v3.16.2

fixes #5536

.github/workflows/ufuzz.yml

@@ -17,13 +17,13 @@ jobs:
       fail-fast: false
       matrix:
         include:
-          - node: latest
+          - node: '16'
             os: macos-latest
-          - node: '8'
+          - node: '12'
             os: ubuntu-latest
           - node: '8'
             os: ubuntu-latest
-          - node: '8'
+          - node: '12'
             os: windows-latest
           - node: '8'
             os: windows-latest

README.md

@@ -118,6 +118,7 @@ a double dash to prevent input files being used as option arguments:
     --keep-fargs                Do not mangle/drop function arguments.
     --keep-fnames               Do not mangle/drop function names.  Useful for
                                 code relying on Function.prototype.name.
+    --module                    Process input as ES module (implies --toplevel)
     --name-cache <file>         File to hold mangled name mappings.
     --self                      Build UglifyJS as a library (implies --wrap UglifyJS)
     --source-map [options]      Enable source map/specify source map options:
@@ -146,7 +147,7 @@ a double dash to prevent input files being used as option arguments:
     --warn                      Print warning messages.
     --webkit                    Support non-standard Safari/Webkit.
                                 Equivalent to setting `webkit: true` in `minify()`
-                                for `mangle` and `output` options.
+                                for `compress`, `mangle` and `output` options.
                                 By default UglifyJS will not try to be Safari-proof.
     --wrap <name>               Embed everything in a big function, making the
                                 “exports” and “global” variables available. You
@@ -517,6 +518,10 @@ if (result.error) throw result.error;
   - `mangle.properties` (default: `false`) — a subcategory of the mangle option.
     Pass an object to specify custom [mangle property options](#mangle-properties-options).
 
+- `module` (default: `false`) — set to `true` if you wish to process input as
+  ES module, i.e. implicit `"use strict";` and support for top-level `await`,
+  alongside with `toplevel` enabled.
+
 - `nameCache` (default: `null`) — pass an empty object `{}` or a previously
   used `nameCache` object if you wish to cache mangled variable and
   property names across multiple invocations of `minify()`. Note: this is
@@ -628,7 +633,13 @@ to be `false` and all symbol names will be omitted.
 
 - `bare_returns` (default: `false`) — support top level `return` statements
 
-- `html5_comments` (default: `true`)
+- `expression` (default: `false`) — parse as a single expression, e.g. JSON
+
+- `html5_comments` (default: `true`) — process HTML comment as workaround for
+  browsers which do not recognise `<script>` tags
+
+- `module` (default: `false`) — set to `true` if you wish to process input as
+  ES module, i.e. implicit `"use strict";` and support for top-level `await`.
 
 - `shebang` (default: `true`) — support `#!command` as the first line
 
@@ -728,6 +739,9 @@ to be `false` and all symbol names will be omitted.
 
 - `merge_vars` (default: `true`) — combine and reuse variables.
 
+- `module` (default: `false`) — set to `true` if you wish to process input as
+  ES module, i.e. implicit `"use strict";` alongside with `toplevel` enabled.
+
 - `negate_iife` (default: `true`) — negate "Immediately-Called Function Expressions"
   where the return value is discarded, to avoid the parens that the
   code generator would insert.
@@ -804,8 +818,9 @@ to be `false` and all symbol names will be omitted.
 
 - `unsafe` (default: `false`) — apply "unsafe" transformations (discussion below)
 
-- `unsafe_comps` (default: `false`) — compress expressions like `a <= b` assuming
+- `unsafe_comps` (default: `false`) — assume operands cannot be (coerced to) `NaN`
-  none of the operands can be (coerced to) `NaN`.
+  in numeric comparisons, e.g. `a <= b`. In addition, expressions involving `in`
+  or `instanceof` would never throw.
 
 - `unsafe_Function` (default: `false`) — compress and mangle `Function(args, code)`
   when both `args` and `code` are string literals.
@@ -1331,11 +1346,9 @@ To allow for better optimizations, the compiler makes various assumptions:
 - Later versions of JavaScript will throw `SyntaxError` with the following:
   ```javascript
   var await;
-  async function f() {
   class A {
       static p = await;
   }
-  }
   // SyntaxError: Unexpected reserved word
   ```
   UglifyJS may modify the input which in turn may suppress those errors.
@@ -1389,3 +1402,41 @@ To allow for better optimizations, the compiler makes various assumptions:
   // Actual:   "FAIL"
   ```
   UglifyJS may modify the input which in turn may suppress those errors.
+- Some versions of Chrome and Node.js will give incorrect results with the
+  following:
+  ```javascript
+  (async function(a) {
+      (function() {
+          var b = await => console.log("PASS");
+          b();
+      })();
+  })().catch(console.error);
+  // Expected: "PASS"
+  // Actual:   SyntaxError: Unexpected reserved word
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.
+- Later versions of Chrome and Node.js will give incorrect results with the
+  following:
+  ```javascript
+  try {
+      f();
+      function f() {
+          throw 42;
+      }
+  } catch (e) {
+      console.log(typeof f, e);
+  }
+  // Expected: "function 42"
+  // Actual:   "undefined 42"
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.
+- Later versions of JavaScript will throw `SyntaxError` with the following:
+  ```javascript
+  "use strict";
+  console.log(function f() {
+      return f = "PASS";
+  }());
+  // Expected: "PASS"
+  // Actual:   TypeError: invalid assignment to const 'f'
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.

bin/uglifyjs

@@ -107,6 +107,7 @@ function process_option(name, no_value) {
                 "  --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.",
+                "  --module                                 Process input as ES module (implies --toplevel)",
                 "  --name-cache <file>                      File to hold mangled name mappings.",
                 "  --rename                                 Force symbol expansion.",
                 "  --no-rename                              Disable symbol expansion.",
@@ -152,6 +153,7 @@ function process_option(name, no_value) {
       case "annotations":
       case "ie":
       case "ie8":
+      case "module":
       case "timings":
       case "toplevel":
       case "v8":

lib/ast.js

@@ -534,7 +534,7 @@ var AST_With = DEFNODE("With", "expression", {
 /* -----[ scope and functions ]----- */
 
 var AST_Scope = DEFNODE("Scope", "fn_defs may_call_this uses_eval uses_with", {
-    $documentation: "Base class for all statements introducing a lexical scope",
+    $documentation: "Base class for all statements introducing a lambda scope",
     $propdoc: {
         uses_eval: "[boolean/S] tells whether this scope contains a direct call to the global `eval`",
         uses_with: "[boolean/S] tells whether this scope uses the `with` statement",
@@ -592,6 +592,10 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     }
 }, AST_Scope);
 
+var AST_ClassInitBlock = DEFNODE("ClassInitBlock", null, {
+    $documentation: "Value for `class` static initialization blocks",
+}, AST_Scope);
+
 var AST_Lambda = DEFNODE("Lambda", "argnames length_read rest safe_ids uses_arguments", {
     $documentation: "Base class for functions",
     $propdoc: {
@@ -827,6 +831,9 @@ var AST_Class = DEFNODE("Class", "extends name properties", {
         extends: "[AST_Node?] the super class, or null if not specified",
         properties: "[AST_ClassProperty*] array of class properties",
     },
+    resolve: function(def_class) {
+        return def_class ? this : this.parent_scope.resolve();
+    },
     walk: function(visitor) {
         var node = this;
         visitor.visit(node, function() {
@@ -851,9 +858,6 @@ var AST_DefClass = DEFNODE("DefClass", null, {
     $propdoc: {
         name: "[AST_SymbolDefClass] the name of this class",
     },
-    resolve: function(def_class) {
-        return def_class ? this : this.parent_scope.resolve();
-    },
     _validate: function() {
         if (!(this.name instanceof AST_SymbolDefClass)) throw new Error("name must be AST_SymbolDefClass");
     },
@@ -874,7 +878,7 @@ var AST_ClassExpression = DEFNODE("ClassExpression", null, {
 var AST_ClassProperty = DEFNODE("ClassProperty", "key private static value", {
     $documentation: "Base class for `class` properties",
     $propdoc: {
-        key: "[string|AST_Node] property name (AST_Node for computed property)",
+        key: "[string|AST_Node?] property name (AST_Node for computed property, null for initialization block)",
         private: "[boolean] whether this is a private property",
         static: "[boolean] whether this is a static property",
         value: "[AST_Node?] property value (AST_Accessor for getters/setters, AST_LambdaExpression for methods, null if not specified for fields)",
@@ -888,7 +892,9 @@ var AST_ClassProperty = DEFNODE("ClassProperty", "key private static value", {
     },
     _validate: function() {
         if (this.TYPE == "ClassProperty") throw new Error("should not instantiate AST_ClassProperty");
-        if (typeof this.key != "string") {
+        if (this instanceof AST_ClassInit) {
+            if (this.key != null) throw new Error("key must be null");
+        } else if (typeof this.key != "string") {
             if (!(this.key instanceof AST_Node)) throw new Error("key must be string or AST_Node");
             must_be_expression(this, "key");
         }
@@ -928,6 +934,17 @@ var AST_ClassMethod = DEFNODE("ClassMethod", null, {
     },
 }, AST_ClassProperty);
 
+var AST_ClassInit = DEFNODE("ClassInit", null, {
+    $documentation: "A `class` static initialization block",
+    _validate: function() {
+        if (!this.static) throw new Error("static must be true");
+        if (!(this.value instanceof AST_ClassInitBlock)) throw new Error("value must be AST_ClassInitBlock");
+    },
+    initialize: function() {
+        this.static = true;
+    },
+}, AST_ClassProperty);
+
 /* -----[ JUMPS ]----- */
 
 var AST_Jump = DEFNODE("Jump", null, {
@@ -1837,7 +1854,7 @@ var AST_Label = DEFNODE("Label", "references", {
     initialize: function() {
         this.references = [];
         this.thedef = this;
-    }
+    },
 }, AST_Symbol);
 
 var AST_SymbolRef = DEFNODE("SymbolRef", "fixed in_arg redef", {
@@ -2039,16 +2056,21 @@ TreeWalker.prototype = {
         return this.stack[this.stack.length - 2 - (n || 0)];
     },
     push: function(node) {
-        if (node instanceof AST_Lambda) {
+        var value;
+        if (node instanceof AST_Class) {
+            this.directives = Object.create(this.directives);
+            value = "use strict";
+        } else if (node instanceof AST_Directive) {
+            value = node.value;
+        } else if (node instanceof AST_Lambda) {
             this.directives = Object.create(this.directives);
-        } else if (node instanceof AST_Directive && !this.directives[node.value]) {
-            this.directives[node.value] = node;
         }
+        if (value && !this.directives[value]) this.directives[value] = node;
         this.stack.push(node);
     },
     pop: function() {
         var node = this.stack.pop();
-        if (node instanceof AST_Lambda) {
+        if (node instanceof AST_Class || node instanceof AST_Lambda) {
             this.directives = Object.getPrototypeOf(this.directives);
         }
     },

lib/minify.js

@@ -81,13 +81,14 @@ function minify(files, options) {
             keep_fargs: false,
             keep_fnames: false,
             mangle: {},
+            module: false,
             nameCache: null,
             output: {},
             parse: {},
             rename: undefined,
             sourceMap: false,
             timings: false,
-            toplevel: false,
+            toplevel: !!(options && options["module"]),
             v8: false,
             validate: false,
             warnings: false,
@@ -101,6 +102,7 @@ function minify(files, options) {
         if (options.ie) set_shorthand("ie", options, [ "compress", "mangle", "output", "rename" ]);
         if (options.keep_fargs) set_shorthand("keep_fargs", options, [ "compress", "mangle", "rename" ]);
         if (options.keep_fnames) set_shorthand("keep_fnames", options, [ "compress", "mangle", "rename" ]);
+        if (options.module) set_shorthand("module", options, [ "compress", "parse" ]);
         if (options.toplevel) set_shorthand("toplevel", options, [ "compress", "mangle", "rename" ]);
         if (options.v8) set_shorthand("v8", options, [ "mangle", "output", "rename" ]);
         if (options.webkit) set_shorthand("webkit", options, [ "compress", "mangle", "output", "rename" ]);

lib/output.js

@@ -260,6 +260,15 @@ function OutputStream(options) {
 
     var require_semicolon = makePredicate("( [ + * / - , .");
 
