(b) {
+            b ||= (a = "FAIL", {});
+            return b;
+        })(console).log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (function(b) {
+            return b ||= (a = "FAIL", {});
+        })(console).log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+logical_collapse_vars_3: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = 6;
+        a *= 7;
+        a ??= "FAIL";
+        console.log(a);
+    }
+    expect: {
+        var a = 6;
+        a = a * 7 ?? "FAIL";
+        console.log(a);
+    }
+    expect_stdout: "42"
+    node_version: ">=15"
+}
+
 logical_reduce_vars: {
    options = {
        evaluate: true,
@@ -550,6 +590,24 @@ logical_side_effects: {
    node_version: ">=15"
 }

+evaluate_lazy_assignment: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 42;
+        console.log(a &&= "PASS");
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
 issue_4815_1: {
    options = {
        evaluate: true,
--- a/test/compress/awaits.js
+++ b/test/compress/awaits.js
--- a/test/compress/bigint.js
+++ b/test/compress/bigint.js
@@ -4,7 +4,7 @@ arithmetic: {
    }
    expect_exact: "console.log((1n+0x2n)*(0o3n- -4n)>>5n-6n);"
    expect_stdout: "42n"
-    node_version: ">=10"
+    node_version: ">=10.4.0"
 }

 minus_dot: {
@@ -13,7 +13,7 @@ minus_dot: {
    }
    expect_exact: "console.log(typeof-42n.toString(),typeof(-42n).toString());"
    expect_stdout: "number string"
-    node_version: ">=10"
+    node_version: ">=10.4.0"
 }

 evaluate: {
@@ -28,7 +28,7 @@ evaluate: {
        console.log(0xdeadbeefn.toString(16));
    }
    expect_stdout: "deadbeef"
-    node_version: ">=10"
+    node_version: ">=10.4.0"
 }

 Number: {
@@ -42,7 +42,7 @@ Number: {
        console.log(+("" + -0xfeed_dead_beef_badn));
    }
    expect_stdout: "-1148098955808013200"
-    node_version: ">=10"
+    node_version: ">=10.4.0"
 }

 issue_4590: {
@@ -58,7 +58,7 @@ issue_4590: {
        0n || console.log("PASS");
    }
    expect_stdout: "PASS"
-    node_version: ">=10"
+    node_version: ">=10.4.0"
 }

 issue_4801: {
@@ -88,5 +88,5 @@ issue_4801: {
        }
    }
    expect_stdout: "PASS"
-    node_version: ">=10"
+    node_version: ">=10.4.0"
 }
--- a/test/compress/booleans.js
+++ b/test/compress/booleans.js
@@ -29,6 +29,404 @@ iife_boolean_context: {
    ]
 }

+de_morgan_1a: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        function f(a) {
+            return a || a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect: {
+        function f(a) {
+            return a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect_stdout: "null 42"
+}
+
+de_morgan_1b: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        function f(a) {
+            return a && a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect: {
+        function f(a) {
+            return a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect_stdout: "null 42"
+}
+
+de_morgan_1c: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        console.log(delete (NaN && NaN));
+    }
+    expect: {
+        console.log(delete (0, NaN));
+    }
+    expect_stdout: "true"
+}
+
+de_morgan_2a: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b) {
+            return a || (a || b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a || b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+}
+
+de_morgan_2b: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a || (a && b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+}
+
+de_morgan_2c: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a && (a || b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+}
+
+de_morgan_2d: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b) {
+            return a && (a && b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a && b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "undefined {}",
+    ]
+}
+
+de_morgan_3a: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a || b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a || b || c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "undefined {} true true",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3b: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a || b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a || b && c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "false false undefined {}",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3c: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a && b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a || c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "undefined {} undefined {}",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3d: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a || ((a && b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3e: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a || b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "42 42 42 42",
+    ]
+}
+
+de_morgan_3f: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a || b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a && c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "undefined {} undefined {}",
+    ]
+}
+
+de_morgan_3g: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a && b) || c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a && (b || c);
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "undefined {} true true",
+    ]
+}
+
+de_morgan_3h: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b, c) {
+            return a && ((a && b) && c);
+        }
+        console.log(f(null, false), f(null, false, {}), f(null, true), f(null, true, {}));
+        console.log(f(42, false), f(42, false, {}), f(42, true), f(42, true, {}));
+    }
+    expect: {
+        function f(a, b, c) {
+            return a && b && c;
+        }
+        console.log(f(null, !1), f(null, !1, {}), f(null, !0), f(null, !0, {}));
+        console.log(f(42, !1), f(42, !1, {}), f(42, !0), f(42, !0, {}));
+    }
+    expect_stdout: [
+        "null null null null",
+        "false false undefined {}",
+    ]
+}
+
+conditional_chain: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ? a : b ? b : 42;
+        }
+        console.log(f("PASS", "FAIL"));
+    }
+    expect: {
+        function f(a, b) {
+            return a || b || 42;
+        }
+        console.log(f("PASS", "FAIL"));
+    }
+    expect_stdout: "PASS"
+}
+
+negated_if: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(function(a) {
+            if (!a)
+                return a ? "FAIL" : "PASS";
+        }(!console));
+    }
+    expect: {
+        console.log(function(a) {
+            if (!a)
+                return "PASS";
+        }(!console));
+    }
+    expect_stdout: "PASS"
+}
+
 issue_3465_1: {
    options = {
        booleans: true,
@@ -181,3 +579,148 @@ issue_4374: {
    }
    expect_stdout: "0"
 }
+
+issue_5028_1: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        var a = 1;
+        console.log(function() {
+            return a-- ? a-- ? "FAIL 1" : "PASS" : "FAIL 2";
+        }());
+    }
+    expect: {
+        var a = 1;
+        console.log(function() {
+            return a-- ? a-- ? "FAIL 1" : "PASS" : "FAIL 2";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5028_2: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        dead_code: true,
+        if_return: true,
+    }
+    input: {
+        var a = 1;
+        (function() {
+            if (a--)
+                if (a--)
+                    a = "FAIL";
+                else
+                    return;
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = 1;
+        (function() {
+            a-- && a-- && (a = "FAIL");
+        })();
+        console.log(a);
+    }
+    expect_stdout: "-1"
+}
+
+issue_5028_3: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        evaluate: true,
+        if_return: true,
+    }
+    input: {
+        var a = 1;
+        (function() {
+            if (a--)
+                if (a--)
+                    a = "FAIL";
+                else
+                    return;
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = 1;
+        (function() {
+            a-- && a-- && (a = "FAIL");
+        })();
+        console.log(a);
+    }
+    expect_stdout: "-1"
+}
+
+issue_5041_1: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        var a = 42;
+        if (a)
+            if ([ a = null ])
+                if (a)
+                    console.log("FAIL");
+                else
+                    console.log("PASS");
+    }
+    expect: {
+        var a = 42;
+        a && [ a = null ] && (a ? console.log("FAIL") : console.log("PASS"));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5041_2: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        var a;
+        if (!a)
+            if (a = 42)
+                if (a)
+                    console.log("PASS");
+                else
+                    console.log("FAIL");
+    }
+    expect: {
+        var a;
+        a || (a = 42) && (a ? console.log("PASS") : console.log("FAIL"));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5228: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        inline: true,
+        passes: 2,
+    }
+    input: {
+        console.log(function() {
+            return !function() {
+                do {
+                    return null;
+                } while (console);
+            }();
+        }());
+    }
+    expect: {
+        console.log(function() {
+            do {
+                return !0;
+            } while (console);
+            return !0;
+        }());
+    }
+    expect_stdout: "true"
+}
--- a/test/compress/classes.js
+++ b/test/compress/classes.js
@@ -434,6 +434,33 @@ static_side_effects: {
        console.log(a);
    }
    expect: {
+        var a = "FAIL 1";
+        (class {
+            static c = a = "PASS";
+        });
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+static_side_effects_strict: {
+    options = {
+        inline: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        var a = "FAIL 1";
+        class A {
+            static p = a = "PASS";
+            q = a = "FAIL 2";
+        }
+        console.log(a);
+    }
+    expect: {
+        "use strict";
        var a = "FAIL 1";
        a = "PASS";
        console.log(a);
@@ -807,6 +834,33 @@ unused_await: {
        })();
    }
    expect: {
+        var await = "PASS";
+        (async function() {
+            (class {
+                static c = console.log(await);
+            });
+        })();
+    }
+    expect_stdout: true
+    node_version: ">=12 <16"
+}
+
+unused_await_strict: {
+    options = {
+        inline: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        var await = "PASS";
+        (async function() {
+            class A {
+                static p = console.log(await);
+            }
+        })();
+    }
+    expect: {
+        "use strict";
        var await = "PASS";
        (async function() {
            (() => console.log(await))();
@@ -890,7 +944,7 @@ keep_fnames: {
 issue_805_1: {
    options = {
        inline: true,
-        passes: 2,
+        passes: 3,
        pure_getters: "strict",
        reduce_vars: true,
        sequences: true,
@@ -926,7 +980,7 @@ issue_805_1: {
 issue_805_2: {
    options = {
        inline: true,
-        passes: 2,
+        passes: 3,
        pure_getters: "strict",
        reduce_vars: true,
        sequences: true,
@@ -1149,6 +1203,31 @@ issue_4705: {
        }
    }
    expect: {
+        (class {
+            [console.log("PASS")]() {}
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_4705_strict: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        var a = "PASS";
+        class A {
+            p = a = "FAIL";
+            [console.log(a)];
+        }
+    }
+    expect: {
+        "use strict";
        console.log("PASS");
    }
    expect_stdout: "PASS"
@@ -1157,7 +1236,7 @@ issue_4705: {

 issue_4720: {
    options = {
-        ie8: true,
+        ie: true,
        reduce_vars: true,
        toplevel: true,
        unused: true,
@@ -1310,6 +1389,7 @@ issue_4725_1: {

 issue_4725_2: {
    options = {
+        if_return: true,
        inline: true,
    }
    input: {
@@ -1370,9 +1450,40 @@ issue_4756: {
    expect: {
        try {
            (class extends 42 {
-                [console.log("foo")]() {}
-            }),
-            (() => console.log("bar"))();
+                static [console.log("foo")] = console.log("bar");
+            });
+        } catch (e) {
+            console.log("baz");
+        }
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+    ]
+    node_version: ">=12"
+}
+
+issue_4756_strict: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            class A extends 42 {
+                static [console.log("foo")] = console.log("bar");
+            }
+        } catch (e) {
+            console.log("baz");
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (class extends 42 {
+                static [console.log("foo")] = console.log("bar");
+            });
        } catch (e) {
            console.log("baz");
        }
@@ -1629,7 +1740,7 @@ issue_4951_2: {

 issue_4962_1: {
    options = {
-        ie8: true,
+        ie: true,
        inline: true,
        reduce_vars: true,
        unused: true,
@@ -1646,9 +1757,38 @@ issue_4962_1: {
    }
    expect: {
        (function g() {}),
-        void function() {
+        void class {
+            static c = function() {
                while (console.log(typeof g));
            }();
+        };
+    }
+    expect_stdout: "undefined"
+    node_version: ">=12"
+}
+
+issue_4962_1_strict: {
+    options = {
+        ie: true,
+        inline: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        (function() {
+            function f() {
+                while (console.log(typeof g));
+            }
+            class A {
+                static p = f();
+            }
+        })(function g() {});
+    }
+    expect: {
+        "use strict";
+        (function g() {});
+        while (console.log(typeof g));
    }
    expect_stdout: "undefined"
    node_version: ">=12"
@@ -1656,7 +1796,7 @@ issue_4962_1: {

 issue_4962_2: {
    options = {
-        ie8: true,
+        ie: true,
        inline: true,
        reduce_vars: true,
        unused: true,
@@ -1672,6 +1812,36 @@ issue_4962_2: {
        }, typeof g));
    }
    expect: {
+        console.log(function f() {}(function g() {
+            (class {
+                static c = f;
+            });
+        }));
+    }
+    expect_stdout: "undefined"
+    node_version: ">=12"
+}
+
+issue_4962_2_strict: {
+    options = {
+        ie: true,
+        inline: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        console.log(function f() {}(function g() {
+            function h() {
+                f;
+            }
+            class A {
+                static p = h();
+            }
+        }, typeof g));
+    }
+    expect: {
+        "use strict";
        console.log(function f() {}(function g() {
            f;
        }));
@@ -1748,3 +1918,534 @@ issue_4992: {
    expect_stdout: "function"
    node_version: ">=12"
 }
+
+issue_4996_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect_stdout: "0"
+    node_version: ">=12"
+}
+
+issue_4996_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect: {
+        var a = 1;
+        console.log(new class A {
+            p = a-- && new A();
+        }().p.p);
+    }
+    expect_stdout: "0"
+    node_version: ">=12"
+}
+
+issue_5015_1: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        var a;
+        try {
+            (class a {
+                [a]() {}
+            });
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        var a;
+        try {
+            (class a {
+                [a]() {}
+            });
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5015_2: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        try {
+            new class A {
+                [(A, 42)]() {}
+            }();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            new class A {
+                [(A, 42)]() {}
+            }();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5015_3: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        (class A {
+            static f() {
+                return A;
+            }
+        });
+        console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        (class A {});
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5015_4: {
+    options = {
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        (class A {
+            static f() {
+                return A;
+            }
+        });
+        console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5053_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        try {
+            console.log(new class A {
+                constructor() {
+                    A = 42;
+                }
+            }());
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            console.log(new class A {
+                constructor() {
+                    A = 42;
+                }
+            }());
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5053_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        try {
+            console.log(new class A {
+                f() {
+                    A = 42;
+                }
+            }().f());
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            console.log(new class A {
+                f() {
+                    A = 42;
+                }
+            }().f());
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5053_3: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        try {
+            console.log(new class A {
+                p = A = 42;
+            }().p);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            console.log(new class A {
+                p = A = 42;
+            }().p);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_5053_4: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {
+            constructor() {
+                A = 42;
+            }
+        }
+        try {
+            console.log(new A());
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        class A {
+            constructor() {
+                A = 42;
+            }
+        }
+        try {
+            console.log(new A());
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5082_1: {
+    options = {
+        inline: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            class A {
+                p = console.log("PASS");
+                q() {}
+            }
+            class B {
+                static P = new A();
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            class A {
+                p = console.log("PASS");
+                q() {}
+            }
+            (class {
+                static c = new A();
+            });
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_5082_1_strict: {
+    options = {
+        inline: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        (function() {
+            class A {
+                p = console.log("PASS");
+                q() {}
+            }
+            class B {
+                static P = new A();
+            }
+        })();
+    }
+    expect: {
+        "use strict";
+        (function() {
+            class A {
+                p = console.log("PASS");
+                q() {}
+            }
+            new A();
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_5082_2: {
+    options = {
+        inline: true,
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            class A {
+                p = console.log("PASS");
+                q() {}
+            }
+            class B {
+                static P = new A();
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            class A {
+                p = console.log("PASS");
+                q() {}
+            }
+            (class {
+                static c = new A();
+            });
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_5082_2_static: {
+    options = {
+        inline: true,
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        (function() {
+            class A {
+                p = console.log("PASS");
+                q() {}
+            }
+            class B {
+                static P = new A();
+            }
+        })();
+    }
+    expect: {
+        "use strict";
+        void new class {
+            p = console.log("PASS");
+            q() {}
+        }();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_5142: {
+    options = {
+        evaluate: true,
+        merge_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 0, b;
+        if (++a)
+            new class {
+                p = b = null;
+                constructor(c) {
+                    console.log(c ? "FAIL" : "PASS");
+                }
+            }(b, a);
+    }
+    expect: {
+        var a = 0, b;
+        if (++a)
+            new class {
+                p = b = null;
+                constructor(c) {
+                    console.log(c ? "FAIL" : "PASS");
+                }
+            }(b, 1);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_5294_1: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        (class A {
+            static p = console.log(typeof A);
+        });
+    }
+    expect: {
+        (class A {
+            static c = console.log(typeof A);
+        });
+    }
+    expect_stdout: "function"
+    node_version: ">=12"
+}
+
+issue_5294_2: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        class A {
+            static p = console.log(typeof A);
+        }
+    }
+    expect: {
+        class A {
+            static p = console.log(typeof A);
+        }
+    }
+    expect_stdout: "function"
+    node_version: ">=12"
+}
+
+issue_5294_3: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = this;
+        (class A {
+            static p = console.log(a === A ? "FAIL" : "PASS");
+        });
+    }
+    expect: {
+        var a = this;
+        (class A {
+            static p = console.log(a === A ? "FAIL" : "PASS");
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_5294_4: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        (class A {
+            static p = function() {
+                var a = this;
+                console.log(a === A ? "FAIL" : "PASS");
+            }();
+        });
+    }
+    expect: {
+        (class A {
+            static p = function() {
+                console.log(this === A ? "FAIL" : "PASS");
+            }();
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -346,9 +346,7 @@ collapse_vars_if: {
            return "x" != "Bar" + x / 4 ? g9 : g5;
        }
        function f3(x) {
-            if (x)
-                return 1;
-            return 2;
+            return x ? 1 : 2;
        }
    }
 }
@@ -1912,6 +1910,42 @@ collapse_vars_regexp: {
    ]
 }

+collapse_arg_sequence: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(a) {
+            a("foo");
+        })((console.log("bar"), console.log));
+    }
+    expect: {
+        (function(a) {
+            (0, console.log)("foo");
+        })(console.log("bar"));
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+}
+
+collapse_for_init: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        for (var a = (Math, console), b = a.log("PASS"); b;);
+    }
+    expect: {
+        Math;
+        for (var a, b = console.log("PASS"); b;);
+    }
+    expect_stdout: "PASS"
+}
+
 issue_1537: {
    options = {
        collapse_vars: true,
@@ -2667,6 +2701,24 @@ chained_4: {
    expect_stdout: "foo undefined"
 }

+chained_5: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "PASS";
+        var a = (console, console.log(a));
+        a && ++a;
+    }
+    expect: {
+        var a = "PASS";
+        console;
+        var a;
+        (a = console.log(a)) && ++a;
+    }
+    expect_stdout: "PASS"
+}
+
 boolean_binary_1: {
    options = {
        collapse_vars: true,
@@ -2906,6 +2958,128 @@ compound_assignment_2: {
    expect_stdout: "4"
 }

+compound_assignment_3: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = 1;
+        a += (console.log("PASS"), 2);
+        a.p;
+    }
+    expect: {
+        var a = 1;
+        (a += (console.log("PASS"), 2)).p;
+    }
+    expect_stdout: "PASS"
+}
+
+compound_assignment_4: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+    }
+    input: {
+        A = "PASS";
+        var a = "";
+        a += (a = "FAIL", A);
+        a.p;
+        console.log(a);
+    }
+    expect: {
+        A = "PASS";
+        var a = "";
+        (a += (a = "FAIL", A)).p;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
+compound_assignment_5: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = 0, b;
+        a += 42;
+        b && (a *= null);
+        console.log(a);
+    }
+    expect: {
+        var a = 0, b;
+        a += 42;
+        b && (a *= null);
+        console.log(a);
+    }
+    expect_stdout: "42"
+}
+
+compound_assignment_6: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a;
+        a ^= 6;
+        a *= a + 1;
+        console.log(a);
+    }
+    expect: {
+        var a;
+        a = (a ^= 6) * (a + 1);
+        console.log(a);
+    }
+    expect_stdout: "42"
+}
+
+compound_assignment_7: {
+    options = {
+        assignments: true,
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "FA";
+        a = a + "I";
+        a = a + "L";
+        if (console)
+            a = "PASS";
+        console.log(a);
+    }
+    expect: {
+        var a = "FA";
+        a = a + "I" + "L";
+        if (console)
+            a = "PASS";
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
+compound_assignment_8: {
+    options = {
+        assignments: true,
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 2;
+        a = 3 * a;
+        a = 7 * a;
+        console || (a = "FAIL");
+        console.log(a);
+    }
+    expect: {
+        var a = 2;
+        a = a * 3 * 7;
+        console || (a = "FAIL");
+        console.log(a);
+    }
+    expect_stdout: "42"
+}
+
 issue_2187_1: {
    options = {
        collapse_vars: true,
@@ -3030,10 +3204,10 @@ issue_2203_2: {
            a: "FAIL",
            b: function() {
                return function(c) {
-                    return (String, (Object, function() {
+                    return (Object, function() {
                        return this;
-                    }())).a;
-                }();
+                    }()).a;
+                }(String);
            }
        }.b());
    }
@@ -3731,6 +3905,7 @@ issue_2437_1: {
    options = {
        collapse_vars: true,
        conditionals: true,
+        if_return: true,
        inline: true,
        join_vars: true,
        passes: 2,
@@ -3763,17 +3938,17 @@ issue_2437_1: {
        console.log(foo());
    }
    expect: {
-        console.log(function() {
-            if (xhrDesc) {
-                var result = !!(req = new XMLHttpRequest()).onreadystatechange;
-                return Object.defineProperty(XMLHttpRequest.prototype, "onreadystatechange", xhrDesc || {}),
-                    result;
-            }
-            var req = new XMLHttpRequest(), detectFunc = function(){};
-            return req.onreadystatechange = detectFunc,
+        var req, detectFunc, result;
+        console.log((
+            xhrDesc ? (result = !!(req = new XMLHttpRequest).onreadystatechange,
+                Object.defineProperty(XMLHttpRequest.prototype, "onreadystatechange", xhrDesc||{})
+            ) : (
+                (req = new XMLHttpRequest).onreadystatechange = detectFunc = function(){},
                result = req[SYMBOL_FAKE_ONREADYSTATECHANGE_1] === detectFunc,
-            req.onreadystatechange = null, result;
-        }());
+                req.onreadystatechange = null
+            ),
+            result
+        ));
    }
 }

@@ -3783,6 +3958,7 @@ issue_2437_2: {
        conditionals: true,
        inline: true,
        join_vars: true,
+        negate_iife: true,
        passes: 3,
        reduce_funcs: true,
        reduce_vars: true,
@@ -3813,15 +3989,15 @@ issue_2437_2: {
        foo();
    }
    expect: {
-        !function() {
-            if (xhrDesc)
-                return (req = new XMLHttpRequest()).onreadystatechange,
-                    Object.defineProperty(XMLHttpRequest.prototype, "onreadystatechange", xhrDesc || {});
-            var req = new XMLHttpRequest();
-            req.onreadystatechange = function(){},
+        var req;
+        xhrDesc ? (
+            (req = new XMLHttpRequest).onreadystatechange,
+            Object.defineProperty(XMLHttpRequest.prototype, "onreadystatechange", xhrDesc || {})
+        ) : (
+            (req = new XMLHttpRequest).onreadystatechange = function(){},
            req[SYMBOL_FAKE_ONREADYSTATECHANGE_1],
-            req.onreadystatechange = null;
-        }();
+            req.onreadystatechange = null
+        );
    }
 }

@@ -4728,7 +4904,7 @@ cascade_statement: {
        }
        function f3(a, b) {
            for (; a < b; a++)
-                if (c = a, a && b)
+                if ((c = a) && b)
                    var c = c = b(a);
        }
    }
@@ -6008,7 +6184,7 @@ issue_3215_1: {
    options = {
        collapse_vars: true,
        evaluate: true,
-        ie8: false,
+        ie: false,
        inline: true,
        passes: 2,
        side_effects: true,
@@ -6030,7 +6206,7 @@ issue_3215_2: {
    options = {
        collapse_vars: true,
        evaluate: true,
-        ie8: true,
+        ie: true,
        inline: true,
        passes: 2,
        side_effects: true,
@@ -6055,7 +6231,7 @@ issue_3215_3: {
    options = {
        collapse_vars: true,
        evaluate: true,
-        ie8: false,
+        ie: false,
        inline: true,
        passes: 2,
        side_effects: true,
@@ -6078,7 +6254,7 @@ issue_3215_4: {
    options = {
        collapse_vars: true,
        evaluate: true,
-        ie8: true,
+        ie: true,
        inline: true,
        passes: 2,
        side_effects: true,
@@ -6443,7 +6619,8 @@ assign_undeclared: {
        console.log(typeof B);
    }
    expect: {
-        B = new (console.log(42), function() {})();
+        console.log(42);
+        B = new function() {}();
        console.log(typeof B);
    }
    expect_stdout: [
@@ -8156,9 +8333,9 @@ issue_3884_1: {
        console.log(a, b);
    }
    expect: {
-        var a = 100, b = 1;
-        b <<= ++a;
-        console.log(a, b);
+        var a = 100;
+        ++a;
+        console.log(a, 32);
    }
    expect_stdout: "101 32"
 }
@@ -8863,7 +9040,7 @@ issue_4732_1: {
    expect: {
        var a = 0;
        (function(b) {
-            (b = a++) && (b && console.log("PASS"));
+            (b = a++) && console.log("PASS");
        })(a++);
    }
    expect_stdout: "PASS"
@@ -9139,9 +9316,7 @@ issue_4908: {
        console.log(d[1]);
    }
    expect: {
-        var a = 0, b;
-        console || a++;
-        var c = a, d = [ (d = a) && d, d += 42 ];
+        var a = 0, b, c = (console || a++, a), d = [ (d = a) && d, d += 42 ];
        console.log(d[1]);
    }
    expect_stdout: "42"
@@ -9253,13 +9428,13 @@ issue_4920_2: {
        console.log(b);
    }
    expect: {
-        var o = {
+        var o;
+        var a = "PASS", b;
+        ({
            get PASS() {
                a = "FAIL";
            },
-        };
-        var a = "PASS", b;
-        o[b = a];
+        })[b = a];
        console.log(b);
    }
    expect_stdout: "PASS"
@@ -9283,16 +9458,47 @@ issue_4920_3: {
    }
    expect: {
        var log = console.log;
-        var o = {
+        var o;
+        var a = "PASS", b;
+        ({
            get PASS() {
                a = "FAIL";
            },
+        })[b = a];
+        log(b);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4920_4: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var log = console.log;
+        var o = {
+            get [(a = "FAIL 1", "PASS")]() {
+                a = "FAIL 2";
+            },
+        };
+        var a = "PASS", b;
+        o[b = a];
+        log(b);
+    }
+    expect: {
+        var log = console.log;
+        var o = {
+            get [(a = "FAIL 1", "PASS")]() {
+                a = "FAIL 2";
+            },
        };
        var a = "PASS", b;
        o[b = a];
        log(b);
    }
    expect_stdout: "PASS"
+    node_version: ">=4"
 }

 issue_4935: {
@@ -9343,9 +9549,8 @@ inline_throw: {
    expect: {
        try {
            (function(a) {
-                return function() {
                throw a;
-                }();
+                return;
            })("PASS");
        } catch (e) {
            console.log(e);
@@ -9412,3 +9617,231 @@ issue_4977_2: {
    }
    expect_stdout: "PASS PASS"
 }
+
+issue_5112_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        console.log(function(a) {
+            try {
+                try {
+                    if (console + (a = "PASS", ""))
+                        return "FAIL 1";
+                    a.p;
+                } catch (e) {}
+            } finally {
+                return a;
+            }
+        }("FAIL 2"));
+    }
+    expect: {
+        console.log(function(a) {
+            try {
+                try {
+                    if (console + (a = "PASS", ""))
+                        return "FAIL 1";
+                    a.p;
+                } catch (e) {}
+            } finally {
+                return a;
+            }
+        }("FAIL 2"));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5112_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        console.log(function(a) {
+            try {
+                return function() {
+                    try {
+                        if (console + (a = "PASS", ""))
+                            return "FAIL 1";
+                        a.p;
+                    } catch (e) {}
+                }();
+            } finally {
+                return a;
+            }
+        }("FAIL 2"));
+    }
+    expect: {
+        console.log(function(a) {
+            try {
+                return function() {
+                    try {
+                        if (console + (a = "PASS", ""))
+                            return "FAIL 1";
+                        a.p;
+                    } catch (e) {}
+                }();
+            } finally {
+                return a;
+            }
+        }("FAIL 2"));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5182: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        evaluate: true,
+        hoist_props: true,
+        inline: true,
+        merge_vars: true,
+        passes: 4,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var con = console;
+        global.log = con.log;
+        var jump = function(x) {
+            console.log("JUMP:", x * 10);
+            return x + x;
+        };
+        var jump2 = jump;
+        var run = function(x) {
+            console.log("RUN:", x * -10);
+            return x * x;
+        };
+        var run2 = run;
+        var bar = (x, y) => {
+            console.log("BAR:", x + y);
+            return x - y;
+        };
+        var bar2 = bar;
+        var obj = {
+            foo: bar2,
+            go: run2,
+            not_used: jump2,
+        };
+        console.log(obj.foo(1, 2), global.log("PASS"));
+    }
+    expect: {
+        var con = console;
+        global.log = con.log,
+        console.log((console.log("BAR:", 3), -1), global.log("PASS"));
+    }
+    expect_stdout: [
+        "BAR: 3",
+        "PASS",
+        "-1 undefined",
+    ]
+    node_version: ">=4"
+}
+
+issue_5273: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        inline: true,
+        reduce_vars: true,
+        sequences: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "10", b = 1;
+        function f(c, d) {
+            return d;
+        }
+        f((b += a, b *= a), f);
+        console.log(b);
+    }
+    expect: {
+        var a = "10", b = 1;
+        function f(c, d) {
+            return d;
+        }
+        b = 1100,
+        f,
+        console.log(b);
+    }
+    expect_stdout: "1100"
+}
+
+issue_5276: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = A = "PASS";
+        a.p += null;
+        a.p -= 42;
+        console.log(a);
+    }
+    expect: {
+        var a = A = "PASS";
+        a.p = a.p + null - 42;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5277: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            var a = function() {
+                a += null;
+                a -= 42;
+            };
+        }());
+    }
+    expect: {
+        console.log(function() {}());
+    }
+    expect_stdout: "undefined"
+}
+
+issue_5309_1: {
+    options = {
+        collapse_vars: true,
+        conditionals: true,
+        toplevel: true,
+    }
+    input: {
+        if (console)
+            var a = (console.log("PASS"), b), b = a;
+        else
+            console.log("FAIL");
+    }
+    expect: {
+        var a, b;
+        console ? (console.log("PASS"), b = b) : console.log("FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5309_2: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a, b;
+        console ? (a = (console.log("PASS"), b), b = a) : console.log("FAIL");
+    }
+    expect: {
+        var a, b;
+        console ? (console.log("PASS"), b = b) : console.log("FAIL");
+    }
+    expect_stdout: "PASS"
+}
--- a/test/compress/concat-strings.js
+++ b/test/compress/concat-strings.js
@@ -289,3 +289,18 @@ issue_3689: {
    }
    expect_stdout: "00"
 }
+
+issue_5145: {
+    options = {
+        strings: true,
+    }
+    input: {
+        var a = [];
+        console.log("" + a + ((a[0] = 4) + "2"));
+    }
+    expect: {
+        var a = [];
+        console.log("" + a + (a[0] = 4) + "2");
+    }
+    expect_stdout: "42"
+}
--- a/test/compress/conditionals.js
+++ b/test/compress/conditionals.js
@@ -822,6 +822,33 @@ cond_13: {
    }
 }

