v3.13.7

fixes #4943

.github/workflows/build.yml

@@ -8,7 +8,12 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        options: [ '-mb braces', '--ie8 -c', '-mc', '--toplevel -mc passes=3,pure_getters,unsafe' ]
+        options:
+          - '-mb braces'
+          - '--ie8 -c'
+          - '-mc'
+          - '-p acorn --toplevel -mco spidermonkey'
+          - '--toplevel -mc passes=3,pure_getters,unsafe'
         script:
           - acorn.sh
           - bootstrap.sh

.github/workflows/ufuzz.yml

@@ -2,7 +2,7 @@ name: Fuzzing
 on:
   pull_request:
   schedule:
-    - cron: '*/5 * * * *'
+    - cron: '*/15 * * * *'
 env:
   BASE_URL: https://api.github.com/repos/${{ github.repository }}
   CAUSE: ${{ github.event_name }}

README.md

@@ -1309,3 +1309,35 @@ To allow for better optimizations, the compiler makes various assumptions:
   // Actual:   { '42': undefined }
   ```
   UglifyJS may modify the input which in turn may suppress those errors.
+- 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.
+- Later versions of JavaScript will throw `SyntaxError` with the following:
+  ```javascript
+  var async;
+  for (async of []);
+  // SyntaxError: The left-hand side of a for-of loop may not be 'async'.
+  ```
+  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
+  console.log({
+      ...console,
+      get 42() {
+          return "FAIL";
+      },
+      [42]: "PASS",
+  }[42]);
+  // Expected: "PASS"
+  // Actual:   "FAIL"
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.

bin/uglifyjs

@@ -235,10 +235,11 @@ if (options.mangle && options.mangle.properties) {
         });
     }
 }
-if (output == "ast") options.output = {
-    ast: true,
-    code: false,
-};
+if (/^ast|spidermonkey$/.test(output)) {
+    if (typeof options.output != "object") options.output = {};
+    options.output.ast = true;
+    options.output.code = false;
+}
 if (options.parse && (options.parse.acorn || options.parse.spidermonkey)
     && options.sourceMap && options.sourceMap.content == "inline") {
     fatal("inline source map only works with built-in parser");
@@ -265,7 +266,9 @@ if (specified["self"]) {
     paths = UglifyJS.FILES;
 }
 if (specified["in-situ"]) {
-    if (output || specified["reduce-test"] || specified["self"]) fatal("incompatible options specified");
+    if (output && output != "spidermonkey" || specified["reduce-test"] || specified["self"]) {
+        fatal("incompatible options specified");
+    }
     paths.forEach(function(name) {
         print(name);
         if (/^ast|spidermonkey$/.test(name)) fatal("invalid file name specified");
@@ -311,13 +314,43 @@ function run() {
     try {
         if (options.parse) {
             if (options.parse.acorn) {
+                var annotations = Object.create(null);
                 files = convert_ast(function(toplevel, name) {
-                    return require("acorn").parse(files[name], {
+                    var content = files[name];
+                    var list = annotations[name] = [];
+                    var prev = -1;
+                    return require("acorn").parse(content, {
+                        allowHashBang: true,
+                        ecmaVersion: "latest",
                         locations: true,
+                        onComment: function(block, text, start, end) {
+                            var match = /[@#]__PURE__/.exec(text);
+                            if (!match) {
+                                if (start != prev) return;
+                                match = [ list[prev] ];
+                            }
+                            while (/\s/.test(content[end])) end++;
+                            list[end] = match[0];
+                            prev = end;
+                        },
+                        preserveParens: true,
                         program: toplevel,
-                        sourceFile: name
+                        sourceFile: name,
+                        sourceType: "module",
                     });
                 });
+                files.walk(new UglifyJS.TreeWalker(function(node) {
+                    if (!(node instanceof UglifyJS.AST_Call)) return;
+                    var list = annotations[node.start.file];
+                    var pure = list[node.start.pos];
+                    if (!pure) {
+                        var pos = node.start.parens;
+                        if (pos) for (var i = 0; !pure && i < pos.length; i++) {
+                            pure = list[pos[i]];
+                        }
+                    }
+                    if (pure) node.pure = pure;
+                }));
             } else if (options.parse.spidermonkey) {
                 files = convert_ast(function(toplevel, name) {
                     var obj = JSON.parse(files[name]);
@@ -409,16 +442,19 @@ function run() {
             return value;
         }, 2));
     } else if (output == "spidermonkey") {
-        print(JSON.stringify(UglifyJS.minify(result.code, {
-            compress: false,
-            mangle: false,
-            output: {
-                ast: true,
-                code: false
-            },
-        }).ast.to_mozilla_ast(), null, 2));
+        print(JSON.stringify(result.ast.to_mozilla_ast(), null, 2));
     } else if (output) {
-        fs.writeFileSync(output, result.code);
+        var code;
+        if (result.ast) {
+            var opts = {};
+            for (var name in options.output) {
+                if (!/^ast|code$/.test(name)) opts[name] = options.output[name];
+            }
+            code = UglifyJS.AST_Node.from_mozilla_ast(result.ast.to_mozilla_ast()).print_to_string(opts);
+        } else {
+            code = result.code;
+        }
+        fs.writeFileSync(output, code);
         if (result.map) fs.writeFileSync(output + ".map", result.map);
     } else {
         print(result.code);

lib/ast.js

@@ -261,9 +261,9 @@ var AST_BlockScope = DEFNODE("BlockScope", "enclosed functions make_def parent_s
     $documentation: "Base class for all statements introducing a lexical scope",
     $propdoc: {
         enclosed: "[SymbolDef*/S] a list of all symbol definitions that are accessed from this scope or any subscopes",
-        functions: "[Object/S] like `variables`, but only lists function declarations",
+        functions: "[Dictionary/S] like `variables`, but only lists function declarations",
         parent_scope: "[AST_Scope?/S] link to the parent scope",
-        variables: "[Object/S] a map of name ---> SymbolDef for all variables/functions defined in this scope",
+        variables: "[Dictionary/S] a map of name ---> SymbolDef for all variables/functions defined in this scope",
     },
     clone: function(deep) {
         var node = this._clone(deep);
@@ -506,7 +506,7 @@ var AST_Scope = DEFNODE("Scope", "uses_eval uses_with", {
 var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     $documentation: "The toplevel scope",
     $propdoc: {
-        globals: "[Object/S] a map of name ---> SymbolDef for all undeclared names",
+        globals: "[Dictionary/S] a map of name ---> SymbolDef for all undeclared names",
     },
     wrap: function(name) {
         var body = this.body;
@@ -1293,11 +1293,13 @@ function must_be_expressions(node, prop, allow_spread, allow_hole) {
     });
 }
 
-var AST_Call = DEFNODE("Call", "expression args pure", {
+var AST_Call = DEFNODE("Call", "args expression optional pure", {
     $documentation: "A function call expression",
     $propdoc: {
+        args: "[AST_Node*] array of arguments",
         expression: "[AST_Node] expression to invoke as function",
-        args: "[AST_Node*] array of arguments"
+        optional: "[boolean] whether the expression is optional chaining",
+        pure: "[string/S] marker for side-effect-free call expression",
     },
     walk: function(visitor) {
         var node = this;
@@ -1315,7 +1317,10 @@ var AST_Call = DEFNODE("Call", "expression args pure", {
 });
 
 var AST_New = DEFNODE("New", null, {
-    $documentation: "An object instantiation.  Derives from a function call since it has exactly the same properties"
+    $documentation: "An object instantiation.  Derives from a function call since it has exactly the same properties",
+    _validate: function() {
+        if (this.optional) throw new Error("optional must be false");
+    },
 }, AST_Call);
 
 var AST_Sequence = DEFNODE("Sequence", "expressions", {