+    function require_space(prev, ch, str) {
+        return is_identifier_char(prev) && (is_identifier_char(ch) || ch == "\\")
+            || (ch == "/" && ch == prev)
+            || ((ch == "+" || ch == "-") && ch == last)
+            || last == "--" && ch == ">"
+            || last == "!" && str == "--"
+            || prev == "/" && (str == "in" || str == "instanceof");
+    }
+
     var print = options.beautify
         || options.comments
         || options.max_line_len
@@ -312,12 +321,7 @@ function OutputStream(options) {
         }
 
         if (might_need_space) {
-            if (is_identifier_char(prev) && (is_identifier_char(ch) || ch == "\\")
+            if (require_space(prev, ch, str)) {
-                || (ch == "/" && ch == prev)
-                || ((ch == "+" || ch == "-") && ch == last)
-                || str == "--" && last == "!"
-                || str == "in" && prev == "/"
-                || last == "--" && ch == ">") {
                 output += " ";
                 current_col++;
             }
@@ -355,14 +359,7 @@ function OutputStream(options) {
             }
         }
         if (might_need_space) {
-            if (is_identifier_char(prev) && (is_identifier_char(ch) || ch == "\\")
+            if (require_space(prev, ch, str)) output += " ";
-                || (ch == "/" && ch == prev)
-                || ((ch == "+" || ch == "-") && ch == last)
-                || str == "--" && last == "!"
-                || str == "in" && prev == "/"
-                || last == "--" && ch == ">") {
-                output += " ";
-            }
             if (prev != "<" || str != "!") might_need_space = false;
         }
         output += str;
@@ -1257,6 +1254,11 @@ function OutputStream(options) {
         }
         print_method(self, output);
     });
+    DEFPRINT(AST_ClassInit, function(output) {
+        output.print("static");
+        output.space();
+        print_braced(this.value, output);
+    });
 
     /* -----[ jumps ]----- */
     function print_jump(kind, prop) {
@@ -1814,9 +1816,6 @@ function OutputStream(options) {
               case "\u2029": return "\\u2029";
             }
         }));
-        var p = output.parent();
-        if (p instanceof AST_Binary && /^in/.test(p.operator) && p.left === this)
-            output.print(" ");
     });
 
     function force_statement(stat, output) {

lib/parse.js

@@ -237,8 +237,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         newline_before  : false,
         regex_allowed   : false,
         comments_before : [],
-        directives      : {},
+        directives      : Object.create(null),
-        directive_stack : [],
         read_template   : with_eof_error("Unterminated template literal", function(strings) {
             var s = "";
             for (;;) {
@@ -635,24 +634,19 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
     };
 
     next_token.add_directive = function(directive) {
-        S.directive_stack[S.directive_stack.length - 1].push(directive);
+        S.directives[directive] = true;
-        if (S.directives[directive]) S.directives[directive]++;
-        else S.directives[directive] = 1;
     }
 
     next_token.push_directives_stack = function() {
-        S.directive_stack.push([]);
+        S.directives = Object.create(S.directives);
     }
 
     next_token.pop_directives_stack = function() {
-        var directives = S.directive_stack.pop();
+        S.directives = Object.getPrototypeOf(S.directives);
-        for (var i = directives.length; --i >= 0;) {
-            S.directives[directives[i]]--;
-        }
     }
 
     next_token.has_directive = function(directive) {
-        return S.directives[directive] > 0;
+        return !!S.directives[directive];
     }
 
     return next_token;
@@ -699,6 +693,7 @@ function parse($TEXT, options) {
         expression     : false,
         filename       : null,
         html5_comments : true,
+        module         : false,
         shebang        : true,
         strict         : false,
         toplevel       : null,
@@ -1124,6 +1119,18 @@ function parse($TEXT, options) {
                 }));
                 continue;
             }
+            if (fixed && is("punc", "{")) {
+                props.push(new AST_ClassInit({
+                    start: start,
+                    value: new AST_ClassInitBlock({
+                        start: start,
+                        body: block_(),
+                        end: prev(),
+                    }),
+                    end: prev(),
+                }));
+                continue;
+            }
             var internal = is("name") && /^#/.test(S.token.value);
             var key = as_property_key();
             if (is("punc", "(")) {
@@ -1340,11 +1347,11 @@ function parse($TEXT, options) {
         var loop = S.in_loop;
         var labels = S.labels;
         ++S.in_function;
-        S.in_directives = true;
         S.input.push_directives_stack();
         S.in_loop = 0;
         S.labels = [];
         if (is("punc", "{")) {
+            S.in_directives = true;
             body = block_();
             value = null;
         } else {
@@ -1412,7 +1419,7 @@ function parse($TEXT, options) {
             name: name,
             argnames: argnames,
             rest: argnames.rest || null,
-            body: body
+            body: body,
         });
         if (is_strict) {
             if (name) strict_verify_symbol(name);
@@ -2550,6 +2557,10 @@ function parse($TEXT, options) {
     return function() {
         var start = S.token;
         var body = [];
+        if (options.module) {
+            S.in_async = true;
+            S.input.add_directive("use strict");
+        }
         S.input.push_directives_stack();
         while (!is("eof"))
             body.push(statement());

lib/scope.js

@@ -64,19 +64,20 @@ SymbolDef.prototype = {
         this.references.forEach(fn);
     },
     mangle: function(options) {
-        var cache = options.cache && options.cache.props;
+        if (this.mangled_name) return;
-        if (this.global && cache && cache.has(this.name)) {
+        var cache = this.global && options.cache && options.cache.props;
+        if (cache && cache.has(this.name)) {
             this.mangled_name = cache.get(this.name);
-        } else if (!this.mangled_name && !this.unmangleable(options)) {
+        } else if (this.unmangleable(options)) {
+            names_in_use(this.scope, options).set(this.name, true);
+        } else {
             var def = this.redefined();
             if (def) {
                 this.mangled_name = def.mangled_name || def.name;
             } else {
                 this.mangled_name = next_mangled_name(this, options);
             }
-            if (this.global && cache) {
+            if (cache) cache.set(this.name, this.mangled_name);
-                cache.set(this.name, this.mangled_name);
-            }
         }
     },
     redefined: function() {
@@ -621,14 +622,10 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
     var lname = -1;
     var redefined = [];
     var tw = new TreeWalker(function(node, descend) {
-        if (node instanceof AST_LabeledStatement) {
+        var save_nesting;
-            // `lname` is incremented when we get to the `AST_Label`
-            var save_nesting = lname;
-            descend();
-            if (!options.v8 || !in_label(tw)) lname = save_nesting;
-            return true;
-        }
         if (node instanceof AST_BlockScope) {
+            // `lname` is incremented when we get to the `AST_Label`
+            if (node instanceof AST_LabeledStatement) save_nesting = lname;
             if (options.webkit && node instanceof AST_IterationStatement && node.init instanceof AST_Let) {
                 node.init.definitions.forEach(function(defn) {
                     defn.name.match_symbol(function(sym) {
@@ -674,6 +671,7 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
                 }));
             }
             to_mangle.forEach(mangle);
+            if (node instanceof AST_LabeledStatement && !(options.v8 && in_label(tw))) lname = save_nesting;
             return true;
         }
         if (node instanceof AST_Label) {

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": "3.15.5",
+  "version": "3.16.2",
   "engines": {
     "node": ">=0.8.0"
   },

test/compress.js

@@ -69,9 +69,7 @@ function make_code(ast, options) {
 function parse_test(file) {
     var script = fs.readFileSync(file, "utf8");
     try {
-        var ast = U.parse(script, {
+        var ast = U.parse(script, { filename: file });
-            filename: file
-        });
     } catch (e) {
         console.error("Caught error while parsing tests in " + file);
         console.error(e);
@@ -98,14 +96,14 @@ function parse_test(file) {
             file: file,
             line: node.start.line,
             col: node.start.col,
-            code: make_code(node, { beautify: false })
+            code: make_code(node, { beautify: false }),
         }));
     }
 
     function read_string(stat) {
         if (stat.TYPE == "SimpleStatement") {
             var body = stat.body;
-            switch(body.TYPE) {
+            switch (body.TYPE) {
               case "String":
                 return body.value;
               case "Array":
@@ -142,7 +140,7 @@ function parse_test(file) {
                 ].indexOf(label.name) >= 0, tmpl("Unsupported label {name} [{line},{col}]", {
                     name: label.name,
                     line: label.start.line,
-                    col: label.start.col
+                    col: label.start.col,
                 }));
                 var stat = node.body;
                 if (label.name == "expect_exact" || label.name == "node_version") {
@@ -155,12 +153,12 @@ function parse_test(file) {
                         var ctor = global[body.expression.name];
                         assert.ok(ctor === Error || ctor.prototype instanceof Error, tmpl("Unsupported expect_stdout format [{line},{col}]", {
                             line: label.start.line,
-                            col: label.start.col
+                            col: label.start.col,
                         }));
                         test[label.name] = ctor.apply(null, body.args.map(function(node) {
                             assert.ok(node instanceof U.AST_Constant, tmpl("Unsupported expect_stdout format [{line},{col}]", {
                                 line: label.start.line,
-                                col: label.start.col
+                                col: label.start.col,
                             }));
                             return node.value;
                         }));

test/compress/arrows.js

@@ -1106,3 +1106,17 @@ issue_5416: {
     expect_stdout: "undefined"
     node_version: ">=4"
 }
+
+issue_5495: {
+    input: {
+        console.log((() => {
+            "use strict";
+            return function() {
+                return this;
+            }();
+        })());
+    }
+    expect_exact: 'console.log((()=>{"use strict";return function(){return this}()})());'
+    expect_stdout: "undefined"
+    node_version: ">=4"
+}

test/compress/awaits.js

@@ -1293,6 +1293,21 @@ functions_inner_var: {
     node_version: ">=8"
 }
 
+instanceof_lambda: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(42 instanceof async function() {});
+    }
+    expect: {
+        console.log(false);
+    }
+    expect_stdout: "false"
+    node_version: ">=8"
+}
+
 issue_4335_1: {
     options = {
         inline: true,
@@ -1748,8 +1763,8 @@ issue_4454_2: {
     expect: {
         function f(a) {
             (async function(c = console.log(a)) {})();
-            var a = 42..toString();
+            var b = 42..toString();
-            console.log(a);
+            console.log(b);
         }
         f("PASS");
     }
@@ -2427,80 +2442,6 @@ issue_5023_2: {
     node_version: ">=8"
 }
 
-issue_5032_normal: {
-    options = {
-        merge_vars: true,
-        webkit: false,
-    }
-    input: {
-        function log(value) {
-            console.log(value);
-            return value;
-        }
-        async function f(a) {
-            var b = log(a), c = b;
-            log(b);
-            log(c);
-        }
-        f("PASS");
-    }
-    expect: {
-        function log(value) {
-            console.log(value);
-            return value;
-        }
-        async function f(a) {
-            var a = log(a), c = a;
-            log(a);
-            log(c);
-        }
-        f("PASS");
-    }
-    expect_stdout: [
-        "PASS",
-        "PASS",
-        "PASS",
-    ]
-    node_version: ">=8"
-}
-
-issue_5032_webkit: {
-    options = {
-        merge_vars: true,
-        webkit: true,
-    }
-    input: {
-        function log(value) {
-            console.log(value);
-            return value;
-        }
-        async function f(a) {
-            var b = log(a), c = b;
-            log(b);
-            log(c);
-        }
-        f("PASS");
-    }
-    expect: {
-        function log(value) {
-            console.log(value);
-            return value;
-        }
-        async function f(a) {
-            var b = log(a), c = b;
-            log(b);
-            log(c);
-        }
-        f("PASS");
-    }
-    expect_stdout: [
-        "PASS",
-        "PASS",
-        "PASS",
-    ]
-    node_version: ">=8"
-}
-
 issue_5034: {
     options = {
         functions: true,
@@ -2959,3 +2900,278 @@ issue_5305_3: {
     expect_stdout: "PASS"
     node_version: ">=8"
 }
+
+issue_5456: {
+    options = {
+        inline: true,
+        merge_vars: true,
+    }
+    input: {
+        var a = true;
+        (function() {
+            (function(b, c) {
+                var d = async function() {
+                    c = await null;
+                }();
+                var e = function() {
+                    if (c)
+                        console.log(typeof d);
+                    while (b);
+                }();
+            })(function(i) {
+                return console.log("foo") && i;
+            }(a));
+        })();
+    }
+    expect: {
+        var a = true;
+        (function() {
+            b = (i = a, console.log("foo") && i),
+            d = async function() {
+                c = await null;
+            }(),
+            e = function() {
+                if (c) console.log(typeof d);
+                while (b);
+            }(),
+            void 0;
+            var b, c, d, e;
+            var i;
+        })();
+    }
+    expect_stdout: "foo"
+    node_version: ">=8"
+}
+
+issue_5478: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        A = {
+            get then() {
+                a = "FAIL";
+            },
+        };
+        var a = "PASS";
+        (async function() {
+            for (var b in "foo")
+                return void A;
+        })();
+        console.log(a);
+    }
+    expect: {
+        A = {
+            get then() {
+                a = "FAIL";
+            },
+        };
+        var a = "PASS";
+        (async function() {
+            for (var b in "foo")
+                return !A;
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5493: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+    }
+    input: {
+        (async function(a) {
+            var b = await [ 42 || b, a = b ];
+            console.log(a);
+        })();
+    }
+    expect: {
+        (async function(a) {
+            var b = await [ 42 || b, a = b ];
+            console.log(a);
+        })();
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8"
+}
+
+issue_5506: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log(function(a) {
+            (async function() {
+                a = null in (a = "PASS");
+            })();
+            return a;
+        }("FAIL"));
+    }
+    expect: {
+        console.log(function(a) {
+            (async function() {
+                a = null in (a = "PASS");
+            })();
+            return a;
+        }("FAIL"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_5528_1: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function() {
+            await function() {
+                try {
+                    return;
+                } finally {
+                    console.log("foo");
+                }
+            }();
+        })();
+        console.log("bar");
+    }
+    expect: {
+        (async function() {
+            await function() {
+                try {
+                    return;
+                } finally {
+                    console.log("foo");
+                }
+            }();
+        })();
+        console.log("bar");
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=8"
+}
+
+issue_5528_2: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function() {
+            await function() {
+                try {
+                    return 42;
+                } finally {
+                    console.log("foo");
+                }
+            }();
+        })();
+        console.log("bar");
+    }
+    expect: {
+        (async function() {
+            await function() {
+                try {
+                    return 42;
+                } finally {
+                    console.log("foo");
+                }
+            }();
+        })();
+        console.log("bar");
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=8"
+}
+
+issue_5528_3: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function() {
+            await function() {
+                try {
+                    FAIL;
+                } catch (e) {
+                    return console.log("foo");
+                } finally {
+                    console.log("bar");
+                }
+            }();
+        })();
+        console.log("baz");
+    }
+    expect: {
+        (async function() {
+            await function() {
+                try {
+                    FAIL;
+                } catch (e) {
+                    return console.log("foo");
+                } finally {
+                    console.log("bar");
+                }
+            }();
+        })();
+        console.log("baz");
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "baz",
+    ]
+    node_version: ">=8"
+}
+
+issue_5528_4: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function() {
+            await function() {
+                try {
+                    return {
+                        then() {
+                            console.log("foo");
+                        },
+                    };
+                } finally {
+                    console.log("bar");
+                }
+            }();
+        })();
+        console.log("baz");
+    }
+    expect: {
+        (async function() {
+            await function() {
+                try {
+                    return {
+                        then() {
+                            console.log("foo");
+                        },
+                    };
+                } finally {
+                    console.log("bar");
+                }
+            }();
+        })();
+        console.log("baz");
+    }
+    expect_stdout: [
+        "bar",
+        "baz",
+        "foo",
+    ]
+    node_version: ">=8"
+}