+cond_14: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a) {
+            if (a)
+                if (a)
+                    console.log("PASS");
+                else
+                    console.log("FAIL");
+        }
+        f(null);
+        f(42);
+    }
+    expect: {
+        function f(a) {
+            a && console.log("PASS");
+        }
+        f(null);
+        f(42);
+    }
+    expect_stdout: "PASS"
+}
+
 ternary_boolean_consequent: {
    options = {
        booleans: true,
@@ -1897,3 +1924,86 @@ object_super: {
    expect_stdout: "PASS"
    node_version: ">=4"
 }
+
+issue_5232_1: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        (function() {
+            if (Math) {
+                function f() {}
+                for (var a in [ 42 ])
+                    console.log(typeof f);
+            } else {
+                var b = null;
+                return true;
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            var b;
+            if (!Math)
+                return b = null, true;
+            function f() {}
+            for (var a in [ 42 ]) console.log(typeof f);
+        })();
+    }
+    expect_stdout: "function"
+}
+
+issue_5232_2: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        console.log(function() {
+            if (!Math);
+            else {
+                var b = null;
+                return "PASS";
+            }
+        }());
+    }
+    expect: {
+        console.log(function() {
+            var b;
+            if (Math)
+                return b = null, "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5232_3: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        console.log(function() {
+            return function() {
+                if (console)
+                    console.log("PASS");
+                else {
+                    var a = null;
+                    return "FAIL";
+                }
+            };
+        }()());
+    }
+    expect: {
+        console.log(function() {
+            return function() {
+                var a;
+                if (!console)
+                    return a = null, "FAIL";
+                console.log("PASS");
+            };
+        }()());
+    }
+    expect_stdout: [
+        "PASS",
+        "undefined",
+    ]
+}
--- a/test/compress/const.js
+++ b/test/compress/const.js
@@ -220,6 +220,32 @@ merge_vars_3: {
    expect_stdout: true
 }

+merge_vars_4: {
+    options = {
+        merge_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        console.log(typeof a);
+        {
+            var b = console;
+            console.log(typeof b);
+            const a = 0;
+        }
+    }
+    expect: {
+        var a = 1;
+        console.log(typeof a);
+        {
+            var b = console;
+            console.log(typeof b);
+            const a = 0;
+        }
+    }
+    expect_stdout: true
+}
+
 use_before_init_1: {
    options = {
        reduce_vars: true,
@@ -486,7 +512,7 @@ do_continue: {

 catch_ie8_1: {
    options = {
-        ie8: true,
+        ie: true,
        unused: true,
    }
    input: {
@@ -506,7 +532,7 @@ catch_ie8_1: {
 catch_ie8_2: {
    options = {
        dead_code: true,
-        ie8: true,
+        ie: true,
        passes: 2,
        toplevel: true,
        unused: true,
@@ -727,7 +753,7 @@ issue_4193: {

 issue_4195: {
    mangle = {
-        ie8: true,
+        ie: true,
    }
    input: {
        console.log(function f(a) {
@@ -838,12 +864,10 @@ issue_4202: {
    expect: {
        {
            const o = {};
-            (function() {
            function f() {
                o.p = 42;
            }
            f(f);
-            })();
            console.log(o.p++);
        }
    }
@@ -1131,7 +1155,7 @@ issue_4225: {

 issue_4229: {
    options = {
-        ie8: true,
+        ie: true,
        side_effects: true,
    }
    input: {
@@ -1151,7 +1175,7 @@ issue_4229: {

 issue_4231: {
    options = {
-        ie8: true,
+        ie: true,
        side_effects: true,
    }
    input: {
@@ -1219,9 +1243,9 @@ issue_4248: {
    expect_stdout: "PASS"
 }

-issue_4261: {
+issue_4261_1: {
    options = {
-        inline: true,
+        inline: 3,
        reduce_funcs: true,
        reduce_vars: true,
        toplevel: true,
@@ -1259,6 +1283,43 @@ issue_4261: {
    expect_stdout: "42"
 }

+issue_4261_2: {
+    options = {
+        if_return: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        {
+            const a = 42;
+            (function() {
+                function f() {
+                    console.log(a);
+                }
+                function g() {
+                    while (f());
+                }
+                (function() {
+                    while (g());
+                })();
+            })();
+        }
+    }
+    expect: {
+        {
+            const a = 42;
+            function g() {
+                while (void console.log(a));
+            }
+            while (g());
+        }
+    }
+    expect_stdout: "42"
+}
+
 issue_4274_1: {
    options = {
        loops: true,
@@ -1692,3 +1753,63 @@ issue_4965_2: {
    expect_stdout: "undefined"
    node_version: ">=4"
 }
+
+issue_5254: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        do {
+            (function() {
+                const a = console.log;
+                a && a("foo");
+            })();
+        } while (console.log("bar"));
+    }
+    expect: {
+        do {
+            const a = console.log;
+            a && a("foo");
+        } while (console.log("bar"));
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}
+
+issue_5260: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        "use strict";
+        var a = "foo", o;
+        while (console.log("bar"));
+        o = {
+            baz: function(b) {
+                console.log(a, b);
+            },
+        };
+        for (const a in o)
+            o[a](a);
+    }
+    expect: {
+        "use strict";
+        var a = "foo", o;
+        while (console.log("bar"));
+        o = {
+            baz: function(b) {
+                console.log(a, b);
+            },
+        };
+        for (const a in o)
+            o[a](a);
+    }
+    expect_stdout: [
+        "bar",
+        "foo baz",
+    ]
+    node_version: ">=4"
+}
--- a/test/compress/dead-code.js
+++ b/test/compress/dead-code.js
@@ -939,6 +939,185 @@ catch_return_assign: {
    expect_stdout: "PASS"
 }

+catch_return_assign_may_throw: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                return e = console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                return console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect_stdout: "PASS"
+}
+
+finally_return_assign: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log(function(a) {
+            try {
+                throw "FAIL";
+            } finally {
+                return a = "PASS";
+            }
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            try {
+                throw "FAIL";
+            } finally {
+                return "PASS";
+            }
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+last_assign_statement: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f(a) {
+            a = a("PASS");
+        }
+        f(console.log);
+    }
+    expect: {
+        function f(a) {
+            a("PASS");
+        }
+        f(console.log);
+    }
+    expect_stdout: "PASS"
+}
+
+last_assign_if_else: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f(a) {
+            if (a)
+                a = console.log("foo");
+            else {
+                console.log("bar");
+                a = console.log("baz");
+            }
+        }
+        f(42);
+        f(null);
+    }
+    expect: {
+        function f(a) {
+            if (a)
+                console.log("foo");
+            else {
+                console.log("bar");
+                console.log("baz");
+            }
+        }
+        f(42);
+        f(null);
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "baz",
+    ]
+}
+
+last_assign_catch: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                e = console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect: {
+        function f() {
+            try {
+                throw "FAIL";
+            } catch (e) {
+                console.log("PASS");
+            }
+        }
+        f();
+    }
+    expect_stdout: "PASS"
+}
+
+last_assign_finally: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f(a) {
+            try {
+                throw a.log;
+            } catch (e) {
+                a = e;
+            } finally {
+                a = a("PASS");
+            }
+        }
+        f(console);
+    }
+    expect: {
+        function f(a) {
+            try {
+                throw a.log;
+            } catch (e) {
+                a = e;
+            } finally {
+                a("PASS");
+            }
+        }
+        f(console);
+    }
+    expect_stdout: "PASS"
+}
+
+consecutive_assignments: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        while (a = void 0, a = "PASS", console.log(a));
+        var a;
+    }
+    expect: {
+        while (void 0, a = "PASS", console.log(a));
+        var a;
+    }
+    expect_stdout: "PASS"
+}
+
 issue_3578: {
    options = {
        dead_code: true,
@@ -1420,3 +1599,73 @@ issue_4570: {
    }
    expect_stdout: "NaN"
 }
+
+issue_5030: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        (function(a, b) {
+            a = function f() {
+                if (a)
+                    if (b--)
+                        setImmediate(f);
+                    else
+                        console.log("FAIL");
+                else
+                    console.log("PASS");
+            }();
+        })(42, 1);
+    }
+    expect: {
+        (function(a, b) {
+            a = function f() {
+                if (a)
+                    if (b--)
+                        setImmediate(f);
+                    else
+                        console.log("FAIL");
+                else
+                    console.log("PASS");
+            }();
+        })(42, 1);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=0.12"
+}
+
+issue_5106_1: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log(typeof function(a) {
+            return a = arguments;
+        }("FAIL")[0]);
+    }
+    expect: {
+        console.log(typeof function(a) {
+            return a = arguments;
+        }("FAIL")[0]);
+    }
+    expect_stdout: "object"
+}
+
+issue_5106_2: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        "use strict";
+        console.log(function(a) {
+            return a = arguments;
+        }("PASS")[0]);
+    }
+    expect: {
+        "use strict";
+        console.log(function(a) {
+            return arguments;
+        }("PASS")[0]);
+    }
+    expect_stdout: "PASS"
+}
--- a/test/compress/default-values.js
+++ b/test/compress/default-values.js
@@ -70,7 +70,7 @@ object_shorthand_assign: {
        ({ a = "PASS" } = 42);
        console.log(a);
    }
-    expect_exact: '({a:a="PASS"}=42);console.log(a);'
+    expect_exact: '({a="PASS"}=42);console.log(a);'
    expect_stdout: "PASS"
    node_version: ">=6"
 }
@@ -80,7 +80,7 @@ object_shorthand_declaration: {
        var { a = "PASS" } = 42;
        console.log(a);
    }
-    expect_exact: 'var{a:a="PASS"}=42;console.log(a);'
+    expect_exact: 'var{a="PASS"}=42;console.log(a);'
    expect_stdout: "PASS"
    node_version: ">=6"
 }
@@ -91,7 +91,7 @@ object_shorthand_function: {
            console.log(a);
        })(42);
    }
-    expect_exact: '(function({a:a="PASS"}){console.log(a)})(42);'
+    expect_exact: '(function({a="PASS"}){console.log(a)})(42);'
    expect_stdout: "PASS"
    node_version: ">=6"
 }
@@ -149,7 +149,7 @@ process_boolean_returns: {
    }
    expect: {
        console.log(function(a = console.log("FAIL 1")) {
-            return a() ? "PASS" : "FAIL 2";
+            return 42 ? "PASS" : "FAIL 2";
        }(function() {
            return 1;
        }));
@@ -158,6 +158,28 @@ process_boolean_returns: {
    node_version: ">=6"
 }

+collapse_arg_sequence: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(a = (console.log("bar"), console.log)) {
+            a("foo");
+        })();
+    }
+    expect: {
+        (function(a = console.log("bar")) {
+            (0, console.log)("foo");
+        })();
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+    node_version: ">=6"
+}
+
 collapse_value_1: {
    options = {
        collapse_vars: true,
@@ -245,21 +267,64 @@ maintain_if: {
    node_version: ">=6"
 }

-reduce_value: {
+reduce_funarg: {
    options = {
        evaluate: true,
+        keep_fargs: false,
        reduce_vars: true,
        unused: true,
    }
    input: {
-        console.log(function(a = "PASS") {
-            return a;
-        }());
+        console.log(...function(a = "foo", b = "bar", c = "baz") {
+            return [ a, b, c ];
+        }(void 0, null));
    }
    expect: {
-        console.log("PASS");
+        console.log(...function() {
+            return [ "foo", null, "baz" ];
+        }());
    }
-    expect_stdout: "PASS"
+    expect_stdout: "foo null baz"
+    node_version: ">=6"
+}
+
+reduce_array: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var [ a = "foo", b = "bar", c = "baz" ] = [ void 0, null ];
+        console.log(a, b, c);
+    }
+    expect: {
+        var [ c = "baz" ] = [];
+        console.log("foo", null, c);
+    }
+    expect_stdout: "foo null baz"
+    node_version: ">=6"
+}
+
+reduce_object: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var { a = "foo", b = "bar", c = "baz" } = { a: void 0, b: null };
+        console.log(a, b, c);
+    }
+    expect: {
+        var { c = "baz" } = {};
+        console.log("foo", null, c);
+    }
+    expect_stdout: "foo null baz"
    node_version: ">=6"
 }

@@ -422,7 +487,9 @@ inline_loop_1: {
 inline_loop_2: {
    options = {
        inline: true,
+        sequences: true,
        toplevel: true,
+        unused: true,
    }
    input: {
        while (function(a = [ "PASS" ]) {
@@ -432,10 +499,11 @@ inline_loop_2: {
        }());
    }
    expect: {
-        while (a = [ "PASS" ], a = function f(b) {
-            console.log(a[b]);
-        }(0), void 0) ;
-        var a;
+        while (a = [ "PASS" ],
+            b = void 0,
+            b = 0,
+            void (a = void console.log(a[b])));
+        var a, b;
    }
    expect_stdout: "PASS"
    node_version: ">=6"
@@ -522,6 +590,20 @@ retain_empty_iife: {
    node_version: ">=6"
 }

+drop_new_function: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        new function(a = console.log("PASS")) {}();
+    }
+    expect: {
+        void console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 retain_fargs: {
    options = {
        unused: true,
@@ -673,7 +755,7 @@ unused_value_var_2: {
        console.log(a);
    }
    expect: {
-        var [ a ] = [ "PASS" ];
+        var a = [ "PASS" ][0];
        console.log(a);
    }
    expect_stdout: "PASS"
@@ -977,7 +1059,7 @@ mangle_arrow_1: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=6"
+    node_version: ">=6.9.3"
 }

 mangle_arrow_1_toplevel: {
@@ -1013,7 +1095,7 @@ mangle_arrow_1_toplevel: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=6"
+    node_version: ">=6.9.3"
 }

 mangle_arrow_2: {
@@ -1049,7 +1131,7 @@ mangle_arrow_2: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=6"
+    node_version: ">=6.9.3"
 }

 mangle_arrow_2_toplevel: {
@@ -1085,7 +1167,7 @@ mangle_arrow_2_toplevel: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=6"
+    node_version: ">=6.9.3"
 }

 issue_4444: {
@@ -1254,7 +1336,7 @@ issue_4468: {
    expect: {
        (function() {
            var {
-                [console.log("PASS")]: b = 0,
+                [console.log("PASS")]: b,
            } = 0;
        })();
    }
@@ -1413,6 +1495,7 @@ issue_4502_1: {
    expect: {
        (function() {
            var a = "PASS";
+            void 0,
            console.log(a),
            a++,
            void 0;
@@ -1436,6 +1519,7 @@ issue_4502_2: {
    expect: {
        (function() {
            var a = "PASS";
+            void 0,
            console.log(a),
            a++,
            void 0;
@@ -1525,7 +1609,7 @@ issue_4510_2: {
        };
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4523: {
@@ -1661,7 +1745,7 @@ issue_4588_2_evaluate: {

 issue_4817: {
    options = {
-        ie8: true,
+        ie: true,
        inline: true,
        unused: true,
    }
@@ -1695,7 +1779,7 @@ issue_4854: {
        }());
    }
    expect: {
-        console.log(void ([] = "foo"));
+        console.log(void 0);
    }
    expect_stdout: "undefined"
    node_version: ">=6"
@@ -1726,3 +1810,274 @@ issue_4916: {
    expect_stdout: "undefined"
    node_version: ">=6"
 }
+
+issue_4994: {
+    options = {
+        loops: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function(b = function() {
+            for (a in { PASS: 42 });
+        }()) {
+            var a;
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function(b = function() {
+            for (a in { PASS: 42 });
+        }()) {})();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5057_1: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        sequences: true,
+        unused: true,
+    }
+    input: {
+        var a = 42;
+        (function() {
+            var b = function(c = (console.log("foo"), b = a)) {
+                a && console.log("bar");
+            }();
+        })();
+    }
+    expect: {
+        var a = 42;
+        console.log("foo"),
+        void (a && console.log("bar"));
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=6"
+}
+
+issue_5057_2: {
+    options = {
+        inline: true,
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            (function(b = console.log("FAIL")) {})(a);
+        })(42);
+        console.log(typeof b);
+    }
+    expect: {
+        (function(a) {
+            [ b = console.log("FAIL") ] = [ a ],
+            void 0;
+            var b;
+        })(42);
+        console.log(typeof b);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=6"
+}
+
+issue_5057_3: {
+    options = {
+        inline: 3,
+        unused: true,
+    }
+    input: {
+        (function(a) {
+            (function f(b) {
+                (function(a = console.log("FAIL 1")) {})(b);
+                console.log(a);
+            })("FAIL 2");
+        })("PASS");
+    }
+    expect: {
+        (function(a) {
+            (function(b) {
+                (function(a = console.log("FAIL 1")) {})(b);
+                console.log(a);
+            })("FAIL 2");
+        })("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5057_4: {
+    options = {
+        if_return: true,
+        inline: true,
+        unused: true,
+    }
+    input: {
+        (function(a) {
+            (function f(b) {
+                (function(a = console.log("FAIL 1")) {})(b);
+                console.log(a);
+            })("FAIL 2");
+        })("PASS");
+    }
+    expect: {
+        (function(a) {
+            var b = "FAIL 2";
+            (function(a = console.log("FAIL 1")) {})(b);
+            console.log(a);
+        })("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5065: {
+    options = {
+        pure_getters: "strict",
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var [ a = console.log("PASS") ] = [ (A = 42).p ];
+    }
+    expect: {
+        var [ a = console.log("PASS") ] = [ (A = 42).p ];
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5138_1: {
+    options = {
+        evaluate: true,
+    }
+    input: {
+        console.log(function(a, b = a = "FAIL") {
+            return a;
+        }() && "PASS");
+    }
+    expect: {
+        console.log(function(a, b = a = "FAIL") {
+            return a;
+        }() && "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5138_2: {
+    options = {
+        evaluate: true,
+    }
+    input: {
+        console.log(function(a, b = a = "FAIL 1") {
+            return a;
+        }(null, "FAIL 2") || "PASS");
+    }
+    expect: {
+        console.log((null, "PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5192: {
+    options = {
+        dead_code: true,
+        ie: true,
+    }
+    input: {
+        (function a(a,  [] = a = "PASS") {
+            console.log(a);
+        })("FAIL");
+    }
+    expect: {
+        (function a(a,  [] = a = "PASS") {
+            console.log(a);
+        })("FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5246_1: {
+    options = {
+        pure_getters: true,
+        unused: true,
+    }
+    input: {
+        console.log(function({} = 42) {
+            return "PASS";
+        }("foo"));
+    }
+    expect: {
+        console.log(function({} = 0) {
+            return "PASS";
+        }("foo"));
+    }
+    expect_stdout: "PASS"
+    expect_warnings: [
+        "INFO: Dropping unused default argument value {}=42 [test/compress/default-values.js:1,29]",
+        "INFO: Dropping unused default argument value {}=0 [test/compress/default-values.js:1,29]",
+    ]
+    node_version: ">=6"
+}
+
+issue_5246_2: {
+    options = {
+        unused: true,
+    }
+    input: {
+        (function f(a = "FAIL", [] = 42) {
+            console.log(a);
+        })("PASS", []);
+    }
+    expect: {
+        (function(a = "FAIL", []) {
+            console.log(a);
+        })("PASS", []);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5246_3: {
+    options = {
+        default_values: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f([ , {} ] = null){}([ , {} ]));
+    }
+    expect: {
+        console.log(function([ {} ]){}([ {} ]));
+    }
+    expect_stdout: "undefined"
+    node_version: ">=6"
+}
+
+issue_5256: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (function(arguments = console.log) {
+            console;
+        })();
+        console.log(typeof arguments);
+    }
+    expect: {
+        // Syntax error on Node.js v6
+        (function(arguments = console.log) {
+            console;
+        })();
+        console.log(typeof arguments);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8"
+}
--- a/test/compress/destructured.js
+++ b/test/compress/destructured.js
@@ -220,7 +220,7 @@ funarg_side_effects_2: {
        }
    }
    expect_stdout: "PASS"
-    node_version: ">=6"
+    node_version: ">=6.9.2"
 }

 funarg_side_effects_3: {
@@ -254,7 +254,7 @@ funarg_side_effects_3: {
        }
    }
    expect_stdout: "PASS"
-    node_version: ">=6"
+    node_version: ">=6.9.2"
 }

 funarg_unused_1: {
@@ -395,7 +395,8 @@ funarg_unused_6_keep_fargs: {
    }
    expect: {
        (function() {
-            var {} = (console, 42);
+            console;
+            var {} = 42;
        })();
        console.log(typeof a);
    }
@@ -1105,7 +1106,7 @@ drop_unused_1: {
            try {
                throw 42;
            } catch (a) {
-                var [ a ] = [];
+                var a = [][0];
            }
        }
    }
@@ -1138,6 +1139,175 @@ drop_unused_2: {
    node_version: ">=6"
 }

+drop_hole: {
+    options = {
+        unused: true,
+    }
+    input: {
+        var [ a ] = [ , ];
+        console.log(a);
+    }
+    expect: {
+        var a = [][0];
+        console.log(a);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=6"
+}
+
+keep_key_1: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = {
+            [(console.log("PASS"), 42)]: null,
+        });
+    }
+    expect: {
+        ({} = {
+            [(console.log("PASS"), 42)]: 0,
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+keep_key_2: {
+    options = {
+        evaluate: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var { 42: a } = { [(console.log("PASS"), 42)](){} };
+    }
+    expect: {
+        var {} = { [(console.log("PASS"), 42)]: 0 };
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+keep_key_2_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var { 42: a } = { [(console.log("PASS"), 42)](){} };
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+keep_reference: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = [ {}, 42 ];
+        var [ b, c ] = a;
+        console.log(a[0] === b ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = [ {}, 42 ];
+        var [ b ] = a;
+        console.log(a[0] === b ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+maintain_position_assign: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(([ , ] = [ , "PASS" ])[1]);
+    }
+    expect: {
+        console.log([ , "PASS" ][1]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+maintain_position_var: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        A = "FAIL";
+        var [ a, b ] = [ A ];
+        console.log(b || "PASS");
+    }
+    expect: {
+        A = "FAIL";
+        var [ , b ] = [ A ];
+        console.log(b || "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+side_effects_array: {
+    options = {
+        unused: true,
+    }
+    input: {
+        try {
+            var [ a ] = 42;
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            var [ a ] = 42;
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+side_effects_object: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = null, b = console, { c } = 42;
+        try {
+            c[a = "PASS"];
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = null, c = (console, 42["c"]);
+        try {
+            c[a = "PASS"];
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 join_vars: {
    options = {
        conditionals: true,
@@ -1412,6 +1582,75 @@ hoist_vars: {
    node_version: ">=6"
 }

+singleton_1: {
+    options = {
+        pure_getters: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var [ a ] = "P", b, o = {};
+        [ { 1: o.p } ] = [ "FAIL" ];
+        ({ foo: [ o.q ] } = { foo: "S" });
+        [ b = "S" ] = [];
+        console.log(a + o.p + o.q + b);
+    }
+    expect: {
+        var b, a = "P"[0], o = {};
+        o.p = [ "FAIL"["1"] ][0];
+        o.q = { foo: "S"[0] }["foo"];
+        [ b = "S" ] = [];
+        console.log(a + o.p + o.q + b);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+singleton_2: {
+    options = {
+        evaluate: true,
+        passes: 2,
+        pure_getters: true,
+        side_effects: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var [ a ] = "P", b, o = {};
+        [ { 1: o.p } ] = [ "FAIL" ];
+        ({ foo: [ o.q ] } = { foo: "S" });
+        [ b = "S" ] = [];
+        console.log(a + o.p + o.q + b);
+    }
+    expect: {
+        var b, a = "P", o = {};
+        o.p = "A";
+        o.q = "S";
+        [ b = "S" ] = [];
+        console.log(a + o.p + o.q + b);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+singleton_side_effects: {
+    options = {
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        [ 42[console.log("foo")] ] = [ console.log("bar") ];
+    }
+    expect: {
+        [ 42[console.log("foo")] ] = [ console.log("bar") ];
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+    node_version: ">=6"
+}
+
 issue_4280: {
    options = {
        evaluate: true,
@@ -1606,13 +1845,13 @@ issue_4294: {
    expect: {
        A = "PASS";
        (function() {
-            var b = function({
-                [b]: {},
+            var a = function({
+                [a]: {},
            }) {}({
-                [b]: 0,
+                [a]: 0,
            });
-            var b = A;
-            console.log(b);
+            var a = A;
+            console.log(a);
        })();
    }
    expect_stdout: "PASS"
@@ -1831,7 +2070,7 @@ issue_4319: {

 issue_4321: {
    options = {
-        inline: true,
+        inline: 3,
        keep_fargs: false,
    }
    input: {
@@ -1860,7 +2099,7 @@ issue_4321: {

 issue_4323: {
    options = {
-        ie8: true,
+        ie: true,
        inline: true,
        merge_vars: true,
        reduce_vars: true,
@@ -1958,7 +2197,7 @@ issue_4372_2: {
    }
    expect: {
        var a;
-        [ a ] = [ "PASS", "FAIL" ];
+        [ a ] = a = [ "PASS", "FAIL" ];
        console.log(a);
    }
    expect_stdout: "PASS"
@@ -2592,3 +2831,598 @@ issue_4608_2: {
    expect_stdout: "f"
    node_version: ">=6"
 }
+
+issue_4994: {
+    options = {
+        loops: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function([
+            {
+                [function() {
+                    for (a in { PASS: null });
+                }()]: b,
+            },
+        ]) {
+            var a;
+        })([ 42 ]);
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function([
+            {
+                [function() {
+                    for (a in { PASS: null });
+                }()]: b,
+            },
+        ]) {})([ 42 ]);
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5017: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = function() {};
+        var b = c = a;
+        var c = [ c ] = [ c ];
+        console.log(c[0] === a ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = function() {};
+        var b = a;
+        var c = [ c ] = [ c = a ];
+        console.log(c[0] === a ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5071_1: {
+    options = {
+        unused: true,
+    }
+    input: {
+        var a;
+        console.log(([ , a ] = [ "PA", , ]).join("SS"));
+    }
+    expect: {
+        var a;
+        console.log(([ , a ] = [ "PA", , ]).join("SS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5071_2: {
+    options = {
+        pure_getters: "strict",
+        unused: true,
+    }
+    input: {
+        var a;
+        ([ a ] = []).p = console.log("PASS");
+    }
+    expect: {
+        var a;
+        ([ a ] = []).p = console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_getter: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { get [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        ({} = { [(console.log("PASS"), 42)]: 0 });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_getter_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { get [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_setter: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { set [(console.log("PASS"), 42)](v) {} });
+    }
+    expect: {
+        ({} = { [(console.log("PASS"), 42)]: 0 });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_setter_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { set [(console.log("PASS"), 42)](v) {} });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_method: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        ({} = { [(console.log("PASS"), 42)]: 0 });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5074_method_pure_getters: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ({} = { [(console.log("PASS"), 42)]() {} });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5085_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        var [ b ] = [ 42, a ], c = b ? 0 : a = "FAIL";
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        var b = [ 42 ][0];
+        b;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5085_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        side_effects: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function(b) {
+            [ b ] = [ 42, a ];
+            var c = b ? 0 : a = "FAIL";
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (function(b) {
+            b = [ 42 ][0];
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5087_1: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        properties: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function() {
+            (function() {
+                (function([ b ]) {
+                    b && console.log(b);
+                })([ a ]);
+            })();
+        })();
+    }
+    expect: {
+        var a = "PASS";
+        (function() {
+            var b;
+            (b = a) && console.log(b);
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5087_2: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        passes: 2,
+        properties: true,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function() {
+            (function() {
+                (function([ b ]) {
+                    b && console.log(b);
+                })([ a ]);
+            })();
+        })();
+    }
+    expect: {
+        var a = "PASS";
+        a && console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5114_1: {
+    options = {
+        inline: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function({}, a) {})(42);
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        [ {} ] = [ 42 ],
+        void 0;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5114_2: {
+    options = {
+        inline: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function f([], a) {
+            f.length;
+        })([]);
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        0;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5114_3: {
+    options = {
+        inline: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function f(a, {}) {
+            f.length;
+        })(null, 42);
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        0;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5153_array_assign: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        var a = function*() {
+            yield b;
+        }(), b;
+        [ b ] = b = a;
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = function*() {
+            yield b;
+        }(), b;
+        [ b ] = b = a;
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5153_array_var: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        var a = function*() {
+            yield b;
+        }(), [ b ] = b = a;
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = function*() {
+            yield b;
+        }(), [ b ] = b = a;
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5153_object_assign: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        var a = {
+            get p() {
+                return b;
+            },
+        }, b;
+        ({
+            p: b
+        } = b = a);
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = {
+            get p() {
+                return b;
+            },
+        }, b;
+        ({
+            p: b
+        } = b = a);
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5153_object_var: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        var a = {
+            get p() {
+                return b;
+            },
+        }, {
+            p: b
+        } = b = a;
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = {
+            get p() {
+                return b;
+            },
+        }, {
+            p: b
+        } = b = a;
+        console.log(a === b ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5168: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        (function a({
+            [console.log(typeof function() {
+                ++a;
+                return a;
+            }())]: b,
+        }) {
+            var a;
+        })({});
+    }
+    expect: {
+        (function a({
+            [console.log(typeof function() {
+                ++a;
+                return a;
+            }())]: b,
+        }) {
+            var a;
+        })({});
+    }
+    expect_stdout: "function"
+    node_version: ">=6"
+}
+
+issue_5189_1: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 42;
+        [ a.p ] = a = "PASS";
+        console.log(a);
+    }
+    expect: {
+        var a;
+        [ a.p ] = a = "PASS";
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5189_2: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 42;
+        ({ p: a.q } = a = "PASS");
+        console.log(a);
+    }
+    expect: {
+        var a;
+        ({ p: a.q } = a = "PASS");
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5222: {
+    options = {
+        hoist_props: true,
+        inline: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            do {
+                (function() {
+                    var a = {
+                        p: [ a ] = [],
+                    };
+                })();
+            } while (console.log("PASS"));
+        }
+        f();
+    }
+    expect: {
+        do {
+            a = void 0,
+            a = {
+                p: [ a ] = [],
+            };
+        } while (console.log("PASS"));
+        var a;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5288: {
+    options = {
+        conditionals: true,
+        inline: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+        varify: true,
+    }
+    input: {
+        while (function([]) {}([ function f() {
+            if (console)
+                return console.log("PASS");
+            else {
+                let a = 0;
+            }
+        }() ]));
+    }
+    expect: {
+        while ([ [ console ? console.log("PASS") : 0 ] ], void 0);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
--- a/test/compress/drop-unused.js
+++ b/test/compress/drop-unused.js
@@ -1233,8 +1233,11 @@ issue_2105_2: {
 issue_2105_3: {
    options = {
        inline: true,
-        passes: 2,
+        join_vars: true,
+        passes: 3,
        reduce_vars: true,
+        side_effects: true,
+        sequences: true,
        unused: true,
    }
    input: {
@@ -1258,12 +1261,12 @@ issue_2105_3: {
        });
    }
    expect: {
-        !void void {
+        ({
            prop: function() {
-                console.log;
-                void console.log("PASS");
-            }
-        }.prop();
+                console.log,
+                console.log("PASS");
+            },
+        }).prop();
    }
    expect_stdout: "PASS"
 }
@@ -1557,9 +1560,9 @@ issue_2665: {
    }
    expect: {
        var a = 1;
-        !function g() {
+        (function g() {
            a-- && g();
-        }();
+        })();
        console.log(a);
    }
    expect_stdout: "-1"
@@ -1728,7 +1731,8 @@ issue_2768: {
    }
    expect: {
        var a = "FAIL";
-        var c = (d = a, void (d && (a = "PASS")));
+        d = a;
+        var c = void (d && (a = "PASS"));
        var d;
        console.log(a, typeof c);
    }
@@ -1765,7 +1769,7 @@ issue_2846: {
 issue_805_1: {
    options = {
        inline: true,
-        passes: 2,
+        passes: 3,
        pure_getters: "strict",
        reduce_vars: true,
        sequences: true,
@@ -1798,7 +1802,7 @@ issue_805_1: {
 issue_805_2: {
    options = {
        inline: true,
-        passes: 2,
+        passes: 3,
        pure_getters: "strict",
        reduce_vars: true,
        sequences: true,
@@ -2345,7 +2349,7 @@ function_argument_reference: {

 function_parameter_ie8: {
    options = {
-        ie8: true,
+        ie: true,
        reduce_vars: true,
        unused: true,
    }
@@ -2382,7 +2386,8 @@ issue_3664: {
    }
    expect: {
        console.log(function() {
-            var a, b = (a = (a = [ b && console.log("FAIL") ]).p = 0, 0);
+            a = (a = [ b && console.log("FAIL") ]).p = 0;
+            var a, b = 0;
            return "PASS";
        }());
    }
@@ -2551,10 +2556,9 @@ issue_3899: {
        console.log(typeof a);
    }
    expect: {
-        function a() {
+        console.log(typeof function() {
            return 2;
-        }
-        console.log(typeof a);
+        });
    }
    expect_stdout: "function"
 }
@@ -2916,7 +2920,7 @@ issue_4133: {
        console.log(a);
    }
    expect: {
-        var b = 1;
+        var a = 1;
        console.log(0);
    }
    expect_stdout: "0"
@@ -3062,7 +3066,7 @@ issue_4184: {
    expect_stdout: "42"
 }