@@ -1337,11 +1342,12 @@ var AST_Sequence = DEFNODE("Sequence", "expressions", {
     },
 });
 
-var AST_PropAccess = DEFNODE("PropAccess", "expression property", {
+var AST_PropAccess = DEFNODE("PropAccess", "expression optional property", {
     $documentation: "Base class for property access expressions, i.e. `a.foo` or `a[\"foo\"]`",
     $propdoc: {
         expression: "[AST_Node] the “container” expression",
-        property: "[AST_Node|string] the property to access.  For AST_Dot this is always a plain string, while for AST_Sub it's an arbitrary AST_Node"
+        optional: "[boolean] whether the expression is optional chaining",
+        property: "[AST_Node|string] the property to access.  For AST_Dot this is always a plain string, while for AST_Sub it's an arbitrary AST_Node",
     },
     getProperty: function() {
         var p = this.property;

lib/minify.js

@@ -204,27 +204,29 @@ function minify(files, options) {
         if (options.mangle && options.mangle.properties) mangle_properties(toplevel, options.mangle.properties);
         if (timings) timings.output = Date.now();
         var result = {};
-        if (options.output.ast) {
-            result.ast = toplevel;
-        }
-        if (!HOP(options.output, "code") || options.output.code) {
+        var output = defaults(options.output, {
+            ast: false,
+            code: true,
+        });
+        if (output.ast) result.ast = toplevel;
+        if (output.code) {
             if (options.sourceMap) {
-                options.output.source_map = SourceMap(options.sourceMap);
+                output.source_map = SourceMap(options.sourceMap);
                 if (options.sourceMap.includeSources) {
                     if (files instanceof AST_Toplevel) {
                         throw new Error("original source content unavailable");
                     } else for (var name in files) if (HOP(files, name)) {
-                        options.output.source_map.setSourceContent(name, files[name]);
+                        output.source_map.setSourceContent(name, files[name]);
                     }
                 }
             }
-            delete options.output.ast;
-            delete options.output.code;
-            var stream = OutputStream(options.output);
+            delete output.ast;
+            delete output.code;
+            var stream = OutputStream(output);
             toplevel.print(stream);
             result.code = stream.get();
             if (options.sourceMap) {
-                result.map = options.output.source_map.toString();
+                result.map = output.source_map.toString();
                 var url = options.sourceMap.url;
                 if (url) {
                     result.code = result.code.replace(/\n\/\/# sourceMappingURL=\S+\s*$/, "");

lib/output.js

@@ -49,8 +49,6 @@ function is_some_comments(comment) {
 }
 
 function OutputStream(options) {
-
-    var readonly = !options;
     options = defaults(options, {
         annotations      : false,
         ascii_only       : false,
@@ -103,12 +101,35 @@ function OutputStream(options) {
         }
     }
 
-    var indentation = options.indent_start;
     var current_col = 0;
     var current_line = 1;
     var current_pos = 0;
-    var OUTPUT = "";
+    var indentation = options.indent_start;
+    var last;
+    var line_end = 0;
+    var line_fixed = true;
+    var mappings = options.source_map && [];
+    var mapping_name;
+    var mapping_token;
+    var might_need_space;
+    var might_need_semicolon;
+    var need_newline_indented = false;
+    var need_space = false;
+    var newline_insert = -1;
+    var stack;
+    var OUTPUT;
 
+    function reset() {
+        last = "";
+        might_need_space = false;
+        might_need_semicolon = false;
+        stack = [];
+        var str = OUTPUT;
+        OUTPUT = "";
+        return str;
+    }
+
+    reset();
     var to_utf8 = options.ascii_only ? function(str, identifier) {
         if (identifier) str = str.replace(/[\ud800-\udbff][\udc00-\udfff]/g, function(ch) {
             return "\\u{" + (ch.charCodeAt(0) - 0xd7c0 << 10 | ch.charCodeAt(1) - 0xdc00).toString(16) + "}";
@@ -141,6 +162,25 @@ function OutputStream(options) {
         return j == 0 ? str : s + str.slice(j);
     };
 
+    function quote_single(str) {
+        return "'" + str.replace(/\x27/g, "\\'") + "'";
+    }
+
+    function quote_double(str) {
+        return '"' + str.replace(/\x22/g, '\\"') + '"';
+    }
+
+    var quote_string = [
+        null,
+        quote_single,
+        quote_double,
+        function(str, quote) {
+            return quote == "'" ? quote_single(str) : quote_double(str);
+        },
+    ][options.quote_style] || function(str, quote, dq, sq) {
+        return dq > sq ? quote_single(str) : quote_double(str);
+    };
+
     function make_string(str, quote) {
         var dq = 0, sq = 0;
         str = str.replace(/[\\\b\f\n\r\v\t\x22\x27\u2028\u2029\0\ufeff]/g, function(s, i) {
@@ -162,54 +202,11 @@ function OutputStream(options) {
             }
             return s;
         });
-        function quote_single() {
-            return "'" + str.replace(/\x27/g, "\\'") + "'";
-        }
-        function quote_double() {
-            return '"' + str.replace(/\x22/g, '\\"') + '"';
-        }
-        str = to_utf8(str);
-        switch (options.quote_style) {
-          case 1:
-            return quote_single();
-          case 2:
-            return quote_double();
-          case 3:
-            return quote == "'" ? quote_single() : quote_double();
-          default:
-            return dq > sq ? quote_single() : quote_double();
-        }
-    }
-
-    function encode_string(str, quote) {
-        var ret = make_string(str, quote);
-        if (options.inline_script) {
-            ret = ret.replace(/<\x2f(script)([>\/\t\n\f\r ])/gi, "<\\/$1$2");
-            ret = ret.replace(/\x3c!--/g, "\\x3c!--");
-            ret = ret.replace(/--\x3e/g, "--\\x3e");
-        }
-        return ret;
-    }
-
-    function make_name(name) {
-        name = name.toString();
-        name = to_utf8(name, true);
-        return name;
+        return quote_string(to_utf8(str), quote, dq, sq);
     }
 
     /* -----[ beautification/minification ]----- */
 
-    var has_parens = false;
-    var line_end = 0;
-    var line_fixed = true;
-    var might_need_space = false;
-    var might_need_semicolon = false;
-    var need_newline_indented = false;
-    var need_space = false;
-    var newline_insert = -1;
-    var last = "";
-    var mapping_token, mapping_name, mappings = options.source_map && [];
-
     var adjust_mappings = mappings ? function(line, col) {
         mappings.forEach(function(mapping) {
             mapping.line += line;
@@ -257,8 +254,14 @@ function OutputStream(options) {
 
     var requireSemicolonChars = makePredicate("( [ + * / - , .");
 
-    function print(str) {
-        str = String(str);
+    var print = options.beautify
+        || options.comments
+        || options.max_line_len
+        || options.preserve_line
+        || options.shebang
+        || !options.semicolons
+        || options.source_map
+        || options.width ? function(str) {
         var ch = str.charAt(0);
         if (need_newline_indented && ch) {
             need_newline_indented = false;
@@ -328,7 +331,6 @@ function OutputStream(options) {
         }
 
         OUTPUT += str;
-        has_parens = str.slice(-1) == "(";
         current_pos += str.length;
         var a = str.split(/\r?\n/), n = a.length - 1;
         current_line += n;
@@ -338,7 +340,30 @@ function OutputStream(options) {
             current_col = a[n].length;
         }
         last = str;
-    }
+    } : function(str) {
+        var ch = str.charAt(0);
+        var prev = last.slice(-1);
+        if (might_need_semicolon) {
+            might_need_semicolon = false;
+            if (prev == ":" && ch == "}" || (!ch || ";}".indexOf(ch) < 0) && prev != ";") {
+                OUTPUT += ";";
+                might_need_space = false;
+            }
+        }
+        if (might_need_space) {
+            if (is_identifier_char(prev) && (is_identifier_char(ch) || ch == "\\")
+                || (ch == "/" && ch == prev)
+                || ((ch == "+" || ch == "-") && ch == last)
+                || str == "--" && last == "!"