test/compress/booleans.js

@@ -762,3 +762,27 @@ issue_5228: {
     }
     expect_stdout: "true"
 }
+
+issue_5469: {
+    options = {
+        assignments: true,
+        booleans: true,
+        conditionals: true,
+        dead_code: true,
+        evaluate: true,
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        console.log(function f(a) {
+            a && 42[a = A && null];
+        }());
+    }
+    expect: {
+        console.log(function f(a) {
+            a && A,
+            0;
+        }());
+    }
+    expect_stdout: "undefined"
+}

test/compress/classes.js

@@ -241,6 +241,208 @@ class_super: {
     node_version: ">=4"
 }
 
+static_init: {
+    input: {
+        var a = "foo";
+        var b = null;
+        class A {
+            static {
+                var a = "bar";
+                b = true;
+                var c = 42;
+                console.log(a, b, c);
+            }
+        }
+        console.log(a, b, typeof c);
+    }
+    expect_exact: 'var a="foo";var b=null;class A{static{var a="bar";b=true;var c=42;console.log(a,b,c)}}console.log(a,b,typeof c);'
+    expect_stdout: [
+        "bar true 42",
+        "foo true undefined",
+    ]
+    node_version: ">=16"
+}
+
+static_field_init: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        (class {
+            static [console.log("foo")] = console.log("bar");
+            static {
+                console.log("baz");
+            }
+            static [console.log("moo")] = console.log("moz");
+        });
+    }
+    expect: {
+        (class {
+            static [(console.log("foo"), console.log("moo"))] = (
+                console.log("bar"),
+                (() => {
+                    console.log("baz");
+                })(),
+                console.log("moz")
+            );
+        });
+    }
+    expect_stdout: [
+        "foo",
+        "moo",
+        "bar",
+        "baz",
+        "moz",
+    ]
+    node_version: ">=16"
+}
+
+static_field_init_strict: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        (class {
+            static [console.log("foo")] = console.log("bar");
+            static {
+                console.log("baz");
+            }
+            static [console.log("moo")] = console.log("moz");
+        });
+    }
+    expect: {
+        "use strict";
+        console.log("foo"),
+        console.log("moo"),
+        (() => (
+            console.log("bar"),
+            (() => {
+                console.log("baz");
+            })(),
+            console.log("moz")
+        ))();
+    }
+    expect_stdout: [
+        "foo",
+        "moo",
+        "bar",
+        "baz",
+        "moz",
+    ]
+    node_version: ">=16"
+}
+
+static_init_side_effects_1: {
+    options = {
+        merge_vars: true,
+        side_effects: true,
+    }
+    input: {
+        var a = "FAIL";
+        (class {
+            static {
+                a = "PASS";
+            }
+        });
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (class {
+            static {
+                a = "PASS";
+            }
+        });
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=16"
+}
+
+static_init_side_effects_1_strict: {
+    options = {
+        merge_vars: true,
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        var a = "FAIL";
+        (class {
+            static {
+                a = "PASS";
+            }
+        });
+        console.log(a);
+    }
+    expect: {
+        "use strict";
+        var a = "FAIL";
+        (() => (() => {
+            a = "PASS";
+        })())();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=16"
+}
+
+static_init_side_effects_2: {
+    options = {
+        hoist_props: true,
+        reduce_vars: true,
+        side_effects: true,
+    }
+    input: {
+        var a = "FAIL";
+        (class {
+            static {
+                a = "PASS";
+            }
+        });
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (class {
+            static {
+                a = "PASS";
+            }
+        });
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=16"
+}
+
+static_init_side_effects_2_strict: {
+    options = {
+        hoist_props: true,
+        reduce_vars: true,
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        var a = "FAIL";
+        (class {
+            static {
+                a = "PASS";
+            }
+        });
+        console.log(a);
+    }
+    expect: {
+        "use strict";
+        var a = "FAIL";
+        (() => (() => {
+            a = "PASS";
+        })())();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=16"
+}
+
 block_scoped: {
     options = {
         evaluate: true,
@@ -341,7 +543,7 @@ drop_extends: {
     node_version: ">=4"
 }
 
-keep_extends: {
+keep_extends_1: {
     options = {
         toplevel: true,
         unused: true,
@@ -366,6 +568,43 @@ keep_extends: {
     node_version: ">=4"
 }
 
+keep_extends_2: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        (class extends Function {});
+        console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        (class extends Function {});
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+keep_extends_3: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A extends Function {}
+        console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        (class extends Function {});
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
 drop_name: {
     options = {
         unused: true,
@@ -670,6 +909,58 @@ single_use_7: {
     node_version: ">=4"
 }
 
+single_use_extends: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A extends class B {
+            f() {
+                return "PASS";
+            }
+        } {}
+        console.log(new A().f());
+    }
+    expect: {
+        "use strict";
+        console.log(new class extends class {
+            f() {
+                return "PASS";
+            }
+        } {}().f());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+single_use_extends_non_strict: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        class A extends class B {
+            f() {
+                return "PASS";
+            }
+        } {}
+        console.log(new A().f());
+    }
+    expect: {
+        console.log(new class extends class {
+            f() {
+                return "PASS";
+            }
+        } {}().f());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 collapse_non_strict: {
     options = {
         collapse_vars: true,
@@ -742,6 +1033,38 @@ collapse_rhs_static: {
     node_version: ">=12"
 }
 
+inline_non_strict: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f(a) {
+            return a.p = "PASS";
+        }
+        class A {
+            g() {
+                return f(42);
+            }
+        }
+        console.log(new A().g());
+    }
+    expect: {
+        function f(a) {
+            return a.p = "PASS";
+        }
+        console.log(new class {
+            g() {
+                return f(42);
+            }
+        }().g());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 self_comparison: {
     options = {
         booleans: true,
@@ -943,6 +1266,105 @@ keep_fnames: {
     node_version: ">=4"
 }
 
+instanceof_lambda: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        console.log(42 instanceof class {});
+    }
+    expect: {
+        "use strict";
+        console.log(false);
+    }
+    expect_stdout: "false"
+    node_version: ">=4"
+}
+
+drop_instanceof: {
+    options = {
+        booleans: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {}
+        console.log({} instanceof A, Math instanceof A);
+    }
+    expect: {
+        "use strict";
+        console.log(!1, (Math, !1));
+    }
+    expect_stdout: "false false"
+    node_version: ">=4"
+}
+
+keep_instanceof_1: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {}
+        var A;
+        console.log({} instanceof A, Math instanceof A);
+    }
+    expect: {
+        "use strict";
+        class A {}
+        var A;
+        console.log({} instanceof A, Math instanceof A);
+    }
+    expect_stdout: SyntaxError("Identifier has already been declared")
+    node_version: ">=4"
+}
+
+keep_instanceof_2: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        var A = Object;
+        class A {}
+        console.log({} instanceof A, Math instanceof A);
+    }
+    expect: {
+        "use strict";
+        var A = Object;
+        class A {}
+        console.log({} instanceof A, Math instanceof A);
+    }
+    expect_stdout: SyntaxError("Identifier has already been declared")
+    node_version: ">=4"
+}
+
+keep_instanceof_3: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {}
+        A = Object;
+        console.log({} instanceof A, Math instanceof A);
+    }
+    expect: {
+        "use strict";
+        class A {}
+        A = Object;
+        console.log({} instanceof A, Math instanceof A);
+    }
+    expect_stdout: "true true"
+    node_version: ">=4"
+}
+
 issue_805_1: {
     options = {
         inline: true,
@@ -1758,12 +2180,14 @@ issue_4962_1: {
         })(function g() {});
     }
     expect: {
-        (function g() {}),
+        (function() {
-        void class {
+            function f() {
-            static c = function() {
                 while (console.log(typeof g));
-            }();
+            }
-        };
+            (class {
+                static c = f();
+            });
+        })(function g() {});
     }
     expect_stdout: "undefined"
     node_version: ">=12"
@@ -1796,6 +2220,37 @@ issue_4962_1_strict: {
     node_version: ">=12"
 }
 
+issue_4962_1_strict_direct: {
+    options = {
+        ie: true,
+        inline: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            function f() {
+                "use strict";
+                while (console.log(typeof g));
+            }
+            class A {
+                static p = f();
+            }
+        })(function g() {});
+    }
+    expect: {
+        (function g() {}),
+        void class {
+            static c = function() {
+                "use strict";
+                while (console.log(typeof g));
+            }();
+        };
+    }
+    expect_stdout: "undefined"
+    node_version: ">=12"
+}
+
 issue_4962_2: {
     options = {
         ie: true,
@@ -1815,8 +2270,11 @@ issue_4962_2: {
     }
     expect: {
         console.log(function f() {}(function g() {
+            function h() {
+                f;
+            }
             (class {
-                static c = f;
+                static c = h();
             });
         }));
     }
@@ -1852,6 +2310,69 @@ issue_4962_2_strict: {
     node_version: ">=12"
 }
 
+issue_4962_2_strict_direct: {
+    options = {
+        ie: true,
+        inline: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f() {}(function g() {
+            function h() {
+                "use strict";
+                f;
+            }
+            class A {
+                static p = h();
+            }
+        }, typeof g));
+    }
+    expect: {
+        console.log(function f() {}(function g() {
+            (class {
+                static c = function() {
+                    "use strict";
+                    f;
+                }();
+            });
+        }));
+    }
+    expect_stdout: "undefined"
+    node_version: ">=12"
+}
+
+issue_4962_2_strict_direct_inline: {
+    options = {
+        directives: true,
+        ie: true,
+        inline: true,
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f() {}(function g() {
+            function h() {
+                "use strict";
+                f;
+            }
+            class A {
+                static p = h();
+            }
+        }, typeof g));
+    }
+    expect: {
+        console.log(function f() {}(function g() {
+            (class {
+                static c = f;
+            });
+        }));
+    }
+    expect_stdout: "undefined"
+    node_version: ">=12"
+}
+
 issue_4982_1: {
     options = {
         dead_code: true,
@@ -2541,7 +3062,7 @@ issue_5387: {
     node_version: ">=4"
 }
 
-issue_5389: {
+issue_5389_1: {
     options = {
         collapse_vars: true,
         toplevel: true,
@@ -2572,6 +3093,37 @@ issue_5389: {
     node_version: ">=12"
 }
 