-issue_4235: {
+issue_4235_1: {
    options = {
        inline: true,
        reduce_vars: true,
@@ -3087,6 +3091,31 @@ issue_4235: {
    expect_stdout: "undefined"
 }

+issue_4235_2: {
+    options = {
+        inline: true,
+        passes: 2,
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+        varify: true,
+    }
+    input: {
+        (function() {
+            {
+                const f = 0;
+            }
+            (function f() {
+                var f = console.log(f);
+            })();
+        })();
+    }
+    expect: {
+        console.log(void 0);
+    }
+    expect_stdout: "undefined"
+}
+
 issue_4404: {
    options = {
        pure_getters: "strict",
@@ -3229,7 +3258,7 @@ issue_4558_1: {
 issue_4558_2: {
    options = {
        evaluate: true,
-        ie8: true,
+        ie: true,
        reduce_vars: true,
        unused: true,
    }
@@ -3378,7 +3407,7 @@ issue_4834: {
    }
    expect: {
        try {
-            void b.p;
+            b.p;
        } catch (e) {
            console.log("PASS");
        }
@@ -3468,3 +3497,96 @@ issue_4912_3: {
    }
    expect_stdout: "PASS"
 }
+
+issue_5079: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        do {
+            (a = 123456).p = a;
+            a.q = null;
+        } while (console.log("PASS"));
+    }
+    expect: {
+        do {
+            0, 0, null;
+        } while (console.log("PASS"));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5224: {
+    options = {
+        evaluate: true,
+        keep_fargs: false,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            try {
+                var b = function() {
+                    var a = "FAIL 1";
+                    null && a;
+                    a = console.log(a);
+                }(new function(c, d) {
+                    console.log(d);
+                    a;
+                }("FAIL 2", Infinity));
+            } finally {
+                return f;
+            }
+        }
+        f();
+    }
+    expect: {
+        (function f() {
+            try {
+                (function() {
+                    var a = "FAIL 1";
+                    null;
+                    a = console.log(a);
+                })(function() {
+                    console.log(1 / 0);
+                    a;
+                }());
+            } finally {
+                return f;
+            }
+        })();
+    }
+    expect_stdout: "Infinity"
+}
+
+issue_5271: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            do {
+                var a = b = 0 ^ f, b = b;
+            } while (console.log(42 - b));
+        }
+        f();
+    }
+    expect: {
+        (function f() {
+            do {
+                var b;
+                b = 0 ^ f;
+            } while (console.log(42 - b));
+        })();
+    }
+    expect_stdout: "42"
+}
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -684,26 +684,47 @@ prototype_function: {
        side_effects: true,
    }
    input: {
-        var a = ({valueOf: 0}) < 1;
-        var b = ({toString: 0}) < 1;
-        var c = ({valueOf: 0}) + "";
-        var d = ({toString: 0}) + "";
-        var e = (({valueOf: 0}) + "")[2];
-        var f = (({toString: 0}) + "")[2];
-        var g = ({valueOf: 0}).valueOf();
-        var h = ({toString: 0}).toString();
+        function v() {
+            return this.valueOf === v ? "PASS" : "FAIL";
+        }
+        console.log(({ valueOf: v }) < 1);
+        console.log(({ valueOf: v }) + "");
+        console.log((( {valueOf: v }) + "")[2]);
+        console.log(({ valueOf: v }).valueOf());
+        function t() {
+            return this.toString === t ? "PASS" : "FAIL";
+        }
+        console.log(({ toString: t }) < 1);
+        console.log(({ toString: t }) + "");
+        console.log((( {toString: t }) + "")[2]);
+        console.log(({ toString: t }).toString());
    }
    expect: {
-        var a = ({valueOf: 0}) < 1;
-        var b = ({toString: 0}) < 1;
-        var c = ({valueOf: 0}) + "";
-        var d = ({toString: 0}) + "";
-        var e = (({valueOf: 0}) + "")[2];
-        var f = (({toString: 0}) + "")[2];
-        var g = 0();
-        var h = 0();
+        function v() {
+            return this.valueOf === v ? "PASS" : "FAIL";
        }
-    expect_stdout: true
+        console.log(({ valueOf: v }) < 1);
+        console.log(({ valueOf: v }) + "");
+        console.log((( {valueOf: v }) + "")[2]);
+        console.log(({ valueOf: v }).valueOf());
+        function t() {
+            return this.toString === t ? "PASS" : "FAIL";
+        }
+        console.log(({ toString: t }) < 1);
+        console.log(({ toString: t }) + "");
+        console.log((( {toString: t }) + "")[2]);
+        console.log(({ toString: t }).toString());
+    }
+    expect_stdout: [
+        "false",
+        "PASS",
+        "S",
+        "PASS",
+        "false",
+        "PASS",
+        "S",
+        "PASS",
+    ]
 }

 call_args: {
@@ -2731,8 +2752,7 @@ issue_3944: {
    }
    expect: {
        void function f() {
-            while (a = 0 == (a = void 0), console.log(a), void 0);
-            var a;
+            while (0 == void 0, console.log(false), void 0);
            f;
        }();
    }
@@ -3182,7 +3202,7 @@ issue_4552: {
    expect_stdout: "NaN"
 }

-issue_4886: {
+issue_4886_1: {
    options = {
        evaluate: true,
        unsafe: true,
@@ -3201,3 +3221,23 @@ issue_4886: {
    }
    expect_stdout: "true"
 }
+
+issue_4886_2: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        console.log("foo" in {
+            "foo": null,
+            __proto__: 42,
+        });
+    }
+    expect: {
+        console.log("foo" in {
+            "foo": null,
+            __proto__: 42,
+        });
+    }
+    expect_stdout: "true"
+}
--- a/test/compress/exponentiation.js
+++ b/test/compress/exponentiation.js
@@ -62,7 +62,7 @@ assignment_2: {
    }
    expect_exact: "var a=8n;a**=a;console.log(a);"
    expect_stdout: "16777216n"
-    node_version: ">=10"
+    node_version: ">=10.4.0"
 }

 evaluate: {
@@ -99,7 +99,7 @@ issue_4664: {
    expect: {
        (function f() {
            new function(a) {
-                console.log(typeof f, 1073741824, typeof this);
+                console.log(typeof f, 2 ** 30, typeof this);
            }(A = 0);
        })();
    }
--- a/test/compress/exports.js
+++ b/test/compress/exports.js
@@ -249,7 +249,7 @@ hoist_exports_2: {
        }
    }
    expect: {
-        let e, { foo: a } = 42;
+        let e, a = 42["foo"];
        function f(t, { [e]: o }) {
            t(o, f);
        }
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
--- a/test/compress/hoist_props.js
+++ b/test/compress/hoist_props.js
@@ -217,7 +217,8 @@ name_collision_1: {
        var obj_foo = 1;
        var obj_bar = 2;
        function f() {
-            var obj_foo$0 = 3,
+            var obj,
+                obj_foo$0 = 3,
                obj_bar = 4,
                obj_b_r = 5,
                obj_b_r$0 = 6,
@@ -249,7 +250,8 @@ name_collision_2: {
        console.log(o.p === o.p, o["+"](4), o["-"](5), o__$0, o__$1);
    }
    expect: {
-        var o_p = 1,
+        var o,
+            o_p = 1,
            o__ = function(x) {
                return x;
            },
@@ -283,7 +285,8 @@ name_collision_3: {
        console.log(o.p === o.p, o["+"](4), o["-"](5));
    }
    expect: {
-        var o_p = 1,
+        var o,
+            o_p = 1,
            o__ = function(x) {
                return x;
            },
@@ -315,7 +318,7 @@ name_collision_4: {
    }
    expect: {
        console.log(function() {
-            var o_p$0 = 0, o_q = "PASS";
+            var o, o_p$0 = 0, o_q = "PASS";
            return function(o_p) {
                if (!o_p$0) return o_p;
            }(o_q);
@@ -768,7 +771,7 @@ issue_3046: {
    expect: {
        console.log(function(a) {
            do {
-                var b_c = a++;
+                var b, b_c = a++;
            } while (b_c && a);
            return a;
        }(0));
@@ -777,6 +780,32 @@ issue_3046: {
 }

 issue_3071_1: {
+    options = {
+        evaluate: true,
+        hoist_props: true,
+        inline: true,
+        join_vars: true,
+        passes: 3,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            var obj = {};
+            obj.one = 1;
+            obj.two = 2;
+            console.log(obj.one, obj.two);
+        })();
+    }
+    expect: {
+        console.log(1, 2);
+    }
+    expect_stdout: "1 2"
+}
+
+issue_3071_1_toplevel: {
    options = {
        evaluate: true,
        hoist_props: true,
@@ -905,7 +934,7 @@ issue_3411: {
    expect: {
        var c = 1;
        !function f() {
-            var o_p = --c && f();
+            var o, o_p = --c && f();
            +{} || console.log("PASS");
        }();
    }
@@ -1016,9 +1045,7 @@ issue_3945_1: {
    expect: {
        function f() {
            o.p;
-            var o = {
-                q: 0,
-            };
+            var o, o_q = 0;
        }
    }
 }
@@ -1037,9 +1064,7 @@ issue_3945_2: {
    }
    expect: {
        console.log(typeof o);
-        var o = {
-            p: 0,
-        };
+        var o, o_p = 0;
    }
    expect_stdout: "undefined"
 }
@@ -1094,3 +1119,60 @@ object_super: {
    expect_stdout: "PASS"
    node_version: ">=4"
 }
+
+issue_4985: {
+    options = {
+        hoist_props: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = { p: 42 };
+        console.log(function() {
+            a;
+        }());
+    }
+    expect: {
+        var a, a_p = 42;
+        console.log(function() {
+            ({});
+        }());
+    }
+    expect_stdout: "undefined"
+}
+
+issue_5182: {
+    options = {
+        hoist_props: true,
+        merge_vars: true,
+        passes: 2,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var o = console;
+        log = o.log;
+        o = {
+            p: function(a) {
+                console.log(a ? "PASS" : "FAIL");
+                return a;
+            },
+        };
+        log(o.p(42));
+    }
+    expect: {
+        var o = console;
+        log = o.log;
+        o = function(a) {
+            console.log(a ? "PASS" : "FAIL");
+            return a;
+        };
+        log(o(42));
+    }
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+}
--- a/test/compress/hoist_vars.js
+++ b/test/compress/hoist_vars.js
@@ -135,7 +135,7 @@ issue_2295: {
    }
 }

-issue_4487: {
+issue_4487_1: {
    options = {
        functions: true,
        hoist_vars: true,
@@ -150,6 +150,31 @@ issue_4487: {
        };
        var b = a();
    }
+    expect: {
+        var a = function f() {
+            var f = console.log(typeof f);
+        };
+        a();
+    }
+    expect_stdout: "undefined"
+}
+
+issue_4487_2: {
+    options = {
+        functions: true,
+        hoist_vars: true,
+        keep_fnames: true,
+        passes: 2,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = function f() {
+            var f = console.log(typeof f);
+        };
+        var b = a();
+    }
    expect: {
        function a() {
            var f = console.log(typeof f);
@@ -159,6 +184,30 @@ issue_4487: {
    expect_stdout: "undefined"
 }

+issue_4487_3: {
+    options = {
+        functions: true,
+        hoist_vars: true,
+        keep_fnames: true,
+        passes: 3,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = function f() {
+            var f = console.log(typeof f);
+        };
+        var b = a();
+    }
+    expect: {
+        (function a() {
+            console.log(typeof void 0);
+        })();
+    }
+    expect_stdout: "undefined"
+}
+
 issue_4489: {
    options = {
        collapse_vars: true,
@@ -233,7 +282,7 @@ issue_4736: {
        (function() {
            (function() {
                0,
-                console.log(1073741824);
+                console.log(1 << 30);
            })();
        })();
    }
@@ -250,18 +299,18 @@ issue_4839: {
        unused: true,
    }
    input: {
-        var o = function(a, b) {
+        var log = console.log, o = function(a, b) {
            return b && b;
        }("foo");
        for (var k in o)
            throw "FAIL";
-        console.log("PASS");
+        log("PASS");
    }
    expect: {
-        var k, o = void 0;
-        for (k in o)
+        var k, log = console.log;
+        for (k in void 0)
            throw "FAIL";
-        console.log("PASS");
+        log("PASS");
    }
    expect_stdout: "PASS"
 }
@@ -287,8 +336,7 @@ issue_4859: {
    }
    expect: {
        (function f(a) {
-            var d = 1 / 0, d = Infinity;
-            console.log(d);
+            console.log(2 + 1 / 0);
            return f;
        })();
    }
@@ -322,9 +370,7 @@ issue_4893_1: {
    expect: {
        try{
            (function f() {
-                var b;
-                b = null;
-                b.p += 42;
+                null.p += 42;
                f;
            })();
        } catch (e) {
@@ -396,3 +442,61 @@ issue_4898: {
    }
    expect_stdout: "PASS"
 }
+
+issue_5187: {
+    options = {
+        hoist_props: true,
+        hoist_vars: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            var a = 42;
+            do {
+                var b = { 0: a++ };
+            } while (console.log(b[b ^= 0]));
+        }
+        f();
+    }
+    expect: {
+        (function() {
+            var b, a = 42;
+            do {
+                b = { 0: a++ };
+            } while (console.log(b[b ^= 0]));
+        })();
+    }
+    expect_stdout: "42"
+}
+
+issue_5195: {
+    options = {
+        hoist_props: true,
+        hoist_vars: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            var a;
+            do {
+                var b = { p: a };
+            } while (console.log(b += ""));
+        }
+        f();
+    }
+    expect: {
+        (function() {
+            var a, b;
+            do {
+                b = { p: a };
+            } while (console.log(b += ""));
+        })();
+    }
+    expect_stdout: "[object Object]"
+}
--- a/test/compress/ie8.js
+++ b/test/compress/ie8.js
--- a/test/compress/if_return.js
+++ b/test/compress/if_return.js
@@ -545,7 +545,36 @@ if_body_return_3: {
    ]
 }

-issue_3600: {
+issue_3600_1: {
+    options = {
+        if_return: true,
+        inline: 3,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var c = 0;
+        (function() {
+            if ([ ][c++]); else return;
+            return void function() {
+                var b = --b, a = c = 42;
+                return c;
+            }();
+        })();
+        console.log(c);
+    }
+    expect: {
+        var c = 0;
+        (function() {
+            if ([][c++]) b = --b, c = 42;
+            var b;
+        })();
+        console.log(c);
+    }
+    expect_stdout: "1"
+}
+
+issue_3600_2: {
    options = {
        if_return: true,
        inline: true,
@@ -566,7 +595,9 @@ issue_3600: {
    expect: {
        var c = 0;
        (function() {
-            if ([][c++]) b = --b, c = 42;
+            if ([][c++])
+                b = --b,
+                c = 42;
            var b;
        })();
        console.log(c);
--- a/test/compress/imports.js
+++ b/test/compress/imports.js
@@ -94,13 +94,31 @@ drop_unused: {
    }
    input: {
        import a, * as b from "foo";
-        import { c, bar as d } from "baz";
-        console.log(c);
+        import { c } from "bar";
+        import { d, _ as e } from "baz";
+        console.log(d);
    }
    expect: {
        import "foo";
-        import { c as c } from "baz";
-        console.log(c);
+        import "bar";
+        import { d as d } from "baz";
+        console.log(d);
+    }
+}
+
+drop_side_effect_free: {
+    options = {
+        imports: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        import foo from "bar";
+        var a = foo;
+    }
+    expect: {
+        import "bar";
    }
 }

--- a/test/compress/issue-1446.js
+++ b/test/compress/issue-1446.js
@@ -24,7 +24,7 @@ typeof_eq_undefined: {
 typeof_eq_undefined_ie8: {
    options = {
        comparisons: true,
-        ie8: true,
+        ie: true,
        typeofs: true,
    }
    input: {
--- a/test/compress/issue-1588.js
+++ b/test/compress/issue-1588.js
@@ -1,9 +1,9 @@
 screw_ie8: {
    options = {
-        ie8: false,
+        ie: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
    }
    input: {
        try { throw "foo"; } catch (x) { console.log(x); }
@@ -16,10 +16,10 @@ screw_ie8: {

 support_ie8: {
    options = {
-        ie8: true,
+        ie: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
    }
    input: {
        try { throw "foo"; } catch (x) { console.log(x); }
--- a/test/compress/issue-1704.js
+++ b/test/compress/issue-1704.js
@@ -1,10 +1,10 @@
 mangle_catch: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -22,11 +22,11 @@ mangle_catch: {

 mangle_catch_ie8: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -44,11 +44,11 @@ mangle_catch_ie8: {

 mangle_catch_var: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -66,11 +66,11 @@ mangle_catch_var: {

 mangle_catch_var_ie8: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -88,11 +88,11 @@ mangle_catch_var_ie8: {

 mangle_catch_toplevel: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -110,11 +110,11 @@ mangle_catch_toplevel: {

 mangle_catch_ie8_toplevel: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -132,11 +132,11 @@ mangle_catch_ie8_toplevel: {

 mangle_catch_var_toplevel: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -154,11 +154,11 @@ mangle_catch_var_toplevel: {

 mangle_catch_var_ie8_toplevel: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -176,11 +176,11 @@ mangle_catch_var_ie8_toplevel: {

 mangle_catch_redef_1: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -198,11 +198,11 @@ mangle_catch_redef_1: {

 mangle_catch_redef_1_ie8: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -220,11 +220,11 @@ mangle_catch_redef_1_ie8: {

 mangle_catch_redef_1_toplevel: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -242,11 +242,11 @@ mangle_catch_redef_1_toplevel: {

 mangle_catch_redef_1_ie8_toplevel: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -264,11 +264,11 @@ mangle_catch_redef_1_ie8_toplevel: {

 mangle_catch_redef_2: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -285,11 +285,11 @@ mangle_catch_redef_2: {

 mangle_catch_redef_2_ie8: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -306,11 +306,11 @@ mangle_catch_redef_2_ie8: {

 mangle_catch_redef_2_toplevel: {
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -327,11 +327,11 @@ mangle_catch_redef_2_toplevel: {

 mangle_catch_redef_2_ie8_toplevel: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -348,7 +348,7 @@ mangle_catch_redef_2_ie8_toplevel: {

 mangle_catch_redef_3: {
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -356,6 +356,7 @@ mangle_catch_redef_3: {
        try {
            throw 0;
        } catch (o) {
+            // prints "FAIL" if inlined on Node.js v4-
            (function() {
                function f() {
                    o = "FAIL";
@@ -366,12 +367,13 @@ mangle_catch_redef_3: {
        console.log(o);
    }
    expect_exact: 'var o="PASS";try{throw 0}catch(o){(function(){function c(){o="FAIL"}c(),c()})()}console.log(o);'
-    expect_stdout: true
+    expect_stdout: "PASS"
+    node_version: ">=6"
 }

 mangle_catch_redef_3_toplevel: {
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -379,6 +381,7 @@ mangle_catch_redef_3_toplevel: {
        try {
            throw 0;
        } catch (o) {
+            // prints "FAIL" if inlined on Node.js v4-
            (function() {
                function f() {
                    o = "FAIL";
@@ -389,12 +392,13 @@ mangle_catch_redef_3_toplevel: {
        console.log(o);
    }
    expect_exact: 'var c="PASS";try{throw 0}catch(c){(function(){function o(){c="FAIL"}o(),o()})()}console.log(c);'
-    expect_stdout: true
+    expect_stdout: "PASS"
+    node_version: ">=6"
 }

 mangle_catch_redef_3_ie8: {
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -402,6 +406,7 @@ mangle_catch_redef_3_ie8: {
        try {
            throw 0;
        } catch (o) {
+            // prints "FAIL" if inlined on Node.js v4-
            (function() {
                function f() {
                    o = "FAIL";
@@ -412,12 +417,13 @@ mangle_catch_redef_3_ie8: {
        console.log(o);
    }
    expect_exact: 'var o="PASS";try{throw 0}catch(o){(function(){function c(){o="FAIL"}c(),c()})()}console.log(o);'
-    expect_stdout: true
+    expect_stdout: "PASS"
+    node_version: ">=6"
 }

 mangle_catch_redef_3_ie8_toplevel: {
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -425,6 +431,7 @@ mangle_catch_redef_3_ie8_toplevel: {
        try {
            throw 0;
        } catch (o) {
+            // prints "FAIL" if inlined on Node.js v4-
            (function() {
                function f() {
                    o = "FAIL";
@@ -435,5 +442,6 @@ mangle_catch_redef_3_ie8_toplevel: {
        console.log(o);
    }
    expect_exact: 'var c="PASS";try{throw 0}catch(c){(function(){function o(){c="FAIL"}o(),o()})()}console.log(c);'
-    expect_stdout: true
+    expect_stdout: "PASS"
+    node_version: ">=6"
 }
--- a/test/compress/issue-1733.js
+++ b/test/compress/issue-1733.js
@@ -1,6 +1,6 @@
 function_iife_catch: {
    mangle = {
-        ie8: false,
+        ie: false,
    }
    input: {
        function f(n) {
@@ -21,7 +21,7 @@ function_iife_catch: {

 function_iife_catch_ie8: {
    mangle = {
-        ie8: true,
+        ie: true,
    }
    input: {
        function f(n) {
@@ -42,7 +42,7 @@ function_iife_catch_ie8: {

 function_catch_catch: {
    mangle = {
-        ie8: false,
+        ie: false,
    }
    input: {
        var o = 0;
@@ -70,7 +70,7 @@ function_catch_catch: {

 function_catch_catch_ie8: {
    mangle = {
-        ie8: true,
+        ie: true,
    }
    input: {
        var o = 0;
--- a/test/compress/issue-892.js
+++ b/test/compress/issue-892.js
@@ -1,6 +1,4 @@
 dont_mangle_arguments: {
-    mangle = {
-    };
    options = {
        booleans: true,
        comparisons: true,
@@ -21,12 +19,13 @@ dont_mangle_arguments: {
        side_effects: true,
        unused: true,
    }
+    mangle = {}
    input: {
        (function(){
            var arguments = arguments, not_arguments = 9;
            console.log(not_arguments, arguments);
        })(5, 6, 7);
    }
-    expect_exact: "(function(){var arguments=arguments,o=9;console.log(o,arguments)})(5,6,7);"
+    expect_exact: "(function(){var arguments,o=9;console.log(o,arguments)})(5,6,7);"
    expect_stdout: true
 }
--- a/test/compress/join_vars.js
+++ b/test/compress/join_vars.js
@@ -489,6 +489,160 @@ join_object_assignments_regex: {
    expect_stdout: "1"
 }

+chained_assignments: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        var a, b = a = {};
+        b.p = "PASS";
+        console.log(a.p);
+    }
+    expect: {
+        var a, b = a = {
+            p: "PASS",
+        };
+        console.log(a.p);
+    }
+    expect_stdout: "PASS"
+}
+
+folded_assignments_1: {
+    options = {
+        evaluate: true,
+        join_vars: true,
+    }
+    input: {
+        var a = {};
+        a[a.PASS = 42] = "PASS";
+        console.log(a[42], a.PASS);
+    }
+    expect: {
+        var a = {
+            PASS: 42,
+            42: "PASS",
+        };
+        console.log(a[42], a.PASS);
+    }
+    expect_stdout: "PASS 42"
+}
+
+folded_assignments_2: {
+    options = {
+        evaluate: true,
+        join_vars: true,
+    }
+    input: {
+        "use strict";
+        var a = {};
+        a[42] = "FAIL";
+        a[a.PASS = 42] = "PASS";
+        console.log(a[42], a.PASS);
+    }
+    expect: {
+        "use strict";
+        var a = {
+            42: "FAIL",
+            PASS: 42,
+        };
+        a[42] = "PASS";
+        console.log(a[42], a.PASS);
+    }
+    expect_stdout: "PASS 42"
+}
+
+inlined_assignments: {
+    options = {
+        join_vars: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        (a = {}).p = "PASS";
+        console.log(a.p);
+    }
+    expect: {
+        var a = {
+            p: "PASS",
+        };
+        console.log(a.p);
+    }
+    expect_stdout: "PASS"
+}
+
+inilne_for: {
+    options = {
+        inline: true,
+        join_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = function() {
+            for (; console.log("PASS"););
+        };
+        a();
+    }
+    expect: {
+        for (; console.log("PASS"););
+    }
+    expect_stdout: "PASS"
+}
+
+inilne_var: {
+    options = {
+        inline: true,
+        join_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        A = "PASS";
+        var a = function() {
+            var b = A;
+            for (b in console.log(b));
+        };
+        a();
+    }
+    expect: {
+        A = "PASS";
+        var b = A;
+        for (b in console.log(b));
+    }
+    expect_stdout: "PASS"
+}
+
+typescript_enum: {
+    rename = true
+    options = {
+        assignments: true,
+        collapse_vars: true,
+        evaluate: true,
+        hoist_props: true,
+        inline: true,
+        join_vars: true,
+        passes: 4,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var Enum;
+        (function (Enum) {
+            Enum[Enum.PASS = 42] = "PASS";
+        })(Enum || (Enum = {}));
+        console.log(Enum[42], Enum.PASS);
+    }
+    expect: {
+        console.log("PASS", 42);
+    }
+    expect_stdout: "PASS 42"
+}
+
 issue_2816: {
    options = {
        join_vars: true,
@@ -1015,7 +1169,7 @@ issue_3856: {
        console.log(function() {
            (function() {
                var a, b;
-                if (a) return !!a;
+                if (a) return a, 1;
                for (a = 0; !console;);
                return 0;
            })();
@@ -1172,10 +1326,7 @@ assign_sequence_var: {
        console.log(a, b, c);
    }
    expect: {
-        var a = 0, b = 1;
-        console.log(a),
-        a++;
-        var b = 2, c = 3;
+        var a = 0, b = 1, c = (console.log(a), a++, b = 2, 3);
        console.log(a, b, c);
    }
    expect_stdout: [
@@ -1183,3 +1334,26 @@ assign_sequence_var: {
        "1 2 3",
    ]
 }
+
+issue_5175: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        function log(f) {
+            console.log(f(), A.p);
+        }
+        log(function() {
+            return (A = {}).p = "PASS";
+        });
+    }
+    expect: {
+        function log(f) {
+            console.log(f(), A.p);
+        }
+        log(function() {
+            return (A = {}).p = "PASS";
+        });
+    }
+    expect_stdout: "PASS PASS"
+}
--- a/test/compress/keep_fargs.js
+++ b/test/compress/keep_fargs.js
@@ -181,10 +181,10 @@ issue_2203_2: {
            a: "FAIL",
            b: function() {
                return function() {
-                    return (String, (Object, function() {
+                    return (Object, function() {
                        return this;
-                    }())).a;
-                }();
+                    }()).a;
+                }(String);
            }
        }.b());
    }
@@ -925,6 +925,28 @@ duplicate_lambda_defun_name_2: {
    expect_stdout: "0"
 }

+function_argument_mangle: {
+    mangle = {
+        keep_fargs: true,
+        toplevel: true,
+    }
+    input: {
+        A = "PASS";
+        var a = A;
+        (function(o) {
+            console.log(a);
+        })("FAIL");
+    }
+    expect: {
+        A = "PASS";
+        var n = A;
+        (function(o) {
+            console.log(n);
+        })("FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
 function_name_mangle: {
    options = {
        keep_fargs: false,
@@ -951,7 +973,7 @@ function_name_mangle_ie8: {
        unused: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -1217,6 +1239,7 @@ issues_3267_1: {
        evaluate: true,
        inline: true,
        keep_fargs: false,
+        negate_iife: true,
        reduce_vars: true,
        sequences: true,
        side_effects: true,
@@ -1235,7 +1258,8 @@ issues_3267_1: {
    }
    expect: {
        !function() {
-            if (Object())
+            var i = Object();
+            if (i)
                return console.log("PASS");
            throw "FAIL";
        }();
--- a/test/compress/labels.js
+++ b/test/compress/labels.js
@@ -83,8 +83,9 @@ labels_5: {
        conditionals: true,
        dead_code: true,
        if_return: true,
+        unused: true,
    }
-    // should keep the break-s in the following
+    // should keep `break`s below
    input: {
        while (foo) {
            if (bar) break;
@@ -100,8 +101,8 @@ labels_5: {
            if (bar) break;
            console.log("foo");
        }
-        out: while (foo) {
-            if (bar) break out;
+        while (foo) {
+            if (bar) break;
            console.log("foo");
        }
    }
@@ -189,23 +190,22 @@ labels_10: {
        conditionals: true,
        dead_code: true,
        if_return: true,
+        unused: true,
    }
    input: {
-        out: while (foo) {
-            x();
-            y();
+        out: while (42) {
+            console.log("PASS");
            break out;
-            z();
-            k();
+            console.log("FAIL");
        }
    };
    expect: {
-        out: while (foo) {
-            x();
-            y();
-            break out;
+        while (42) {
+            console.log("PASS");
+            break;
        }
    }
+    expect_stdout: "PASS"
 }

 issue_4466_1: {
--- a/test/compress/let.js
+++ b/test/compress/let.js
@@ -1,4 +1,4 @@
-retain_block: {
+retain_block_1: {
    options = {}
    input: {
        "use strict";
@@ -20,6 +20,94 @@ retain_block: {
    node_version: ">=4"
 }