+                || str == "in" && prev == "/"
+                || last == "--" && ch == ">") {
+                OUTPUT += " ";
+            }
+            if (prev != "<" || str != "!") might_need_space = false;
+        }
+        OUTPUT += str;
+        last = str;
+    };
 
     var space = options.beautify ? function() {
         print(" ");
@@ -351,14 +376,12 @@ function OutputStream(options) {
         print(repeat_string(" ", half ? indentation - (options.indent_level >> 1) : indentation));
     } : noop;
 
-    var with_indent = options.beautify ? function(col, cont) {
-        if (col === true) col = next_indent();
+    var with_indent = options.beautify ? function(cont) {
         var save_indentation = indentation;
-        indentation = col;
-        var ret = cont();
+        indentation += options.indent_level;
+        cont();
         indentation = save_indentation;
-        return ret;
-    } : function(col, cont) { return cont() };
+    } : function(cont) { cont() };
 
     var may_add_newline = options.max_line_len || options.preserve_line ? function() {
         fix_line();
@@ -387,41 +410,28 @@ function OutputStream(options) {
         print(";");
     }
 
-    function next_indent() {
-        return indentation + options.indent_level;
-    }
-
     function with_block(cont) {
-        var ret;
         print("{");
         newline();
-        with_indent(next_indent(), function() {
-            ret = cont();
-        });
+        with_indent(cont);
         indent();
         print("}");
-        return ret;
     }
 
     function with_parens(cont) {
         print("(");
         may_add_newline();
-        //XXX: still nice to have that for argument lists
-        //var ret = with_indent(current_col, cont);
-        var ret = cont();
+        cont();
         may_add_newline();
         print(")");
-        return ret;
     }
 
     function with_square(cont) {
         print("[");
         may_add_newline();
-        //var ret = with_indent(current_col, cont);
-        var ret = cont();
+        cont();
         may_add_newline();
         print("]");
-        return ret;
     }
 
     function comma() {
@@ -472,31 +482,37 @@ function OutputStream(options) {
         return true;
     }
 
+    function should_merge_comments(node, parent) {
+        if (parent instanceof AST_Binary) return parent.left === node;
+        if (parent.TYPE == "Call") return parent.expression === node;
+        if (parent instanceof AST_Conditional) return parent.condition === node;
+        if (parent instanceof AST_Dot) return parent.expression === node;
+        if (parent instanceof AST_Exit) return true;
+        if (parent instanceof AST_Sequence) return parent.expressions[0] === node;
+        if (parent instanceof AST_Sub) return parent.expression === node;
+        if (parent instanceof AST_UnaryPostfix) return true;
+        if (parent instanceof AST_Yield) return true;
+    }
+
     function prepend_comments(node) {
         var self = this;
-        var scan = node instanceof AST_Exit && node.value;
+        var scan;
+        if (node instanceof AST_Exit) {
+            scan = node.value;
+        } else if (node instanceof AST_Yield) {
+            scan = node.expression;
+        }
         var comments = dump(node);
         if (!comments) comments = [];
 
         if (scan) {
             var tw = new TreeWalker(function(node) {
-                var parent = tw.parent();
-                if (parent instanceof AST_Exit
-                    || parent instanceof AST_Binary && parent.left === node
-                    || parent.TYPE == "Call" && parent.expression === node
-                    || parent instanceof AST_Conditional && parent.condition === node
-                    || parent instanceof AST_Dot && parent.expression === node
-                    || parent instanceof AST_Sequence && parent.expressions[0] === node
-                    || parent instanceof AST_Sub && parent.expression === node
-                    || parent instanceof AST_UnaryPostfix) {
-                    var before = dump(node);
-                    if (before) comments = comments.concat(before);
-                } else {
-                    return true;
-                }
+                if (!should_merge_comments(node, tw.parent())) return true;
+                var before = dump(node);
+                if (before) comments = comments.concat(before);
             });
             tw.push(node);
-            node.value.walk(tw);
+            scan.walk(tw);
         }
 
         if (current_pos == 0) {
@@ -553,15 +569,14 @@ function OutputStream(options) {
         if (OUTPUT.length > insert) newline_insert = insert;
     }
 
-    var stack = [];
     return {
         get             : get,
-        toString        : get,
+        reset           : reset,
         indent          : indent,
-        should_break    : readonly ? noop : function() {
-            return options.width && current_col - indentation >= options.width;
-        },
-        has_parens      : function() { return has_parens },
+        should_break    : options.width ? function() {
+            return current_col - indentation >= options.width;
+        } : return_false,
+        has_parens      : function() { return last.slice(-1) == "(" },
         newline         : newline,
         print           : print,
         space           : space,
@@ -571,20 +586,21 @@ function OutputStream(options) {
         semicolon       : semicolon,
         force_semicolon : force_semicolon,
         to_utf8         : to_utf8,
-        print_name      : function(name) { print(make_name(name)) },
-        print_string    : function(str, quote) { print(encode_string(str, quote)) },
-        next_indent     : next_indent,
+        print_name      : function(name) { print(to_utf8(name.toString(), true)) },
+        print_string    : options.inline_script ? function(str, quote) {
+            str = make_string(str, quote).replace(/<\x2f(script)([>\/\t\n\f\r ])/gi, "<\\/$1$2");
+            print(str.replace(/\x3c!--/g, "\\x3c!--").replace(/--\x3e/g, "--\\x3e"));
+        } : function(str, quote) {
+            print(make_string(str, quote));
+        },
         with_indent     : with_indent,
         with_block      : with_block,
         with_parens     : with_parens,
         with_square     : with_square,
         add_mapping     : add_mapping,
         option          : function(opt) { return options[opt] },
-        prepend_comments: readonly ? noop : prepend_comments,
-        append_comments : readonly || comment_filter === return_false ? noop : append_comments,
-        line            : function() { return current_line },
-        col             : function() { return current_col },
-        pos             : function() { return current_pos },
+        prepend_comments: options.comments || options.shebang ? prepend_comments : noop,
+        append_comments : options.comments ? append_comments : noop,
         push_node       : function(node) { stack.push(node) },
         pop_node        : options.preserve_line ? function() {
             var node = stack.pop();
@@ -629,10 +645,19 @@ function OutputStream(options) {
             stream.append_comments(self);
         }
     });
+    var readonly = OutputStream({
+        inline_script: false,
+        shebang: false,
+        width: false,
+    });
     AST_Node.DEFMETHOD("print_to_string", function(options) {
-        var s = OutputStream(options);
-        this.print(s);
-        return s.get();
+        if (options) {
+            var stream = OutputStream(options);
+            this.print(stream);
+            return stream.get();
+        }
+        this.print(readonly);
+        return readonly.reset();
     });
 
     /* -----[ PARENTHESES ]----- */
@@ -684,6 +709,8 @@ function OutputStream(options) {
         // (x++)[y]
         // (typeof x).y
         if (p instanceof AST_PropAccess) return p.expression === this;
+        // (~x)`foo`