+issue_5389_2: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        function log(m, n) {
+            console.log(m, n);
+        }
+        var a = log;
+        var A = class {
+            [a = "FAIL"] = a = "PASS";
+        };
+        var b = new A();
+        log(a, b.FAIL);
+    }
+    expect: {
+        function log(m, n) {
+            console.log(m, n);
+        }
+        var a = log;
+        var A;
+        var b = new class {
+            [a = "FAIL"] = a = "PASS";
+        }();
+        log(a, b.FAIL);
+    }
+    expect_stdout: "PASS PASS"
+    node_version: ">=12"
+}
+
 issue_5436: {
     options = {
         merge_vars: true,
@@ -2601,3 +3153,290 @@ issue_5436: {
     expect_stdout: "PASS"
     node_version: ">=12"
 }
+
+issue_5481: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        "use strict";
+        var a = "FAIL 1", log = console.log;
+        try {
+            a = "PASS";
+            (class extends 42 {});
+            log("FAIL 2", a);
+        } catch (e) {
+            log(a);
+        }
+    }
+    expect: {
+        "use strict";
+        var a = "FAIL 1", log = console.log;
+        try {
+            a = "PASS";
+            (class extends 42 {});
+            log("FAIL 2", a);
+        } catch (e) {
+            log(a);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5489: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        (class {
+            [console.log("foo")];
+            static {
+                console.log("bar");
+            }
+            static [console.log("baz")]() {}
+        });
+    }
+    expect: {
+        (class {
+            [(console.log("foo"), console.log("baz"))];
+            static {
+                console.log("bar");
+            }
+        });
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+        "bar",
+    ]
+    node_version: ">=16"
+}
+
+issue_5489_strict: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        "use strict";
+        (class {
+            [console.log("foo")];
+            static {
+                console.log("bar");
+            }
+            static [console.log("baz")]() {}
+        });
+    }
+    expect: {
+        "use strict";
+        console.log("foo"),
+        console.log("baz"),
+        (() => (() => {
+            console.log("bar");
+        })())();
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+        "bar",
+    ]
+    node_version: ">=16"
+}
+
+issue_5502: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        "use strict";
+        var a = "FAIL";
+        class A {
+            static p = a;
+            [a = "PASS"];
+        }
+        try {
+            b++;
+        } finally {
+            var a, b = 42;
+        }
+        console.log(a, b);
+    }
+    expect: {
+        "use strict";
+        var a = "FAIL";
+        class A {
+            static p = a;
+            [a = "PASS"];
+        }
+        try {
+            b++;
+        } finally {
+            var a, b = 42;
+        }
+        console.log(a, b);
+    }
+    expect_stdout: "PASS 42"
+    node_version: ">=12"
+}
+
+issue_5504: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        "use strict";
+        var a;
+        console.log((a = 42, class {
+            static p;
+        }).p);
+    }
+    expect: {
+        "use strict";
+        var a;
+        console.log((a = 42, class {
+            static p;
+        }).p);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=12"
+}
+
+issue_5512: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        "use strict";
+        a = "PASS";
+        class A {
+            static {
+                console.log(a);
+            }
+            static p = "PASS";
+        }
+        var a;
+    }
+    expect: {
+        "use strict";
+        a = "PASS";
+        class A {
+            static {
+                console.log(a);
+            }
+            static p = "PASS";
+        }
+        var a;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=16"
+}
+
+issue_5531_1: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        class A {
+            p = function() {
+                var a = function f() {
+                    if (!a)
+                        console.log("foo");
+                    return 42;
+                }(a++);
+            }();
+        }
+        new A();
+        new A();
+    }
+    expect: {
+        class A {
+            p = function() {
+                var a = function f() {
+                    if (!a)
+                        console.log("foo");
+                    return 42;
+                }(a++);
+            }();
+        }
+        new A();
+        new A();
+    }
+    expect_stdout: [
+        "foo",
+        "foo",
+    ]
+    node_version: ">=12"
+}
+
+issue_5531_2: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        class A {
+            static p = function() {
+                var a = function f() {
+                    if (!a)
+                        console.log("foo");
+                    return 42;
+                }(a++);
+            }();
+        }
+        new A();
+        new A();
+    }
+    expect: {
+        class A {
+            static p = (a = function f() {
+                if (!a)
+                    console.log("foo");
+                return 42;
+            }(a++), void 0);
+        }
+        var a;
+        new A();
+        new A();
+    }
+    expect_stdout: "foo"
+    node_version: ">=12"
+}
+
+issue_5531_3: {
+    options = {
+        inline: true,
+    }
+    input: {
+        class A {
+            static {
+                (function() {
+                    var a = function f() {
+                        if (!a)
+                            console.log("foo");
+                        return 42;
+                    }(a++);
+                })();
+            }
+        }
+        new A();
+        new A();
+    }
+    expect: {
+        class A {
+            static {
+                a = function f() {
+                    if (!a)
+                        console.log("foo");
+                    return 42;
+                }(a++),
+                void 0;
+                var a;
+            }
+        }
+        new A();
+        new A();
+    }
+    expect_stdout: "foo"
+    node_version: ">=16"
+}

test/compress/comparisons.js

@@ -40,6 +40,22 @@ unsafe_comps: {
     }
 }
 
+unsafe_in_instanceof: {
+    options = {
+        side_effects: true,
+        unsafe_comps: true,
+    }
+    input: {
+        var a;
+        42 in a;
+        f() instanceof "foo";
+    }
+    expect: {
+        var a;
+        f();
+    }
+}
+
 dont_change_in_or_instanceof_expressions: {
     input: {
         1 in 1;

test/compress/const.js

@@ -1855,3 +1855,54 @@ issue_5338: {
     }
     expect_stdout: true
 }
+
+issue_5476: {
+    mangle = {
+        keep_fargs: true,
+    }
+    input: {
+        console.log(function(n) {
+            const a = 42;
+        }());
+    }
+    expect: {
+        console.log(function(n) {
+            const o = 42;
+        }());
+    }
+    expect_stdout: "undefined"
+}
+
+issue_5516: {
+    options = {
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function() {
+            try {} catch (a) {
+                (function f() {
+                    a;
+                })();
+            }
+            {
+                const a = function() {};
+                return a;
+            }
+        }());
+    }
+    expect: {
+        console.log(typeof function() {
+            try {} catch (a) {
+                void a;
+            }
+            {
+                const a = function() {};
+                return a;
+            }
+        }());
+    }
+    expect_stdout: "function"
+}

test/compress/dead-code.js

@@ -1669,3 +1669,41 @@ issue_5106_2: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5506: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        try {
+            (function(a) {
+                var b = 1;
+                (function f() {
+                    try {
+                        b-- && f();
+                    } catch (c) {}
+                    console.log(a);
+                    a = 42 in (a = "bar");
+                })();
+            })("foo");
+        } catch (e) {}
+    }
+    expect: {
+        try {
+            (function(a) {
+                var b = 1;
+                (function f() {
+                    try {
+                        b-- && f();
+                    } catch (c) {}
+                    console.log(a);
+                    a = 42 in (a = "bar");
+                })();
+            })("foo");
+        } catch (e) {}
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}

test/compress/default-values.js

@@ -541,7 +541,7 @@ inline_side_effects_2: {
     }
     expect: {
         var a = 42;
-        [ [].e = --a ] = [ console ];
+        [ [][0] = --a ] = [ console ];
         console.log(a);
     }
     expect_stdout: "42"
@@ -1558,7 +1558,7 @@ issue_4502_4: {
         (function(a, b = console.log("FAIL")) {})(..."" + console.log(42));
     }
     expect: {
-        [ , [].e = console.log("FAIL") ] = [ ..."" + console.log(42) ];
+        [ , [][0] = console.log("FAIL") ] = [ ..."" + console.log(42) ];
     }
     expect_stdout: "42"
     node_version: ">=6"
@@ -2183,7 +2183,7 @@ issue_5340_2: {
     }
     expect: {
         var a;
-        [ [].e = 0 ] = [ ({ p: a } = true).q ];
+        [ [][0] = 0 ] = [ ({ p: a } = true).q ];
         console.log(a);
     }
     expect_stdout: "undefined"
@@ -2239,3 +2239,593 @@ issue_5407: {
     ]
     node_version: ">=6"
 }
+
+issue_5444_1: {
+    options = {
+        merge_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 42;
+        var b = function({} = setImmediate(function() {
+            console.log(a++);
+        })) {
+            return this;
+        }();
+        console.log(typeof b);
+    }
+    expect: {
+        var a = 42;
+        var b = function({} = setImmediate(function() {
+            console.log(a++);
+        })) {
+            return this;
+        }();
+        console.log(typeof b);
+    }
+    expect_stdout: [
+        "object",
+        "42",
+    ]
+    node_version: ">=6"
+}
+
+issue_5444_2: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        function f(a, b = a++) {
+            return b;
+        }
+        console.log(f("FAIL") || "PASS");
+    }
+    expect: {
+        function f(a, b = a++) {
+            return b;
+        }
+        console.log(f("FAIL") || "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5444_3: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        function f(a, b = function(c = a *= this) {
+            return c;
+        }()) {
+            return b;
+        }
+        console.log(f("FAIL") || "PASS");
+    }
+    expect: {
+        function f(a, b = function(c = a *= this) {
+            return c;
+        }()) {
+            return b;
+        }
+        console.log(f("FAIL") || "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5448_1: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(a = typeof console.log) {
+            do {
+                var b = [ ...a ];
+            } while (console.log("PASS"));
+        })();
+    }
+    expect: {
+        (function(a = console.log) {
+            do {} while (console.log("PASS"));
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5448_2: {
+    options = {
+        keep_fargs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(a = typeof console) {
+            do {
+                var b = [ ...a ];
+            } while (console.log("PASS"));
+        })();
+    }
+    expect: {
+        (function(a = 0) {
+            do {} while (console.log("PASS"));
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5448_3: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var [ a = typeof console ] = [ void console.log("PASS") ];
+        var b = [ ...a ];
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5448_4: {
+    options = {
+        evaluate: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var { p: a = typeof console } = { p: void console.log("PASS") };
+        var b = [ ...a ];
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5463: {
+    options = {
+        collapse_vars: true,
+        conditionals: true,
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+    }
+    input: {
+        if (console.log("PASS"))
+            var a = void 0,
+                b = void 0,
+                b = ([ a = FAIL ] = b && b);
+    }
+    expect: {
+        var a, b, b;
+        console.log("PASS") && (
+            b = a = void 0,
+            b = [a = FAIL] = a && a
+        );
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5465: {
+    options = {
+        inline: true,
+        merge_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f(a, b) {
+            (function(c = b = "FAIL 2") {
+                this && console.log(b || "PASS");
+            })(42 - a && a);
+        }
+        f("FAIL 1");
+    }
+    expect: {
+        a = "FAIL 1",
+        void function(c = b = "FAIL 2") {
+            this && console.log(b || "PASS");
+        }(42 - a && a);
+        var a, b;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5485: {
+    options = {
+        comparisons: true,
+    }
+    input: {
+        (function f(f, a = console.log(void 0 === f ? "PASS" : "FAIL")) {})();
+    }
+    expect: {
+        (function f(f, a = console.log(void 0 === f ? "PASS" : "FAIL")) {})();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_1_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b = 42) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_1_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b = 42) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_2_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f([ b ] = []) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;) {
+                    var [ [] = [] ] = [];
+                    throw "PASS";
+                }
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_2_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f([ b ] = []) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;) {
+                    var [ [] = [] ] = [];
+                    throw "PASS";
+                }
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_3_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b = 42, c = null) {
+                            c;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_3_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b = 42, c = null) {
+                            c;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_4_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b = 42, [ c ] = []) {
+                            c;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;) {
+                    var [ [] = [] ] = [];
+                    throw "PASS";
+                }
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_4_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b = 42, [ c ] = []) {
+                            c;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;) {
+                    var [ [] = [] ] = [];
+                    throw "PASS";
+                }
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5536: {
+    options = {
+        inline: true,
+        keep_fargs: true,
+        unused: true,
+    }
+    input: {
+        (function*() {
+            (([], a = 42) => {})([]);
+            console.log(typeof a);
+        })().next();
+    }
+    expect: {
+        (function*() {
+            [ , [][0] = 0 ] = [ [] ],
+            void 0;
+            console.log(typeof a);
+        })().next();
+    }
+    expect_stdout: "undefined"
+    node_version: ">=6"
+}

test/compress/destructured.js

@@ -1848,8 +1848,8 @@ issue_4294: {
             }) {}({
                 [a]: 0,
             });
-            var a = A;
+            var b = A;
-            console.log(a);
+            console.log(b);
         })();
     }
     expect_stdout: "PASS"
@@ -3020,6 +3020,7 @@ issue_5074_method_pure_getters: {
 issue_5085_1: {
     options = {
         evaluate: true,
+        passes: 2,
         reduce_vars: true,
         toplevel: true,
         unsafe: true,
@@ -3032,8 +3033,7 @@ issue_5085_1: {
     }
     expect: {
         var a = "PASS";
-        var b = [ 42 ][0];
+        42;
-        b;
         console.log(a);
     }
     expect_stdout: "PASS"
@@ -3043,6 +3043,7 @@ issue_5085_1: {
 issue_5085_2: {
     options = {
         evaluate: true,
+        passes: 2,
         reduce_vars: true,
         side_effects: true,
         unsafe: true,
@@ -3059,7 +3060,7 @@ issue_5085_2: {
     expect: {
         var a = "PASS";
         (function(b) {
-            b = [ 42 ][0];
+            0;
         })();
         console.log(a);
     }
@@ -3400,7 +3401,7 @@ issue_5222: {
     node_version: ">=6"
 }
 