+retain_block_2: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        {
+            var a;
+            let a;
+        }
+    }
+    expect: {
+        "use strict";
+        {
+            var a;
+            let a;
+        }
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+retain_block_2_mangle: {
+    rename = true
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        {
+            var a;
+            let a;
+        }
+    }
+    expect: {
+        "use strict";
+        {
+            var t;
+            let t;
+        }
+    }
+}
+
+retain_block_3: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        {
+            let a;
+            var a;
+        }
+    }
+    expect: {
+        "use strict";
+        {
+            let a;
+            var a;
+        }
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+retain_block_3_mangle: {
+    rename = true
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        {
+            let a;
+            var a;
+        }
+    }
+    expect: {
+        "use strict";
+        {
+            let t;
+            var t;
+        }
+    }
+}
+
 retain_assignment: {
    options = {
        dead_code: true,
@@ -182,8 +270,8 @@ merge_vars_3: {
            var b = console;
            console.log(typeof b);
        }
-        var a = 1;
-        console.log(typeof a);
+        var b = 1;
+        console.log(typeof b);
    }
    expect_stdout: [
        "object",
@@ -192,6 +280,38 @@ merge_vars_3: {
    node_version: ">=4"
 }

+merge_vars_4: {
+    options = {
+        merge_vars: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        var a = 1;
+        console.log(typeof a);
+        {
+            var b = console;
+            console.log(typeof b);
+            let a = 0;
+        }
+    }
+    expect: {
+        "use strict";
+        var a = 1;
+        console.log(typeof a);
+        {
+            var b = console;
+            console.log(typeof b);
+            let a = 0;
+        }
+    }
+    expect_stdout: [
+        "number",
+        "object",
+    ]
+    node_version: ">=4"
+}
+
 use_before_init_1: {
    options = {
        evaluate: true,
@@ -494,6 +614,41 @@ reduce_vars_3: {
    node_version: ">=4"
 }

+reduce_lambda: {
+    options = {
+        evaluate: true,
+        functions: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        let f = function() {
+            console.log(a, b);
+        };
+        let a = "foo", b = 42;
+        f();
+        b = "bar";
+        f();
+    }
+    expect: {
+        "use strict";
+        function f() {
+            console.log("foo", b);
+        }
+        let b = 42;
+        f();
+        b = "bar";
+        f();
+    }
+    expect_stdout: [
+        "foo 42",
+        "foo bar",
+    ]
+    node_version: ">=4"
+}
+
 hoist_props: {
    options = {
        hoist_props: true,
@@ -931,12 +1086,10 @@ issue_4202: {
        "use strict";
        {
            let o = {};
-            (function() {
            function f() {
                o.p = 42;
            }
            f(f);
-            })();
            console.log(o.p++);
        }
    }
@@ -1129,7 +1282,7 @@ issue_4225: {

 issue_4229: {
    options = {
-        ie8: true,
+        ie: true,
        side_effects: true,
    }
    input: {
@@ -1160,7 +1313,7 @@ issue_4229: {

 issue_4231: {
    options = {
-        ie8: true,
+        ie: true,
        side_effects: true,
    }
    input: {
@@ -1518,7 +1671,7 @@ issue_4438: {
                ;
            else {
                let a = console.log;
-                a("PASS");
+                void a("PASS");
            }
        }
        f();
@@ -1529,7 +1682,7 @@ issue_4438: {

 issue_4531_1: {
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -1555,11 +1708,11 @@ issue_4531_1: {
 issue_4531_2: {
    options = {
        evaluate: true,
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -1712,3 +1865,111 @@ issue_4985: {
    expect_stdout: "undefined"
    node_version: ">=4"
 }
+
+issue_5240: {
+    options = {
+        inline: true,
+    }
+    input: {
+        "use strict";
+        function f() {
+            if (console) {
+                let g = function() {
+                    e;
+                }, e;
+                (function() {
+                    if (console) {
+                        console.log(e);
+                        var e = "FAIL";
+                    }
+                })(console.log(e));
+            }
+        }
+        f();
+    }
+    expect: {
+        "use strict";
+        function f() {
+            if (console) {
+                let g = function() {
+                    e;
+                }, e;
+                (function() {
+                    if (console) {
+                        console.log(e);
+                        var e = "FAIL";
+                    }
+                })(console.log(e));
+            }
+        }
+        f();
+    }
+    expect_stdout: [
+        "undefined",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+issue_5254: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        do {
+            (function() {
+                let a = console.log;
+                a && a("foo");
+            })();
+        } while (console.log("bar"));
+    }
+    expect: {
+        "use strict";
+        do {
+            let a = console.log;
+            a && a("foo");
+        } while (console.log("bar"));
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=4"
+}
+
+issue_5260: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        "use strict";
+        var a = "foo", o;
+        while (console.log("bar"));
+        o = {
+            baz: function(b) {
+                console.log(a, b);
+            },
+        };
+        for (let a in o)
+            o[a](a);
+    }
+    expect: {
+        "use strict";
+        var a = "foo", o;
+        while (console.log("bar"));
+        o = {
+            baz: function(b) {
+                console.log(a, b);
+            },
+        };
+        for (let a in o)
+            o[a](a);
+    }
+    expect_stdout: [
+        "bar",
+        "foo baz",
+    ]
+    node_version: ">=4"
+}
--- a/test/compress/loops.js
+++ b/test/compress/loops.js
@@ -265,7 +265,7 @@ issue_1532_2: {
 issue_186: {
    beautify = {
        beautify: false,
-        ie8: false,
+        ie: false,
    }
    input: {
        var x = 3;
@@ -284,7 +284,7 @@ issue_186: {
 issue_186_ie8: {
    beautify = {
        beautify: false,
-        ie8: true,
+        ie: true,
    }
    input: {
        var x = 3;
@@ -303,7 +303,7 @@ issue_186_ie8: {
 issue_186_beautify: {
    beautify = {
        beautify: true,
-        ie8: false,
+        ie: false,
    }
    input: {
        var x = 3;
@@ -330,7 +330,7 @@ issue_186_beautify: {
 issue_186_beautify_ie8: {
    beautify = {
        beautify: true,
-        ie8: true,
+        ie: true,
    }
    input: {
        var x = 3;
@@ -360,7 +360,7 @@ issue_186_braces: {
    beautify = {
        beautify: false,
        braces: true,
-        ie8: false,
+        ie: false,
    }
    input: {
        var x = 3;
@@ -380,7 +380,7 @@ issue_186_braces_ie8: {
    beautify = {
        beautify: false,
        braces: true,
-        ie8: true,
+        ie: true,
    }
    input: {
        var x = 3;
@@ -400,7 +400,7 @@ issue_186_beautify_braces: {
    beautify = {
        beautify: true,
        braces: true,
-        ie8: false,
+        ie: false,
    }
    input: {
        var x = 3;
@@ -432,7 +432,7 @@ issue_186_beautify_braces_ie8: {
    beautify = {
        beautify: true,
        braces: true,
-        ie8: true,
+        ie: true,
    }
    input: {
        var x = 3;
--- a/test/compress/merge_vars.js
+++ b/test/compress/merge_vars.js
@@ -19,11 +19,11 @@ merge: {
    expect: {
        var a = "foo";
        console.log(a);
-        function f(c) {
-            var c;
-            console.log(c);
-            c = "bar";
-            console.log(c);
+        function f(b) {
+            var b;
+            console.log(b);
+            b = "bar";
+            console.log(b);
        }
        f("baz");
        var d = "moo";
@@ -56,17 +56,17 @@ merge_toplevel: {
        console.log(d);
    }
    expect: {
-        var d = "foo";
-        console.log(d);
-        function f(c) {
-            var c;
-            console.log(c);
-            c = "bar";
-            console.log(c);
+        var a = "foo";
+        console.log(a);
+        function f(b) {
+            var b;
+            console.log(b);
+            b = "bar";
+            console.log(b);
        }
        f("baz");
-        var d = "moo";
-        console.log(d);
+        var a = "moo";
+        console.log(a);
    }
    expect_stdout: [
        "foo",
@@ -94,16 +94,16 @@ segment: {
        console.log(d);
    }
    expect: {
-        var d = "foo";
-        console.log(d);
-        for (var c, i = 0; i < 1; i++) {
-            var c = "bar";
-            console.log(c);
-            c = "baz";
-            console.log(c);
+        var a = "foo";
+        console.log(a);
+        for (var b, i = 0; i < 1; i++) {
+            var b = "bar";
+            console.log(b);
+            b = "baz";
+            console.log(b);
        }
-        var d = "moo";
-        console.log(d);
+        var a = "moo";
+        console.log(a);
    }
    expect_stdout: [
        "foo",
@@ -298,6 +298,89 @@ read_before_assign_2: {
    expect_stdout: "PASS"
 }

+collapse_vars_1: {
+    options = {
+        collapse_vars: true,
+        merge_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = a && a.p;
+        var b = "PASS";
+        var b = b && console.log(b);
+    }
+    expect: {
+        var a = a && a.p;
+        var a;
+        var a = (a = "PASS") && console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
+collapse_vars_2: {
+    options = {
+        collapse_vars: true,
+        merge_vars: true,
+    }
+    input: {
+        "use strict";
+        var log = console.log;
+        (function g(a) {
+            var b = a;
+            var c = Math.random();
+            var c = b;
+            log(c);
+            return c;
+        })("PASS");
+    }
+    expect: {
+        "use strict";
+        var log = console.log;
+        (function g(a) {
+            var a = a;
+            var c = Math.random();
+            var c;
+            log(c = a);
+            return c;
+        })("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+not_redefined: {
+    options = {
+        inline: true,
+        join_vars: true,
+        merge_vars: true,
+        reduce_vars: true,
+        unused: true,
+        varify: true,
+    }
+    input: {
+        var log = console.log;
+        (function() {
+            return f("PASS");
+            function f(a) {
+                const b = a;
+                const c = log(b);
+                const d = log;
+                c && log(d);
+            }
+        })();
+    }
+    expect: {
+        var log = console.log;
+        (function() {
+            return a = "PASS",
+                a = log(a),
+                d = log,
+                void (a && log(d));
+            var a, d;
+        })();
+    }
+    expect_stdout: "PASS"
+}
+
 issue_4103: {
    options = {
        merge_vars: true,
@@ -325,7 +408,7 @@ issue_4103: {
    ]
 }

-issue_4107: {
+issue_4107_1: {
    options = {
        keep_fargs: false,
        merge_vars: true,
@@ -342,6 +425,38 @@ issue_4107: {
        })();
        console.log(typeof a);
    }
+    expect: {
+        (function() {
+            (function(c) {
+                c = console || c;
+                console.log(typeof c);
+            })();
+        })();
+        console.log(typeof a);
+    }
+    expect_stdout: [
+        "object",
+        "undefined",
+    ]
+}
+
+issue_4107_2: {
+    options = {
+        keep_fargs: false,
+        merge_vars: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            function f(b, b, a) {
+                var d = 1 && c, c = console || a;
+                console.log(typeof c);
+            }
+            f();
+        })();
+        console.log(typeof a);
+    }
    expect: {
        (function() {
            (function(a) {
@@ -359,7 +474,7 @@ issue_4107: {

 issue_4109: {
    options = {
-        ie8: true,
+        ie: true,
        merge_vars: true,
        toplevel: true,
    }
@@ -476,9 +591,9 @@ issue_4112: {
            try {
                throw 42;
            } catch (e) {
-                var a = e;
-                for (e in a);
-                a = function() {};
+                var o = e;
+                for (e in o);
+                function a() {}
                console.log(typeof a);
                return a;
            }
@@ -538,12 +653,12 @@ cross_branch_1_1: {
    expect: {
        var a;
        function f() {
-            var y, y;
+            var x, x;
            if (a)
-                y = "foo";
-            console.log(y);
-            y = "bar";
-            console.log(y);
+                x = "foo";
+            console.log(x);
+            x = "bar";
+            console.log(x);
        }
        a = 0;
        f();
@@ -581,13 +696,13 @@ cross_branch_1_2: {
    expect: {
        var a;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
-                y = "foo";
-                console.log(y);
+                x = "foo";
+                console.log(x);
            }
-            y = "bar";
-            console.log(y);
+            x = "bar";
+            console.log(x);
        }
        a = 0;
        f();
@@ -624,13 +739,13 @@ cross_branch_1_3: {
    expect: {
        var a;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
-                y = "foo";
-                console.log(y);
-                y = "bar";
+                x = "foo";
+                console.log(x);
+                x = "bar";
            }
-            console.log(y);
+            console.log(x);
        }
        a = 0;
        f();
@@ -666,12 +781,12 @@ cross_branch_1_4: {
    expect: {
        var a;
        function f() {
-            var y, y;
-            y = "foo";
+            var x, x;
+            x = "foo";
            if (a)
-                console.log(y);
-            y = "bar";
-            console.log(y);
+                console.log(x);
+            x = "bar";
+            console.log(x);
        }
        a = 0;
        f();
@@ -751,12 +866,12 @@ cross_branch_1_6: {
    expect: {
        var a;
        function f() {
-            var y, y;
-            y = "foo";
+            var x, x;
+            x = "foo";
            if (a) {
-                console.log(y);
-                y = "bar";
-                console.log(y);
+                console.log(x);
+                x = "bar";
+                console.log(x);
            }
        }
        a = 0;
@@ -835,12 +950,12 @@ cross_branch_1_8: {
    expect: {
        var a;
        function f() {
-            var y, y;
-            y = "foo";
-            console.log(y);
+            var x, x;
+            x = "foo";
+            console.log(x);
            if (a) {
-                y = "bar";
-                console.log(y);
+                x = "bar";
+                console.log(x);
            }
        }
        a = 0;
@@ -877,12 +992,12 @@ cross_branch_1_9: {
    expect: {
        var a;
        function f() {
-            var y, y;
-            y = "foo";
-            console.log(y);
-            y = "bar";
+            var x, x;
+            x = "foo";
+            console.log(x);
+            x = "bar";
            if (a)
-                console.log(y);
+                console.log(x);
        }
        a = 0;
        f();
@@ -924,14 +1039,14 @@ cross_branch_2a_1: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
                if (b)
-                    y = "foo";
-                console.log(y);
+                    x = "foo";
+                console.log(x);
            }
-            y = "bar";
-            console.log(y);
+            x = "bar";
+            console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -980,14 +1095,14 @@ cross_branch_2a_2: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
-                y = "foo";
+                x = "foo";
                if (b)
-                    console.log(y);
+                    console.log(x);
            }
-            y = "bar";
-            console.log(y);
+            x = "bar";
+            console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -1035,14 +1150,14 @@ cross_branch_2a_3: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
                if (b)
-                    y = "foo";
-                console.log(y);
-                y = "bar";
+                    x = "foo";
+                console.log(x);
+                x = "bar";
            }
-            console.log(y);
+            console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -1092,15 +1207,15 @@ cross_branch_2a_4: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
                if (b) {
-                    y = "foo";
-                    console.log(y);
+                    x = "foo";
+                    console.log(x);
                }
-                y = "bar";
+                x = "bar";
            }
-            console.log(y);
+            console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -1148,14 +1263,14 @@ cross_branch_2a_5: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
-                y = "foo";
+                x = "foo";
                if (b)
-                    console.log(y);
-                y = "bar";
+                    console.log(x);
+                x = "bar";
            }
-            console.log(y);
+            console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -1427,13 +1542,13 @@ cross_branch_2a_10: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
-            y = "foo";
+            var x, x;
+            x = "foo";
            if (a) {
                if (b)
-                    console.log(y);
-                y = "bar";
-                console.log(y);
+                    console.log(x);
+                x = "bar";
+                console.log(x);
            }
        }
        a = 0, b = 0;
@@ -1590,13 +1705,13 @@ cross_branch_2a_13: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
-            y = "foo";
+            var x, x;
+            x = "foo";
            if (a) {
-                console.log(y);
+                console.log(x);
                if (b) {
-                    y = "bar";
-                    console.log(y);
+                    x = "bar";
+                    console.log(x);
                }
            }
        }
@@ -1644,13 +1759,13 @@ cross_branch_2a_14: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
-            y = "foo";
+            var x, x;
+            x = "foo";
            if (a) {
-                console.log(y);
-                y = "bar";
+                console.log(x);
+                x = "bar";
                if (b)
-                    console.log(y);
+                    console.log(x);
            }
        }
        a = 0, b = 0;
@@ -1753,13 +1868,13 @@ cross_branch_2a_16: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
-            y = "foo";
-            console.log(y);
+            var x, x;
+            x = "foo";
+            console.log(x);
            if (a) {
-                y = "bar";
+                x = "bar";
                if (b)
-                    console.log(y);
+                    console.log(x);
            }
        }
        a = 0, b = 0;
@@ -1807,13 +1922,13 @@ cross_branch_2b_1: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a)
-                y = "foo";
+                x = "foo";
            if (b)
-                console.log(y);
-            y = "bar";
-            console.log(y);
+                console.log(x);
+            x = "bar";
+            console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -1918,13 +2033,13 @@ cross_branch_2b_3: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a)
-                y = "foo";
+                x = "foo";
            if (b) {
-                console.log(y);
-                y = "bar";
-                console.log(y);
+                console.log(x);
+                x = "bar";
+                console.log(x);
            }
        }
        a = 0, b = 0;
@@ -2028,13 +2143,13 @@ cross_branch_2b_5: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a)
-                y = "foo";
-            console.log(y);
+                x = "foo";
+            console.log(x);
            if (b) {
-                y = "bar";
-                console.log(y);
+                x = "bar";
+                console.log(x);
            }
        }
        a = 0, b = 0;
@@ -2141,14 +2256,14 @@ cross_branch_2b_7: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
-                y = "foo";
-                console.log(y);
+                x = "foo";
+                console.log(x);
            }
            if (b) {
-                y = "bar";
-                console.log(y);
+                x = "bar";
+                console.log(x);
            }
        }
        a = 0, b = 0;
@@ -2195,13 +2310,13 @@ cross_branch_2b_8: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a)
-                y = "foo";
-            console.log(y);
-            y = "bar";
+                x = "foo";
+            console.log(x);
+            x = "bar";
            if (b)
-                console.log(y);
+                console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -2250,14 +2365,14 @@ cross_branch_2b_9: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
-                y = "foo";
-                console.log(y);
+                x = "foo";
+                console.log(x);
            }
-            y = "bar";
+            x = "bar";
            if (b)
-                console.log(y);
+                console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -2304,14 +2419,14 @@ cross_branch_2b_10: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
+            var x, x;
            if (a) {
-                y = "foo";
-                console.log(y);
-                y = "bar";
+                x = "foo";
+                console.log(x);
+                x = "bar";
            }
            if (b)
-                console.log(y);
+                console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -2412,13 +2527,13 @@ cross_branch_2b_12: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
-            y = "foo";
+            var x, x;
+            x = "foo";
            if (a)
-                console.log(y);
+                console.log(x);
            if (b) {
-                y = "bar";
-                console.log(y);
+                x = "bar";
+                console.log(x);
            }
        }
        a = 0, b = 0;
@@ -2465,13 +2580,13 @@ cross_branch_2b_13: {
    expect: {
        var a, b;
        function f() {
-            var y, y;
-            y = "foo";
+            var x, x;
+            x = "foo";
            if (a)
-                console.log(y);
-            y = "bar";
+                console.log(x);
+            x = "bar";
            if (b)
-                console.log(y);
+                console.log(x);
        }
        a = 0, b = 0;
        f();
@@ -2620,11 +2735,11 @@ issue_4126_1: {
            try {
                console.log("PASS");
            } catch (e) {
-                var c = a;
+                var b = a;
            } finally {
-                var c = c;
+                var a = b;
            }
-            console.log(c);
+            console.log(a);
        }
        f("FAIL");
    }
@@ -2735,8 +2850,7 @@ issue_4135: {
        0;
        a++;
        if (!a)
-            c = (a++, c = 0, void (c && c.p));
-        var c;
+            var c = void a++;
        console.log(a, -1, c);
    }
    expect_stdout: "1 -1 undefined"
@@ -2817,11 +2931,11 @@ conditional_write: {
        console.log(b);
    }
    expect: {
-        var b = "FAIL", b;
+        var a = "FAIL", a;
        if (console)
-            b = "PASS";
-        b = [b, 42].join();
-        console.log(b);
+            a = "PASS";
+        a = [a, 42].join();
+        console.log(a);
    }
    expect_stdout: "PASS,42"
 }
@@ -2995,13 +3109,13 @@ issue_4168_use_strict: {
    expect: {
        "use strict";
        var o = {
-            f: function(d, e, f) {
-                var d = d.d;
-                var e = e.e;
-                var f = f.f;
+            f: function(a, b, c) {
+                var a = a.d;
+                var b = b.e;
+                var c = c.f;
                this.g(arguments);
-                if (d)
-                    console.log(e, f);
+                if (a)
+                    console.log(b, c);
            },
            g: function(args) {
                console.log(args[0], args[1], args[2]);
@@ -3075,7 +3189,7 @@ issue_4237_2: {
        console.log(function(a) {
            do {
                switch (0) {
-                  case 0:
+                  default:
                    var b = a++;
                    if (b)
                        return "FAIL";
@@ -3229,10 +3343,10 @@ issue_4653: {
        f(a++ + (b = b), b |= console.log(a));
    }
    expect: {
-        var b = 1;
+        var b, a = 1;
        (function(c, d) {
            c || console.log(d);
-        })(+b + (b = void 0), b |= console.log(2));
+        })(+a + (b = b), b |= console.log(2));
    }
    expect_stdout: [
        "2",
@@ -3378,3 +3492,60 @@ issue_4956_2: {
    }
    expect_stdout: "42"
 }
+
+issue_5182: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        evaluate: true,
+        hoist_props: true,
+        inline: true,
+        merge_vars: true,
+        passes: 4,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        try {
+            var con = console;
+        } catch (x) {}
+        global.log = con.log;
+        var jump = function(x) {
+            console.log("JUMP:", x * 10);
+            return x + x;
+        };
+        var jump2 = jump;
+        var run = function(x) {
+            console.log("RUN:", x * -10);
+            return x * x;
+        };
+        var run2 = run;
+        var bar = (x, y) => {
+            console.log("BAR:", x + y);
+            return x - y;
+        };
+        var bar2 = bar;
+        var obj = {
+            foo: bar2,
+            go: run2,
+            not_used: jump2,
+        };
+        console.log(obj.foo(1, 2), global.log("PASS"));
+    }
+    expect: {
+        try {
+            var con = console;
+        } catch (x) {}
+        global.log = con.log,
+        console.log((console.log("BAR:", 3), -1), global.log("PASS"));
+    }
+    expect_stdout: [
+        "BAR: 3",
+        "PASS",
+        "-1 undefined",
+    ]
+    node_version: ">=4"
+}
--- a/test/compress/negate-iife.js
+++ b/test/compress/negate-iife.js
@@ -389,6 +389,7 @@ issue_1288_side_effects: {
    options = {
        conditionals: true,
        negate_iife: true,
+        sequences: true,
        side_effects: true,
    }
    input: {
@@ -409,10 +410,10 @@ issue_1288_side_effects: {
            })(0);
    }
    expect: {
-        w;
+        w,
        x || function() {
            x = {};
-        }();
+        }(),
        y;
    }
 }
--- a/test/compress/nullish.js
+++ b/test/compress/nullish.js
@@ -110,10 +110,186 @@ conditional_assignment_4: {
    node_version: ">=14"
 }

+de_morgan_1: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        function f(a) {
+            return a ?? a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect: {
+        function f(a) {
+            return a;
+        }
+        console.log(f(null), f(42));
+    }
+    expect_stdout: "null 42"
+    node_version: ">=14"
+}
+
+de_morgan_2a: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a || (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a || (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2b: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a && (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2c: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ?? (a || b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a ?? b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2d: {
+    options = {
+        booleans: true,
+        evaluate: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ?? (a && b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "null null",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+de_morgan_2e: {
+    options = {
+        booleans: true,
+        conditionals: true,
+    }
+    input: {
+        function f(a, b) {
+            return a ?? (a ?? b);
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect: {
+        function f(a, b) {
+            return a ?? b;
+        }
+        console.log(f(null), f(null, {}));
+        console.log(f(42), f(42, {}));
+    }
+    expect_stdout: [
+        "undefined {}",
+        "42 42",
+    ]
+    node_version: ">=14"
+}
+
+inline_binary_nullish: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (function() {
+            while (console.log("foo"));
+        })() ?? (function() {
+            while (console.log("bar"));
+        })();
+    }
+    expect: {
+        if (null == function() {
+            while (console.log("foo"));
+        }())
+            while (console.log("bar"));
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=14"
+}
+
 issue_4679: {
    options = {
        comparisons: true,
-        ie8: true,
+        ie: true,
    }
    input: {
        var a;
@@ -128,3 +304,42 @@ issue_4679: {
    expect_stdout: "PASS"
    node_version: ">=14"
 }
+
+issue_5266: {
+    options = {
+        inline: true,
+    }
+    input: {
+        [
+            42,
+            null,
+            false,
+            void 0,
+            "FAIL",
+        ].forEach(function (a) {
+            a ?? function() {
+                while (console.log(a));
+            }();
+        });
+    }
+    expect: {
+        [
+            42,
+            null,
+            false,
+            void 0,
+            "FAIL",
+        ].forEach(function (a) {
+            if (null == a) {
+                while (console.log(a));
+                return;
+            } else
+                return;
+        });
+    }
+    expect_stdout: [
+        "null",
+        "undefined",
+    ]
+    node_version: ">=14"
+}
--- a/test/compress/objects.js
+++ b/test/compress/objects.js
@@ -521,3 +521,25 @@ issue_4415: {
    expect_stdout: "PASS"
    node_version: ">=4"
 }
+
+issue_5213: {
+    options = {
+        objects: true,
+    }
+    input: {
+        var a = "FAIL";
+        console.log({
+            p: a = "PASS",
+            0: a,
+            p: null,
+        }[0]);
+    }
+    expect: {
+        var a = "FAIL";
+        console.log({
+            p: (a = "PASS", null),
+            0: a,
+        }[0]);
+    }
+    expect_stdout: "PASS"
+}
--- a/test/compress/optional-chains.js
+++ b/test/compress/optional-chains.js
@@ -58,7 +58,7 @@ assign_parentheses_dot: {
    input: {
        (console?.log).name.p = console.log("PASS");
    }
-    expect_exact: '(console?.log.name).p=console.log("PASS");'
+    expect_exact: '(console?.log).name.p=console.log("PASS");'
    expect_stdout: "PASS"
    node_version: ">=14"
 }
@@ -72,6 +72,26 @@ assign_no_parentheses: {
    node_version: ">=14"
 }

+call_parentheses: {
+    input: {
+        (function(o) {
+            console.log(o.f("FAIL"), (o.f)("FAIL"), (0, o.f)(42));
+            console.log(o?.f("FAIL"), (o?.f)("FAIL"), (0, o?.f)(42));
+        })({
+            a: "PASS",
+            f(b) {
+                return this.a || b;
+            },
+        });
+    }
+    expect_exact: '(function(o){console.log(o.f("FAIL"),o.f("FAIL"),(0,o.f)(42));console.log(o?.f("FAIL"),(o?.f)("FAIL"),(0,o?.f)(42))})({a:"PASS",f(b){return this.a||b}});'
+    expect_stdout: [
+        "PASS PASS 42",
+        "PASS PASS 42",
+    ]
+    node_version: ">=14"
+}
+
 unary_parentheses: {
    input: {
        var o = { p: 41 };
@@ -237,6 +257,99 @@ trim_2: {
    node_version: ">=14"
 }

+trim_dot_call_1: {
+    options = {
+        evaluate: true,
+        optional_chains: true,
+    }
+    input: {
+        console.log(null?.f());
+    }
+    expect: {
+        console.log(void 0);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+trim_dot_call_2: {
+    options = {
+        evaluate: true,
+        optional_chains: true,
+        unsafe: true,
+    }
+    input: {
+        try {
+            (null?.p)();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            (void 0)();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+trim_dot_call_3: {
+    options = {
+        evaluate: true,
+        optional_chains: true,
+        unsafe: true,
+    }
+    input: {
+        try {
+            ({ p: null })?.p();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            null();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+trim_dot_sub: {
+    options = {
+        evaluate: true,
+        optional_chains: true,
+    }
+    input: {
+        console.log(null?.p[42]);
+    }
+    expect: {
+        console.log(void 0);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+trim_sub_call_call: {
+    options = {
+        evaluate: true,
+        optional_chains: true,
+    }
+    input: {
+        console.log(null?.[42]()());
+    }
+    expect: {
+        console.log(void 0);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
 issue_4906: {
    options = {
        toplevel: true,
@@ -248,7 +361,9 @@ issue_4906: {
        } while (console.log("PASS"));
    }
    expect: {
-        do {} while (console.log("PASS"));
+        do {
+            var a = a?.[42];
+        } while (console.log("PASS"));
    }
    expect_stdout: "PASS"
    node_version: ">=14"
@@ -256,7 +371,7 @@ issue_4906: {

 issue_4928: {
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
        unused: true,
    }
@@ -305,3 +420,200 @@ issue_4947_2: {
    expect_stdout: "PASS"
    node_version: ">=14"
 }
+
+issue_5039: {
+    options = {
+        ie: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = a?.[function f() {
+            f;
+            a;
+        }];
+        console.log("PASS");
+    }
+    expect: {
+        var a = a?.[function f() {}];
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_5091: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        function f(a) {
+            var b = a.p;
+            var c;
+            b?.[c = "FAIL 2"];
+            return b || c;
+        }
+        console.log(f("FAIL 1") || "PASS");
+    }
+    expect: {
+        function f(a) {
+            var a = a.p;
+            var c;
+            a?.[c = "FAIL 2"];
+            return a || c;
+        }
+        console.log(f("FAIL 1") || "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_5292_dot: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_5292_dot_pure_getters: {
+    options = {
+        pure_getters: true,
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+    }
+}
+
+issue_5292_dot_pure_getters_strict: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            }
+        };
+        o?.p;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_5292_sub: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+    node_version: ">=14"
+}
+
+issue_5292_sub_pure_getters: {
+    options = {
+        pure_getters: true,
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        console.log("bar");
+    }
+}
+
+issue_5292_sub_pure_getters_strict: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("foo");
+            }
+        };
+        o?.[console.log("bar"), "p"];
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+    node_version: ">=14"
+}
--- a/test/compress/properties.js
+++ b/test/compress/properties.js
@@ -17,7 +17,7 @@ dot_properties: {
        properties: true,
    }
    beautify = {
-        ie8: true,
+        ie: true,
    }
    input: {
        a["foo"] = "bar";
@@ -43,7 +43,7 @@ dot_properties_es5: {
        properties: true,
    }
    beautify = {
-        ie8: false,
+        ie: false,
    }
    input: {
        a["foo"] = "bar";
@@ -1463,3 +1463,118 @@ issue_4888: {
    }
    expect_stdout: "object"
 }
+
+issue_5093: {
+    beautify = {
+        keep_quoted_props: true,
+    }
+    input: {
+        console.log({
+            a: true,
+            '42': "PASS",
+            "null": [],
+        }[6 * 7]);
+    }
+    expect_exact: 'console.log({a:true,"42":"PASS","null":[]}[6*7]);'
+    expect_stdout: "PASS"
+}
+
+issue_5093_quote_keys: {
+    beautify = {
+        keep_quoted_props: true,
+        quote_keys: true,
+    }
+    input: {
+        console.log({
+            a: true,
+            '42': "PASS",
+            "null": [],
+        }[6 * 7]);
+    }
+    expect_exact: 'console.log({"a":true,"42":"PASS","null":[]}[6*7]);'
+    expect_stdout: "PASS"
+}
+
+issue_5093_quote_style: {
+    beautify = {
+        keep_quoted_props: true,
+        quote_style: 3,
+    }
+    input: {
+        console.log({
+            a: true,
+            '42': "PASS",
+            "null": [],
+        }[6 * 7]);
+    }
+    expect_exact: 'console.log({a:true,\'42\':"PASS","null":[]}[6*7]);'
+    expect_stdout: "PASS"
+}
+
+object_methods: {
+    options = {
+        properties: true,
+    }
+    input: {
+        ({
+            p() {
+                console.log("FAIL 1");
+            },
+            *q() {
+                console.log("FAIL 2");
+            },
+            async r() {
+                console.log("FAIL 3");
+            },
+            async *s() {
+                console.log("PASS");
+            },
+        }).s().next();
+    }
+    expect: {
+        [
+            () => {
+                console.log("FAIL 1");
+            },
+            function*() {
+                console.log("FAIL 2");
+            },
+            async () => {
+                console.log("FAIL 3");
+            },
+            async function*() {
+                console.log("PASS");
+            },
+        ][3]().next();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=10"
+}
+
+issue_5177: {
+    options = {
+        properties: true,
+    }
+    input: {
+        var a = "FAIL";
+        var o = { a: "PASS" };
+        o.p = {
+            q() {
+                return this.a;
+            },
+        }.q;
+        console.log(o.p());
+    }
+    expect: {
+        var a = "FAIL";
+        var o = { a: "PASS" };
+        o.p = {
+            q() {
+                return this.a;
+            },
+        }.q;
+        console.log(o.p());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
--- a/test/compress/pure_getters.js
+++ b/test/compress/pure_getters.js
@@ -1320,6 +1320,7 @@ issue_2878: {

 issue_3427: {
    options = {
+        assignments: true,
        evaluate: true,
        inline: true,
        pure_getters: "strict",
@@ -1362,9 +1363,8 @@ issue_3490_1: {
    }
    expect: {
        var b = 42, c = "FAIL";
-        if (function() {
        var a;
-        }(), c = "PASS", b) while ("" == typeof d);
+        if (c = "PASS", b) while ("" == typeof d);
        console.log(c, b);
    }
    expect_stdout: "PASS 42"
@@ -1639,6 +1639,26 @@ nested_property_assignments_3: {
    expect_stdout: "PASS"
 }