+        if (p instanceof AST_Template) return p.tag === this;
     }
     PARENS(AST_Await, needs_parens_unary);
     PARENS(AST_Unary, needs_parens_unary);
@@ -757,14 +784,29 @@ function OutputStream(options) {
         if (p instanceof AST_Class) return true;
         // (foo && bar)["prop"], (foo && bar).prop
         if (p instanceof AST_PropAccess) return p.expression === this;
+        // (foo && bar)``
+        if (p instanceof AST_Template) return p.tag === this;
         // typeof (foo && bar)
         if (p instanceof AST_Unary) return true;
     });
 
+    function lhs_has_optional(node, output) {
+        var p = output.parent();
+        if (p instanceof AST_PropAccess && p.expression === node && is_lhs(p, output.parent(1))) {
+            // ++(foo?.bar).baz
+            // (foo?.()).bar = baz
+            do {
+                if (node.optional) return true;
+                node = node.expression;
+            } while (node.TYPE == "Call" || node instanceof AST_PropAccess);
+        }
+    }
+
     PARENS(AST_PropAccess, function(output) {
         var node = this;
         var p = output.parent();
-        if (p instanceof AST_New && p.expression === node) {
+        if (p instanceof AST_New) {
+            if (p.expression !== node) return false;
             // i.e. new (foo().bar)
             //
             // if there's one call into this subtree, then we need
@@ -776,20 +818,22 @@ function OutputStream(options) {
             } while (node instanceof AST_PropAccess);
             return node.TYPE == "Call";
         }
+        return lhs_has_optional(node, output);
     });
 
     PARENS(AST_Call, function(output) {
+        var node = this;
         var p = output.parent();
-        if (p instanceof AST_New) return p.expression === this;
+        if (p instanceof AST_New) return p.expression === node;
         // https://bugs.webkit.org/show_bug.cgi?id=123506
-        if (output.option("webkit")) {
+        if (output.option("webkit")
+            && node.expression instanceof AST_Function
+            && p instanceof AST_PropAccess
+            && p.expression === node) {
             var g = output.parent(1);
-            return this.expression instanceof AST_Function
-                && p instanceof AST_PropAccess
-                && p.expression === this
-                && g instanceof AST_Assign
-                && g.left === p;
+            if (g instanceof AST_Assign && g.left === p) return true;
         }
+        return lhs_has_optional(node, output);
     });
 
     PARENS(AST_New, function(output) {
@@ -915,7 +959,7 @@ function OutputStream(options) {
     });
     function print_braced_empty(self, output) {
         output.print("{");
-        output.with_indent(output.next_indent(), function() {
+        output.with_indent(function() {
             output.append_comments(self, true);
         });
         output.print("}");
@@ -1431,7 +1475,7 @@ function OutputStream(options) {
             parent = output.parent(level++);
             if (parent instanceof AST_Call && parent.expression === node) return;
         } while (parent instanceof AST_PropAccess && parent.expression === node);
-        output.print("/*" + self.pure + "*/");
+        output.print(typeof self.pure == "string" ? "/*" + self.pure + "*/" : "/*@__PURE__*/");
     }
     function print_call_args(self, output) {
         if (self.expression instanceof AST_Call || self.expression instanceof AST_Lambda) {
@@ -1448,6 +1492,7 @@ function OutputStream(options) {
         var self = this;
         print_annotation(self, output);
         self.expression.print(output);
+        if (self.optional) output.print("?.");
         print_call_args(self, output);
     });
     DEFPRINT(AST_New, function(output) {
@@ -1476,26 +1521,23 @@ function OutputStream(options) {
         expr.print(output);
         var prop = self.property;
         if (output.option("ie8") && RESERVED_WORDS[prop]) {
-            output.print("[");
+            output.print(self.optional ? "?.[" : "[");
             output.add_mapping(self.end);
             output.print_string(prop);
             output.print("]");
         } else {
-            if (expr instanceof AST_Number && expr.value >= 0) {
-                if (!/[xa-f.)]/i.test(output.last())) {
-                    output.print(".");
-                }
-            }
-            output.print(".");
+            if (expr instanceof AST_Number && !/[ex.)]/i.test(output.last())) output.print(".");
+            output.print(self.optional ? "?." : ".");
             // the name after dot would be mapped about here.
             output.add_mapping(self.end);
             output.print_name(prop);
         }
     });
     DEFPRINT(AST_Sub, function(output) {
-        this.expression.print(output);
-        output.print("[");
-        this.property.print(output);
+        var self = this;
+        self.expression.print(output);
+        output.print(self.optional ? "?.[" : "[");
+        self.property.print(output);
         output.print("]");
     });
     DEFPRINT(AST_Spread, function(output) {
@@ -1735,7 +1777,7 @@ function OutputStream(options) {
         output.print("`");
     });
     DEFPRINT(AST_Constant, function(output) {
-        output.print(this.value);
+        output.print("" + this.value);
     });
     DEFPRINT(AST_String, function(output) {
         output.print_string(this.value, this.quote);
@@ -1791,7 +1833,7 @@ function OutputStream(options) {
     function force_statement(stat, output) {
         if (output.option("braces") && !(stat instanceof AST_Const || stat instanceof AST_Let)) {
             make_block(stat, output);
-        } else if (!stat || stat instanceof AST_EmptyStatement) {
+        } else if (stat instanceof AST_EmptyStatement) {
             output.force_semicolon();
         } else {
             stat.print(output);
@@ -1842,11 +1884,11 @@ function OutputStream(options) {
     }
 
     function make_block(stmt, output) {
-        if (!stmt || stmt instanceof AST_EmptyStatement)
-            output.print("{}");
-        else if (stmt instanceof AST_BlockStatement)
+        if (stmt instanceof AST_EmptyStatement) {
+            print_braced_empty(stmt, output);
+        } else if (stmt instanceof AST_BlockStatement) {
             stmt.print(output);
-        else output.with_block(function() {
+        } else output.with_block(function() {
             output.indent();
             stmt.print(output);
             output.newline();

lib/parse.js

@@ -104,12 +104,15 @@ var OPERATORS = makePredicate([
     ">>=",
     "<<=",
     ">>>=",
+    "&=",
     "|=",
     "^=",
-    "&=",
     "&&",
     "||",
     "??",
+    "&&=",
+    "||=",
+    "??=",
 ]);
 
 var NEWLINE_CHARS = "\n\r\u2028\u2029";
@@ -348,7 +351,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
 
     function read_while(pred) {
         var ret = "", ch;
-        while ((ch = peek()) && pred(ch)) ret += next();
+        while ((ch = peek()) && pred(ch, ret)) ret += next();
         return ret;
     }
 
@@ -356,24 +359,27 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         js_error(err, filename, S.tokline, S.tokcol, S.tokpos);
     }
 
+    function is_octal(num) {
+        return /^0[0-7_]+$/.test(num);
+    }
+
     function read_num(prefix) {
         var has_e = false, after_e = false, has_x = false, has_dot = prefix == ".";
-        var num = read_while(function(ch) {
-            var code = ch.charCodeAt(0);
-            switch (code) {
-              case 120: case 88: // xX
+        var num = read_while(function(ch, str) {
+            switch (ch) {
+              case "x": case "X":
                 return has_x ? false : (has_x = true);
-              case 101: case 69: // eE
+              case "e": case "E":
                 return has_x ? true : has_e ? false : (has_e = after_e = true);
-              case 43: case 45: // +-
+              case "+": case "-":
                 return after_e;
-              case (after_e = false, 46): // .