-issue_5288: {
+issue_5288_1: {
     options = {
         conditionals: true,
         inline: true,
@@ -3420,7 +3421,37 @@ issue_5288: {
         }() ]));
     }
     expect: {
-        while (console ? console.log("PASS") : 0, void 0);
+        while (function() {
+            if (console)
+                console.log("PASS");
+        }(), void 0);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5288_2: {
+    options = {
+        conditionals: true,
+        inline: true,
+        keep_fargs: false,
+        passes: 2,
+        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"), void 0);
     }
     expect_stdout: "PASS"
     node_version: ">=6"
@@ -3466,7 +3497,7 @@ issue_5314_2: {
         A = this;
         new function() {
             [ {
-                [console.log(this === A ? "FAIL" : "PASS")]: [].e,
+                [console.log(this === A ? "FAIL" : "PASS")]: [][0],
             } ] = [ 42 ];
         }();
     }
@@ -3566,3 +3597,136 @@ issue_5423: {
     expect_stdout: "function"
     node_version: ">=6"
 }
+
+issue_5454: {
+    options = {
+        hoist_props: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f(a) {
+            var a = 42, a = {
+                p: [ a ] = [],
+            };
+            return "PASS";
+        }
+        console.log(f());
+    }
+    expect: {
+        console.log(function(a) {
+            a = 42, a = {
+                p: [ a ] = [],
+            };
+            return "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5485: {
+    options = {
+        comparisons: true,
+    }
+    input: {
+        (function f({
+            p: f,
+            [console.log(void 0 === f ? "PASS" : "FAIL")]: a,
+        }) {})(42);
+    }
+    expect: {
+        (function f({
+            p: f,
+            [console.log(void 0 === f ? "PASS" : "FAIL")]: a,
+        }) {})(42);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f([ b ]) {
+                            b;
+                            throw "PASS";
+                        })([]);
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f([ b ]) {
+                            b;
+                            throw "PASS";
+                        })([]);
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}

test/compress/drop-unused.js

@@ -671,6 +671,76 @@ iife: {
     }
 }
 
+drop_instanceof: {
+    options = {
+        booleans: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {}
+        console.log({} instanceof f, Math instanceof f);
+    }
+    expect: {
+        console.log(!1, (Math, !1));
+    }
+    expect_stdout: "false false"
+}
+
+keep_instanceof_1: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {}
+        var f;
+        console.log({} instanceof f, Math instanceof f);
+    }
+    expect: {
+        function f() {}
+        var f;
+        console.log({} instanceof f, Math instanceof f);
+    }
+    expect_stdout: "false false"
+}
+
+keep_instanceof_2: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {}
+        var f = Object;
+        console.log({} instanceof f, Math instanceof f);
+    }
+    expect: {
+        function f() {}
+        var f = Object;
+        console.log({} instanceof f, Math instanceof f);
+    }
+    expect_stdout: "true true"
+}
+
+keep_instanceof_3: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        f = Object;
+        function f() {}
+        console.log({} instanceof f, Math instanceof f);
+    }
+    expect: {
+        f = Object;
+        function f() {}
+        console.log({} instanceof f, Math instanceof f);
+    }
+    expect_stdout: "true true"
+}
+
 issue_1539: {
     options = {
         collapse_vars: true,
@@ -3615,3 +3685,85 @@ issue_5271: {
     }
     expect_stdout: "42"
 }
+
+issue_5533_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5533_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(b) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+}

test/compress/evaluate.js

@@ -907,6 +907,20 @@ chained_side_effects: {
     ]
 }
 
+instanceof_lambda: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(42 instanceof function() {});
+    }
+    expect: {
+        console.log(false);
+    }
+    expect_stdout: "false"
+}
+
 issue_1649: {
     options = {
         evaluate: true,

test/compress/exports.js

@@ -417,6 +417,46 @@ hoist_funs: {
     expect_exact: "export function f(){}export default async function*g(){}"
 }
 
+instanceof_default_class: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        export default class A {
+            f(a) {
+                return a instanceof A;
+            }
+        }
+    }
+    expect: {
+        export default class A {
+            f(a) {
+                return a instanceof A;
+            }
+        }
+    }
+}
+
+instanceof_default_function: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        export default function f() {
+            if (!(this instanceof f))
+                throw new Error("must instantiate");
+        }
+    }
+    expect: {
+        export default function f() {
+            if (!(this instanceof f))
+                throw new Error("must instantiate");
+        }
+    }
+}
+
 issue_4742_join_vars_1: {
     options = {
         join_vars: true,
@@ -496,3 +536,16 @@ issue_4766: {
         export var a = "bar";
     }
 }
+
+issue_5444: {
+    options = {
+        unused: true,
+    }
+    input: {
+        export var a = (console, console);
+    }
+    expect: {
+        console;
+        export var a = console;
+    }
+}

test/compress/functions.js

@@ -629,7 +629,7 @@ inline_binary_and: {
                 return void "moo";
                 return;
             } else
-                return;
+                return void 0;
         }());
     }
     expect_stdout: [
@@ -5582,7 +5582,7 @@ issue_3835: {
             return f();
         })();
     }
-    expect_stdout: true
+    expect_stdout: RangeError("Maximum call stack size exceeded")
 }
 
 issue_3836_1: {
@@ -7835,7 +7835,7 @@ issue_5249_1: {
                 while (console.log("FAIL 2"));
                 return;
             } else
-                return;
+                return void 0;
             throw "FAIL 3";
         }());
     }
@@ -8398,3 +8398,251 @@ issue_5409: {
     }
     expect_stdout: "undefined"
 }
+
+mixed_mode_inline_1: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            return this;
+        }
+        console.log(function() {
+            return f();
+        }() ? "PASS" : "FAIL");
+    }
+    expect: {
+        console.log(function() {
+            return this;
+        }() ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+mixed_mode_inline_1_strict: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {
+            return this;
+        }
+        console.log(function() {
+            return f();
+        }() ? "FAIL" : "PASS");
+    }
+    expect: {
+        "use strict";
+        console.log(function() {
+            return this;
+        }() ? "FAIL" : "PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+mixed_mode_inline_2: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            "use strict";
+            return this;
+        }
+        console.log(function() {
+            return f();
+        }() ? "FAIL" : "PASS");
+    }
+    expect: {
+        console.log(function() {
+            "use strict";
+            return this;
+        }() ? "FAIL" : "PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+mixed_mode_inline_2_strict: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {
+            "use strict";
+            return this;
+        }
+        console.log(function() {
+            return f();
+        }() ? "FAIL" : "PASS");
+    }
+    expect: {
+        "use strict";
+        console.log(function() {
+            return this;
+        }() ? "FAIL" : "PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+mixed_mode_inline_3: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            return this;
+        }
+        console.log(function() {
+            "use strict";
+            return f();
+        }() ? "PASS" : "FAIL");
+    }
+    expect: {
+        function f() {
+            return this;
+        }
+        console.log(function() {
+            "use strict";
+            return f();
+        }() ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+mixed_mode_inline_3_strict: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {
+            return this;
+        }
+        console.log(function() {
+            "use strict";
+            return f();
+        }() ? "FAIL" : "PASS");
+    }
+    expect: {
+        "use strict";
+        console.log(function() {
+            return this;
+        }() ? "FAIL" : "PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+mixed_mode_inline_4: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            "use strict";
+            return this;
+        }
+        console.log(function() {
+            "use strict";
+            return f();
+        }() ? "FAIL" : "PASS");
+    }
+    expect: {
+        console.log(function() {
+            "use strict";
+            return function() {
+                "use strict";
+                return this;
+            }();
+        }() ? "FAIL" : "PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+mixed_mode_inline_4_strict: {
+    options = {
+        directives: true,
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        function f() {
+            "use strict";
+            return this;
+        }
+        console.log(function() {
+            "use strict";
+            return f();
+        }() ? "FAIL" : "PASS");
+    }
+    expect: {
+        "use strict";
+        console.log(function() {
+            return this;
+        }() ? "FAIL" : "PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+module_inline: {
+    options = {
+        inline: true,
+        module: true,
+        reduce_vars: true,
+    }
+    input: {
+        var a = f;
+        function f() {
+            return a;
+        }
+        console.log(f() === a);
+    }
+    expect: {
+        var a = f;
+        function f() {
+            return a;
+        }
+        console.log(a === a);
+    }
+    expect_stdout: "true"
+}

test/compress/hoist_props.js

@@ -1176,3 +1176,51 @@ issue_5182: {
         "42",
     ]
 }
+
+issue_5441: {
+    options = {
+        hoist_props: true,
+        passes: 2,
+        reduce_vars: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(function(a) {
+            (function() {
+                a = { p: this };
+            })();
+            return typeof a;
+        }());
+    }
+    expect: {
+        console.log(function(a) {
+            (function() {
+                a_p = this;
+            })();
+            var a_p;
+            return typeof {};
+        }());
+    }
+    expect_stdout: "object"
+}
+
+issue_5498: {
+    options = {
+        hoist_props: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var o = {
+            __proto__: 42,
+        };
+        while (console.log(typeof o.__proto__));
+    }
+    expect: {
+        var o = {
+            __proto__: 42,
+        };
+        while (console.log(typeof o.__proto__));
+    }
+    expect_stdout: "object"
+}

test/compress/if_return.js

@@ -850,3 +850,170 @@ issue_866_2: {
         })();
     }
 }
+
+identical_returns_1: {
+    options = {
+        conditionals: true,
+        if_return: true,
+    }
+    input: {
+        console.log(function() {
+            if (console.log("foo"))
+                return 42;
+            else
+                while (console.log("bar"));
+            return 42;
+        }());
+    }
+    expect: {
+        console.log(function() {
+            if (!console.log("foo"))
+                while (console.log("bar"));
+            return 42;
+        }());
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "42",
+    ]
+}
+
+identical_returns_2: {
+    options = {
+        conditionals: true,
+        if_return: true,
+    }
+    input: {
+        console.log(function() {
+            if (console.log("foo"))
+                while (console.log("FAIL"));
+            else
+                return "bar";
+            return "bar";
+        }());
+    }
+    expect: {
+        console.log(function() {
+            if (console.log("foo"))
+                while (console.log("FAIL"));
+            return "bar";
+        }());
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}
+
+identical_returns_3: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        function f(a) {
+            if (a)
+                return 42;
+            if (a)
+                return;
+            return 42;
+        }
+        if (f(console))
+            console.log("PASS");
+    }
+    expect: {
+        function f(a) {
+            if (a)
+                return 42;
+            if (a)
+                ;
+            else
+                return 42;
+        }
+        if (f(console))
+            console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4374: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        if_return: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            console.log(f(console));
+            function f(a) {
+                if (console) return 0;
+                if (a) return 1;
+                return 0;
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            console.log(function(a) {
+                return !console && a ? 1 : 0;
+            }(console));
+        })();
+    }
+    expect_stdout: "0"
+}
+
+issue_5521: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        console.log(function() {
+            if (console)
+                try {
+                    return "FAIL";
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect: {
+        console.log(function() {
+            if (console)
+                try {
+                    return "FAIL";
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect_stdout: "undefined"
+}
+
+issue_5523: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        console.log(function() {
+            if (console)
+                try {
+                    FAIL;
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect: {
+        console.log(function() {
+            if (console)
+                try {
+                    FAIL;
+                } finally {
+                    return;
+                }
+        }());
+    }
+    expect_stdout: "undefined"
+}

test/compress/labels.js

@@ -111,6 +111,7 @@ labels_5: {
 labels_6: {
     options = {
         dead_code: true,
+        unused: true,
     }
     input: {
         out: break out;
@@ -208,6 +209,59 @@ labels_10: {
     expect_stdout: "PASS"
 }
 
+labels_11: {
+    options = {
+        conditionals: true,
+        if_return: true,
+        unused: true,
+    }
+    input: {
+        L: if (console.log("PASS"))
+            break L;
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+labels_12: {
+    options = {
+        conditionals: true,
+        dead_code: true,
+        if_return: true,
+    }
+    input: {
+        L: try {
+            if (console.log("foo"))
+                break L;
+            throw "bar";
+        } catch (e) {
+            console.log(e);
+            break L;
+        } finally {
+            if (console.log("baz"))
+                break L;
+        }
+    }
+    expect: {
+        L: try {
+            if (!console.log("foo"))
+                throw "bar";
+        } catch (e) {
+            console.log(e);
+        } finally {
+            if (console.log("baz"))
+                break L;
+        }
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "baz",
+    ]
+}
+
 issue_4466_1: {
     mangle = {
         v8: false,
@@ -327,3 +381,53 @@ issue_4466_2_toplevel_v8: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5522: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log(function() {
+            L: try {
+                return "FAIL";
+            } finally {
+                break L;
+            }
+            return "PASS";
+        }());
+    }
+    expect: {
+        console.log(function() {
+            L: try {
+                return "FAIL";
+            } finally {
+                break L;
+            }
+            return "PASS";
+        }());
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5524: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        L: try {
+            FAIL;
+        } finally {
+            break L;
+        }
+        console.log("PASS");
+    }
+    expect: {
+        L: try {
+            FAIL;
+        } finally {
+            break L;
+        }
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}

test/compress/let.js

@@ -892,6 +892,40 @@ if_return_2: {
     node_version: ">=4"
 }
 
+if_return_3: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        "use strict";
+        var a = "PASS";
+        function f(b) {
+            if (console) {
+                let b = a;
+                return b;
+            } else
+                while (console.log("FAIL 1"));
+            return b;
+        }
+        console.log(f("FAIL 2"));
+    }
+    expect: {
+        "use strict";
+        var a = "PASS";
+        function f(b) {
+            if (console) {
+                let b = a;
+                return b;
+            } else
+                while (console.log("FAIL 1"));
+            return b;
+        }
+        console.log(f("FAIL 2"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
 do_if_continue_1: {
     options = {
         if_return: true,
@@ -1604,48 +1638,6 @@ issue_4305_2: {
     node_version: ">=4"
 }
 