+nested_property_assignments_4: {
+    options = {
+        pure_getters: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var n, o = { p: { q: { r: "PASS" } } };
+        (n = o.p).r = n.q.r;
+        console.log(o.p.r);
+    }
+    expect: {
+        var n, o = { p: { q: { r: "PASS" } } };
+        (n = o.p).r = n.q.r;
+        console.log(o.p.r);
+    }
+    expect_stdout: "PASS"
+}
+
 issue_4939: {
    options = {
        pure_getters: "strict",
--- a/test/compress/reduce_vars.js
+++ b/test/compress/reduce_vars.js
@@ -41,10 +41,8 @@ reduce_vars: {
    }
    expect: {
        var A = 1;
-        (function() {
        console.log(-3);
        console.log(A - 5);
-        })();
        (function f1() {
            var a = 2;
            console.log(a - 5);
@@ -905,7 +903,7 @@ use_before_var: {
    }
    expect: {
        function f(){
-            console.log(void 0);
+            console.log(t);
            var t = 1;
        }
    }
@@ -981,7 +979,7 @@ inner_var_for_1: {
    expect: {
        function f() {
            var a = 1;
-            x(1, void 0, d);
+            x(1, b, d);
            for (var b = 2, c = 3; x(1, 2, 3, d); x(1, 2, 3, d)) {
                var d = 4, e = 5;
                x(1, 2, 3, d, e);
@@ -1292,6 +1290,7 @@ toplevel_on_loops_3: {
        loops: true,
        reduce_funcs: true,
        reduce_vars: true,
+        side_effects: true,
        toplevel: true,
        unused: true,
    }
@@ -2071,72 +2070,6 @@ issue_1670_2: {
 }

 issue_1670_3: {
-    options = {
-        comparisons: true,
-        conditionals: true,
-        dead_code: true,
-        evaluate: true,
-        reduce_funcs: true,
-        reduce_vars: true,
-        side_effects: true,
-        switches: true,
-        typeofs: true,
-        unused: true,
-    }
-    input: {
-        (function f() {
-            switch (1) {
-              case 0:
-                var a = true;
-                break;
-              case 1:
-                if (typeof a === "undefined") console.log("PASS");
-                else console.log("FAIL");
-            }
-        })();
-    }
-    expect: {
-        (function() {
-            var a;
-            void 0 === a ? console.log("PASS") : console.log("FAIL");
-        })();
-    }
-    expect_stdout: "PASS"
-}
-
-issue_1670_4: {
-    options = {
-        conditionals: true,
-        dead_code: true,
-        evaluate: true,
-        passes: 2,
-        reduce_funcs: true,
-        reduce_vars: true,
-        side_effects: true,
-        switches: true,
-        unused: true,
-    }
-    input: {
-        (function f() {
-            switch (1) {
-              case 0:
-                var a = true;
-                break;
-              case 1:
-                if (typeof a === "undefined") console.log("PASS");
-                else console.log("FAIL");
-            }
-        })();
-    }
-    expect: {
-        (function() {
-            console.log("PASS");
-        })();
-    }
-    expect_stdout: "PASS"
-}
-
-issue_1670_5: {
    options = {
        conditionals: true,
        dead_code: true,
@@ -2168,7 +2101,7 @@ issue_1670_5: {
    expect_stdout: "1"
 }

-issue_1670_6: {
+issue_1670_4: {
    options = {
        conditionals: true,
        dead_code: true,
@@ -3158,7 +3091,7 @@ accessor_1: {
                a = 2;
                return a;
            },
-            b: 1
+            b: 1,
        }.b, a);
    }
    expect: {
@@ -3168,7 +3101,7 @@ accessor_1: {
                a = 2;
                return a;
            },
-            b: 1
+            b: 1,
        }.b, a);
    }
    expect_stdout: "1 1"
@@ -3188,7 +3121,7 @@ accessor_2: {
        var B = {
            get c() {
                console.log(A);
-            }
+            },
        };
        B.c;
    }
@@ -3196,7 +3129,7 @@ accessor_2: {
        ({
            get c() {
                console.log(1);
-            }
+            },
        }).c;
    }
    expect_stdout: "1"
@@ -3242,7 +3175,7 @@ obj_var_1: {
        var obj = {
            bar: function() {
                return C + C;
-            }
+            },
        };
        console.log(obj.bar());
    }
@@ -3250,7 +3183,7 @@ obj_var_1: {
        console.log({
            bar: function() {
                return 2;
-            }
+            },
        }.bar());
    }
    expect_stdout: "2"
@@ -3274,7 +3207,7 @@ obj_var_2: {
        var obj = {
            bar: function() {
                return C + C;
-            }
+            },
        };
        console.log(obj.bar());
    }
@@ -4488,6 +4421,7 @@ perf_2: {

 perf_3: {
    options = {
+        passes: 2,
        reduce_funcs: true,
        reduce_vars: true,
        toplevel: true,
@@ -4496,10 +4430,10 @@ perf_3: {
    input: {
        var foo = function(x, y, z) {
            return x < y ? x * y + z : x * z - y;
-        }
+        };
        var indirect_foo = function(x, y, z) {
            return foo(x, y, z);
-        }
+        };
        var sum = 0;
        for (var i = 0; i < 100; ++i)
            sum += indirect_foo(i, i + 1, 3 * i);
@@ -4528,10 +4462,10 @@ perf_4: {
    input: {
        var foo = function(x, y, z) {
            return x < y ? x * y + z : x * z - y;
-        }
+        };
        var indirect_foo = function(x, y, z) {
            return foo(x, y, z);
-        }
+        };
        var sum = 0;
        for (var i = 0; i < 100; ++i)
            sum += indirect_foo(i, i + 1, 3 * i);
@@ -4540,10 +4474,10 @@ perf_4: {
    expect: {
        var foo = function(x, y, z) {
            return x < y ? x * y + z : x * z - y;
-        }
+        };
        var indirect_foo = function(x, y, z) {
            return foo(x, y, z);
-        }
+        };
        var sum = 0;
        for (var i = 0; i < 100; ++i)
            sum += indirect_foo(i, i + 1, 3 * i);
@@ -4632,9 +4566,9 @@ perf_7: {
        var indirect_foo = function(x, y, z) {
            var foo = function(x, y, z) {
                return x < y ? x * y + z : x * z - y;
-            }
+            };
            return foo(x, y, z);
-        }
+        };
        var sum = 0;
        for (var i = 0; i < 100; ++i)
            sum += indirect_foo(i, i + 1, 3 * i);
@@ -4664,9 +4598,9 @@ perf_8: {
        var indirect_foo = function(x, y, z) {
            var foo = function(x, y, z) {
                return x < y ? x * y + z : x * z - y;
-            }
+            };
            return foo(x, y, z);
-        }
+        };
        var sum = 0;
        for (var i = 0; i < 100; ++i)
            sum += indirect_foo(i, i + 1, 3 * i);
@@ -4677,7 +4611,7 @@ perf_8: {
            return function(x, y, z) {
                return x < y ? x * y + z : x * z - y;
            }(x, y, z);
-        }
+        };
        var sum = 0;
        for (var i = 0; i < 100; ++i)
            sum += indirect_foo(i, i + 1, 3 * i);
@@ -6735,6 +6669,7 @@ issues_3267_1: {
        dead_code: true,
        evaluate: true,
        inline: true,
+        negate_iife: true,
        reduce_vars: true,
        sequences: true,
        side_effects: true,
@@ -6752,8 +6687,9 @@ issues_3267_1: {
        });
    }
    expect: {
-        !function(i) {
-            if (Object())
+        !function(x) {
+            var i = Object();
+            if (i)
                return console.log("PASS");
            throw "FAIL";
        }();
@@ -6769,6 +6705,7 @@ issues_3267_2: {
        evaluate: true,
        inline: true,
        keep_fargs: false,
+        negate_iife: true,
        passes: 2,
        reduce_vars: true,
        sequences: true,
@@ -7384,6 +7321,64 @@ local_assignment_loop: {
    expect_stdout: "PASS"
 }

+local_assignment_modified: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        var a;
+        (a = a || {}).p = 42;
+        console.log(a.p);
+    }
+    expect: {
+        var a;
+        (a = {}).p = 42;
+        console.log(a.p);
+    }
+    expect_stdout: "42"
+}
+
+local_declaration: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        var a;
+        a || console.log(a = "PASS");
+    }
+    expect: {
+        var a;
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+local_definition_modified: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        var a = a || {};
+        a.p = 42;
+        console.log(a.p);
+    }
+    expect: {
+        var a = {};
+        a.p = 42;
+        console.log(a.p);
+    }
+    expect_stdout: "42"
+}
+
 issue_3957_1: {
    options = {
        evaluate: true,
@@ -7499,6 +7494,7 @@ issue_4030: {
        collapse_vars: true,
        evaluate: true,
        reduce_vars: true,
+        side_effects: true,
        toplevel: true,
        unused: true,
    }
@@ -7742,3 +7738,97 @@ issue_4949: {
    }
    expect_stdout: "0 1"
 }
+
+issue_5048: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            var a = function() {
+                return a + 42;
+            };
+        }());
+    }
+    expect: {
+        console.log(function() {}());
+    }
+    expect_stdout: "undefined"
+}
+
+issue_5050: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        function f() {
+            console.log(a);
+        }
+        this;
+        var a = 1;
+        f(console.log(2), f(), a = 3);
+    }
+    expect: {
+        function f() {
+            console.log(a);
+        }
+        this;
+        var a = 1;
+        f(console.log(2), f(), a = 3);
+    }
+    expect_stdout: [
+        "2",
+        "1",
+        "3",
+    ]
+}
+
+issue_5055_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "PASS";
+        function f() {
+            console.log(a || "FAIL");
+        }
+        f(0 && (a = 0)(f(this)));
+    }
+    expect: {
+        var a = "PASS";
+        function f() {
+            console.log(a || "FAIL");
+        }
+        f(0);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5055_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        function f() {
+            console.log(a || "FAIL");
+        }
+        f(0 && (a = 0)(f(this)));
+    }
+    expect: {
+        var a = "PASS";
+        function f() {
+            console.log(a || "FAIL");
+        }
+        f(0 && (a = 0)(f()));
+    }
+    expect_stdout: "PASS"
+}
--- a/test/compress/rename.js
+++ b/test/compress/rename.js
@@ -1,11 +1,11 @@
 mangle_catch: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -24,11 +24,11 @@ mangle_catch: {
 mangle_catch_ie8: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -47,11 +47,11 @@ mangle_catch_ie8: {
 mangle_catch_var: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -70,11 +70,11 @@ mangle_catch_var: {
 mangle_catch_var_ie8: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -93,11 +93,11 @@ mangle_catch_var_ie8: {
 mangle_catch_toplevel: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -116,11 +116,11 @@ mangle_catch_toplevel: {
 mangle_catch_ie8_toplevel: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -139,11 +139,11 @@ mangle_catch_ie8_toplevel: {
 mangle_catch_var_toplevel: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -162,11 +162,11 @@ mangle_catch_var_toplevel: {
 mangle_catch_var_ie8_toplevel: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -185,11 +185,11 @@ mangle_catch_var_ie8_toplevel: {
 mangle_catch_redef_1: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -208,11 +208,11 @@ mangle_catch_redef_1: {
 mangle_catch_redef_1_ie8: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -231,11 +231,11 @@ mangle_catch_redef_1_ie8: {
 mangle_catch_redef_1_toplevel: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -254,11 +254,11 @@ mangle_catch_redef_1_toplevel: {
 mangle_catch_redef_1_ie8_toplevel: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -277,11 +277,11 @@ mangle_catch_redef_1_ie8_toplevel: {
 mangle_catch_redef_2: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -299,11 +299,11 @@ mangle_catch_redef_2: {
 mangle_catch_redef_2_ie8: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -321,11 +321,11 @@ mangle_catch_redef_2_ie8: {
 mangle_catch_redef_2_toplevel: {
    rename = true
    options = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -343,11 +343,11 @@ mangle_catch_redef_2_toplevel: {
 mangle_catch_redef_2_ie8_toplevel: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -365,7 +365,7 @@ mangle_catch_redef_2_ie8_toplevel: {
 issue_2120_1: {
    rename = true
    mangle = {
-        ie8: false,
+        ie: false,
    }
    input: {
        "aaaaaaaa";
@@ -401,7 +401,7 @@ issue_2120_1: {
 issue_2120_2: {
    rename = true
    mangle = {
-        ie8: true,
+        ie: true,
    }
    input: {
        "aaaaaaaa";
@@ -436,7 +436,7 @@ issue_2120_2: {
 function_iife_catch: {
    rename = true
    mangle = {
-        ie8: false,
+        ie: false,
    }
    input: {
        function f(n) {
@@ -458,7 +458,7 @@ function_iife_catch: {
 function_iife_catch_ie8: {
    rename = true
    mangle = {
-        ie8: true,
+        ie: true,
    }
    input: {
        function f(n) {
@@ -480,7 +480,7 @@ function_iife_catch_ie8: {
 function_catch_catch: {
    rename = true
    mangle = {
-        ie8: false,
+        ie: false,
    }
    input: {
        var o = 0;
@@ -509,7 +509,7 @@ function_catch_catch: {
 function_catch_catch_ie8: {
    rename = true
    mangle = {
-        ie8: true,
+        ie: true,
    }
    input: {
        var o = 0;
@@ -538,12 +538,12 @@ function_catch_catch_ie8: {
 function_do_catch_ie8: {
    rename = true
    options = {
-        ie8: true,
+        ie: true,
        side_effects: true,
        unused: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -615,7 +615,7 @@ function_do_catch_ie8: {
 issue_3480: {
    rename = true,
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: false,
    }
    input: {
@@ -647,7 +647,7 @@ issue_3480: {
 issue_3480_ie8: {
    rename = true,
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: false,
    }
    input: {
@@ -679,7 +679,7 @@ issue_3480_ie8: {
 issue_3480_toplevel: {
    rename = true,
    mangle = {
-        ie8: false,
+        ie: false,
        toplevel: true,
    }
    input: {
@@ -711,7 +711,7 @@ issue_3480_toplevel: {
 issue_3480_ie8_toplevel: {
    rename = true,
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
--- a/test/compress/rests.js
+++ b/test/compress/rests.js
@@ -51,7 +51,7 @@ arrow_destructured_object_1: {
    }
    expect_exact: "var f=({...a})=>a,o=f({PASS:42});for(var k in o)console.log(k,o[k]);"
    expect_stdout: "PASS 42"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 arrow_destructured_object_2: {
@@ -62,7 +62,7 @@ arrow_destructured_object_2: {
    }
    expect_exact: "var f=({FAIL:a,...b})=>b,o=f({PASS:42,FAIL:null});for(var k in o)console.log(k,o[k]);"
    expect_stdout: "PASS 42"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 arrow_destructured_object_3: {
@@ -79,7 +79,7 @@ arrow_destructured_object_3: {
        "2 S",
        "3 S",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 funarg_1: {
@@ -131,7 +131,7 @@ destructured_object_1: {
    }
    expect_exact: 'var{...a}=["FAIL","PASS",42];console.log(a[1],a[2]);'
    expect_stdout: "PASS 42"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 destructured_object_2: {
@@ -141,7 +141,7 @@ destructured_object_2: {
    }
    expect_exact: 'var{0:a,...b}=["FAIL","PASS",42];console.log(b[1],b[2]);'
    expect_stdout: "PASS 42"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 drop_fargs: {
@@ -231,7 +231,7 @@ reduce_destructured_object: {
        console.log(a[0]);
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 retain_destructured_array: {
@@ -244,7 +244,7 @@ retain_destructured_array: {
        console.log.apply(console, b);
    }
    expect: {
-        var [ , ...b ] = [ "FAIL", "PASS", 42 ];
+        var [ ...b ] = [ "PASS", 42 ];
        console.log.apply(console, b);
    }
    expect_stdout: "PASS 42"
@@ -270,7 +270,7 @@ retain_destructured_object_1: {
        "1 PASS",
        "2 42",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 retain_destructured_object_2: {
@@ -284,7 +284,7 @@ retain_destructured_object_2: {
            console.log(k, b[k]);
    }
    expect: {
-        var { foo: [], ...b } = { foo: [ "FAIL" ], bar: "PASS", baz: 42 };
+        var { foo: {}, ...b } = { foo: 0, bar: "PASS", baz: 42 };
        for (var k in b)
            console.log(k, b[k]);
    }
@@ -292,7 +292,7 @@ retain_destructured_object_2: {
        "bar PASS",
        "baz 42",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 retain_funarg_destructured_array_1: {
@@ -344,7 +344,7 @@ retain_funarg_destructured_object_1: {
        console.log((({ ...a }) => a)([ "PASS" ])[0]);
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 retain_funarg_destructured_object_2: {
@@ -359,10 +359,10 @@ retain_funarg_destructured_object_2: {
    expect: {
        console.log(function({ p: a, ... b }) {
            return b;
-        }({ p: "FAIL" }).p || "PASS");
+        }({}).p || "PASS");
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 drop_unused_call_args_1: {
@@ -407,6 +407,24 @@ drop_unused_call_args_2: {
    node_version: ">=6"
 }

+maintain_position: {
+    options = {
+        unused: true,
+    }
+    input: {
+        A = "FAIL";
+        var [ , ...a ] = [ A, "PASS" ];
+        console.log(a[0]);
+    }
+    expect: {
+        A = "FAIL";
+        var [ , ...a ] = [ A, "PASS" ];
+        console.log(a[0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 merge_funarg: {
    options = {
        merge_vars: true,
@@ -418,9 +436,9 @@ merge_funarg: {
        })();
    }
    expect: {
-        (function(...b) {
-            var b = b.length;
-            console.log(b);
+        (function(...a) {
+            var a = a.length;
+            console.log(a);
        })();
    }
    expect_stdout: "0"
@@ -438,9 +456,9 @@ merge_funarg_destructured_array: {
        })([]);
    }
    expect: {
-        (function([ ...b ]) {
-            var b = b.length;
-            console.log(b);
+        (function([ ...a ]) {
+            var a = a.length;
+            console.log(a);
        })([]);
    }
    expect_stdout: "0"
@@ -458,13 +476,13 @@ merge_funarg_destructured_object: {
        })([ "PASS" ]);
    }
    expect: {
-        (function({ ...b }) {
-            var b = b[0];
-            console.log(b);
+        (function({ ...a }) {
+            var a = a[0];
+            console.log(a);
        })([ "PASS" ]);
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 keep_arguments: {
@@ -542,6 +560,100 @@ drop_rest_lambda: {
    node_version: ">=6"
 }

+keep_rest_array: {
+    options = {
+        rests: true,
+    }
+    input: {
+        var [ ...[ ...a ] ] = "PASS";
+        console.log(a.join(""));
+    }
+    expect: {
+        var [ ...a ] = "PASS";
+        console.log(a.join(""));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+keep_rest_arrow: {
+    options = {
+        arrows: true,
+        keep_fargs: false,
+        reduce_vars: true,
+        rests: true,
+    }
+    input: {
+        console.log(((...[ ...a ]) => a.join(""))("PASS"));
+    }
+    expect: {
+        console.log(((...a) => a.join(""))("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+keep_rest_lambda_1: {
+    options = {
+        keep_fargs: false,
+        reduce_vars: true,
+        rests: true,
+        toplevel: true,
+    }
+    input: {
+        function f(...[ ...a ]) {
+            return a.join("");
+        }
+        console.log(f("PASS"), f([ 42 ]));
+    }
+    expect: {
+        function f(...a) {
+            return a.join("");
+        }
+        console.log(f("PASS"), f([ 42 ]));
+    }
+    expect_stdout: "PASS 42"
+    node_version: ">=6"
+}
+
+keep_rest_lambda_2: {
+    options = {
+        unused: true,
+    }
+    input: {
+        function f(...[ ...a ]) {
+            return a.join("");
+        }
+        console.log(f("PASS"), f([ 42 ]));
+    }
+    expect: {
+        function f(...[ ...a ]) {
+            return a.join("");
+        }
+        console.log(f("PASS"), f([ 42 ]));
+    }
+    expect_stdout: "PASS 42"
+    node_version: ">=6"
+}
+
+drop_new_function: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        new function(...{
+            [console.log("PASS")]: a,
+        }) {}();
+    }
+    expect: {
+        void ([ ... {
+            [console.log("PASS")]: [].e,
+        }] = []);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 issue_4525_1: {
    options = {
        arguments: true,
@@ -647,6 +759,78 @@ issue_4544_2: {
    node_version: ">=6"
 }

+issue_4560_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 0;
+        (function(...{
+            [a++]: {},
+        }) {})(2);
+        console.log(a);
+    }
+    expect: {
+        var a = 0;
+        (function(...{
+            [a++]: {},
+        }) {})(2);
+        console.log(a);
+    }
+    expect_stdout: "1"
+    node_version: ">=6"
+}
+
+issue_4560_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 0;
+        (function(...{
+            [a++]: {},
+        }) {})(2);
+        console.log(a);
+    }
+    expect: {
+        var a = 0;
+        (function(...{
+            [a++]: {},
+        }) {})(2);
+        console.log(a);
+    }
+    expect_stdout: "1"
+    node_version: ">=6"
+}
+
+issue_4560_3: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 0, b;
+        [ ...{
+            [a++]: b,
+        } ] = [ "PASS" ];
+        console.log(b);
+    }
+    expect: {
+        var a = 0, b;
+        [ ...{
+            [a++]: b,
+        } ] = [ "PASS" ];
+        console.log(b);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 issue_4562: {
    options = {
        evaluate: true,
@@ -667,7 +851,7 @@ issue_4562: {
 issue_4575: {
    options = {
        collapse_vars: true,
-        ie8: true,
+        ie: true,
        reduce_vars: true,
        rests: true,
        unused: true,
@@ -682,9 +866,9 @@ issue_4575: {
    }
    expect: {
        (function(a) {
-            (function a(...d) {
+            (function(d) {
                console.log(d.length);
-            })();
+            })([]);
        })();
    }
    expect_stdout: "0"
@@ -784,3 +968,299 @@ issue_4666: {
    expect_stdout: "1 2"
    node_version: ">=6"
 }
+
+issue_5089_1: {
+    options = {
+        unused: true,
+    }
+    input: {
+        var {
+            p: [] = 42,
+            ...o
+        } = {
+            p: [],
+        };
+        console.log(o.p);
+    }
+    expect: {
+        var {
+            p: {},
+            ...o
+        } = {
+            p: 0,
+        };
+        console.log(o.p);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8.3.0"
+}
+
+issue_5089_2: {
+    options = {
+        pure_getters: "strict",
+        unused: true,
+    }
+    input: {
+        var {
+            p: {} = null,
+            ...o
+        } = {
+            p: {},
+        };
+        console.log(o.p);
+    }
+    expect: {
+        var {
+            p: {},
+            ...o
+        } = {
+            p: 0,
+        };
+        console.log(o.p);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8.3.0"
+}
+
+issue_5100_1: {
+    options = {
+        passes: 2,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        [ {
+            p: {},
+            ...a
+        } ] = [ {
+            p: {
+                q: a,
+            } = 42,
+            r: "PASS",
+        } ];
+        console.log(a.r);
+    }
+    expect: {
+        var a;
+        ({
+            p: {},
+            ...a
+        } = [ {
+            p: [ a = 42["q"] ],
+            r: "PASS",
+        } ][0]);
+        console.log(a.r);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8.3.0"
+}
+
+issue_5100_2: {
+    options = {
+        passes: 2,
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        [ {
+            p: {},
+            ...a
+        } ] = [ {
+            p: (console.log("PASS"), {
+                q: a,
+            } = 42),
+        } ];
+    }
+    expect: {
+        var a;
+        ({
+            p: {},
+            ...a
+        } = [ {
+            p: [ console.log("PASS"), a = 42["q"] ],
+        } ][0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=10.22.0"
+}
+
+issue_5108: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        rests: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        console.log(function([ ...[ a ] ]) {
+            return a;
+        }([ "PASS", "FAIL" ]));
+    }
+    expect: {
+        console.log(function([]) {
+            return "PASS";
+        }([]));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5128_1: {
+    options = {
+        inline: true,
+    }
+    input: {
+        console.log(function() {
+            return function f(...[ a ]) {
+                return a;
+            }("PASS");
+        }());
+    }
+    expect: {
+        console.log(function f(...[ a ]) {
+            return a;
+        }("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5128_2: {
+    options = {
+        inline: true,
+        keep_fnames: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            return function f(...[ a ]) {
+                return a;
+            }("PASS");
+        }());
+    }
+    expect: {
+        console.log(function f(...[ a ]) {
+            return a;
+        }("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5165_1: {
+    options = {
+        conditionals: true,
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        rests: true,
+        side_effects: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function([ ...a ]) {
+            switch (a) {
+              case a:
+                return "PASS";
+            }
+        }([]));
+    }
+    expect: {
+        console.log(function([ ...a ]) {
+            return "PASS";
+        }([]));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5165_2: {
+    options = {
+        conditionals: true,
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        rests: true,
+        side_effects: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(...a) {
+            switch (a) {
+              case a:
+                return "PASS";
+            }
+        }());
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5246_1: {
+    options = {
+        reduce_vars: true,
+        rests: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function([ , ...a ]) {
+            return this && a;
+        }([ , function(){} ])[0]);
+    }
+    expect: {
+        console.log(typeof function([]) {
+            return this && [ function(){} ];
+        }([])[0]);
+    }
+    expect_stdout: "function"
+    node_version: ">=6"
+}
+
+issue_5246_2: {
+    options = {
+        reduce_vars: true,
+        rests: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        A = [ , "PASS", "FAIL" ];
+        var  [ , ...a ] = [ ... A ];
+        console.log(a[0]);
+    }
+    expect: {
+        A = [ , "PASS", "FAIL" ];
+        var  [ , ...a ] = [ ... A ];
+        console.log(a[0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5246_3: {
+    options = {
+        unused: true,
+    }
+    input: {
+        (function f(...[ [ a ] ]) {
+            console.log(a);
+        })([ "PASS" ]);
+    }
+    expect: {
+        (function(...[ a ]) {
+            console.log(a);
+        })([ "PASS" ][0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
--- a/test/compress/sandbox.js
+++ b/test/compress/sandbox.js
@@ -201,3 +201,20 @@ issue_4811_2: {
    expect_stdout: "PASS [object global] true"
    node_version: ">=8"
 }
+
+issue_5197: {
+    rename = true
+    input: {
+        function f(async) {
+            async(")=>{}");
+        }
+        console.log("" + this.__proto__);
+    }
+    expect: {
+        function f(a) {
+            a(")=>{}");
+        }
+        console.log("" + this.__proto__);
+    }
+    expect_stdout: "[object global]"
+}
--- a/test/compress/sequences.js
+++ b/test/compress/sequences.js
@@ -774,7 +774,7 @@ side_effects_cascade_3: {
    }
    expect: {
        function f(a, b) {
-            (b += a) || (b = a) || (b -= a, b ^= a),
+            (b += a) || (b = a) || (b = b - a ^ a),
            a--;
        }
    }
@@ -910,9 +910,7 @@ hoist_decl: {
        var d;
    }
    expect: {
-        var a;
-        w();
-        var b = x(), c, d;
+        var a, b = (w(), x()), c, d;
        for (y(); 0;) z();
    }
 }
@@ -1162,10 +1160,8 @@ issue_3490_1: {
    }
    expect: {
        var b = 42, c = "FAIL";
-        if (function() {
        var a;
-            a && a.p;
-        }(), c = "PASS", b) while ("" == typeof d);
+        if (a && a.p, c = "PASS", b) while ("" == typeof d);
        console.log(c, b);
    }
    expect_stdout: "PASS 42"
@@ -1195,9 +1191,8 @@ issue_3490_2: {
    }
    expect: {
        var b = 42, c = "FAIL";
-        for (function() {
        var a;
-        }(), c = "PASS", b; "" == typeof d;);
+        for (c = "PASS", b; "" == typeof d;);
        console.log(c, b);
    }
    expect_stdout: "PASS 42"
--- a/test/compress/spreads.js
+++ b/test/compress/spreads.js
@@ -147,7 +147,7 @@ dont_inline: {
    node_version: ">=6"
 }

-do_inline: {
+do_inline_1: {
    options = {
        inline: true,
        spreads: true,
@@ -164,6 +164,46 @@ do_inline: {
    node_version: ">=6"
 }