-                return (!has_dot && !has_x && !has_e) ? (has_dot = true) : false;
+              case (after_e = false, "."):
+                return has_dot || has_e || has_x || is_octal(str) ? false : (has_dot = true);
             }
-            return is_digit(code) || /[_0-9a-fo]/i.test(ch);
+            return /[_0-9a-dfo]/i.test(ch);
         });
         if (prefix) num = prefix + num;
-        if (/^0[0-7_]+$/.test(num)) {
+        if (is_octal(num)) {
             if (next_token.has_directive("use strict")) parse_error("Legacy octal literals are not allowed in strict mode");
         } else {
             num = num.replace(has_x ? /([1-9a-f]|.0)_(?=[0-9a-f])/gi : /([1-9]|.0)_(?=[0-9])/gi, "$1");
@@ -653,7 +659,7 @@ var UNARY_PREFIX = makePredicate("typeof void delete -- ++ ! ~ - +");
 
 var UNARY_POSTFIX = makePredicate("-- ++");
 
-var ASSIGNMENT = makePredicate("= += -= /= *= %= **= >>= <<= >>>= |= ^= &=");
+var ASSIGNMENT = makePredicate("= += -= /= *= %= **= >>= <<= >>>= &= |= ^= &&= ||= ??=");
 
 var PRECEDENCE = function(a, ret) {
     for (var i = 0; i < a.length;) {
@@ -851,7 +857,8 @@ function parse($TEXT, options) {
                 next();
                 return export_();
               case "import":
-                if (!is_token(peek(), "punc", "(")) {
+                var token = peek();
+                if (!(token.type == "punc" && /^[(.]$/.test(token.value))) {
                     next();
                     return import_();
                 }
@@ -1182,7 +1189,7 @@ function parse($TEXT, options) {
         var await = is("name", "await") && next();
         expect("(");
         var init = null;
-        if (!is("punc", ";")) {
+        if (await || !is("punc", ";")) {
             init = is("keyword", "const")
                 ? (next(), const_(true))
                 : is("keyword", "let")
@@ -1233,6 +1240,7 @@ function parse($TEXT, options) {
     }
 
     function for_enum(ctor, init) {
+        handle_regexp();
         var obj = expression();
         expect(")");
         return new ctor({
@@ -1488,6 +1496,7 @@ function parse($TEXT, options) {
                 body.start = start;
                 body.end = prev();
             } else {
+                handle_regexp();
                 body = expression();
                 semicolon();
             }
@@ -2236,44 +2245,52 @@ function parse($TEXT, options) {
         });
     }
 
-    var subscripts = function(expr, allow_calls) {
+    var subscripts = function(expr, allow_calls, optional) {
         var start = expr.start;
-        if (is("punc", ".")) {
-            next();
-            return subscripts(new AST_Dot({
-                start      : start,
-                expression : expr,
-                property   : as_name(),
-                end        : prev()
-            }), allow_calls);
-        }
         if (is("punc", "[")) {
             next();
             var prop = expression();
             expect("]");
             return subscripts(new AST_Sub({
-                start      : start,
-                expression : expr,
-                property   : prop,
-                end        : prev()
+                start: start,
+                optional: optional,
+                expression: expr,
+                property: prop,
+                end: prev(),
             }), allow_calls);
         }
         if (allow_calls && is("punc", "(")) {
             next();
             var call = new AST_Call({
-                start      : start,
-                expression : expr,
-                args       : expr_list(")", !options.strict),
-                end        : prev()
+                start: start,
+                optional: optional,
+                expression: expr,
+                args: expr_list(")", !options.strict),
+                end: prev(),
             });
             return subscripts(call, true);
         }
+        if (optional || is("punc", ".")) {
+            if (!optional) next();
+            return subscripts(new AST_Dot({
+                start: start,
+                optional: optional,
+                expression: expr,
+                property: as_name(),
+                end: prev(),
+            }), allow_calls);
+        }
         if (is("punc", "`")) {
             var tmpl = template(expr);
             tmpl.start = expr.start;
             tmpl.end = prev();
             return subscripts(tmpl, allow_calls);
         }
+        if (is("operator", "?") && is_token(peek(), "punc", ".")) {
+            next();
+            next();
+            return subscripts(expr, allow_calls, true);
+        }
         if (expr instanceof AST_Call && !expr.pure) {
             var start = expr.start;
             var comments = start.comments_before;
@@ -2396,7 +2413,7 @@ function parse($TEXT, options) {
     };
 
     function is_assignable(expr) {
-        return expr instanceof AST_PropAccess || expr instanceof AST_SymbolRef;
+        return expr instanceof AST_PropAccess && !expr.optional || expr instanceof AST_SymbolRef;
     }
 
     function to_destructured(node) {
@@ -2518,7 +2535,7 @@ function parse($TEXT, options) {
         while (!is("eof"))
             body.push(statement());
         S.input.pop_directives_stack();
-        var end = prev();
+        var end = prev() || start;
         var toplevel = options.toplevel;
         if (toplevel) {
             toplevel.body = toplevel.body.concat(body);

lib/propmangle.js

@@ -81,7 +81,9 @@ var builtins = function() {
 
 function reserve_quoted_keys(ast, reserved) {
     ast.walk(new TreeWalker(function(node) {
-        if (node instanceof AST_ObjectProperty) {
+        if (node instanceof AST_ClassProperty) {
+            if (node.start && node.start.quote) add(node.key);
+        } else if (node instanceof AST_ObjectProperty) {
             if (node.start && node.start.quote) add(node.key);
         } else if (node instanceof AST_Sub) {
             addStrings(node.property, add);
@@ -163,6 +165,8 @@ function mangle_properties(ast, options) {
                 addStrings(node.args[0], add);
                 break;
             }
+        } else if (node instanceof AST_ClassProperty) {
+            if (typeof node.key == "string") add(node.key);
         } else if (node instanceof AST_Dot) {
             add(node.property);
         } else if (node instanceof AST_ObjectProperty) {
@@ -193,6 +197,8 @@ function mangle_properties(ast, options) {
                 mangleStrings(node.args[0]);
                 break;
             }
+        } else if (node instanceof AST_ClassProperty) {
+            if (typeof node.key == "string") node.key = mangle(node.key);
         } else if (node instanceof AST_Dot) {
             node.property = mangle(node.property);
         } else if (node instanceof AST_ObjectProperty) {
@@ -222,9 +228,7 @@ function mangle_properties(ast, options) {
     }
 
     function mangle(name) {
-        if (!should_mangle(name)) {
-            return name;
-        }
+        if (!should_mangle(name)) return name;
         var mangled = cache.get(name);
         if (!mangled) {
             if (debug) {
@@ -236,6 +240,7 @@ function mangle_properties(ast, options) {
             if (!mangled) do {
                 mangled = base54(++cname);
             } while (!can_mangle(mangled));
+            if (/^#/.test(name)) mangled = "#" + mangled;
             cache.set(name, mangled);
         }
         return mangled;

lib/scope.js

@@ -273,16 +273,18 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             return true;
         }
         if (node instanceof AST_SymbolDeclaration) {
+            var def = node.definition();
+            def.preinit = def.references.length;
             if (node instanceof AST_SymbolCatch) {
                 // ensure mangling works if `catch` reuses a scope variable
-                var def = node.definition().redefined();
-                if (def) for (var s = node.scope; s; s = s.parent_scope) {
-                    push_uniq(s.enclosed, def);
-                    if (s === def.scope) break;
+                var redef = def.redefined();
+                if (redef) for (var s = node.scope; s; s = s.parent_scope) {
+                    push_uniq(s.enclosed, redef);
+                    if (s === redef.scope) break;
                 }
             } else if (node instanceof AST_SymbolConst) {
                 // ensure compression works if `const` reuses a scope variable
-                var redef = node.definition().redefined();
+                var redef = def.redefined();
                 if (redef) redef.const_redefs = true;
             }
             if (node.name != "arguments") return true;
@@ -798,6 +800,7 @@ var base54 = (function() {
     var leading = init("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_");
     var chars, frequency;
     function reset() {
+        chars = null;
         frequency = Object.create(freq);
     }
     base54.consider = function(str, delta) {
@@ -809,19 +812,15 @@ var base54 = (function() {
         return frequency[b] - frequency[a];
     }
     base54.sort = function() {
-        chars = leading.sort(compare).concat(digits.sort(compare));
+        chars = leading.sort(compare).concat(digits).sort(compare);
     };
     base54.reset = reset;
     reset();
     function base54(num) {
-        var ret = "", base = 54;
-        num++;
-        do {
-            num--;
-            ret += chars[num % base];
-            num = Math.floor(num / base);
-            base = 64;
-        } while (num > 0);
+        var ret = leading[num % 54];
+        for (num = Math.floor(num / 54); --num >= 0; num >>= 6) {
+            ret += chars[num & 0x3F];
+        }
         return ret;
     }
     return base54;

package.json

@@ -3,7 +3,7 @@
   "description": "JavaScript parser, mangler/compressor and beautifier toolkit",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "3.13.2",
+  "version": "3.13.7",