-issue_1753: {
-    mangle = {
-        toplevel: false,
-        webkit: true,
-    }
-    input: {
-        "use strict";
-        let l = null;
-        for (let i = 0; i < 1; i++)
-            console.log(i);
-    }
-    expect: {
-        "use strict";
-        let l = null;
-        for (let i = 0; i < 1; i++)
-            console.log(i);
-    }
-    expect_stdout: "0"
-    node_version: ">=4"
-}
-
-issue_1753_toplevel: {
-    mangle = {
-        toplevel: true,
-        webkit: true,
-    }
-    input: {
-        "use strict";
-        let l = null;
-        for (let i = 0; i < 1; i++)
-            console.log(i);
-    }
-    expect: {
-        "use strict";
-        let l = null;
-        for (let e = 0; e < 1; e++)
-            console.log(e);
-    }
-    expect_stdout: "0"
-    node_version: ">=4"
-}
-
 issue_4438: {
     options = {
         if_return: true,
@@ -2020,3 +2012,23 @@ issue_5338: {
     expect_stdout: ReferenceError("a is not defined")
     node_version: ">=4"
 }
+
+issue_5476: {
+    mangle = {
+        keep_fargs: true,
+    }
+    input: {
+        "use strict";
+        console.log(function(n) {
+            let a;
+        }());
+    }
+    expect: {
+        "use strict";
+        console.log(function(n) {
+            let o;
+        }());
+    }
+    expect_stdout: "undefined"
+    node_version: ">=4"
+}

test/compress/merge_vars.js

@@ -3732,3 +3732,116 @@ issue_5420: {
     }
     expect_stdout: "PASS"
 }
+
+issue_5451: {
+    options = {
+        merge_vars: true,
+        toplevel: true,
+    }
+    input: {
+        A = 1;
+        var a = 1, b;
+        console.log(function f() {
+            return a-- && f(b = A, b);
+        }());
+    }
+    expect: {
+        A = 1;
+        var a = 1, b;
+        console.log(function f() {
+            return a-- && f(b = A, b);
+        }());
+    }
+    expect_stdout: "0"
+}
+
+issue_5471_1: {
+    options = {
+        conditionals: true,
+        inline: true,
+        merge_vars: true,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL 1";
+        function f(b, c) {
+            function g() {
+                if (console)
+                    return 42;
+                else
+                    c = "FAIL 2";
+            }
+            var d = g();
+            console.log(c || "PASS");
+            var e = function h() {
+                while (b && e);
+            }();
+        }
+        f(a++) && a;
+    }
+    expect: {
+        var a = "FAIL 1";
+        var b, c, e;
+        b = +a,
+        function() {
+            if (console)
+                return;
+            c = "FAIL 2";
+        }(),
+        console.log(c || "PASS"),
+        e = function() {
+            while (b && e);
+        }();
+    }
+    expect_stdout: "PASS"
+}
+
+issue_5471_2: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        inline: true,
+        merge_vars: true,
+        reduce_vars: true,
+        sequences: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL 1";
+        function f(b, c) {
+            function g() {
+                if (console)
+                    return 42;
+                else
+                    c = "FAIL 2";
+            }
+            var d = g();
+            console.log(c || "PASS");
+            var e = function h() {
+                while (b && e);
+            }();
+        }
+        f(a++) && a;
+    }
+    expect: {
+        var a = "FAIL 1";
+        var b, c, e;
+        b = +a,
+        function() {
+            if (console)
+                return;
+            c = "FAIL 2";
+        }(),
+        console.log(c || "PASS"),
+        e = function() {
+            while (b && e);
+        }(),
+        void 0;
+    }
+    expect_stdout: "PASS"
+}

test/compress/nullish.js

@@ -308,6 +308,7 @@ issue_4679: {
 issue_5266: {
     options = {
         inline: true,
+        side_effects: true,
     }
     input: {
         [

test/compress/pure_funcs.js

@@ -147,7 +147,7 @@ relational: {
         "bar" >= "bar";
     }
     expect: {
-        bar();
+        0 instanceof bar();
         bar();
         bar(), bar();
         bar();

test/compress/regexp.js

@@ -50,6 +50,22 @@ regexp_properties: {
     expect_stdout: "abc true false 0 false"
 }
 
+instanceof_1: {
+    input: {
+        console.log(/foo/ instanceof RegExp);
+    }
+    expect_exact: "console.log(/foo/ instanceof RegExp);"
+    expect_stdout: "true"
+}
+
+instanceof_2: {
+    input: {
+        console.log(42 + /foo/ instanceof Object);
+    }
+    expect_exact: "console.log(42+/foo/ instanceof Object);"
+    expect_stdout: "false"
+}
+
 issue_3434_1: {
     options = {
         evaluate: true,

test/compress/rests.js

@@ -648,7 +648,7 @@ drop_new_function: {
     }
     expect: {
         void ([ ... {
-            [console.log("PASS")]: [].e,
+            [console.log("PASS")]: [][0],
         }] = []);
     }
     expect_stdout: "PASS"
@@ -1363,3 +1363,171 @@ issue_5391: {
     expect_stdout: "NaN"
     node_version: ">=8.3.0"
 }
+
+issue_5533_1_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(...b) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_1_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(...b) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_2_keep_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(...[ b ]) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_5533_2_drop_fargs: {
+    options = {
+        evaluate: true,
+        inline: true,
+        join_vars: true,
+        keep_fargs: false,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        try {
+            (function() {
+                var a;
+                for (; 1;)
+                    a = function() {
+                        (function f(...[ b ]) {
+                            b;
+                            throw "PASS";
+                        })();
+                    }();
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            (function() {
+                for (;;)
+                    throw "PASS";
+            })();
+        } catch (e) {
+            console.log(e);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}

test/compress/side_effects.js

@@ -645,3 +645,56 @@ issue_4751: {
     }
     expect_stdout: "PASS"
 }
+
+drop_instanceof: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        42 instanceof function() {};
+        console.log("PASS");
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+drop_instanceof_reference: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        function f() {}
+        42 instanceof f;
+        console.log("PASS");
+    }
+    expect: {
+        function f() {}
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+retain_instanceof: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        try {
+            42 instanceof "foo";
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            0 instanceof "foo";
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+}

test/compress/transform.js

@@ -127,7 +127,7 @@ if_return: {
                 if (w) {
                     if (y) return;
                 } else if (z) return;
-                return x == y || (x && w(), y && z()), !0;
+                return x != y && (x && w(), y && z()), !0;
             }
         }
     }

test/compress/varify.js

@@ -111,7 +111,7 @@ hoist_props_const: {
         }
     }
     expect: {
-        var o = 0, o_p = "PASS";
+        var o, o_p = "PASS";
         console.log(o_p);
     }
     expect_stdout: "PASS"
@@ -613,3 +613,35 @@ issue_4954: {
     ]
     node_version: ">=4"
 }
+
+issue_5516: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+        varify: true,
+    }
+    input: {
+        "use strict";
+        console.log(typeof function() {
+            {
+                let a;
+            }
+            {
+                const a = function() {};
+                return a;
+            }
+        }());
+    }
+    expect: {
+        "use strict";
+        console.log(typeof function() {
+            {
+                const a = function() {};
+                return a;
+            }
+        }());
+    }
+    expect_stdout: "function"
+    node_version: ">=4"
+}

test/compress/webkit.js

@@ -107,3 +107,209 @@ function_name_mangle_ie8: {
     expect_exact: "(function(){console.log(typeof function n(o){})})();"
     expect_stdout: "function"
 }
+
+issue_1753: {
+    mangle = {
+        toplevel: false,
+        webkit: true,
+    }
+    input: {
+        "use strict";
+        let l = null;
+        for (let i = 0; i < 1; i++)
+            console.log(i);
+    }
+    expect: {
+        "use strict";
+        let l = null;
+        for (let i = 0; i < 1; i++)
+            console.log(i);
+    }
+    expect_stdout: "0"
+    node_version: ">=4"
+}
+
+issue_1753_toplevel: {
+    mangle = {
+        toplevel: true,
+        webkit: true,
+    }
+    input: {
+        "use strict";
+        let l = null;
+        for (let i = 0; i < 1; i++)
+            console.log(i);
+    }
+    expect: {
+        "use strict";
+        let l = null;
+        for (let e = 0; e < 1; e++)
+            console.log(e);
+    }
+    expect_stdout: "0"
+    node_version: ">=4"
+}
+
+issue_5032_await: {
+    options = {
+        merge_vars: true,
+        webkit: false,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(a) {
+            var a = log(a), c = a;
+            log(a);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=8"
+}
+
+issue_5032_await_webkit: {
+    options = {
+        merge_vars: true,
+        webkit: true,
+    }
+    input: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect: {
+        function log(value) {
+            console.log(value);
+            return value;
+        }
+        async function f(a) {
+            var b = log(a), c = b;
+            log(b);
+            log(c);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+    node_version: ">=8"
+}
+
+issue_5032_yield: {
+    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_yield_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_5480: {
+    mangle = {
+        webkit: true,
+    }
+    input: {
+        "use strict";
+        L: for (let a in console.log("PASS"));
+    }
+    expect: {
+        "use strict";
+        o: for (let o in console.log("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/yields.js

@@ -907,7 +907,7 @@ drop_body: {
         })([ console.log("baz") ]);
     }
     expect: {
-        [ [ , [].e = console.log("foo") ] ] = [ [ console.log("baz") ] ];
+        [ [ , [][0] = console.log("foo") ] ] = [ [ console.log("baz") ] ];
     }
     expect_stdout: [
         "baz",
@@ -934,6 +934,21 @@ drop_unused_call: {
     node_version: ">=4"
 }
 
+instanceof_lambda: {
+    options = {
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(42 instanceof function*() {});
+    }
+    expect: {
+        console.log(false);
+    }
+    expect_stdout: "false"
+    node_version: ">=4"
+}
+
 issue_4454_1: {
     rename = false
     options = {
@@ -978,8 +993,8 @@ issue_4454_2: {
     expect: {
         function f(a) {
             (function*(c = console.log(a)) {})();
-            var a = 42..toString();
+            var b = 42..toString();
-            console.log(a);
+            console.log(b);
         }
         f("PASS");
     }
@@ -1267,80 +1282,6 @@ issue_5019_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,
@@ -1526,6 +1467,80 @@ issue_5385_2: {
     node_version: ">=10"
 }
 