+do_inline_2: {
+    options = {
+        inline: true,
+        side_effects: true,
+    }
+    input: {
+        (function() {
+            (function() {
+                console.log("PASS");
+            })(..."");
+        })();
+    }
+    expect: {
+        [] = [ ..."" ],
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+do_inline_3: {
+    options = {
+        if_return: true,
+        inline: true,
+    }
+    input: {
+        (function() {
+            (function() {
+                while (console.log("PASS"));
+            })(..."");
+        })();
+    }
+    expect: {
+        var [] = [ ..."" ];
+        while (console.log("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 drop_empty_call_1: {
    options = {
        side_effects: true,
@@ -201,7 +241,29 @@ drop_empty_call_2: {
    node_version: ">=6"
 }

-convert_hole: {
+convert_hole_array: {
+    options = {
+        spreads: true,
+    }
+    input: {
+        [ ...[ "PASS", , 42 ] ].forEach(function(a) {
+            console.log(a);
+        });
+    }
+    expect: {
+        [ "PASS", void 0, 42 ].forEach(function(a) {
+            console.log(a);
+        });
+    }
+    expect_stdout: [
+        "PASS",
+        "undefined",
+        "42",
+    ]
+    node_version: ">=6"
+}
+
+convert_hole_call: {
    options = {
        spreads: true,
    }
@@ -341,7 +403,7 @@ convert_setter: {
            console.log(k, o[k]);
    }
    expect_stdout: "PASS undefined"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 keep_getter_1: {
@@ -370,7 +432,7 @@ keep_getter_1: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 keep_getter_2: {
@@ -399,7 +461,7 @@ keep_getter_2: {
        "foo",
        "bar",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 keep_getter_3: {
@@ -429,7 +491,7 @@ keep_getter_3: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 keep_getter_4: {
@@ -460,7 +522,7 @@ keep_getter_4: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 keep_accessor: {
@@ -508,7 +570,7 @@ keep_accessor: {
        "q undefined",
        "r null",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 object_key_order_1: {
@@ -538,7 +600,7 @@ object_key_order_1: {
        "a 3",
        "b 2",
    ]
-    node_version: ">=8 <=10"
+    node_version: ">=8.3.0 <=10"
 }

 object_key_order_2: {
@@ -568,7 +630,7 @@ object_key_order_2: {
        "a 3",
        "b 2",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 object_key_order_3: {
@@ -598,7 +660,7 @@ object_key_order_3: {
        "a 3",
        "b 2",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 object_key_order_4: {
@@ -628,7 +690,7 @@ object_key_order_4: {
        "a 3",
        "b 2",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 object_spread_array: {
@@ -654,7 +716,7 @@ object_spread_array: {
        "0 foo",
        "1 bar",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 object_spread_string: {
@@ -681,7 +743,7 @@ object_spread_string: {
        "1 o",
        "2 o",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 unused_var_side_effects: {
@@ -711,7 +773,7 @@ unused_var_side_effects: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 unsafe_join_1: {
@@ -793,7 +855,7 @@ issue_4329: {
        }[0]);
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4331: {
@@ -871,7 +933,7 @@ issue_4345: {
        }[42]);
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4361: {
@@ -901,7 +963,7 @@ issue_4361: {
        "foo",
        "undefined",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4363: {
@@ -922,7 +984,7 @@ issue_4363: {
        });
    }
    expect_stdout: "PASS"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4556: {
@@ -945,78 +1007,6 @@ issue_4556: {
    node_version: ">=6"
 }

-issue_4560_1: {
-    options = {
-        evaluate: true,
-        reduce_vars: true,
-        toplevel: true,
-    }
-    input: {
-        var a = 0;
-        (function(...{
-            [a++]: {},
-        }) {})(2);
-        console.log(a);
-    }
-    expect: {
-        var a = 0;
-        (function(...{
-            [a++]: {},
-        }) {})(2);
-        console.log(a);
-    }
-    expect_stdout: "1"
-    node_version: ">=6"
-}
-
-issue_4560_2: {
-    options = {
-        reduce_vars: true,
-        toplevel: true,
-        unused: true,
-    }
-    input: {
-        var a = 0;
-        (function(...{
-            [a++]: {},
-        }) {})(2);
-        console.log(a);
-    }
-    expect: {
-        var a = 0;
-        (function(...{
-            [a++]: {},
-        }) {})(2);
-        console.log(a);
-    }
-    expect_stdout: "1"
-    node_version: ">=6"
-}
-
-issue_4560_3: {
-    options = {
-        collapse_vars: true,
-        reduce_vars: true,
-        toplevel: true,
-    }
-    input: {
-        var a = 0, b;
-        [ ...{
-            [a++]: b,
-        } ] = [ "PASS" ];
-        console.log(b);
-    }
-    expect: {
-        var a = 0, b;
-        [ ...{
-            [a++]: b,
-        } ] = [ "PASS" ];
-        console.log(b);
-    }
-    expect_stdout: "PASS"
-    node_version: ">=6"
-}
-
 issue_4614: {
    options = {
        pure_getters: "strict",
@@ -1066,7 +1056,7 @@ issue_4849: {
        }()));
    }
    expect_stdout: "object"
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4882_1: {
@@ -1098,7 +1088,7 @@ issue_4882_1: {
        "PASS",
        "undefined",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4882_2: {
@@ -1124,7 +1114,7 @@ issue_4882_2: {
        "42",
        "PASS",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
 }

 issue_4882_3: {
@@ -1154,5 +1144,25 @@ issue_4882_3: {
        "PASS",
        "42",
    ]
-    node_version: ">=8"
+    node_version: ">=8.3.0"
+}
+
+issue_5006: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        console.log(function(b, c) {
+            c = "FAIL 2";
+            return arguments[1];
+        }(...[], "FAIL 1") || "PASS");
+    }
+    expect: {
+        console.log(function(b, c) {
+            c = "FAIL 2";
+            return arguments[1];
+        }(...[], "FAIL 1") || "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
 }
--- a/test/compress/switches.js
+++ b/test/compress/switches.js
@@ -113,7 +113,7 @@ constant_switch_5: {
        // the break inside the if ruins our job
        // we can still get rid of irrelevant cases.
        switch (1) {
-          case 1:
+          default:
            x();
            if (foo) break;
            y();
@@ -300,6 +300,37 @@ drop_default_2: {
    }
 }

+drop_default_3: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        function f() {
+            console.log("PASS");
+            return 42;
+        }
+        switch (42) {
+          case f():
+            break;
+          case void console.log("FAIL"):
+          default:
+        }
+    }
+    expect: {
+        function f() {
+            console.log("PASS");
+            return 42;
+        }
+        switch (42) {
+          case f():
+          case void console.log("FAIL"):
+        }
+    }
+    expect_stdout: "PASS"
+}
+
 keep_default: {
    options = {
        dead_code: true,
@@ -423,7 +454,6 @@ drop_case_3: {
        switch ({}.p) {
          default:
          case void 0:
-            break;
          case c = "FAIL":
        }
        console.log(c);
@@ -454,7 +484,168 @@ drop_case_4: {
    expect_stdout: "PASS"
 }

-keep_case: {
+drop_case_5: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (42) {
+          case void console.log("PASS 1"):
+            console.log("FAIL 1");
+          case 42:
+          case console.log("FAIL 2"):
+            console.log("PASS 2");
+        }
+    }
+    expect: {
+        switch (42) {
+          default:
+            void console.log("PASS 1");
+            console.log("PASS 2");
+        }
+    }
+    expect_stdout: [
+        "PASS 1",
+        "PASS 2",
+    ]
+}
+
+drop_case_6: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (console.log("PASS 1"), 2) {
+          case 0:
+            console.log("FAIL 1");
+          case (console.log("PASS 2"), 1):
+            console.log("FAIL 2");
+        }
+    }
+    expect: {
+        switch (console.log("PASS 1"), 2) {
+          case (console.log("PASS 2"), 1):
+        }
+    }
+    expect_stdout: [
+        "PASS 1",
+        "PASS 2",
+    ]
+}
+
+drop_case_7: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (2) {
+          case 0:
+            console.log("FAIL 1");
+          case (console.log("PASS 1"), 1):
+            console.log("FAIL 2");
+          case 2:
+            console.log("PASS 2");
+        }
+    }
+    expect: {
+        switch (2) {
+          default:
+            console.log("PASS 1"), 1;
+            console.log("PASS 2");
+        }
+    }
+    expect_stdout: [
+        "PASS 1",
+        "PASS 2",
+    ]
+}
+
+drop_case_8: {
+    options = {
+        dead_code: true,
+        switches: true,
+    }
+    input: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          case "bar":
+            log("moo");
+            break;
+          case log("baz"):
+            log("moo");
+            break;
+          default:
+            log("moo");
+        }
+    }
+    expect: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          case "bar":
+          case log("baz"):
+          default:
+            log("moo");
+        }
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+        "moo",
+    ]
+}
+
+drop_case_9: {
+    options = {
+        dead_code: true,
+        switches: true,
+    }
+    input: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          case log("bar"):
+            log("moo");
+            break;
+          case "baz":
+            log("moo");
+            break;
+          default:
+            log("moo");
+        }
+    }
+    expect: {
+        function log(msg) {
+            console.log(msg);
+            return msg;
+        }
+        switch (log("foo")) {
+          default:
+            log("bar");
+            log("moo");
+        }
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "moo",
+    ]
+}
+
+keep_case_1: {
    options = {
        dead_code: true,
        switches: true,
@@ -474,6 +665,76 @@ keep_case: {
    }
 }

+keep_case_2: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch ("foo") {
+          case console.log("bar"):
+          case console.log("baz"), "moo":
+        }
+    }
+    expect: {
+        switch ("foo") {
+          case console.log("bar"):
+          case console.log("baz"), "moo":
+        }
+    }
+    expect_stdout: [
+        "bar",
+        "baz",
+    ]
+}
+
+keep_case_3: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case console.log("FAIL"), 42:
+        }
+    }
+    expect: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case console.log("FAIL"), 42:
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+keep_case_4: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case void console.log("FAIL"):
+        }
+    }
+    expect: {
+        var a;
+        switch (void console.log("PASS")) {
+          case a:
+          case void console.log("FAIL"):
+        }
+    }
+    expect_stdout: "PASS"
+}
+
 issue_376: {
    options = {
        dead_code: true,
@@ -661,7 +922,7 @@ issue_1680_1: {
          case f(0):
          case f(1):
            f(2);
-          case 2:
+          default:
            f(5);
        }
    }
@@ -924,7 +1185,6 @@ issue_2535: {
    }
    expect: {
        w(), 42;
-        42;
        y();
        z();
    }
@@ -950,7 +1210,6 @@ issue_1750: {
    expect: {
        var a = 0, b = 1;
        true;
-        a, true;
        b = 2;
        console.log(a, b);
    }
@@ -1088,7 +1347,8 @@ drop_switch_6: {
        }
    }
    expect: {
-        A === B;
+        A;
+        B;
        x();
        C !== D;
        y();
@@ -1181,3 +1441,170 @@ issue_4059: {
    }
    expect_stdout: "PASS"
 }
+
+issue_5008_1: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function f() {
+            switch (f) {
+              case f:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }());
+    }
+    expect: {
+        console.log(function f() {
+            switch (f) {
+              default:
+                return "PASS";
+            }
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5008_2: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(a) {
+            switch (a) {
+              case a:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }([]));
+    }
+    expect: {
+        console.log(function(a) {
+            switch (a) {
+              default:
+                return "PASS";
+            }
+        }([]));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5008_3: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(a) {
+            switch (a) {
+              case a:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }({}));
+    }
+    expect: {
+        console.log(function(a) {
+            switch (a) {
+              default:
+                return "PASS";
+            }
+        }({}));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5008_4: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        reduce_vars: true,
+        switches: true,
+    }
+    input: {
+        console.log(function(a) {
+            switch (a) {
+              case a:
+                return "PASS";
+              default:
+                return "FAIL";
+            }
+        }(/foo/));
+    }
+    expect: {
+        console.log(function(a) {
+            switch (a) {
+              default:
+                return "PASS";
+            }
+        }(/foo/));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5010: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        var a;
+        switch (42) {
+          case console.log("PASS"):
+          case a:
+            console.log("FAIL");
+          case 42:
+        }
+    }
+    expect: {
+        var a;
+        switch (42) {
+          case console.log("PASS"):
+          case a:
+            console.log("FAIL");
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5012: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        switches: true,
+    }
+    input: {
+        switch (void 0) {
+          case console.log("PASS"):
+            break;
+          case void 0:
+          case 42:
+            console.log("FAIL");
+        }
+    }
+    expect: {
+        switch (void 0) {
+          case console.log("PASS"):
+            break;
+          default:
+            console.log("FAIL");
+        }
+    }
+    expect_stdout: "PASS"
+}
--- a/test/compress/templates.js
+++ b/test/compress/templates.js
@@ -131,6 +131,105 @@ malformed_escape: {
    node_version: ">=4"
 }

+booleans: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        var a;
+        console.log(`$${a}${a}` ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a;
+        console.log("$" + a + a ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+escape_placeholder_1: {
+    options = {
+        templates: true,
+    }
+    input: {
+        console.log(`\${\n`);
+    }
+    expect: {
+        console.log(`\${
+`);
+    }
+    expect_stdout: [
+        "${",
+        "",
+    ]
+    node_version: ">=4"
+}
+
+escape_placeholder_2: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`\n${"${"}\n`);
+    }
+    expect: {
+        console.log(`
+\${
+`);
+    }
+    expect_stdout: [
+        "",
+        "${",
+        "",
+    ]
+    node_version: ">=4"
+}
+
+escape_placeholder_3: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`\n$${"{"}\n`);
+    }
+    expect: {
+        console.log(`
+\${
+`);
+    }
+    expect_stdout: [
+        "",
+        "${",
+        "",
+    ]
+    node_version: ">=4"
+}
+
+escape_placeholder_4: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`\n${"$"}${"{"}\n`);
+    }
+    expect: {
+        console.log(`
+\${
+`);
+    }
+    expect_stdout: [
+        "",
+        "${",
+        "",
+    ]
+    node_version: ">=4"
+}
+
 evaluate: {
    options = {
        evaluate: true,
@@ -174,7 +273,7 @@ partial_evaluate: {
        console.log(`${6 * 7} foo ${console ? `PA` + "SS" : `FA` + `IL`}`);
    }
    expect: {
-        console.log(`42 foo ${console ? "PASS" : "FAIL"}`);
+        console.log("42 foo " + (console ? "PASS" : "FAIL"));
    }
    expect_stdout: "42 foo PASS"
    node_version: ">=4"
@@ -204,7 +303,7 @@ malformed_evaluate_2: {
        console.log(`\u0${0}b${5}`);
    }
    expect: {
-        console.log(`\u0${0}b5`);
+        console.log(`\u00b` + 5);
    }
    expect_stdout: true
    node_version: ">=4"
@@ -238,7 +337,7 @@ malformed_evaluate_4: {
        console.log("\\u00b5");
    }
    expect_stdout: "\\u00b5"
-    node_version: ">=8"
+    node_version: ">=8.10.0"
 }

 unsafe_evaluate: {
@@ -254,7 +353,7 @@ unsafe_evaluate: {
        console.log("\\uFo");
    }
    expect_stdout: "\\uFo"
-    node_version: ">=8"
+    node_version: ">=8.10.0"
 }

 side_effects_1: {
@@ -357,13 +456,14 @@ issue_4604: {
 issue_4606: {
    options = {
        evaluate: true,
+        strings: true,
        templates: true,
    }
    input: {
        console.log(`${typeof A} ${"\r"} ${"\\"} ${"`"}`);
    }
    expect: {
-        console.log(`${typeof A} \r \\ \``);
+        console.log(typeof A + " \r \\ `");
    }
    expect_stdout: "undefined \r \\ `"
    node_version: ">=4"
@@ -434,3 +534,238 @@ issue_4931: {
    ]
    node_version: ">=4"
 }
+
+issue_5125_1: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`PASS ${typeof A}`);
+    }
+    expect: {
+        console.log("PASS " + typeof A);
+    }
+    expect_stdout: "PASS undefined"
+    node_version: ">=4"
+}
+
+issue_5125_2: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`PASS
+${typeof A}`);
+    }
+    expect: {
+        console.log(`PASS
+` + typeof A);
+    }
+    expect_stdout: [
+        "PASS",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+issue_5125_3: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`PASS\n${typeof A}`);
+    }
+    expect: {
+        console.log(`PASS
+` + typeof A);
+    }
+    expect_stdout: [
+        "PASS",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+issue_5125_4: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`PASS
+
+${typeof A}`);
+    }
+    expect: {
+        console.log(`PASS
+
+` + typeof A);
+    }
+    expect_stdout: [
+        "PASS",
+        "",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+issue_5125_5: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`PASS\n\n${typeof A}`);
+    }
+    expect: {
+        console.log(`PASS
+
+` + typeof A);
+    }
+    expect_stdout: [
+        "PASS",
+        "",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+issue_5125_6: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`${typeof A} ${typeof B} PASS`);
+    }
+    expect: {
+        console.log(typeof A + ` ${typeof B} PASS`);
+    }
+    expect_stdout: "undefined undefined PASS"
+    node_version: ">=4"
+}
+
+issue_5125_7: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`${typeof A} ${typeof B} ${typeof C} PASS`);
+    }
+    expect: {
+        console.log(typeof A + ` ${typeof B} ${typeof C} PASS`);
+    }
+    expect_stdout: "undefined undefined undefined PASS"
+    node_version: ">=4"
+}
+
+issue_5125_8: {
+    options = {
+        evaluate: true,
+        strings: true,
+        templates: true,
+    }
+    input: {
+        console.log(`${typeof A}${typeof B}${typeof C} PASS`);
+    }
+    expect: {
+        console.log(typeof A + typeof B + typeof C + " PASS");
+    }
+    expect_stdout: "undefinedundefinedundefined PASS"
+    node_version: ">=4"
+}
+
+issue_5136: {
+    options = {
+        templates: true,
+    }
+    input: {
+        console.log(`${A = []}${A[0] = 42}`);
+    }
+    expect: {
+        console.log(`` + (A = []) + (A[0] = 42));
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+issue_5145_1: {
+    options = {
+        strings: true,
+        templates: true,
+    }
+    input: {
+        var a = [];
+        console.log(`${a}${a[0] = 42}
+`);
+    }
+    expect: {
+        var a = [];
+        console.log(`${a}${a[0] = 42}
+`);
+    }
+    expect_stdout: [
+        "42",
+        "",
+    ]
+    node_version: ">=4"
+}
+
+issue_5145_2: {
+    options = {
+        strings: true,
+        templates: true,
+    }
+    input: {
+        var a = [];
+        console.log(`${a}${a}${a[0] = 42}
+`);
+    }
+    expect: {
+        var a = [];
+        console.log("" + a + a + (a[0] = 42) + `
+`);
+    }
+    expect_stdout: [
+        "42",
+        "",
+    ]
+    node_version: ">=4"
+}
+
+issue_5199: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = function() {
+            console.log(typeof b);
+        }``;
+        {
+            const b = a;
+        }
+    }
+    expect: {
+        var a = function() {
+            console.log(typeof b);
+        }``;
+        {
+            const b = a;
+        }
+    }
+    expect_stdout: "undefined"
+    node_version: ">=4"
+}
--- a/test/compress/typeof.js
+++ b/test/compress/typeof.js
@@ -436,6 +436,245 @@ emberjs_global: {
    expect_stdout: Error("PASS")
 }

+reassign: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        passes: 2,
+        typeofs: true,
+    }
+    input: {
+        A = console;
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            A = void 0;
+            while (console.log(void 0 === A ? "PASS" : "FAIL 2"));
+        }
+    }
+    expect: {
+        A = console;
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            A = void 0;
+            while (console.log(void 0 === A ? "PASS" : "FAIL 2"));
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+reassign_call: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        passes: 2,
+        typeofs: true,
+    }
+    input: {
+        A = console;
+        function f() {
+            A = void 0;
+        }
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            f();
+            while (console.log(void 0 === A ? "PASS" : "FAIL 2"));
+        }
+    }
+    expect: {
+        A = console;
+        function f() {
+            A = void 0;
+        }
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            f();
+            while (console.log(void 0 === A ? "PASS" : "FAIL 2"));
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+reassign_conditional: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        passes: 2,
+        typeofs: true,
+    }
+    input: {
+        A = console;
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            A &&= void 0;
+            while (console.log(void 0 === A ? "PASS" : "FAIL 2"));
+        }
+    }
+    expect: {
+        A = console;
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            A &&= void 0;
+            while (console.log(void 0 === A ? "PASS" : "FAIL 2"));
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+reassign_do: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        if_return: true,
+        passes: 2,
+        reduce_vars: true,
+        typeofs: true,
+    }
+    input: {
+        A = console;
+        (function() {
+            if ("undefined" == typeof A)
+                return;
+            var a = A, i = 2;
+            do {
+                console.log(void 0 === A, void 0 === a);
+                A = void 0;
+            } while (--i);
+        })();
+    }
+    expect: {
+        A = console;
+        (function() {
+            if ("undefined" != typeof A) {
+                var a = A, i = 2;
+                do {
+                    console.log(void 0 === A, (a, false));
+                    A = void 0;
+                } while (--i);
+            }
+        })();
+    }
+    expect_stdout: [
+        "false false",
+        "true false",
+    ]
+}
+
+reassign_for: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        passes: 2,
+        reduce_vars: true,
+        toplevel: true,
+        typeofs: true,
+    }
+    input: {
+        if (A = console, "undefined" != typeof A)
+            for (var a = A, i = 0; i < 2; i++)
+                console.log(void 0 === A, void 0 === a),
+                A = void 0;
+    }
+    expect: {
+        if (A = console, "undefined" != typeof A)
+            for (var a = A, i = 0; i < 2; i++)
+                console.log(void 0 === A, (a, false)),
+                A = void 0;
+    }
+    expect_stdout: [
+        "false false",
+        "true false",
+    ]
+}
+
+reassign_for_in: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        passes: 2,
+        reduce_vars: true,
+        typeofs: true,
+    }
+    input: {
+        (A = console) && "undefined" != typeof A && function(a) {
+            for (var k in [ a = A, 42 ]) {
+                console.log(void 0 === A, void 0 === a);
+                A = void 0;
+            }
+        }();
+    }
+    expect: {
+        (A = console) && "undefined" != typeof A && function(a) {
+            for (var k in [ a = A, 42 ]) {
+                console.log(void 0 === A, (a, false));
+                A = void 0;
+            }
+        }();
+    }
+    expect_stdout: [
+        "false false",
+        "true false",
+    ]
+}
+
+reassign_iife: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        passes: 2,
+        typeofs: true,
+    }
+    input: {
+        A = console;
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else (function() {
+            A = void 0;
+        })(console.log(void 0 === A ? "FAIL 2" : "PASS"));
+    }
+    expect: {
+        A = console;
+        "undefined" == typeof A ? console.log("FAIL 1") : function() {
+            A = void 0;
+        }(console.log((A, false) ? "FAIL 2" : "PASS"));
+    }
+    expect_stdout: "PASS"
+}
+
+reassign_property: {
+    options = {
+        comparisons: true,
+        conditionals: true,
+        passes: 2,
+        typeofs: true,
+    }
+    input: {
+        A = console;
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            A.p = void 0;
+            console.log(void 0 === A ? "FAIL 2" : "PASS");
+        }
+    }
+    expect: {
+        A = console;
+        if ("undefined" == typeof A)
+            console.log("FAIL 1");
+        else {
+            A.p = void 0;
+            console.log((A, false) ? "FAIL 2" : "PASS");
+        }
+    }
+    expect_stdout: "PASS"
+}
+
 issue_3817: {
    options = {
        comparisons: true,
--- a/test/compress/unicode.js
+++ b/test/compress/unicode.js
@@ -67,7 +67,8 @@ unicode_escaped_identifier_2: {
    }
    expect_exact: 'var a="foo";var \u{10000}="bar";console.log(a,\u{10000});'
    expect_stdout: "foo bar"
-    node_version: ">=4"
+    // non-BMP support is platform-dependent on Node.js v4
+    node_version: ">=6"
 }

 unicode_identifier_ascii_only: {
@@ -200,7 +201,8 @@ surrogate_pair: {
    }
    expect_exact: 'var \ud87e\udc00={"\ud87e\udc01":"\udbc0\udc00"};\ud87e\udc00.\ud87e\udc02="\udbc0\udc01";console.log(typeof \ud87e\udc00,\ud87e\udc00.\ud87e\udc01,\ud87e\udc00["\ud87e\udc02"]);'
    expect_stdout: "object \udbc0\udc00 \udbc0\udc01"
-    node_version: ">=4"
+    // non-BMP support is platform-dependent on Node.js v4
+    node_version: ">=6"
 }

 surrogate_pair_ascii: {
@@ -216,5 +218,6 @@ surrogate_pair_ascii: {
    }
    expect_exact: 'var \\u{2f800}={"\\ud87e\\udc01":"\\udbc0\\udc00"};\\u{2f800}.\\u{2f802}="\\udbc0\\udc01";console.log(typeof \\u{2f800},\\u{2f800}.\\u{2f801},\\u{2f800}["\\ud87e\\udc02"]);'
    expect_stdout: "object \udbc0\udc00 \udbc0\udc01"
-    node_version: ">=4"
+    // non-BMP support is platform-dependent on Node.js v4
+    node_version: ">=6"
 }
--- a/test/compress/varify.js
+++ b/test/compress/varify.js
@@ -13,10 +13,10 @@ reduce_merge_const: {
        console.log(b);
    }
    expect: {
-        var b = console;
-        console.log(typeof b);
-        b = typeof b;
-        console.log(b);
+        var a = console;
+        console.log(typeof a);
+        a = typeof a;
+        console.log(a);
    }
    expect_stdout: [
        "object",
@@ -41,10 +41,10 @@ reduce_merge_let: {
    }
    expect: {
        "use strict";
-        var b = console;
-        console.log(typeof b);
-        b = typeof b;
-        console.log(b);
+        var a = console;
+        console.log(typeof a);
+        a = typeof a;
+        console.log(a);
    }
    expect_stdout: [
        "object",
@@ -111,7 +111,7 @@ hoist_props_const: {
        }
    }
    expect: {
-        var o_p = "PASS";
+        var o = 0, o_p = "PASS";
        console.log(o_p);
    }
    expect_stdout: "PASS"
@@ -136,7 +136,7 @@ hoist_props_let: {
    }
    expect: {
        "use strict";
-        var o_p = "PASS";
+        var o, o_p = "PASS";
        console.log(o_p);
    }
    expect_stdout: "PASS"
--- a/test/compress/webkit.js
+++ b/test/compress/webkit.js
@@ -61,7 +61,7 @@ lambda_name_mangle: {

 lambda_name_mangle_ie8: {
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
@@ -95,7 +95,7 @@ function_name_mangle_ie8: {
        unused: true,
    }
    mangle = {
-        ie8: true,
+        ie: true,
        toplevel: true,
    }
    input: {
--- a/test/compress/yields.js
+++ b/test/compress/yields.js
@@ -96,7 +96,7 @@ pause_resume: {
    node_version: ">=4"
 }

-arrow_yield: {
+arrow_yield_1: {
    input: {
        yield = "PASS";
        console.log(function*() {
@@ -108,6 +108,18 @@ arrow_yield: {
    node_version: ">=4"
 }

+arrow_yield_2: {
+    input: {
+        console.log(typeof function *() {
+            // Syntax error on Node.js v6+
+            return (yield) => {};
+        }().next().value);
+    }
+    expect_exact: "console.log(typeof function*(){return(yield)=>{}}().next().value);"
+    expect_stdout: "function"
+    node_version: "4"
+}
+
 for_of: {
    input: {
        function* f() {
@@ -737,7 +749,7 @@ lift_sequence: {
    node_version: ">=4"
 }

-inline_nested_yield: {
+inline_nested: {
    options = {
        inline: true,
        sequences: true,
@@ -772,6 +784,118 @@ inline_nested_yield: {
    node_version: ">=4"
 }