   "engines": {
     "node": ">=0.8.0"
   },
@@ -23,7 +23,7 @@
     "LICENSE"
   ],
   "devDependencies": {
-    "acorn": "~7.1.0",
+    "acorn": "~8.2.1",
     "semver": "~6.3.0"
   },
   "scripts": {

test/compress/assignments.js

@@ -475,3 +475,274 @@ issue_4521: {
     }
     expect_stdout: "42"
 }
+
+logical_assignments: {
+    input: {
+        var a = 42, b = null, c;
+        a &&= "foo";
+        b ||= "bar";
+        c ??= "baz";
+        console.log(a, b, c);
+    }
+    expect_exact: 'var a=42,b=null,c;a&&="foo";b||="bar";c??="baz";console.log(a,b,c);'
+    expect_stdout: "foo bar baz"
+    node_version: ">=15"
+}
+
+logical_collapse_vars: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL", b = false;
+        a = "PASS";
+        b ??= a;
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL", b = false;
+        a = "PASS";
+        b ??= a;
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+logical_reduce_vars: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS", b = 42;
+        b ??= a = "FAIL";
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS", b = 42;
+        b ??= a = "FAIL";
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+logical_side_effects: {
+    options = {
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS", b = 42;
+        b ??= a = "FAIL";
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS", b = 42;
+        b ??= a = "FAIL";
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+issue_4815_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        42..p &&= a = "FAIL";
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        42..p &&= a = "FAIL";
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+issue_4815_2: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        var a = "PASS";
+        42..p &&= a = "FAIL";
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        42..p &&= a = "FAIL";
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+issue_4819: {
+    options = {
+        comparisons: true,
+    }
+    input: {
+        console.log(void 0 === ([].p &&= 42));
+    }
+    expect: {
+        console.log(void 0 === ([].p &&= 42));
+    }
+    expect_stdout: "true"
+    node_version: ">=15"
+}
+
+issue_4827_1: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        A = "FAIL";
+        var a = A, b = "PASS", c;
+        c &&= b = a, console.log(b);
+    }
+    expect: {
+        A = "FAIL";
+        var a = A, b = "PASS", c;
+        c &&= b = a, console.log(b);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+issue_4827_2: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 0, b = "PASS";
+        function f(c) {
+            a++,
+            c &&= b = a;
+        }
+        f();
+        console.log(b);
+    }
+    expect: {
+        var a = 0, b = "PASS";
+        a++,
+        c &&= b = a;
+        var c;
+        console.log(b);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+issue_4827_3: {
+    options = {
+        merge_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 0, b, c;
+        a++;
+        c &&= b = a;
+        console.log(b);
+    }
+    expect: {
+        var a = 0, b, c;
+        a++;
+        c &&= b = a;
+        console.log(b);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=15"
+}
+
+issue_4876: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        try {
+            var a = null;
+            var b = a &&= 42;
+            b.p;
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            var a = null;
+            var b = a &&= 42;
+            b.p;
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+issue_4924_1: {
+    options = {
+        collapse_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a, b;
+        console.log("PASS");
+        a = function() {};
+        b = function() {}(b ||= a);
+    }
+    expect: {
+        var b;
+        console.log("PASS");
+        b = void (b ||= function() {});
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}
+
+issue_4924_2: {
+    options = {
+        collapse_vars: true,
+        dead_code: true,
+        passes: 2,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a, b;
+        console.log("PASS");
+        a = function() {};
+        b = function() {}(b ||= a);
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=15"
+}

test/compress/classes.js

@@ -583,6 +583,31 @@ single_use_6: {
     node_version: ">=4"
 }
 
+single_use_7: {
+    options = {
+        passes: 2,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {
+            static foo() {}
+        }
+        var a = "foo" in A;
+        console.log(a);
+    }
+    expect: {
+        "use strict";
+        console.log("foo" in class {
+            static foo() {}
+        });
+    }
+    expect_stdout: "true"
+    node_version: ">=4"
+}
+
 collapse_non_strict: {
     options = {
         collapse_vars: true,
@@ -654,6 +679,32 @@ collapse_rhs_static: {
     node_version: ">=12"
 }
 
+self_comparison: {
+    options = {
+        booleans: true,
+        comparisons: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {}
+        console.log(A == A, A != A);
+        console.log(A === A, A !== A);
+    }
+    expect: {
+        "use strict";
+        console.log(!0, !1);
+        console.log(!0, !1);
+    }
+    expect_stdout: [
+        "true false",
+        "true false",
+    ]
+    node_version: ">=4"
+}
+
 property_side_effects: {
     options = {
         inline: true,
@@ -726,7 +777,7 @@ unused_await: {
         })();
     }
     expect_stdout: true
-    node_version: ">=12"
+    node_version: ">=12 <16"
 }
 
 computed_key_side_effects: {
@@ -1296,3 +1347,219 @@ issue_4756: {
     ]
     node_version: ">=12"
 }
+
+issue_4821_1: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        class A {
+            static p = void (a = this);
+        }
+        console.log(typeof a);
+    }
+    expect: {
+        var a;
+        class A {
+            static p = void (a = this);
+        }
+        console.log(typeof a);
+    }
+    expect_stdout: "function"
+    node_version: ">=12"
+}
+
+issue_4821_2: {
+    options = {
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        class A {
+            static p = void (a = this);
+        }
+        console.log(typeof a);
+    }
+    expect: {
+        var a;
+        (class {
+            static p = void (a = this);
+        });
+        console.log(typeof a);
+    }
+    expect_stdout: "function"
+    node_version: ">=12"
+}
+
+issue_4829_1: {
+    options = {
+        properties: true,
+    }
+    input: {
+        "use strict";
+        try {
+            class A extends { f(){} }.f {}
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            class A extends [ () => {} ][0] {}
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4829_2: {
+    options = {
+        properties: true,
+    }
+    input: {
+        "use strict";
+        try {
+            class A extends {
+                f() {
+                    return arguments;
+                },
+            }.f {}
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        "use strict";
+        try {
+            class A extends {
+                f() {
+                    return arguments;
+                },
+            }.f {}
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+mangle_properties: {
+    mangle = {
+        properties: {
+            keep_quoted: true,
+        },
+    }
+    input: {
+        class A {
+            static #P = "PASS";
+            static get Q() {
+                return this.#P;
+            }
+            #p(n) {
+                return (this["q"] = n) * this.r;
+            }
+            set q(v) {
+                this.r = v + 1;
+            }
+            r = this.#p(6);
+        }
+        console.log(A.Q, new A().r);
+    }
+    expect: {
+        class A {
+            static #t = "PASS";
+            static get s() {
+                return this.#t;
+            }
+            #i(t) {
+                return (this["q"] = t) * this.e;
+            }
+            set q(t) {
+                this.e = t + 1;
+            }
+            e = this.#i(6);
+        }
+        console.log(A.s, new A().e);
+    }
+    expect_stdout: "PASS 42"
+    node_version: ">=14.6"
+}
+
+issue_4848: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        "use strict";
+        function f(a) {
+            a(function() {
+                new A();
+            });
+            if (!console)
+                return;
+            class A {
+                constructor() {
+                    console.log("PASS");
+                }
+            }
+        }
+        var g;
+        f(function(h) {
+            g = h;
+        });
+        g();
+    }
+    expect: {
+        "use strict";
+        function f(a) {
+            a(function() {
+                new A();
+            });
+            if (!console)
+                return;
+            class A {
+                constructor() {
+                    console.log("PASS");
+                }
+            }
+        }
+        var g;
+        f(function(h) {
+            g = h;
+        });
+        g();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+drop_unused_self_reference: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        class A {}
+        (A.p = A).q = console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/collapse_vars.js

@@ -2868,7 +2868,7 @@ lvalues_def: {
     expect_stdout: true
 }
 
-compound_assignment: {
+compound_assignment_1: {
     options = {
         collapse_vars: true,
     }
@@ -2887,6 +2887,23 @@ compound_assignment: {
     expect_stdout: "4"
 }
 
+compound_assignment_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a;
+        a = 1;
+        for (a += a + 2; console.log(a););
+    }
+    expect: {
+        var a;
+        a = 1;
+        for (a += a + 2; console.log(a););
+    }
+    expect_stdout: "4"
+}
+
 issue_2187_1: {
     options = {
         collapse_vars: true,