+issue_5385_3: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function*() {
+            return function() {
+                try {
+                    throw console.log("foo");
+                } catch (e) {
+                    return console.log("bar");
+                }
+            }();
+        })().next();
+        console.log("moo");
+    }
+    expect: {
+        (async function*() {
+            try {
+                throw console.log("foo");
+            } catch (e) {
+                return console.log("bar");
+            }
+            return void 0;
+        })().next();
+        console.log("moo");
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "moo",
+    ]
+    node_version: ">=10"
+}
+
+issue_5385_4: {
+    options = {
+        awaits: true,
+        inline: true,
+    }
+    input: {
+        (async function*() {
+            return async function() {
+                try {
+                    return {
+                        then(resolve) {
+                            resolve(console.log("FAIL"));
+                        },
+                    };
+                } finally {
+                    return "PASS";
+                }
+            }();
+        })().next().then(o => console.log(o.value, o.done));
+    }
+    expect: {
+        (async function*() {
+            return async function() {
+                try {
+                    return {
+                        then(resolve) {
+                            resolve(console.log("FAIL"));
+                        },
+                    };
+                } finally {
+                    return "PASS";
+                }
+            }();
+        })().next().then(o => console.log(o.value, o.done));
+    }
+    expect_stdout: "PASS true"
+    node_version: ">=10"
+}
+
 issue_5425: {
     options = {
         assignments: true,
@@ -1547,3 +1562,113 @@ issue_5425: {
     expect_stdout: "PASS undefined"
     node_version: ">=4"
 }
+
+issue_5456: {
+    options = {
+        inline: true,
+        merge_vars: true,
+    }
+    input: {
+        var a = true;
+        (function() {
+            (function(b, c) {
+                var d = function*() {
+                    c = null;
+                }();
+                var e = function() {
+                    if (c)
+                        console.log(typeof d);
+                    while (b);
+                }();
+            })(function(i) {
+                return console.log("foo") && i;
+            }(a));
+        })();
+    }
+    expect: {
+        var a = true;
+        (function() {
+            b = (i = a, console.log("foo") && i),
+            d = function*() {
+                c = null;
+            }(),
+            e = function() {
+                if (c) console.log(typeof d);
+                while (b);
+            }(),
+            void 0;
+            var b, c, d, e;
+            var i;
+        })();
+    }
+    expect_stdout: "foo"
+    node_version: ">=4"
+}
+
+issue_5506: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        console.log(function(a) {
+            var b = function*() {
+                a = null in (a = "PASS");
+            }();
+            try {
+                b.next();
+            } catch (e) {
+                return a;
+            }
+        }("FAIL"));
+    }
+    expect: {
+        console.log(function(a) {
+            var b = function*() {
+                a = null in (a = "PASS");
+            }();
+            try {
+                b.next();
+            } catch (e) {
+                return a;
+            }
+        }("FAIL"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_5526: {
+    options = {
+        inline: true,
+        side_effects: true,
+    }
+    input: {
+        (async function*() {
+            try {
+                return function() {
+                    while (console.log("foo"));
+                }();
+            } finally {
+                console.log("bar");
+            }
+        })().next();
+        console.log("baz");
+    }
+    expect: {
+        (async function*() {
+            try {
+                while (console.log("foo"));
+                return void 0;
+            } finally {
+                console.log("bar");
+            }
+        })().next();
+        console.log("baz");
+    }
+    expect_stdout: [
+        "foo",
+        "baz",
+        "bar",
+    ]
+    node_version: ">=10"
+}

test/input/module/expect.js

@@ -0,0 +1 @@
+function n(){return this||arguments[0]+arguments[1]}function o(){return this||arguments[0]+arguments[1]}console.log(n(n(1,3),5)),console.log(o(o(2,4),6));

test/input/module/input.js

@@ -0,0 +1,13 @@
+console.log(function() {
+    function sum(...params) {
+        return this || arguments[0] + arguments[1];
+    }
+    return sum(sum(1, 3), 5);
+}());
+console.log(function() {
+    "use strict";
+    function sum(...params) {
+        return this || arguments[0] + arguments[1];
+    }
+    return sum(sum(2, 4), 6);
+}());

test/mocha/cli.js

@@ -928,6 +928,14 @@ describe("bin/uglifyjs", function() {
             done();
         });
     });
+    it("Should work with --module", function(done) {
+        var command = uglifyjscmd + " test/input/module/input.js --module -mc";
+        exec(command, function(err, stdout, stderr) {
+            if (err) throw err;
+            assert.strictEqual(stdout, read("test/input/module/expect.js"));
+            done();
+        });
+    });
     it("Should compress swarm of unused variables with reasonable performance", function(done) {
         var code = [
             "console.log(function() {",

test/mocha/minify.js

@@ -1,6 +1,7 @@
 var assert = require("assert");
 var readFileSync = require("fs").readFileSync;
 var run_code = require("../sandbox").run_code;
+var semver = require("semver");
 var UglifyJS = require("../..");
 
 function read(path) {
@@ -320,6 +321,24 @@ describe("minify", function() {
         });
     });
 
+    describe("module", function() {
+        it("Should not inline `await` variables", function() {
+            if (semver.satisfies(process.version, "<8")) return;
+            var code = [
+                "console.log(function() {",
+                "    return typeof await;",
+                "}());",
+            ].join("\n");
+            assert.strictEqual(run_code("(async function(){" + code + "})();"), "undefined\n");
+            var result = UglifyJS.minify(code, {
+                module: true,
+            });
+            if (result.error) throw result.error;
+            assert.strictEqual(result.code, "console.log(function(){return typeof await}());");
+            assert.strictEqual(run_code("(async function(){" + result.code + "})();"), "undefined\n");
+        });
+    });
+
     describe("rename", function() {
         it("Should be repeatable", function() {
             var code = "!function(x){return x(x)}(y);";

test/reduce.js

@@ -210,10 +210,10 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
             }
             if (node.expression instanceof U.AST_Function) {
                 // hoist and return expressions from the IIFE function expression
-                var seq = [];
+                var scope = tt.find_parent(U.AST_Scope), seq = [];
                 node.expression.body.forEach(function(node) {
                     var expr = node instanceof U.AST_Exit ? node.value : node.body;
-                    if (expr instanceof U.AST_Node && !U.is_statement(expr) && can_hoist(expr)) {
+                    if (expr instanceof U.AST_Node && !U.is_statement(expr) && can_hoist(expr, scope)) {
                         // collect expressions from each statement's body
                         seq.push(expr);
                     }
@@ -264,11 +264,12 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 CHANGED = true;
                 return List.skip;
               default:
-                if (!has_exit(node) && can_hoist(node)) {
+                if (can_hoist(node, tt.find_parent(U.AST_Scope))) {
                     // hoist function declaration body
                     var body = node.body;
                     node.body = [];
-                    body.push(node); // retain function with empty body to be dropped later
+                    // retain function with empty body to be dropped later
+                    body.push(node);
                     CHANGED = true;
                     return List.splice(body);
                 }
@@ -382,7 +383,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
             if (node.body instanceof U.AST_Call && node.body.expression instanceof U.AST_Function) {
                 // hoist simple statement IIFE function expression body
                 node.start._permute++;
-                if (!has_exit(node.body.expression) && can_hoist(node.body.expression)) {
+                if (can_hoist(node.body.expression, tt.find_parent(U.AST_Scope))) {
                     CHANGED = true;
                     return List.splice(node.body.expression.body);
                 }
@@ -647,21 +648,6 @@ function trim_trailing_whitespace(value) {
     return ("" + value).replace(/\s+$/, "");
 }
 
-function has_exit(fn) {
-    var found = false;
-    var tw = new U.TreeWalker(function(node) {
-        if (found) return found;
-        if (node instanceof U.AST_Exit) {
-            return found = true;
-        }
-        if (node instanceof U.AST_Scope && node !== fn) {
-            return true; // don't descend into nested functions
-        }
-    });
-    fn.walk(tw);
-    return found;
-}
-
 function has_loopcontrol(body, loop, label) {
     var found = false;
     var tw = new U.TreeWalker(function(node) {
@@ -676,17 +662,31 @@ function has_loopcontrol(body, loop, label) {
     return found;
 }
 
-function can_hoist(body) {
+function can_hoist(body, scope) {
     var found = false;
-    body.walk(new U.TreeWalker(function(node) {
+    var tw = new U.TreeWalker(function(node) {
         if (found) return true;
+        if (node instanceof U.AST_Exit) return found = true;
         if (node instanceof U.AST_NewTarget) return found = true;
         if (node instanceof U.AST_Scope) {
             if (node === body) return;
+            if (node instanceof U.AST_Arrow || node instanceof U.AST_AsyncArrow) node.argnames.forEach(function(sym) {
+                sym.walk(tw);
+            });
+            // don't descend into nested functions
             return true;
         }
         if (node instanceof U.AST_Super) return found = true;
-    }));
+        if (node instanceof U.AST_SymbolDeclaration || node instanceof U.AST_SymbolRef) switch (node.name) {
+          case "await":
+            if (/^Async/.test(scope.TYPE)) return found = true;
+            return;
+          case "yield":
+            if (/Generator/.test(scope.TYPE)) return found = true;
+            return;
+        }
+    });
+    body.walk(tw);
     return !found;
 }
 
@@ -760,9 +760,9 @@ function compare_run_code(code, minify_options, result_cache, max_timeout) {
     if (minified.error) return minified;
 
     var toplevel = sandbox.has_toplevel(minify_options);
-    var unminified = run_code(code, toplevel, result_cache, max_timeout);
+    var unminified = run(code, max_timeout);
     var timeout = Math.min(100 * unminified.elapsed, max_timeout);
-    var minified_result = run_code(minified.code, toplevel, result_cache, timeout).result;
+    var minified_result = run(minified.code, timeout).result;
 
     if (sandbox.same_stdout(unminified.result, minified_result)) {
         return is_timed_out(unminified.result) && is_timed_out(minified_result) && {
@@ -774,6 +774,16 @@ function compare_run_code(code, minify_options, result_cache, max_timeout) {
         minified_result: minified_result,
         elapsed: unminified.elapsed,
     };
+
+    function run(code, timeout) {
+        if (minify_options.module) code = [
+            '"use strict";',
+            "(async()=>{",
+            code,
+            '})().catch(e=>process.on("exit",()=>{throw e}));',
+        ].join("\n");
+        return run_code(code, toplevel, result_cache, timeout);
+    }
 }
 
 function test_minify(code, minify_options) {

test/release/web-tooling-benchmark.sh

@@ -54,7 +54,7 @@ ERR=$?; if [ "$ERR" != "0" ]; then echo "Error: $ERR"; exit $ERR; fi
 minify_in_situ "src" \
 && minify_in_situ "third_party" \
 && rm -rf node_modules \
-&& npm_install \
+&& npm_install --package-lock \
 && rm -rf build/* \
 && npm run build:terser-bundled \
 && npm run build:uglify-js-bundled \

test/ufuzz/index.js

@@ -140,6 +140,7 @@ var SUPPORT = function(matrix) {
     class: "class C { f() {} }",
     class_field: "class C { p = 0; }",
     class_private: "class C { #f() {} }",
+    class_static_init: "class C { static {} }",
     computed_key: "({[0]: 0});",
     const_block: "var a; { const a = 0; }",
     default_value: "[ a = 0 ] = [];",
@@ -252,7 +253,7 @@ BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
 if (SUPPORT.exponentiation) BINARY_OPS.push("**");
 BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
 BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
-BINARY_OPS.push(" in ");
+BINARY_OPS.push(" in ", " instanceof ");
 
 var ASSIGNMENTS = [ "=" ];
 ASSIGNMENTS = ASSIGNMENTS.concat(ASSIGNMENTS);
@@ -405,7 +406,7 @@ function createTopLevelCode() {
     unique_vars.length = 0;
     classes.length = 0;
     allow_this = true;
-    async = false;
+    async = SUPPORT.async && rng(200) == 0;
     has_await = false;
     export_default = false;
     generator = false;
@@ -413,7 +414,7 @@ function createTopLevelCode() {
     funcs = 0;
     clazz = 0;
     imports = 0;
-    in_class = 0;
+    in_class = async;
     called = Object.create(null);
     var s = [
         strictMode(),
@@ -1181,7 +1182,11 @@ function createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn
                 unique_vars.length = unique_len;
             });
         }
-        if (n !== 0) s += " finally { " + createStatements(3, recurmax, canThrow, canBreak, canContinue, cannotReturn, stmtDepth) + " }";
+        if (n !== 0) s += [
+            " finally { ",
+            createStatements(rng(5) + 1, recurmax, canThrow, canBreak, canContinue, cannotReturn, stmtDepth),
+            " }",
+        ].join("");
         return s;
       case STMT_C:
         return "c = c + 1;";
@@ -1805,7 +1810,7 @@ function createClassLiteral(recurmax, stmtDepth, canThrow, name) {
         if (canThrow && rng(20) == 0) {
             s += p;
         } else {
-            s += "(" + p + " && " + p + ".constructor === Function ? " + p + " : function() {})";
+            s += "(typeof " + p + ' == "function" && typeof ' + p + '.prototype == "object" && ' + p + ".constructor === Function ? " + p + " : function() {})";
         }
     }
     s += " {\n";
@@ -1826,19 +1831,29 @@ function createClassLiteral(recurmax, stmtDepth, canThrow, name) {
         if (SUPPORT.class_field && rng(2)) {
             if (internal) {
                 s += internal;
-            } else if (fixed && bug_static_class_field) {
+            } else if (fixed && bug_class_static_nontrivial) {
                 s += getDotKey();
             } else {
                 s += createObjectKey(recurmax, stmtDepth, canThrow);
             }
             if (rng(5)) {
-                async = bug_async_class_await && fixed && 0;
+                async = false;
                 generator = false;
                 s += " = " + createExpression(recurmax, NO_COMMA, stmtDepth, fixed ? canThrow : CANNOT_THROW);
                 generator = save_generator;
                 async = save_async;
             }
             s += ";\n";
+        } else if (SUPPORT.class_static_init && fixed && !internal && rng(10) == 0) {
+            async = false;
+            generator = false;
+            s += [
+                "{ ",
+                createStatements(rng(5) + 1, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CANNOT_RETURN, stmtDepth),
+                " }\n",
+            ].join("");
+            generator = save_generator;
+            async = save_async;
         } else {
             if (!fixed && !internal && constructor && rng(10) == 0) {
                 internal = constructor;
@@ -1994,7 +2009,7 @@ function createBinaryOp(noComma, canThrow) {
     var op;
     do {
         op = BINARY_OPS[rng(BINARY_OPS.length)];
-    } while (noComma && op == "," || !canThrow && op == " in ");
+    } while (noComma && op == "," || !canThrow && /^ in/.test(op));
     return op;
 }
 