+inline_nested_async: {
+    options = {
+        awaits: true,
+        inline: true,
+        sequences: true,
+        side_effects: true,
+        yields: true,
+    }
+    input: {
+        console.log("foo");
+        var a = async function*() {
+            console.log(await(yield* async function*() {
+                yield {
+                    then: r => r("bar"),
+                };
+                return "baz";
+            }()));
+        }();
+        console.log("moo");
+        a.next().then(function f(b) {
+            console.log(b.value);
+            b.done || a.next().then(f);
+        });
+        console.log("moz");
+    }
+    expect: {
+        console.log("foo");
+        var a = async function*() {
+            console.log((yield {
+                then: r => r("bar"),
+            }, await "baz"));
+        }();
+        console.log("moo"),
+        a.next().then(function f(b) {
+            console.log(b.value),
+            b.done || a.next().then(f);
+        }),
+        console.log("moz");
+    }
+    expect_stdout: [
+        "foo",
+        "moo",
+        "moz",
+        "bar",
+        "baz",
+        "undefined",
+    ]
+    node_version: ">=10"
+}
+
+inline_nested_block: {
+    options = {
+        if_return: true,
+        inline: true,
+        yields: true,
+    }
+    input: {
+        var a = function*() {
+            yield* function*() {
+                for (var a of [ "foo", "bar" ])
+                    yield a;
+                return "FAIL";
+            }();
+        }(), b;
+        do {
+            b = a.next();
+            console.log(b.value);
+        } while (!b.done);
+    }
+    expect: {
+        var a = function*() {
+            for (var a of [ "foo", "bar" ])
+                yield a;
+            "FAIL";
+        }(), b;
+        do {
+            b = a.next();
+            console.log(b.value);
+        } while (!b.done);
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+dont_inline_nested: {
+    options = {
+        inline: true,
+    }
+    input: {
+        var yield = "PASS";
+        (function*() {
+            (function() {
+                console.log(yield);
+            })();
+        })().next();
+    }
+    expect: {
+        var yield = "PASS";
+        (function*() {
+            (function() {
+                console.log(yield);
+            })();
+        })().next();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
 drop_body: {
    options = {
        side_effects: true,
@@ -852,10 +976,10 @@ issue_4454_2: {
        f("PASS");
    }
    expect: {
-        function f(b) {
-            (function*(c = console.log(b)) {})();
-            var b = 42..toString();
-            console.log(b);
+        function f(a) {
+            (function*(c = console.log(a)) {})();
+            var a = 42..toString();
+            console.log(a);
        }
        f("PASS");
    }
@@ -958,7 +1082,7 @@ issue_4639_1: {
        }().next().value());
    }
    expect_stdout: "PASS"
-    node_version: ">=4"
+    node_version: ">=4 <7 || >=8.7.0"
 }

 issue_4639_2: {
@@ -1083,3 +1207,245 @@ issue_4769_2: {
    expect_stdout: "PASS"
    node_version: ">=6"
 }
+
+issue_5019_1: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        (function(a) {
+            return a = function*() {
+                console.log(typeof a);
+            }();
+        })().next();
+    }
+    expect: {
+        (function(a) {
+            return a = function*() {
+                console.log(typeof a);
+            }();
+        })().next();
+    }
+    expect_stdout: "object"
+    node_version: ">=4"
+}
+
+issue_5019_2: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        var a = [];
+        for (var b in "foo")
+            a.push(function(c) {
+                return function*() {
+                    console.log(c);
+                }();
+            }(b));
+        a.map(function(d) {
+            return d.next();
+        });
+    }
+    expect: {
+        var a = [];
+        for (var b in "foo")
+            a.push(function(c) {
+                return function*() {
+                    console.log(c);
+                }();
+            }(b));
+        a.map(function(d) {
+            return d.next();
+        });
+    }
+    expect_stdout: [
+        "0",
+        "1",
+        "2",
+    ]
+    node_version: ">=4"
+}
+
+issue_5032_normal: {
+    options = {
+        merge_vars: true,
+        webkit: false,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(a) {
+            var a = log(a), c = a;
+            log(a);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=4"
+}
+
+issue_5032_webkit: {
+    options = {
+        merge_vars: true,
+        webkit: true,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        function *f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS").next();
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=4"
+}
+
+issue_5034: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            var yield = function f() {
+                return function*() {
+                    return f;
+                };
+            };
+            return yield()().next().value === yield;
+        }() ? "PASS" : "FAIL");
+    }
+    expect: {
+        console.log(function() {
+            var yield = function f() {
+                return function*() {
+                    return f;
+                };
+            };
+            return yield()().next().value === yield;
+        }() ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5076_1: {
+    options = {
+        evaluate: true,
+        hoist_vars: true,
+        pure_getters: "strict",
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+        yields: true,
+    }
+    input: {
+        var a;
+        console.log("PASS");
+        var b = function*({
+            p: {},
+        }) {}({
+            p: { a } = 42,
+        });
+    }
+    expect: {
+        var a;
+        console.log("PASS"),
+        a = 42["a"];
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5076_2: {
+    options = {
+        evaluate: true,
+        hoist_vars: true,
+        passes: 2,
+        pure_getters: "strict",
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+        yields: true,
+    }
+    input: {
+        var a;
+        console.log("PASS");
+        var b = function*({
+            p: {},
+        }) {}({
+            p: { a } = 42,
+        });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5177: {
+    options = {
+        properties: true,
+    }
+    input: {
+        console.log(typeof function*() {
+            return {
+                p(yield) {},
+            }.p;
+        }().next().value);
+    }
+    expect: {
+        console.log(typeof function*() {
+            return {
+                p(yield) {},
+            }.p;
+        }().next().value);
+    }
+    expect_stdout: "function"
+    node_version: ">=4"
+}
--- a/test/input/invalid/optional-template.js
+++ b/test/input/invalid/optional-template.js
@@ -0,0 +1 @@
+console?.log``;
--- a/test/input/reduce/diff_error.reduced.js
+++ b/test/input/reduce/diff_error.reduced.js
@@ -1,7 +1,5 @@
 // (beautified)
-console.log(function() {
-    return 1 + .1 + .1;
-}());
+console.log(1 + .1 + .1);
 // output: 1.2000000000000002
 // 
 // minify: 1.2
--- a/test/jetstream.js
+++ b/test/jetstream.js
@@ -68,6 +68,8 @@ if (typeof phantom == "undefined") {
        (function install() {
            npm([
                "install",
+                "graceful-fs@4.2.6",
+                "is-my-json-valid@2.20.5",
                "phantomjs-prebuilt@2.1.14",
                "--no-audit",
                "--no-optional",
--- a/test/mocha/cli.js
+++ b/test/mocha/cli.js
@@ -2,6 +2,7 @@ var assert = require("assert");
 var exec = require("child_process").exec;
 var fs = require("fs");
 var run_code = require("../sandbox").run_code;
+var semver = require("semver");
 var to_ascii = require("../node").to_ascii;

 function read(path) {
@@ -12,10 +13,13 @@ describe("bin/uglifyjs", function() {
    var uglifyjscmd = '"' + process.argv[0] + '" bin/uglifyjs';
    it("Should produce a functional build when using --self", function(done) {
        this.timeout(30000);
-        var command = uglifyjscmd + ' --self -cm --wrap WrappedUglifyJS';
-        exec(command, {
-            maxBuffer: 1048576
-        }, function(err, stdout) {
+        var command = [
+            uglifyjscmd,
+            "--self",
+            semver.satisfies(process.version, "<=0.12") ? "-mc hoist_funs" : "-mc",
+            "--wrap WrappedUglifyJS",
+        ].join(" ");
+        exec(command, { maxBuffer: 1048576 }, function(err, stdout) {
            if (err) throw err;
            eval(stdout);
            assert.strictEqual(typeof WrappedUglifyJS, "object");
@@ -184,6 +188,30 @@ describe("bin/uglifyjs", function() {
            child.stdin.end(read("test/input/issue-3040/input.js"));
        }, 1000);
    });
+    it("Should work with --keep-fargs (mangle only)", function(done) {
+        var command = uglifyjscmd + ' test/input/issue-1431/sample.js --keep-fargs -m';
+        exec(command, function(err, stdout) {
+            if (err) throw err;
+            assert.strictEqual(stdout, "function f(x){return function(){function n(a){return a*a}return x(n)}}function g(op){return op(1)+op(2)}console.log(f(g)()==5);\n");
+            done();
+        });
+    });
+    it("Should work with --keep-fargs (mangle & compress)", function(done) {
+        var command = uglifyjscmd + ' test/input/issue-1431/sample.js --keep-fargs -m -c';
+        exec(command, function(err, stdout) {
+            if (err) throw err;
+            assert.strictEqual(stdout, "function f(x){return function(){return x(function(a){return a*a})}}function g(op){return op(1)+op(2)}console.log(5==f(g)());\n");
+            done();
+        });
+    });
+    it("Should work with keep_fargs under mangler options", function(done) {
+        var command = uglifyjscmd + ' test/input/issue-1431/sample.js -m keep_fargs=true';
+        exec(command, function(err, stdout) {
+            if (err) throw err;
+            assert.strictEqual(stdout, "function f(x){return function(){function n(a){return a*a}return x(n)}}function g(op){return op(1)+op(2)}console.log(f(g)()==5);\n");
+            done();
+        });
+    });
    it("Should work with --keep-fnames (mangle only)", function(done) {
        var command = uglifyjscmd + ' test/input/issue-1431/sample.js --keep-fnames -m';
        exec(command, function(err, stdout) {
@@ -193,10 +221,10 @@ describe("bin/uglifyjs", function() {
        });
    });
    it("Should work with --keep-fnames (mangle & compress)", function(done) {
-        var command = uglifyjscmd + ' test/input/issue-1431/sample.js --keep-fnames -m -c unused=false';
+        var command = uglifyjscmd + ' test/input/issue-1431/sample.js --keep-fnames -m -c';
        exec(command, function(err, stdout) {
            if (err) throw err;
-            assert.strictEqual(stdout, "function f(r){return function(){function n(n){return n*n}return r(n)}}function g(n){return n(1)+n(2)}console.log(5==f(g)());\n");
+            assert.strictEqual(stdout, "function f(n){return function(){return n(function n(r){return r*r})}}function g(n){return n(1)+n(2)}console.log(5==f(g)());\n");
            done();
        });
    });
@@ -721,6 +749,20 @@ describe("bin/uglifyjs", function() {
            done();
        });
    });
+    it("Should throw syntax error (console?.log``)", function(done) {
+        var command = uglifyjscmd + " test/input/invalid/optional-template.js";
+        exec(command, function(err, stdout, stderr) {
+            assert.ok(err);
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/optional-template.js:1,12",
+                "console?.log``;",
+                "            ^",
+                "ERROR: Invalid template on optional chain",
+            ].join("\n"));
+            done();
+        });
+    });
    it("Should handle literal string as source map input", function(done) {
        var command = [
            uglifyjscmd,
--- a/test/mocha/comments.js
+++ b/test/mocha/comments.js
@@ -191,7 +191,7 @@ describe("comments", function() {
    });

    it("Should correctly preserve new lines around comments", function() {
-        var tests = [
+        [
            [
                "// foo",
                "// bar",
--- a/test/mocha/glob.js
+++ b/test/mocha/glob.js
@@ -1,7 +1,6 @@
 var assert = require("assert");
 var exec = require("child_process").exec;
 var path = require("path");
-var readFileSync = require("fs").readFileSync;

 describe("bin/uglifyjs with input file globs", function() {
    var uglifyjscmd = '"' + process.argv[0] + '" bin/uglifyjs';
--- a/test/mocha/ie8.js
+++ b/test/mocha/ie8.js
@@ -1,21 +0,0 @@
-var assert = require("assert");
-var UglifyJS = require("../..");
-
-describe("ie8", function() {
-    it("Should be able to minify() with undefined as catch parameter in a try...catch statement", function() {
-        assert.strictEqual(
-            UglifyJS.minify([
-                "function a(b){",
-                "    try {",
-                "        throw 'Stuff';",
-                "    } catch (undefined) {",
-                "        console.log('caught: ' + undefined);",
-                "    }",
-                "    console.log('undefined is ' + undefined);",
-                "    return b === undefined;",
-                "};",
-            ].join("\n")).code,
-            'function a(o){try{throw"Stuff"}catch(o){console.log("caught: "+o)}return console.log("undefined is "+void 0),void 0===o}'
-        );
-    });
-});
--- a/test/mocha/let.js
+++ b/test/mocha/let.js
@@ -1,5 +1,5 @@
 var assert = require("assert");
-var UglifyJS = require("../..");
+var UglifyJS = require("../node");

 describe("let", function() {
    this.timeout(30000);
@@ -41,7 +41,7 @@ describe("let", function() {
        }
        var result = UglifyJS.minify(s, {
            compress: false,
-            ie8: true,
+            ie: true,
            mangle: {
                properties: true,
            }
@@ -54,4 +54,43 @@ describe("let", function() {
            assert.notStrictEqual(result.indexOf('v["' + name + '"]'), -1);
        });
    });
+    it("Should parse `let` as name correctly", function() {
+        [
+            "for(var let;let;let)let;",
+            "function let(let){let}",
+        ].forEach(function(code) {
+            var ast = UglifyJS.parse(code);
+            assert.strictEqual(ast.print_to_string(), code);
+            assert.throws(function() {
+                UglifyJS.parse('"use strict";' + code);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error && e.message == "Unexpected let in strict mode";
+            }, code);
+        });
+    });
+    it("Should throw on ambiguous use of `let`", function() {
+        [
+            "export let",
+            [
+                "let",
+                "console.log(42)",
+            ].join("\n"),
+            [
+                "let",
+                "[ console.log(42) ]",
+            ].join("\n"),
+            [
+                "let",
+                "{",
+                "    console.log(42)",
+                "}",
+            ].join("\n"),
+        ].forEach(function(code) {
+            assert.throws(function() {
+                UglifyJS.parse(code);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
 });
--- a/test/mocha/minify.js
+++ b/test/mocha/minify.js
@@ -25,7 +25,7 @@ describe("minify", function() {
        if (result.error) throw result.error;
        assert.strictEqual(result.code, "print(42);");
        assert.strictEqual(JSON.stringify(options), value);
-    })
+    });
    it("Should skip inherited keys from `files`", function() {
        var files = Object.create({ skip: this });
        files[0] = "alert(1 + 1)";
--- a/test/mocha/reduce.js
+++ b/test/mocha/reduce.js
@@ -1,5 +1,4 @@
 var assert = require("assert");
-var exec = require("child_process").exec;
 var fs = require("fs");
 var reduce_test = require("../reduce");
 var semver = require("semver");
@@ -282,7 +281,8 @@ describe("test/reduce.js", function() {
        });
        if (result.error) throw result.error;
        assert.deepEqual(result.warnings, []);
-        assert.strictEqual(result.code.replace(/function \(/g, "function("), (semver.satisfies(process.version, "<=0.10") ? [
+        if (semver.satisfies(process.version, "<=0.10")) {
+            assert.strictEqual(result.code, [
                "// Can't reproduce test failure",
                "// minify options: {",
                '//   "compress": false,',
@@ -291,7 +291,10 @@ describe("test/reduce.js", function() {
                '//     "beautify": true',
                "//   }",
                "// }",
-        ] : [
+            ].join("\n"));
+        } else {
+            var message = result.code.split(/\n/, 3)[1].slice("// output: ".length);
+            assert.strictEqual(result.code, [
                [
                    "try{",
                    "null[function(){}]",
@@ -299,9 +302,9 @@ describe("test/reduce.js", function() {
                    "console.log(e)",
                    "}",
                ].join(""),
-            "// output: TypeError: Cannot read property 'function(){}' of null",
+                "// output: " + message,
                "// ",
-            "// minify: TypeError: Cannot read property 'function() {}' of null",
+                "// minify: " + message.replace("(){}", "() {}"),
                "// ",
                "// options: {",
                '//   "compress": false,',
@@ -310,7 +313,8 @@ describe("test/reduce.js", function() {
                '//     "beautify": true',
                "//   }",
                "// }",
-        ]).join("\n"));
+            ].join("\n"));
+        }
    });
    it("Should maintain block-scope for const/let", function() {
        if (semver.satisfies(process.version, "<4")) return;
@@ -414,4 +418,20 @@ describe("test/reduce.js", function() {
        if (result.error) throw result.error;
        assert.deepEqual(result.warnings, []);
    });
+    it("Should handle thrown falsy values gracefully", function() {
+        var code = [
+            "throw 0;",
+            "setTimeout(null, 42);",
+        ].join("\n");
+        var result = reduce_test(code, {
+            mangle: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, [
+            "// Can't reproduce test failure",
+            "// minify options: {",
+            '//   "mangle": false',
+            "// }",
+        ].join("\n"));
+    });
 });
--- a/test/mocha/sourcemaps.js
+++ b/test/mocha/sourcemaps.js
@@ -205,8 +205,8 @@ describe("sourcemaps", function() {
            });
            if (result.error) throw result.error;
            assert.strictEqual(result.code, [
-                "var Foo=function(){console.log(3)};new Foo;var bar=function(o){return o};",
-                "//# sourceMappingURL=data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInN0ZGluIiwiMSJdLCJuYW1lcyI6WyJGb28iLCJjb25zb2xlIiwibG9nIiwiYmFyIl0sIm1hcHBpbmdzIjoiQUFBQSxJQUFNQSxJQUFJLFdBQWdCQyxRQUFRQyxJQUFJLElBQVMsSUFBSUYsSUNBbkQsSUFBSUcsSUFDQSxTQUFjQSxHQUNWLE9BQU9BIn0=",
+                "var Foo=function(){console.log(3)},bar=(new Foo,function(o){return o});",
+                "//# sourceMappingURL=data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJzb3VyY2VzIjpbInN0ZGluIiwiMSJdLCJuYW1lcyI6WyJGb28iLCJjb25zb2xlIiwibG9nIiwiYmFyIl0sIm1hcHBpbmdzIjoiQUFBQSxJQUFNQSxJQUFJLFdBQWdCQyxRQUFRQyxJQUFJLElDQWxDQyxLREEyQyxJQUFJSCxJQ0MvQyxTQUFjRyxHQUNWLE9BQU9BIn0=",
            ].join("\n"));
            assert.deepEqual(result.warnings, [ "WARN: inline source map not found: 1" ]);
        });
@@ -362,7 +362,7 @@ describe("sourcemaps", function() {
        it("Should not modify input source map", function() {
            var orig = get_map();
            var original = JSON.stringify(orig);
-            var map = prepare_map(orig);
+            prepare_map(orig);
            assert.strictEqual(JSON.stringify(orig), original);
        });
        it("Should copy over original sourcesContent", function() {
--- a/test/mocha/spidermonkey.js
+++ b/test/mocha/spidermonkey.js
@@ -1,37 +1,42 @@
 var assert = require("assert");
 var exec = require("child_process").exec;
+var semver = require("semver");
 var UglifyJS = require("../..");

 describe("spidermonkey export/import sanity test", function() {
    it("Should produce a functional build when using --self with spidermonkey", function(done) {
-        this.timeout(60000);
-
+        this.timeout(120000);
        var uglifyjs = '"' + process.argv[0] + '" bin/uglifyjs';
-        var command = uglifyjs + " --self -cm --wrap SpiderUglify -o spidermonkey | " +
-            uglifyjs + " -p spidermonkey -cm";
-
-        exec(command, {
-            maxBuffer: 1048576
-        }, function(err, stdout) {
+        var options = semver.satisfies(process.version, "<=0.12") ? "-mc hoist_funs" : "-mc";
+        var command = [
+            [
+                uglifyjs,
+                "--self",
+                options,
+                "--wrap SpiderUglify",
+                "-o spidermonkey",
+            ].join(" "),
+            [
+                uglifyjs,
+                "-p spidermonkey",
+                options,
+            ].join(" "),
+        ].join(" | ");
+        exec(command, { maxBuffer: 1048576 }, function(err, stdout) {
            if (err) throw err;
-
            eval(stdout);
            assert.strictEqual(typeof SpiderUglify, "object");
            var result = SpiderUglify.minify("foo([true,,2+3]);");
            assert.strictEqual(result.error, undefined);
            assert.strictEqual(result.code, "foo([!0,,5]);");
-
            done();
        });
    });

-    it("Should not add unnecessary escape slashes to regexps", function() {
+    it("Should not add unnecessary escape slashes to RegExp", function() {
        var input = "/[\\\\/]/;";
        var ast = UglifyJS.parse(input).to_mozilla_ast();
-        assert.equal(
-            UglifyJS.AST_Node.from_mozilla_ast(ast).print_to_string(),
-            input
-        );
+        assert.strictEqual(UglifyJS.AST_Node.from_mozilla_ast(ast).print_to_string(), input);
    });

    it("Should judge between directives and strings correctly on import", function() {
--- a/test/mocha/string-literal.js
+++ b/test/mocha/string-literal.js
@@ -12,7 +12,7 @@ describe("String literals", function() {
            '"\u2029"',
        ].forEach(function(input) {
            assert.throws(function() {
-                var ast = UglifyJS.parse(input);
+                UglifyJS.parse(input);
            }, function(e) {
                return e instanceof UglifyJS.JS_Parse_Error
                    && e.message === "Unterminated string constant";
@@ -44,7 +44,7 @@ describe("String literals", function() {
            '"use strict";\n"\\011"',
        ].forEach(function(input) {
            assert.throws(function() {
-                var output = UglifyJS.parse(input);
+                UglifyJS.parse(input);
            }, function(e) {
                return e instanceof UglifyJS.JS_Parse_Error
                    && e.message === "Legacy octal escape sequences are not allowed in strict mode";
--- a/test/mocha/templates.js
+++ b/test/mocha/templates.js
@@ -34,20 +34,20 @@ describe("Template literals", function() {
        [
            // native line breaks
            [ "`foo\nbar`", "`foo\nbar`" ],
-            [ "`foo\rbar`", "`foo\rbar`" ],
+            [ "`foo\rbar`", "`foo\nbar`" ],
            [ "`foo\r\nbar`", "`foo\nbar`" ],
-            [ "`foo\r\n\rbar`", "`foo\n\rbar`" ],
+            [ "`foo\r\n\rbar`", "`foo\n\nbar`" ],
            // escaped line breaks
            [ "`foo\\nbar`", "`foo\\nbar`" ],
            [ "`foo\\rbar`", "`foo\\rbar`" ],
-            [ "`foo\r\\nbar`", "`foo\r\\nbar`" ],
+            [ "`foo\r\\nbar`", "`foo\n\\nbar`" ],
            [ "`foo\\r\nbar`", "`foo\\r\nbar`" ],
            [ "`foo\\r\\nbar`", "`foo\\r\\nbar`" ],
            // continuation
            [ "`foo\\\nbar`", "`foo\\\nbar`" ],
-            [ "`foo\\\rbar`", "`foo\\\rbar`" ],
+            [ "`foo\\\rbar`", "`foo\\\nbar`" ],
            [ "`foo\\\r\nbar`", "`foo\\\nbar`" ],
-            [ "`foo\\\r\n\rbar`", "`foo\\\n\rbar`" ],
+            [ "`foo\\\r\n\rbar`", "`foo\\\n\nbar`" ],
            [ "`foo\\\\nbar`", "`foo\\\\nbar`" ],
            [ "`foo\\\\rbar`", "`foo\\\\rbar`" ],
            [ "`foo\\\\r\nbar`", "`foo\\\\r\nbar`" ],
--- a/test/reduce.js
+++ b/test/reduce.js
@@ -22,7 +22,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
    reduce_options = reduce_options || {};
    var print_options = {};
    [
-        "ie8",
+        "ie",
        "v8",
        "webkit",
    ].forEach(function(name) {
@@ -215,9 +215,9 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                    // hoist and return expressions from the IIFE function expression
                    var seq = [];
                    node.expression.body.forEach(function(node) {
-                        var expr = expr instanceof U.AST_Exit ? node.value : node.body;
+                        var expr = node instanceof U.AST_Exit ? node.value : node.body;
                        if (expr instanceof U.AST_Node && !U.is_statement(expr) && can_hoist(expr)) {
-                            // collect expressions from each statements' body
+                            // collect expressions from each statement's body
                            seq.push(expr);
                        }
                    });
@@ -395,7 +395,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                var expr = [
                    node.expression,                         // switch expression
                    node.body[0] && node.body[0].expression, // first case expression or undefined
-                    node.body[0] && node.body[0],            // first case body or undefined
+                    node.body[0],                            // first case body or undefined
                ][ (node.start._permute * steps | 0) % 4 ];
                node.start._permute += step;
                if (expr && (!(expr instanceof U.AST_Statement) || !has_loopcontrol(expr, node, parent))) {
@@ -548,7 +548,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
            }));
            var before_iterations = testcase;
            for (var c = 0; c < max_iterations; ++c) {
-                if (verbose && pass == 1 && c % 25 == 0) {
+                if (verbose && c % (pass == 1 ? 25 : 100) == 0) {
                    log("// reduce test pass " + pass + ", iteration " + c + ": " + testcase.length + " bytes");
                }
                var CHANGED = false;
@@ -726,7 +726,7 @@ function to_statement_init(node) {
    return node instanceof U.AST_Const || node instanceof U.AST_Let ? new U.AST_BlockStatement({
        body: [ node ],
        start: {},
-    }) : to_statement(node);;
+    }) : to_statement(node);
 }

 function wrap_with_console_log(node) {
--- a/test/release/rollup-ts.sh
+++ b/test/release/rollup-ts.sh
@@ -43,6 +43,9 @@ rm -rf tmp/rollup \
 -    "postpublish": "pinst --enable",
 -    "prepare": "npm run build",
 -    "prepublishOnly": "pinst --disable && npm ci && npm run lint:nofix && npm run security && npm run build:bootstrap && npm run test:all",
+@@ -93 +89 @@
+-    "is-reference": "lukastaegert/is-reference#update-class-features",
+    "is-reference": "3.0.0",
 --- a/test/cli/index.js
 +++ b/test/cli/index.js
@@ -13,0 +14,3 @@ sander.rimrafSync(__dirname, 'node_modules');
--- a/test/sandbox.js
+++ b/test/sandbox.js
@@ -26,9 +26,11 @@ exports.run_code = semver.satisfies(process.version, "0.8") ? function(code, top
    return stdout;
 } : semver.satisfies(process.version, "<0.12") ? run_code_vm : function(code, toplevel, timeout) {
    if ([
-        /\basync[ \t]*\([\s\S]*?\)[ \t]*=>/,
        /\b(async[ \t]+function|Promise|setImmediate|setInterval|setTimeout)\b/,
-        /\basync([ \t]+|[ \t]*#|[ \t]*\*[ \t]*)[^\s()[\]{},.&|!~=*%/+-]+(\s*\(|[ \t]*=>)/,
+        /\basync([ \t]+|[ \t]*#)[^\s()[\]{}#:;,.&|!~=*%/+-]+(\s*\(|[ \t]*=>)/,
+        /\basync[ \t]*\*[ \t]*[^\s()[\]{}#:;,.&|!~=*%/+-]+\s*\(/,
+        /\basync([ \t]*\*)?[ \t]*\[[\s\S]*?\]\s*\(/,
+        /\basync[ \t]*\([\s\S]*?\)[ \t]*=>/,
    ].some(function(pattern) {
        return pattern.test(code);
    })) {
@@ -51,13 +53,13 @@ exports.same_stdout = semver.satisfies(process.version, "0.12") ? function(expec
 };
 exports.patch_module_statements = function(code) {
    var count = 0, imports = [];
-    code = code.replace(/\bexport(?:\s*\{[^}]*}\s*?(?:$|\n|;)|\s+default\b(?:\s*(\(|\{|class\s*\{|class\s+(?=extends\b)|(?:async\s+)?function\s*(?:\*\s*)?\())?|\b)/g, function(match, header) {
+    code = code.replace(/\bexport(?:\s*\{[^{}]*}\s*?(?:$|\n|;)|\s+default\b(?:\s*(\(|\{|class\s*\{|class\s+(?=extends\b)|(?:async\s+)?function\s*(?:\*\s*)?\())?|\b)/g, function(match, header) {
        if (!header) return "";
        if (header.length == 1) return "0, " + header;
        return header.slice(0, -1) + " _" + ++count + header.slice(-1);
    }).replace(/\bimport\.meta\b/g, function() {
        return '({ url: "https://example.com/path/index.html" })';
-    }).replace(/\bimport\b(?:\s*([^('"]+)\bfrom\b)?\s*(['"]).*?\2(?:$|\n|;)/g, function(match, symbols) {
+    }).replace(/\bimport\b(?:\s*([^\s('"][^('"]*)\bfrom\b)?\s*(['"]).*?\2(?:$|\n|;)/g, function(match, symbols) {
        if (symbols) {
            if (!/^[{*]/.test(symbols)) symbols = "default:" + symbols;
            symbols = symbols.replace(/[{}]/g, "").trim().replace(/\s*,\s*/g, ",");
@@ -146,7 +148,8 @@ function setup(global, builtins, setup_log, setup_tty) {
                    delete ex[name];
                }
            }
-            process.stderr.write(inspect(value) + "\n\n-----===== UNCAUGHT EXCEPTION =====-----\n\n");
+            var marker = "\n\n-----===== UNCAUGHT EXCEPTION =====-----\n\n";
+            process.stderr.write(marker + inspect(value) + marker);
            throw ex;
        }).on("unhandledRejection", function() {});
    }
@@ -202,13 +205,11 @@ function setup(global, builtins, setup_log, setup_tty) {
    });
    Object.defineProperties(global, props);
    // for Node.js v8+
-    if (global.toString !== Object.prototype.toString) {
    global.__proto__ = Object.defineProperty(Object.create(global.__proto__), "toString", {
        value: function() {
            return "[object global]";
        },
    });
-    }

    function self() {
        return this;
@@ -254,8 +255,11 @@ function run_code_vm(code, toplevel, timeout) {
        var ctx = vm.createContext({ console: console });
        // for Node.js v6
        vm.runInContext(setup_code, ctx);
-        vm.runInContext(toplevel ? "(function(){" + code + "})();" : code, ctx, { timeout: timeout });
-        return strip_color_codes(stdout);
+        vm.runInContext(toplevel ? "(function(){\n" + code + "\n})();" : code, ctx, { timeout: timeout });
+        // for Node.js v4
+        return strip_color_codes(stdout.replace(/\b(Array \[|Object {)/g, function(match) {
+            return match.slice(-1);
+        }));
    } catch (ex) {
        return ex;
    } finally {
@@ -265,7 +269,7 @@ function run_code_vm(code, toplevel, timeout) {

 function run_code_exec(code, toplevel, timeout) {
    if (toplevel) {
-        code = setup_code + "(function(){" + code + "})();";
+        code = setup_code + "(function(){\n" + code + "\n})();";
    } else {
        code = code.replace(/^((["'])[^"']*\2(;|$))?/, function(directive) {
            return directive + setup_code;
@@ -278,22 +282,26 @@ function run_code_exec(code, toplevel, timeout) {
        timeout: timeout || 5000,
    });
    if (result.status === 0) return result.stdout;
+    var msg = ("" + result.stderr).replace(/\r\n/g, "\n");
    if (result.error && result.error.code == "ETIMEDOUT" || /FATAL ERROR:/.test(msg)) {
        return new Error("Script execution timed out.");
    }
    if (result.error) return result.error;
-    var msg = result.stderr.replace(/\r\n/g, "\n");
-    var end = msg.indexOf("\n\n-----===== UNCAUGHT EXCEPTION =====-----\n\n");
+    var match = /\n([^:\s]*Error)(?:: ([\s\S]+?))?\n(    at [\s\S]+)\n$/.exec(msg);
+    var marker = "\n\n-----===== UNCAUGHT EXCEPTION =====-----\n\n";
+    var start = msg.indexOf(marker) + marker.length;
+    var end = msg.indexOf(marker, start);
    var details;
    if (end >= 0) {
-        details = msg.slice(0, end).replace(/<([1-9][0-9]*) empty items?>/g, function(match, count) {
+        details = msg.slice(start, end).replace(/<([1-9][0-9]*) empty items?>/g, function(match, count) {
            return new Array(+count).join();
        });
        try {
            details = vm.runInNewContext("(" + details + ")");
        } catch (e) {}
+    } else if (!match) {
+        return new Error("Script execution aborted.");
    }
-    var match = /\n([^:\s]*Error)(?:: ([\s\S]+?))?\n(    at [\s\S]+)\n$/.exec(msg);
    if (!match) return details;
    var ex = new global[match[1]](match[2]);
    ex.stack = ex.stack.slice(0, ex.stack.indexOf("    at ")) + match[3];
--- a/test/ufuzz/index.js
+++ b/test/ufuzz/index.js
@@ -334,6 +334,7 @@ var VAR_NAMES = [
    "arguments",
    "async",
    "await",
+    "let",
    "yield",
 ];
 var INITIAL_NAMES_LEN = VAR_NAMES.length;
@@ -352,7 +353,7 @@ var TYPEOF_OUTCOMES = [
 ];

 var avoid_vars = [];
-var block_vars = [];
+var block_vars = [ "let" ];
 var lambda_vars = [];
 var unique_vars = [];
 var classes = [];
@@ -399,7 +400,7 @@ function mayDefer(code) {

 function createTopLevelCode() {
    VAR_NAMES.length = INITIAL_NAMES_LEN; // prune any previous names still in the list
-    block_vars.length = 0;
+    block_vars.length = 1;
    lambda_vars.length = 0;
    unique_vars.length = 0;
    classes.length = 0;
@@ -2027,6 +2028,7 @@ function removeAvoidVar(name) {
 function isBannedKeyword(name) {
    switch (name) {
      case "arguments":
+      case "let":
        return in_class;
      case "await":
        return async !== false;
@@ -2078,8 +2080,8 @@ if (require.main !== module) {
    return;
 }

-function run_code(code, toplevel) {
-    return sandbox.run_code(sandbox.patch_module_statements(code), toplevel);
+function run_code(code, toplevel, timeout) {
+    return sandbox.run_code(sandbox.patch_module_statements(code), toplevel, timeout);
 }

 function writeln(stream, msg) {
@@ -2256,7 +2258,7 @@ function sort_globals(code) {
            return (typeof global[n] == "function") - (typeof global[m] == "function")
                || (m < n ? -1 : m > n ? 1 : 0);
        };
-    } + "(this));" + code);
+    } + "(this));\n" + code);
    if (!Array.isArray(globals)) {
        errorln();
        errorln();
@@ -2288,12 +2290,26 @@ function fuzzy_match(original, uglified) {
    return true;

    function collect(input, nums) {
-        return input.replace(/-?([1-9][0-9]*(\.[0-9]+)?|0\.[0-9]+)(e-?[1-9][0-9]*)?/ig, function(num) {
+        return input.replace(/-?([1-9][0-9]*(\.[0-9]+)?|0\.[0-9]+)(e-?[1-9][0-9]*)?/gi, function(num) {
            return "<|" + nums.push(+num) + "|>";
        });
    }
 }