@@ -4707,7 +4724,7 @@ cascade_statement: {
         }
         function f3(a, b) {
             for (; a < b; a++)
-                if ((c = a) && b)
+                if (c = a, a && b)
                     var c = c = b(a);
         }
     }
@@ -8047,6 +8064,67 @@ mangleable_var: {
     expect_stdout: "PASS"
 }
 
+mangleable_assignment_1: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var o = {
+            p: function() {
+                return 6;
+            },
+        };
+        (function() {
+            var a, b = a = o.p();
+            console.log(a * (b / a + b));
+        })();
+    }
+    expect: {
+        var o = {
+            p: function() {
+                return 6;
+            },
+        };
+        (function() {
+            var a;
+            a = o.p();
+            console.log(a * (a / a + a));
+        })();
+    }
+    expect_stdout: "42"
+}
+
+mangleable_assignment_2: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var o = {
+            p: function() {
+                return 6;
+            },
+        };
+        (function(a, b) {
+            b = a = o.p();
+            console.log(a * (b / a + b));
+        })();
+    }
+    expect: {
+        var o = {
+            p: function() {
+                return 6;
+            },
+        };
+        (function(a, b) {
+            a = o.p();
+            console.log(a * (a / a + a));
+        })();
+    }
+    expect_stdout: "42"
+}
+
 issue_3884_1: {
     options = {
         collapse_vars: true,
@@ -8482,7 +8560,7 @@ issue_4047_1: {
     expect: {
         var b = 1;
         var a;
-        console.log((a = --b + ((a = 0) !== typeof A), +void ((a >>= 0) && console.log("PASS"))));
+        console.log((a = --b + (0 !== typeof A), +void ((a >>= 0) && console.log("PASS"))));
     }
     expect_stdout: [
         "PASS",
@@ -8880,3 +8958,290 @@ issue_4806: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4852: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "PASS";
+        (function(b) {
+            switch (b = a) {
+              case 42:
+                try {
+                    console;
+                } catch (b) {
+                    b.p;
+                }
+              case console.log(b):
+            }
+        })("FAIL");
+    }
+    expect: {
+        var a = "PASS";
+        (function(b) {
+            switch (a) {
+              case 42:
+                try {
+                    console;
+                } catch (b) {
+                    b.p;
+                }
+              case console.log(a):
+            }
+        })("FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4865: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var NaN;
+        var a = NaN = "PASS";
+        console.log(a, NaN);
+    }
+    expect: {
+        var NaN;
+        var a = NaN = "PASS";
+        console.log(a, NaN);
+    }
+    expect_stdout: true
+}
+
+issue_4868: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        (function(b) {
+            console.log(b[0]);
+        })(a = [ "PASS" ], a = [ "FAIL" ]);
+    }
+    expect: {
+        var a;
+        (function(b) {
+            console.log(b[0]);
+        })(a = [ "PASS" ], a = [ "FAIL" ]);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4874: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        a = null;
+        (function(b) {
+            for (var c in b = b && b[console.log("PASS")])
+                console;
+        })(a = 42);
+    }
+    expect: {
+        var a;
+        null;
+        (function(b) {
+            for (var c in a && a[console.log("PASS")])
+                console;
+        })(a = 42);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4891: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 0, b;
+        a++;
+        console.log(b = a, b);
+        b--;
+        a.a += 0;
+        console.log(b);
+    }
+    expect: {
+        var a = 0, b;
+        a++;
+        console.log(a, b = a);
+        b--;
+        a.a += 0;
+        console.log(b);
+    }
+    expect_stdout: [
+        "1 1",
+        "0",
+    ]
+}
+
+issue_4895: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a, b;
+        (function f() {
+            a = 42;
+        })();
+        console.log((b = a) || b, b += 0);
+    }
+    expect: {
+        var a, b;
+        (function f() {
+            a = 42;
+        })();
+        console.log((b = a) || b, b += 0);
+    }
+    expect_stdout: "42 42"
+}
+
+issue_4908: {
+    options = {
+        collapse_vars: true,
+        join_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 0;
+        var b;
+        console || a++;
+        var c = d = a, d = [ c && c, d += 42 ];
+        console.log(d[1]);
+    }
+    expect: {
+        var a = 0, b;
+        console || a++;
+        var c = a, d = [ (d = a) && d, d += 42 ];
+        console.log(d[1]);
+    }
+    expect_stdout: "42"
+}
+
+issue_4910: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "foo", b;
+        var c = b = a;
+        1 && c[a = "bar"];
+        console.log(a, b);
+    }
+    expect: {
+        var a = "foo", b;
+        var c = b = a;
+        1 && b[a = "bar"];
+        console.log(a, b);
+    }
+    expect_stdout: "bar foo"
+}
+
+issue_4914: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+    }
+    input: {
+        console.log(typeof function f() {
+            f.__proto__ = 42;
+            return f.__proto__;
+        }());
+    }
+    expect: {
+        console.log(typeof function f() {
+            f.__proto__ = 42;
+            return f.__proto__;
+        }());
+    }
+    expect_stdout: "function"
+}
+
+issue_4918: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        ({
+            get 42() {
+                console.log(a);
+            }
+        }[a = "PASS", 42] += "PASS");
+    }
+    expect: {
+        var a = "FAIL";
+        ({
+            get 42() {
+                console.log(a);
+            }
+        }[a = "PASS", 42] += "PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4920: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "PASS", b;
+        ({
+            get PASS() {
+                a = "FAIL";
+            },
+        })[b = a];
+        console.log(b);
+    }
+    expect: {
+        var a = "PASS", b;
+        ({
+            get PASS() {
+                a = "FAIL";
+            },
+        })[b = a];
+        console.log(b);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4935: {
+    options = {
+        collapse_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        var b;
+        var c = b = a;
+        console || c(a++);
+        --b;
+        console.log(a, b);
+    }
+    expect: {
+        var a = 1;
+        var b;
+        var c = b = a;
+        console || a(a++);
+        --b;
+        console.log(a, b);
+    }
+    expect_stdout: "1 0"
+}

test/compress/const.js

@@ -1498,3 +1498,40 @@ issue_4691: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4848: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        function f(a) {
+            a(function() {
+                console.log(b);
+            });
+            if (!console)
+                return;
+            const b = "PASS";
+        }
+        var g;
+        f(function(h) {
+            g = h;
+        });
+        g();
+    }
+    expect: {
+        function f(a) {
+            a(function() {
+                console.log(b);
+            });
+            if (!console)
+                return;
+            const b = "PASS";
+        }
+        var g;
+        f(function(h) {
+            g = h;
+        });
+        g();
+    }
+    expect_stdout: "PASS"
+}

test/compress/default-values.js

@@ -1661,3 +1661,71 @@ issue_4588_2_evaluate: {
     expect_stdout: "1"
     node_version: ">=6"
 }
+
+issue_4817: {
+    options = {
+        ie8: true,
+        inline: true,
+        unused: true,
+    }
+    input: {
+        (function f(a = console.log(typeof f)) {
+            return 42;
+        })();
+    }
+    expect: {
+        (function f(a = console.log(typeof f)) {
+            return 42;
+        })();
+    }
+    expect_stdout: "function"
+    node_version: ">=6"
+}
+
+issue_4854: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(a) {
+            (function(b = a = "foo") {
+                [] = "foo";
+            })();
+            a;
+        }());
+    }
+    expect: {
+        console.log(void ([] = "foo"));
+    }
+    expect_stdout: "undefined"
+    node_version: ">=6"
+}
+
+issue_4916: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+    }
+    input: {
+        var log = console.log;
+        (function(b = "foo") {
+            b.value = "FAIL";
+            b;
+            log(b.value);
+        })();
+    }
+    expect: {
+        var log = console.log;
+        (function(b = "foo") {
+            b.value = "FAIL";
+            b;
+            log(b.value);
+        })();
+    }
+    expect_stdout: "undefined"
+    node_version: ">=6"
+}

test/compress/drop-unused.js

@@ -2371,6 +2371,7 @@ function_parameter_ie8: {
 issue_3664: {
     options = {
         pure_getters: "strict",
+        side_effects: true,
         unused: true,
     }
     input: {
@@ -2381,7 +2382,7 @@ issue_3664: {
     }
     expect: {
         console.log(function() {
-            var b = ([ b && console.log("FAIL") ].p = 0, 0);
+            var a, b = (a = (a = [ b && console.log("FAIL") ]).p = 0, 0);
             return "PASS";
         }());
     }
@@ -2391,6 +2392,7 @@ issue_3664: {
 issue_3673: {
     options = {
         pure_getters: "strict",
+        sequences: true,
         side_effects: true,
         toplevel: true,
         unused: true,
@@ -2401,8 +2403,6 @@ issue_3673: {
         console.log("PASS");
     }
     expect: {
-        var a;
-        (a = [ a ]).p = 42;
         console.log("PASS");
     }
     expect_stdout: "PASS"
@@ -3357,3 +3357,116 @@ issue_4806_3: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4834: {