@@ -2037,7 +2052,7 @@ function isBannedKeyword(name) {
       case "let":
         return in_class;
       case "await":
-        return async !== false;
+        return async || in_class && bug_class_static_await;
       case "yield":
         return generator || in_class;
     }
@@ -2087,6 +2102,12 @@ if (require.main !== module) {
 }
 
 function run_code(code, toplevel, timeout) {
+    if (async && has_await) code = [
+        '"use strict";',
+        "(async()=>{",
+        code,
+        '})().catch(e=>process.on("exit",()=>{throw e}));',
+    ].join("\n");
     return sandbox.run_code(sandbox.patch_module_statements(code), toplevel, timeout);
 }
 
@@ -2106,7 +2127,9 @@ function errorln(msg) {
 }
 
 function try_beautify(code, toplevel, result, printfn, options) {
-    var beautified = UglifyJS.minify(code, JSON.parse(beautify_options));
+    var o = JSON.parse(beautify_options);
+    if (async && has_await) o.module = true;
+    var beautified = UglifyJS.minify(code, o);
     if (beautified.error) {
         printfn("// !!! beautify failed !!!");
         printfn(beautified.error);
@@ -2259,12 +2282,27 @@ function log(options) {
 }
 
 function sort_globals(code) {
-    var globals = run_code("throw Object.keys(this).sort(" + function(global) {
+    var injected = "throw Object.keys(this).sort(" + function(global) {
         return function(m, n) {
             return (typeof global[n] == "function") - (typeof global[m] == "function")
                 || (m < n ? -1 : m > n ? 1 : 0);
         };
-    } + "(this));\n" + code);
+    } + "(this));";
+    var save_async = async;
+    if (async && has_await) {
+        async = false;
+        injected = [
+            '"use strict";',
+            injected,
+            "(async function(){",
+            code,
+            "})();"
+        ].join("\n");
+    } else {
+        injected += "\n" + code;
+    }
+    var globals = run_code(injected);
+    async = save_async;
     if (!Array.isArray(globals)) {
         errorln();
         errorln();
@@ -2324,20 +2362,28 @@ function is_error_in(ex) {
     return ex.name == "TypeError" && /'in'/.test(ex.message);
 }
 
+function is_error_tdz(ex) {
+    return ex.name == "ReferenceError";
+}
+
 function is_error_spread(ex) {
-    return ex.name == "TypeError" && /Found non-callable @@iterator| is not iterable| not a function/.test(ex.message);
+    return ex.name == "TypeError" && /Found non-callable @@iterator| is not iterable| not a function|Symbol\(Symbol\.iterator\)/.test(ex.message);
 }
 
 function is_error_recursion(ex) {
     return ex.name == "RangeError" && /Invalid string length|Maximum call stack size exceeded/.test(ex.message);
 }
 
+function is_error_set_property(ex) {
+    return ex.name == "TypeError" && /^Cannot set propert[\s\S]+? of (null|undefined)/.test(ex.message);
+}
+
 function is_error_redeclaration(ex) {
     return ex.name == "SyntaxError" && /already been declared|redeclaration/.test(ex.message);
 }
 
 function is_error_destructuring(ex) {
-    return ex.name == "TypeError" && /^Cannot destructure /.test(ex.message);
+    return ex.name == "TypeError" && /^Cannot (destructure|read propert)/.test(ex.message);
 }
 
 function is_error_class_constructor(ex) {
@@ -2351,6 +2397,8 @@ function is_error_getter_only_property(ex) {
 }
 
 function patch_try_catch(orig, toplevel) {
+    var patched = Object.create(null);
+    var patches = [];
     var stack = [ {
         code: orig,
         index: 0,
@@ -2388,7 +2436,7 @@ function patch_try_catch(orig, toplevel) {
                     "throw " + match[1] + ";",
                 ].join("\n");
             }
-            var new_code = code.slice(0, index) + insert + code.slice(index) + tail_throw;
+            var new_code = code.slice(0, index) + insert + code.slice(index) + tail_throw + "var UFUZZ_ERROR;";
             var result = run_code(new_code, toplevel);
             if (!sandbox.is_error(result)) {
                 if (!stack.filled && match[1]) stack.push({
@@ -2400,27 +2448,35 @@ function patch_try_catch(orig, toplevel) {
                 offset += insert.length;
                 code = new_code;
             } else if (is_error_in(result)) {
-                index = result.ufuzz_catch;
+                patch(result.ufuzz_catch, result.ufuzz_var + ' = new Error("invalid `in`");');
-                return orig.slice(0, index) + result.ufuzz_var + ' = new Error("invalid `in`");' + orig.slice(index);
+            } else if (is_error_tdz(result)) {
+                patch(result.ufuzz_catch, result.ufuzz_var + ' = new Error("TDZ");');
             } else if (is_error_spread(result)) {
-                index = result.ufuzz_catch;
+                patch(result.ufuzz_catch, result.ufuzz_var + ' = new Error("spread not iterable");');
-                return orig.slice(0, index) + result.ufuzz_var + ' = new Error("spread not iterable");' + orig.slice(index);
             } else if (is_error_recursion(result)) {
-                index = result.ufuzz_try;
+                patch(result.ufuzz_try, 'throw new Error("skipping infinite recursion");');
-                return orig.slice(0, index) + 'throw new Error("skipping infinite recursion");' + orig.slice(index);
+            } else if (is_error_set_property(result)) {
+                patch(result.ufuzz_catch, result.ufuzz_var + ' = new Error("cannot set property");');
             } else if (is_error_destructuring(result)) {
-                index = result.ufuzz_catch;
+                patch(result.ufuzz_catch, result.ufuzz_var + ' = new Error("cannot destructure");');
-                return orig.slice(0, index) + result.ufuzz_var + ' = new Error("cannot destructure");' + orig.slice(index);
             } else if (is_error_class_constructor(result)) {
-                index = result.ufuzz_catch;
+                patch(result.ufuzz_catch, result.ufuzz_var + ' = new Error("missing new for class");');
-                return orig.slice(0, index) + result.ufuzz_var + ' = new Error("missing new for class");' + orig.slice(index);
             } else if (is_error_getter_only_property(result)) {
-                index = result.ufuzz_catch;
+                patch(result.ufuzz_catch, result.ufuzz_var + ' = new Error("setting getter-only property");');
-                return orig.slice(0, index) + result.ufuzz_var + ' = new Error("setting getter-only property");' + orig.slice(index);
             }
         }
         stack.filled = true;
     }
+    if (patches.length) return patches.reduce(function(code, patch) {
+        var index = patch[0];
+        return code.slice(0, index) + patch[1] + code.slice(index);
+    }, orig);
+
+    function patch(index, code) {
+        if (patched[index]) return;
+        patched[index] = true;
+        patches.unshift([ index, code ]);
+    }
 }
 
 var beautify_options = {
@@ -2444,10 +2500,13 @@ if (SUPPORT.arrow && SUPPORT.async && SUPPORT.rest && sandbox.is_error(sandbox.r
         return ex.name == "SyntaxError" && ex.message == "Rest parameter must be last formal parameter";
     };
 }
-var bug_async_class_await = SUPPORT.async && SUPPORT.class_field && sandbox.is_error(sandbox.run_code("var await; async function f() { class A { static p = await; } }"));
+var bug_class_static_await = SUPPORT.async && SUPPORT.class_field && sandbox.is_error(sandbox.run_code("var await; class A { static p = await; }"));
+var bug_class_static_nontrivial = SUPPORT.class_field && sandbox.is_error(sandbox.run_code("class A { static 42; static get 42() {} }"));
 var bug_for_of_async = SUPPORT.for_await_of && sandbox.is_error(sandbox.run_code("var async; for (async of []);"));
 var bug_for_of_var = SUPPORT.for_of && SUPPORT.let && sandbox.is_error(sandbox.run_code("try {} catch (e) { for (var e of []); }"));
-var bug_static_class_field = SUPPORT.class_field && sandbox.is_error(sandbox.run_code("class A { static 42; static get 42() {} }"));
+var bug_proto_stream = function(ex) {
+    return ex.name == "TypeError" && ex.message == "callback is not a function";
+}
 if (SUPPORT.destructuring && sandbox.is_error(sandbox.run_code("console.log([ 1 ], {} = 2);"))) {
     beautify_options.output.v8 = true;
     minify_options.forEach(function(o) {
@@ -2478,11 +2537,17 @@ for (var round = 1; round <= num_iterations; round++) {
         println();
             // ignore v8 parser bug
         return bug_async_arrow_rest(result)
+            // ignore Node.js `__proto__` quirks
+            || bug_proto_stream(result)
             // ignore runtime platform bugs
             || result.message == "Script execution aborted.";
     })) continue;
     minify_options.forEach(function(options) {
         var o = JSON.parse(options);
+        if (async && has_await) {
+            o.module = true;
+            options = JSON.stringify(o);
+        }
         var toplevel = sandbox.has_toplevel(o);
         o.validate = true;
         uglify_code = UglifyJS.minify(original_code, o);
@@ -2495,6 +2560,8 @@ for (var round = 1; round <= num_iterations; round++) {
             var uglify_erred = sandbox.is_error(uglify_result);
             // ignore v8 parser bug
             if (!ok && uglify_erred && bug_async_arrow_rest(uglify_result)) ok = true;
+            // ignore Node.js `__proto__` quirks
+            if (!ok && uglify_erred && bug_proto_stream(uglify_result)) ok = true;
             // ignore runtime platform bugs
             if (!ok && uglify_erred && uglify_result.message == "Script execution aborted.") ok = true;
             // handle difference caused by time-outs
@@ -2532,55 +2599,34 @@ for (var round = 1; round <= num_iterations; round++) {
                     ok = sandbox.same_stdout(fuzzy_result, uglify_result);
                 }
             }
+            if (!ok && original_erred && uglify_erred && (
+                // ignore difference in error message caused by `in`
+                is_error_in(original_result) && is_error_in(uglify_result)
                 // ignore difference in error message caused by Temporal Dead Zone
-            if (!ok && original_erred && uglify_erred && original_result.name == "ReferenceError" && uglify_result.name == "ReferenceError") ok = true;
+                || is_error_tdz(original_result) && is_error_tdz(uglify_result)
-            // ignore difference due to implicit strict-mode in `class`
+                // ignore difference in error message caused by spread syntax
-            if (!ok && /\bclass\b/.test(original_code)) {
+                || is_error_spread(original_result) && is_error_spread(uglify_result)
-                var original_strict = run_code('"use strict";\n' + original_code, toplevel);
+                // ignore difference in error message caused by destructuring assignment
-                if (uglify_erred && /^(Syntax|Type)Error$/.test(uglify_result.name)) {
+                || is_error_set_property(original_result) && is_error_set_property(uglify_result)
-                    ok = sandbox.is_error(original_strict);
-                } else {
-                    ok = sandbox.same_stdout(original_strict, uglify_result);
-                }
-            }
                 // ignore difference in error message caused by `import` symbol redeclaration
-            if (!ok && original_erred && uglify_erred && /\bimport\b/.test(original_code)) {
+                || /\bimport\b/.test(original_code) && is_error_redeclaration(original_result) && is_error_redeclaration(uglify_result)
-                if (is_error_redeclaration(original_result) && is_error_redeclaration(uglify_result)) ok = true;
+                // ignore difference in error message caused by destructuring
-            }
+                || is_error_destructuring(original_result) && is_error_destructuring(uglify_result)
+                // ignore difference in error message caused by call on class
+                || is_error_class_constructor(original_result) && is_error_class_constructor(uglify_result)
+                // ignore difference in error message caused by setting getter-only property
+                || is_error_getter_only_property(original_result) && is_error_getter_only_property(uglify_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 && original_erred && uglify_erred) {
-                if (is_error_in(original_result) && is_error_in(uglify_result)) ok = true;
-            }
-            // ignore difference in error message caused by spread syntax
-            if (!ok && original_erred && uglify_erred) {
-                if (is_error_spread(original_result) && is_error_spread(uglify_result)) ok = true;
-            }
             // ignore difference in depth of termination caused by infinite recursion
             if (!ok && original_erred && is_error_recursion(original_result)) {
                 if (!uglify_erred || is_error_recursion(uglify_result)) ok = true;
             }
-            // ignore difference in error message caused by destructuring
-            if (!ok && original_erred && uglify_erred) {
-                if (is_error_destructuring(original_result) && is_error_destructuring(uglify_result)) ok = true;
-            }
-            // ignore difference in error message caused by call on class
-            if (!ok && original_erred && uglify_erred) {
-                if (is_error_class_constructor(original_result) && is_error_class_constructor(uglify_result)) {
-                    ok = true;
-                }
-            }
-            // ignore difference in error message caused by setting getter-only property
-            if (!ok && original_erred && uglify_erred) {
-                if (is_error_getter_only_property(original_result) && is_error_getter_only_property(uglify_result)) {
-                    ok = true;
-                }
-            }
             // ignore errors above when caught by try-catch
             if (!ok) {
                 var orig_skipped = patch_try_catch(original_code, toplevel);