+function patch_proto() {
+    [ Array, Boolean, Error, Function, Number, Object, RegExp, String ].forEach(function(type) {
+        [ "toString", "valueOf" ].forEach(function(prop) {
+            type.prototype[prop] = function(fn) {
+                return function() {
+                    try {
+                        return fn.apply(this, arguments);
+                    } catch (e) {}
+                };
+            }(type.prototype[prop]);
+        });
+    });
+}
+
 function is_error_timeout(ex) {
    return /timed out/.test(ex.message);
 }
@@ -2336,7 +2352,7 @@ function patch_try_catch(orig, toplevel) {
        tries: [],
    } ];
    var tail_throw = '\nif (typeof UFUZZ_ERROR == "object") throw UFUZZ_ERROR;\n';
-    var re = /(?:(?:^|[\s{}):;])try|}\s*catch\s*\(([^)[{]+)\)|}\s*finally)\s*(?={)/g;
+    var re = /(?:(?:^|[\s{}):;])try|}\s*catch\s*\(([^()[{]+)\)|}\s*finally)\s*(?={)/g;
    while (stack.length) {
        var code = stack[0].code;
        var offset = stack[0].offset;
@@ -2454,7 +2470,9 @@ for (var round = 1; round <= num_iterations; round++) {
        println(result);
        println();
            // ignore v8 parser bug
-        return bug_async_arrow_rest(result);
+        return bug_async_arrow_rest(result)
+            // ignore runtime platform bugs
+            || result.message == "Script execution aborted.";
    })) continue;
    minify_options.forEach(function(options) {
        var o = JSON.parse(options);
@@ -2469,6 +2487,8 @@ for (var round = 1; round <= num_iterations; round++) {
            ok = sandbox.same_stdout(original_result, uglify_result);
            // ignore v8 parser bug
            if (!ok && bug_async_arrow_rest(uglify_result)) ok = true;
+            // ignore runtime platform bugs
+            if (!ok && uglify_result.message == "Script execution aborted.") ok = true;
            // handle difference caused by time-outs
            if (!ok && errored && is_error_timeout(original_result)) {
                if (is_error_timeout(uglify_result)) {
@@ -2481,7 +2501,7 @@ for (var round = 1; round <= num_iterations; round++) {
                }
            }
            // ignore declaration order of global variables
-            if (!ok && !toplevel) {
+            if (!ok && !toplevel && uglify_result.name != "SyntaxError" && original_result.name != "SyntaxError") {
                ok = sandbox.same_stdout(run_code(sort_globals(original_code)), run_code(sort_globals(uglify_code)));
            }
            // ignore numerical imprecision caused by `unsafe_math`
@@ -2500,18 +2520,23 @@ for (var round = 1; round <= num_iterations; round++) {
            if (!ok && errored && uglify_result.name == "ReferenceError" && original_result.name == "ReferenceError") ok = true;
            // ignore difference due to implicit strict-mode in `class`
            if (!ok && /\bclass\b/.test(original_code)) {
-                var original_strict = run_code('"use strict";' + original_code, toplevel);
-                var uglify_strict = run_code('"use strict";' + uglify_code, toplevel);
-                if (typeof original_strict != "string") {
-                    ok = typeof uglify_strict != "string";
+                var original_strict = run_code('"use strict";\n' + original_code, toplevel);
+                if (/^(Syntax|Type)Error$/.test(uglify_result.name)) {
+                    ok = typeof original_strict != "string";
                } else {
-                    ok = sandbox.same_stdout(original_strict, uglify_strict);
+                    ok = sandbox.same_stdout(original_strict, uglify_result);
                }
            }
            // ignore difference in error message caused by `import` symbol redeclaration
            if (!ok && errored && /\bimport\b/.test(original_code)) {
                if (is_error_redeclaration(uglify_result) && is_error_redeclaration(original_result)) ok = true;
            }
+            // ignore difference due to `__proto__` assignment
+            if (!ok && /\b__proto__\b/.test(original_code)) {
+                var original_proto = run_code("(" + patch_proto + ")();\n" + original_code, toplevel);
+                var uglify_proto = run_code("(" + patch_proto + ")();\n" + uglify_code, toplevel);
+                ok = sandbox.same_stdout(original_proto, uglify_proto);
+            }
            // ignore difference in error message caused by `in`
            if (!ok && errored && is_error_in(uglify_result) && is_error_in(original_result)) ok = true;
            // ignore difference in error message caused by spread syntax
--- a/test/ufuzz/options.json
+++ b/test/ufuzz/options.json
@@ -16,7 +16,7 @@
    },
    {},
    {
-        "ie8": true,
+        "ie": true,
        "toplevel": true
    },
    {
@@ -26,6 +26,7 @@
            "passes": 1e6,
            "unsafe": true
        },
+        "keep_fargs": true,
        "keep_fnames": true,
        "toplevel": true
    },
Author	SHA1	Message	Date
Alex Lam S.L	6de708af37	v3.15.0	2022-01-26 01:33:13 +08:00
Alex Lam S.L	b9b2a4f7f8	fix corner case in `inline` (#5311 ) fixes #5222	2022-01-26 00:47:24 +08:00
Alex Lam S.L	b46c7944c6	fix corner case in `collapse_vars` (#5310 ) fixes #5309	2022-01-23 00:45:11 +08:00
Alex Lam S.L	866cd4a975	enhance `merge_vars` (#5308 )	2022-01-21 09:40:33 +08:00
Alex Lam S.L	e24b255350	implement `keep_fargs` for `mangle` (#5307 ) closes #4657	2022-01-21 05:13:26 +08:00
Alex Lam S.L	efed55f42d	fix corner case in `inline` (#5306 ) fixes #5305	2022-01-19 08:14:19 +08:00
Alex Lam S.L	8c2b76eff9	enhance `side_effects` (#5304 )	2022-01-17 23:18:42 +08:00
Alex Lam S.L	b636e97e3b	fix corner cases in `awaits` (#5303 )	2022-01-17 16:22:26 +08:00
Alex Lam S.L	35d7f316ef	fix corner cases in `typeofs` (#5301 )	2022-01-17 14:03:41 +08:00
Alex Lam S.L	43807c26fb	fix performance regression (#5302 ) fixes #5297	2022-01-17 11:49:47 +08:00
Alex Lam S.L	774feeadb8	minor clean-ups (#5300 )	2022-01-17 01:14:52 +08:00
Alex Lam S.L	d96c59f9e6	fix corner case in `side_effects` (#5299 ) fixes #5298	2022-01-16 02:33:14 +08:00
Alex Lam S.L	dfd6418878	fix corner case in `inline` (#5297 ) fixes #5296	2022-01-15 04:18:35 +08:00
Alex Lam S.L	87e8aca245	fix corner cases in `reduce_vars`, `side_effects` & `unused` (#5295 ) fixes #5294	2022-01-15 01:44:36 +08:00
Alex Lam S.L	14e1311bdf	fix corner cases in `side_effects` (#5293 ) fixes #5292	2022-01-14 09:14:04 +08:00
Alex Lam S.L	ff3c2ed7a2	fix corner case in `inline` (#5291 ) fixes #5290	2022-01-12 20:17:34 +08:00
Alex Lam S.L	f8602aca96	fix corner case in `inline` (#5289 ) fixes #5288	2022-01-12 16:24:50 +08:00
Alex Lam S.L	9a58270b70	enhance `imports` (#5287 )	2022-01-12 16:24:04 +08:00
Alex Lam S.L	f639a30bd2	fix corner cases in `typeofs` (#5286 )	2022-01-11 13:13:46 +08:00
Alex Lam S.L	082013c20f	report runtime process aborts correctly (#5285 )	2022-01-11 09:12:01 +08:00
Alex Lam S.L	c7d2837184	fix corner case in `inline` (#5284 ) fixes #5283	2022-01-10 15:43:26 +08:00
Alex Lam S.L	caaa753861	minor clean-ups (#5282 )	2022-01-10 13:02:26 +08:00
Alex Lam S.L	4b949f6686	suppress false positives in `ufuzz` (#5281 )	2022-01-10 05:05:35 +08:00
Alex Lam S.L	e9d9d5a9d2	improve `class` compatibility in `side_effects` (#5279 )	2022-01-09 21:15:42 +08:00
Alex Lam S.L	f473b4db38	fix corner case in `collapse_vars` (#5278 ) fixes #5277	2022-01-08 09:46:21 +08:00
Alex Lam S.L	b0df5d7b55	enhance `collapse_vars` & `reduce_vars` (#5275 ) fixes #5276	2022-01-08 05:26:49 +08:00
Alex Lam S.L	be8c75bae1	fix corner case in `collapse_vars` (#5274 ) fixes #5273	2022-01-07 15:00:23 +08:00
Alex Lam S.L	58bea676ac	fix corner case in `unused` (#5272 ) fixes #5271	2022-01-07 14:33:42 +08:00
Alex Lam S.L	9aab1f3661	fix corner case in `inline` (#5270 ) fixes #5269	2022-01-07 13:22:16 +08:00
Alex Lam S.L	10a1523ee6	enhance `collapse_vars` (#5268 )	2022-01-07 05:13:37 +08:00
Alex Lam S.L	d46eb69320	fix corner case in `inline` (#5267 ) fixes #5266	2022-01-05 04:25:48 +08:00
Alex Lam S.L	3a3666a94e	fix corner cases in `inline` (#5265 ) fixes #5263 fixes #5264	2022-01-04 22:05:03 +08:00
Alex Lam S.L	2f568b9357	enhance `mangle` (#5262 )	2022-01-04 10:06:00 +08:00
Alex Lam S.L	c94624f36c	fix corner case in `collapse_vars` (#5261 ) fixes #5260	2022-01-04 04:18:41 +08:00
Alex Lam S.L	dec359ce58	fix corner case in `awaits` & `inline` (#5259 ) fixes #5258	2022-01-03 20:57:24 +08:00
Alex Lam S.L	1a054e869e	fix corner case in `inline` (#5257 ) fixes #5256	2022-01-03 10:13:29 +08:00
Alex Lam S.L	7889192cae	fix corner cases in `inline` (#5255 ) fixes #5254	2022-01-02 21:24:41 +08:00
Alex Lam S.L	f7841bc8b8	fix corner case in `inline` (#5253 ) fixes #5251	2022-01-02 16:10:39 +08:00
Alex Lam S.L	aa6eb0d5be	fix corner cases in `inline` (#5252 ) fixes #5249 fixes #5250	2022-01-02 14:59:32 +08:00
Alex Lam S.L	87a7426598	enhance `inline` & `unused` (#5245 )	2022-01-02 05:40:43 +08:00
Alex Lam S.L	8d0422b6f3	enhance `reduce_vars` (#5248 )	2022-01-01 07:53:47 +08:00
Alex Lam S.L	e7ce1051fe	fix corner cases in `reduce_vars` & `unused` (#5247 ) fixes #5246	2021-12-31 04:47:13 +08:00
Alex Lam S.L	80d5f23fee	fix corner case with lexical variables (#5244 )	2021-12-30 05:15:53 +08:00
Alex Lam S.L	d51caaf358	enhance `inline` (#5243 )	2021-12-28 00:53:12 +08:00
Alex Lam S.L	835d130ccf	fix corner cases in `inline` (#5241 ) fixes #5239 fixes #5240	2021-12-26 08:39:06 +08:00
Alex Lam S.L	e1013bd56d	fix corner case in `inline` (#5238 ) fixes #5237	2021-12-25 19:30:49 +08:00
Alex Lam S.L	13d41778b3	suppress false positives in `test/reduce` (#5235 )	2021-12-25 03:13:37 +08:00
Alex Lam S.L	bab416465f	fix corner case in `conditionals` (#5233 ) fixes #5232	2021-12-23 22:25:02 +08:00
Alex Lam S.L	29a1e71705	fix corner case in `inline` (#5231 ) fixes #5230	2021-12-23 14:26:07 +08:00
Alex Lam S.L	7b2eb4b5ff	improve handling of non-trivial assignment values (#5227 )	2021-12-23 07:55:06 +08:00
Alex Lam S.L	343bf6d7a5	fix corner case in `booleans` & `inline` (#5229 ) fixes #5228	2021-12-21 23:46:20 +08:00
Alex Lam S.L	ba42cbad3f	enhance `inline` (#5226 )	2021-12-21 13:03:11 +08:00
Alex Lam S.L	86406e71ec	fix corner case in `unused` (#5225 ) fixes #5224	2021-12-20 02:25:38 +08:00
Alex Lam S.L	9e927ecc9a	fix corner case in `hoist_props` (#5223 ) fixes #5222	2021-12-16 02:57:34 +08:00
Alex Lam S.L	509896a410	improve `compress` efficiency (#5220 )	2021-12-15 08:08:24 +08:00
Alex Lam S.L	7fe7c39a01	speed up `compress` (#5219 )	2021-12-14 07:42:47 +08:00
Alex Lam S.L	2c5e23506b	v3.14.5	2021-12-13 08:11:48 +08:00
Alex Lam S.L	07f35ea2c9	suppress false positives in `ufuzz` (#5216 ) closes #5212 closes #5215	2021-12-12 06:19:06 +08:00
Alex Lam S.L	57a9519c3d	fix corner case in `objects` (#5214 ) fixes #5213	2021-12-10 06:02:22 +08:00
Alex Lam S.L	9e4c4c995c	minor clean-up (#5210 )	2021-12-10 04:48:06 +08:00
Alex Lam S.L	d11c82f8ca	minor clean-up (#5209 )	2021-12-09 05:14:57 +08:00
Alex Lam S.L	bc27966a19	workaround v8 performance quirks (#5207 )	2021-12-08 13:40:47 +08:00
Alex Lam S.L	8f39491e96	workaround Unicode compatibility in testing (#5206 )	2021-12-07 18:56:57 +08:00
Alex Lam S.L	065c50ebde	improve sandbox resilience against process aborts (#5205 )	2021-12-07 04:54:58 +08:00
Alex Lam S.L	d2e7c4af20	improve testing compatibility with Node.js (#5204 )	2021-12-06 22:42:45 +08:00
Alex Lam S.L	033d8d9405	reduce memory pressure via bit fields (#5203 )	2021-12-06 11:30:05 +08:00
Alex Lam S.L	b0799105c2	improve `Dictionary` performance (#5202 ) - workaround `__proto__` quirks on v8	2021-12-05 14:58:52 +08:00
Alex Lam S.L	860aa9531b	v3.14.4	2021-12-01 02:34:20 +08:00
Alex Lam S.L	2547542873	workaround sporadic slowdown in GitHub Actions (#5201 )	2021-11-28 08:45:29 +08:00
Alex Lam S.L	3f8f0e246e	fix corner case in `collapse_vars` (#5200 ) fixes #5199	2021-11-28 01:43:43 +08:00
Alex Lam S.L	12227ebbb0	workaround `toString()` quirks on global context (#5198 ) closes #5197	2021-11-27 23:17:51 +08:00
Alex Lam S.L	1b4bd7082b	fix corner case in `hoist_vars` (#5196 ) fixes #5195	2021-11-25 04:49:38 +08:00
Alex Lam S.L	0b6c185818	enhance `merge_vars` (#5194 ) closes #5182	2021-11-24 19:08:40 +08:00
Alex Lam S.L	bfd0ac7f4b	fix corner case in `ie` (#5193 ) fixes #5192	2021-11-24 17:29:26 +08:00
Alex Lam S.L	1a8f2ecc65	enhance `collapse_vars` (#5186 ) closes #5182	2021-11-24 17:28:36 +08:00
Alex Lam S.L	dc9e1ff0b1	fix corner case in `unused` (#5190 ) fixes #5189	2021-11-23 20:10:05 +08:00
Alex Lam S.L	ea10498902	fix corner case in `hoist_vars` (#5188 ) fixes #5187	2021-11-23 18:00:47 +08:00
Alex Lam S.L	69636dad69	improve sandbox `async` detection (#5185 ) closes #5184	2021-11-23 02:29:54 +08:00
Alex Lam S.L	3ee1b0d00d	enhance `hoist_props` & `reduce_vars` (#5183 ) closes #5182	2021-11-23 00:31:10 +08:00
Alex Lam S.L	1e3ca4c6f7	enhance `side_effects` & `unused` (#5181 )	2021-11-22 11:14:28 +08:00
Alex Lam S.L	839f4361f4	minor clean-up (#5180 )	2021-11-19 16:34:11 +08:00
Alex Lam S.L	ae5c3ee8a1	fix corner cases in `properties` (#5178 ) fixes #5177	2021-11-17 04:21:44 +08:00
Alex Lam S.L	77f7ae5ba2	fix corner case in `join_vars` (#5176 ) fixes #5175	2021-11-15 21:35:54 +08:00
Alex Lam S.L	2d0f8bcff5	fix corner case in `inline` (#5174 ) fixes #5173	2021-11-15 07:14:08 +08:00
Alex Lam S.L	f97e107c09	enhance `reduce_vars` (#5171 )	2021-11-13 22:18:56 +08:00
Alex Lam S.L	e9932e1314	fix corner case in `collapse_vars` (#5169 ) fixes #5168	2021-11-13 22:18:18 +08:00
Alex Lam S.L	eaa84d32df	include Node.js v16 in CI tests (#5170 ) - fix compatibility issues on v0.10 & v0.12	2021-11-13 18:34:18 +08:00
Alex Lam S.L	6e4aa0326f	enhance `reduce_vars` (#5164 ) - fix corner case in `join_vars`	2021-11-04 18:36:39 +08:00
Alex Lam S.L	f9a4b36dd1	fix corner cases in `reduce_vars` & `rests` (#5166 ) fixes #5165	2021-11-03 21:29:01 +08:00
Alex Lam S.L	3acb5a329e	enhance `join_vars` (#5162 )	2021-11-02 11:33:24 +08:00
Alex Lam S.L	6d94242318	enhance `reduce_vars` (#5163 )	2021-11-02 11:32:26 +08:00
Alex Lam S.L	bca83cb9df	v3.14.3	2021-11-02 05:03:46 +08:00
Alex Lam S.L	a841d45bc3	fix corner case in `awaits` (#5160 ) fixes #5159	2021-10-31 23:46:55 +08:00
Alex Lam S.L	eb93d92357	fix corner case in `awaits` (#5158 ) fixes #5157	2021-10-29 23:33:10 +08:00
Alex Lam S.L	a0250ec923	fix corner case in `dead_code` (#5154 ) fixes #5153	2021-10-25 06:18:16 +08:00
Alex Lam S.L	25801627be	parse `let` as symbol names correctly (#5151 ) fixes #5149	2021-10-21 02:14:29 +08:00
Alex Lam S.L	32ae994f88	fix issues in tests flagged by LGTM (#5150 )	2021-10-21 02:07:23 +08:00
Alex Lam S.L	03aec89f60	fix corner cases in `strings` & `templates` (#5147 ) fixes #5145	2021-10-16 18:02:23 +08:00
Alex Lam S.L	faf0190546	document ECMAScript quirks (#5148 ) - exclude Node.js v0.8 from CI as npm registry no longer works closes #5146	2021-10-16 13:28:13 +08:00
Alex Lam S.L	c8b0f685ee	fix corner case in `merge_vars` (#5143 ) fixes #5142	2021-10-05 00:42:46 +08:00
Alex Lam S.L	87b99162fb	fix corner case in `inline` (#5141 ) fixes #5140	2021-10-02 06:54:42 +08:00
Alex Lam S.L	940887f20f	fix corner case in `evaluate` (#5139 ) fixes #5138	2021-10-01 02:52:21 +08:00
Alex Lam S.L	0b2573c3fa	fix corner case in `templates` (#5137 ) fixes #5136	2021-09-30 21:43:34 +08:00
Alex Lam S.L	157521066f	avoid potential RegExp denial-of-service (#5135 ) closes #5133 closes #5134	2021-09-30 01:49:46 +08:00
Alex Lam S.L	f766babf5e	enhance `templates` (#5131 ) closes #5125	2021-09-23 18:26:26 +08:00
Alex Lam S.L	436a29367c	enhance `dead_code` (#5130 )	2021-09-22 03:11:45 +08:00
Alex Lam S.L	55418fd460	fix corner case in `rests` (#5129 ) fixes #5128	2021-09-20 05:02:35 +08:00
Alex Lam S.L	85786889bd	v3.14.2	2021-09-07 21:52:59 +08:00
Alex Lam S.L	4b88dfb8d9	tweak test & warnings (#5123 ) closes #5116 closes #5117 closes #5122	2021-09-07 01:33:23 +08:00
Alex Lam S.L	c3aef23614	fix corner case in `reduce_vars` (#5121 ) fixes #5120	2021-08-25 10:39:35 +08:00
Alex Lam S.L	db94d21980	fix corner case in `side_effects` (#5118 )	2021-08-23 08:51:59 +08:00
Alex Lam S.L	9634a9d1fd	fix corner cases in `optional_chains` (#5110 )	2021-08-20 10:10:10 +08:00
Alex Lam S.L	befb99bd71	fix corner case in `inline` (#5115 ) fixes #5114	2021-08-18 15:57:08 +08:00
Alex Lam S.L	02eb8baa1c	fix corner case in `collapse_vars` (#5113 ) fixes #5112	2021-08-18 10:54:24 +08:00
Alex Lam S.L	c09f63aefb	fix corner case in `rests` (#5109 ) fixes #5108	2021-08-09 08:59:33 +08:00
Alex Lam S.L	fdcc6d3a9c	fix corner case in `dead_code` (#5107 ) fixes #5106	2021-08-06 08:35:11 +08:00
Alex Lam S.L	4fe2cac35e	enhance `inline` (#5105 )	2021-07-27 21:47:01 +08:00
Alex Lam S.L	e219a9a78a	v3.14.1	2021-07-27 16:53:57 +08:00
Alex Lam S.L	c80eabd61e	fix `ie8` option alias (#5103 ) fixes #5102	2021-07-26 16:45:43 +08:00
Alex Lam S.L	9b82f9be91	fix corner case in `unused` (#5101 ) fixes #5100	2021-07-26 16:44:34 +08:00
Alex Lam S.L	657d525c80	fix corner case in `reduce_vars` (#5099 ) fixes #5098	2021-07-24 07:10:14 +08:00
Alex Lam S.L	6a3fe9d1df	fix corner cases in `reduce_vars` (#5097 ) fixes #5096	2021-07-23 17:17:20 +08:00
Alex Lam S.L	ec7fadcb5b	v3.14.0	2021-07-22 21:13:43 +08:00
Alex Lam S.L	65adeba55d	extend `keep_quoted_props` over numeric keys (#5094 ) fixes #5093	2021-07-22 06:12:57 +08:00
Alex Lam S.L	7fac839c62	fix corner case in `merge_vars` (#5092 ) fixes #5091	2021-07-21 02:47:53 +08:00
Alex Lam S.L	8926a2f327	fix corner case in `unused` (#5090 ) fixes #5089	2021-07-21 01:10:58 +08:00
Alex Lam S.L	85968dee54	fix corner case in `inline` (#5088 ) fixes #5087	2021-07-19 22:35:45 +08:00
Alex Lam S.L	a7e7865e6b	fix corner case in `unused` (#5086 ) fixes #5085	2021-07-18 19:38:09 +08:00
Alex Lam S.L	ef5f7fc25e	workaround various IE quirks (#5084 ) fixes #5081	2021-07-17 20:20:56 +08:00
Alex Lam S.L	902997b73d	fix corner case in `inline` (#5083 ) fixes #5082	2021-07-16 22:13:33 +08:00
Alex Lam S.L	f18804fa06	fix corner case in `unused` (#5080 ) fixes #5079	2021-07-14 23:02:45 +08:00
Alex Lam S.L	8e2dff632e	suppress false positives in `ufuzz` (#5078 )	2021-07-13 04:10:59 +08:00
Alex Lam S.L	92c3fddd7a	fix corner case in `unused` & `yields` (#5077 ) fixes #5076	2021-07-12 23:16:12 +08:00
Alex Lam S.L	0d350b78bf	fix corner cases in `unused` (#5075 ) fixes #5074	2021-07-12 07:43:13 +08:00
Alex Lam S.L	1ad830facb	fix corner cases in `unused` (#5073 ) fixes #5071	2021-07-11 14:52:38 +08:00
Alex Lam S.L	64ebf6efe9	fix corner case in `awaits` & `side_effects` (#5072 ) fixes #5070	2021-07-11 13:43:08 +08:00
Alex Lam S.L	08391b8e1c	fix corner case in `hoist_props` (#5069 )	2021-07-11 10:59:57 +08:00
Alex Lam S.L	d147d5d7f0	fix corner case in `inline` (#5068 ) fixes #5067	2021-07-11 04:11:10 +08:00
Alex Lam S.L	aae1fcd12d	fix corner case in `unused` (#5066 ) fixes #5065	2021-07-11 00:43:01 +08:00
Alex Lam S.L	f67dd31cbb	enhance `unused` (#5064 )	2021-07-10 19:58:57 +08:00
Alex Lam S.L	450aabaaa0	fix corner cases in `rests` & `unused` (#5063 )	2021-07-10 00:28:23 +08:00
Alex Lam S.L	ea7829daf5	fix corner case in `reduce_vars` (#5062 ) fixes #5061	2021-07-08 16:31:04 +08:00
Alex Lam S.L	6577d641ac	enhance `evaluate` & `reduce_vars` (#5060 )	2021-07-08 00:29:23 +08:00
Alex Lam S.L	2340feff87	support destructured shorthand for default parameters (#5059 ) closes #4990	2021-07-07 22:45:24 +08:00
Alex Lam S.L	0c48b84540	fix corner cases in `inline` & `unused` (#5058 ) fixes #5057	2021-07-07 10:29:16 +08:00
Alex Lam S.L	1fefe3f1d1	fix corner case in `reduce_vars` (#5056 ) fixes #5055	2021-07-07 02:23:09 +08:00
Alex Lam S.L	0668fad5e9	fix corner case with `class` (#5054 ) fixes #5053	2021-07-06 16:04:11 +08:00
Alex Lam S.L	d0e3f6955d	enhance `functions` (#5052 )	2021-07-06 02:43:09 +08:00
Alex Lam S.L	6961c57d1e	fix corner case in `reduce_vars` (#5051 ) fixes #5050	2021-07-05 11:57:58 +08:00
Alex Lam S.L	f5dbb672b9	fix corner case in `reduce_funcs` (#5049 ) fixes #5048	2021-07-04 15:09:05 +08:00
Alex Lam S.L	f4ae267920	fix corner case in `reduce_vars` (#5047 ) fixes #5046	2021-07-04 13:45:09 +08:00
Alex Lam S.L	972b9f0bef	enhance `functions` & `reduce_vars` (#5045 )	2021-07-04 06:19:08 +08:00
Alex Lam S.L	668f96623c	tweak `beautify` output (#5044 )	2021-07-03 23:10:39 +08:00
Alex Lam S.L	1b745494ce	enhance `booleans` (#5043 )	2021-07-01 03:05:52 +08:00
Alex Lam S.L	611abff49f	fix corner case in `booleans` (#5042 ) fixes #5041	2021-07-01 00:52:54 +08:00
Alex Lam S.L	4ba8b66c5a	fix corner case in `ie8` (#5040 ) fixes #5039	2021-06-30 02:14:07 +08:00
Alex Lam S.L	798121c9f3	enhance `reduce_vars` (#5038 )	2021-06-29 03:51:44 +08:00
Alex Lam S.L	b23b333d9d	v3.13.10	2021-06-27 22:59:34 +08:00
Alex Lam S.L	7621527a5f	fix corner case in `functions` (#5037 ) fixes #5036	2021-06-25 03:43:52 +08:00
Alex Lam S.L	1a064b6e74	fix corner case in `functions` (#5035 ) fixes #5034	2021-06-24 19:43:46 +08:00
Alex Lam S.L	82772ccb12	workaround Safari quirks (#5033 ) closes #5032	2021-06-24 17:09:19 +08:00
Alex Lam S.L	7cbcd11440	fix corner case in `dead_code` (#5031 ) fixes #5030	2021-06-23 22:56:28 +08:00
Alex Lam S.L	980dbde171	fix corner cases in `booleans` (#5029 ) fixes #5028	2021-06-23 07:42:57 +08:00
Alex Lam S.L	8b05677c15	fix corner case in `collapse_vars` (#5026 ) fixes #5025	2021-06-23 05:03:11 +08:00
Alex Lam S.L	95090dbf24	fix corner case in `side_effects` (#5024 ) fixes #5023	2021-06-23 00:36:07 +08:00
Alex Lam S.L	7c5b6f349e	enhance `booleans` (#5022 ) closes #5021	2021-06-23 00:35:50 +08:00
Alex Lam S.L	e9c902b044	fix corner cases in `dead_code` & `inline` (#5020 ) fixes #5019	2021-06-21 22:28:54 +08:00
Alex Lam S.L	111366fca0	fix corner case in `collapse_vars` (#5018 ) fixes #5017	2021-06-21 11:12:45 +08:00
Alex Lam S.L	e368d39715	fix corner cases in `reduce_vars` & `side_effects` (#5016 ) fixes #5015	2021-06-21 03:13:05 +08:00
Alex Lam S.L	fd8dec61ad	enhance `dead_code` (#5014 )	2021-06-20 15:30:04 +08:00
Alex Lam S.L	7880568d15	fix corner case in `switches` (#5013 ) fixes #5012	2021-06-15 23:51:53 +08:00
Alex Lam S.L	21fc8f4630	fix corner case in `switches` (#5011 ) fixes #5010	2021-06-15 20:59:53 +08:00
Alex Lam S.L	bf76e35772	fix corner case in `switches` (#5009 ) fixes #5008	2021-06-15 18:27:55 +08:00
Alex Lam S.L	ac1262dc97	fix corner case in `arguments` (#5007 ) fixes #5006	2021-06-15 12:53:22 +08:00
Alex Lam S.L	498ac83541	enhance `switches` (#5005 ) closes #5004	2021-06-15 10:32:39 +08:00
Alex Lam S.L	6fc7a2ab6a	fix corner case in `side_effects` (#5002 ) fixes #5001	2021-06-13 20:29:14 +08:00
Alex Lam S.L	f8b2215145	fix corner cases in `parse` & `unused` (#5000 )	2021-06-13 00:10:01 +08:00
Alex Lam S.L	70ceda5398	minor clean-up (#4998 )	2021-06-12 09:20:06 +08:00
Alex Lam S.L	ce75477670	fix corner case in `reduce_vars` (#4997 ) fixes #4996	2021-06-10 08:03:17 +08:00
Alex Lam S.L	e70b84895c	fix corner cases in `loops` & `unused` (#4995 ) fixes #4994	2021-06-10 07:58:33 +08:00