+    options = {
+        inline: true,
+        keep_fargs: false,
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        try {
+            new function(a, b) {
+                b;
+                b.p;
+            }(42);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            void b.p;
+        } catch (e) {
+            console.log("PASS");
+        }
+        var b;
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4912_1: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = A = function() {};
+        A;
+        a.prototype = {
+            f: function() {
+                console.log("PASS");
+            },
+        };
+        new A().f();
+    }
+    expect: {
+        var a = A = function() {};
+        A;
+        a.prototype = {
+            f: function() {
+                console.log("PASS");
+            },
+        };
+        new A().f();
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4912_2: {
+    options = {
+        pure_getters: "strict",
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            var g, f = function() {};
+            f.p = {};
+            (g = f.p.q = function() {}).r = "PASS";
+            return f;
+        }().p.q.r);
+    }
+    expect: {
+        console.log(function() {
+            var g, f = function() {};
+            f.p = {};
+            (f.p.q = function() {}).r = "PASS";
+            return f;
+        }().p.q.r);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4912_3: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(f, g) {
+            f = function() {};
+            f.p = {};
+            g = f.p.q = function() {};
+            g.r = "PASS";
+            return f;
+        }().p.q.r);
+    }
+    expect: {
+        console.log(function(f, g) {
+            f = function() {};
+            f.p = {};
+            g = f.p.q = function() {};
+            g.r = "PASS";
+            return f;
+        }().p.q.r);
+    }
+    expect_stdout: "PASS"
+}

test/compress/evaluate.js

@@ -3181,3 +3181,23 @@ issue_4552: {
     }
     expect_stdout: "NaN"
 }
+
+issue_4886: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        console.log("length" in {
+            __proto__: function() {},
+            length: void 0,
+        });
+    }
+    expect: {
+        console.log("length" in {
+            __proto__: function() {},
+            length: void 0,
+        });
+    }
+    expect_stdout: "true"
+}

test/compress/exponentiation.js

@@ -99,8 +99,8 @@ issue_4664: {
     expect: {
         (function f() {
             new function(a) {
-                console.log(typeof f, 2 ** 30, typeof this);
-            }(0, A = 0);
+                console.log(typeof f, 1073741824, typeof this);
+            }(A = 0);
         })();
     }
     expect_stdout: "function 1073741824 object"

test/compress/exports.js

@@ -91,6 +91,13 @@ defaults_parentheses_6: {
     expect_exact: 'export default(function(){while(!console);})()?"FAIL":"PASS";'
 }
 
+defaults_regexp: {
+    input: {
+        export default /foo/;
+    }
+    expect_exact: "export default/foo/;"
+}
+
 foreign: {
     input: {
         export * from "foo";

test/compress/functions.js

@@ -5991,3 +5991,220 @@ issue_4788: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4823: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function() {
+            {
+                function f() {}
+                var arguments = f();
+                function g() {}
+                var arguments = g;
+            }
+            return f && arguments;
+        }());
+    }
+    expect: {
+        console.log(typeof function() {
+            {
+                function f() {}
+                f();
+                var arguments = function() {};
+            }
+            return f && arguments;
+        }());
+    }
+    expect_stdout: "function"
+}
+
+drop_unused_self_reference: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {}
+        (f.p = f).q = console.log("PASS");
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+reduce_cross_reference_1: {
+    options = {
+        passes: 3,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function(a, b) {
+            a = b = function() {};
+            a.p = a;
+            b = a = function() {};
+            b.q = b;
+        })();
+    }
+    expect: {}
+    expect_stdout: true
+}
+
+reduce_cross_reference_1_toplevel: {
+    options = {
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = b = function() {};
+        a.p = a;
+        var b = a = function() {};
+        b.q = b;
+    }
+    expect: {}
+    expect_stdout: true
+}
+
+reduce_cross_reference_2: {
+    options = {
+        collapse_vars: true,
+        passes: 3,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function(a, b) {
+            a = b = function() {};
+            b.p = a;
+            b = a = function() {};
+            a.q = b;
+        })();
+    }
+    expect: {}
+    expect_stdout: true
+}
+
+reduce_cross_reference_2_toplevel: {
+    options = {
+        collapse_vars: true,
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = b = function() {};
+        b.p = a;
+        var b = a = function() {};
+        a.q = b;
+    }
+    expect: {}
+    expect_stdout: true
+}
+
+reduce_cross_reference_3: {
+    options = {
+        collapse_vars: true,
+        passes: 3,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function(a, b) {
+            a = b = function() {};
+            a.p = b;
+            b = a = function() {};
+            b.q = a;
+        })();
+    }
+    expect: {}
+    expect_stdout: true
+}
+
+reduce_cross_reference_3_toplevel: {
+    options = {
+        collapse_vars: true,
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = b = function() {};
+        a.p = b;
+        var b = a = function() {};
+        b.q = a;
+    }
+    expect: {}
+    expect_stdout: true
+}
+
+reduce_cross_reference_4: {
+    options = {
+        passes: 3,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function(a, b) {
+            a = b = function() {};
+            b.p = b;
+            b = a = function() {};
+            a.q = a;
+        })();
+    }
+    expect: {}
+    expect_stdout: true
+}
+
+reduce_cross_reference_4_toplevel: {
+    options = {
+        passes: 2,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = b = function() {};
+        b.p = b;
+        var b = a = function() {};
+        a.q = a;
+    }
+    expect: {}
+    expect_stdout: true
+}

test/compress/hoist_vars.js

@@ -140,7 +140,6 @@ issue_4487: {
         functions: true,
         hoist_vars: true,
         keep_fnames: true,
-        passes: 2,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -240,3 +239,160 @@ issue_4736: {
     }
     expect_stdout: "1073741824"
 }
+
+issue_4839: {
+    options = {
+        evaluate: true,
+        hoist_vars: true,
+        keep_fargs: false,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var o = function(a, b) {
+            return b && b;
+        }("foo");
+        for (var k in o)
+            throw "FAIL";
+        console.log("PASS");
+    }
+    expect: {
+        var k, o = void 0;
+        for (k in o)
+            throw "FAIL";
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4859: {
+    options = {
+        evaluate: true,
+        hoist_vars: true,
+        keep_infinity: true,
+        merge_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f(a) {
+            var b = (a = 2, 1 / 0), c = 3;
+            var d = a + b;
+            console.log(d);
+            return f;
+        }
+        f();
+    }
+    expect: {
+        (function f(a) {
+            var d = 1 / 0, d = Infinity;
+            console.log(d);
+            return f;
+        })();
+    }
+    expect_stdout: "Infinity"
+}
+
+issue_4893_1: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        hoist_vars: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            function g() {}
+            var a = null;
+            var b = null;
+            var c = null;
+            b.p += a = 42;
+            f;
+        }
+        try {
+            f();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try{
+            (function f() {
+                var b;
+                b = null;
+                b.p += 42;
+                f;
+            })();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4893_2: {
+    options = {
+        collapse_vars: true,
+        hoist_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            function g() {}
+            var a = null;
+            var b = null;
+            var c = null;
+            b.p += a = 42;
+            f;
+        }
+        try {
+            f();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try{
+            (function() {
+                var b;
+                b = null;
+                b.p += 42;
+            })();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4898: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        hoist_vars: true,
+        loops: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        do {
+            var b = [ console.log("PASS") ];
+            var c = b;
+        } while (c.p = 0);
+    }
+    expect: {
+        var b;
+        b = [ console.log("PASS") ];
+        b.p = 0;
+    }
+    expect_stdout: "PASS"
+}

test/compress/ie8.js

@@ -2653,7 +2653,9 @@ issue_4019: {
             try {
                 console.log("FAIL");
             } catch (o) {}
-        }, o = (console.log(o.length), ++o);
+        };
+        console.log(o.length),
+        ++o;
     }
     expect_stdout: "0"
 }
@@ -2945,3 +2947,53 @@ issue_4729: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4928_1: {
+    options = {
+        ie8: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = function f() {
+            f(a);
+        };
+        console.log(typeof f);
+    }
+    expect: {
+        var a = function f() {
+            f(a);
+        };
+        console.log(typeof f);
+    }
+    expect_stdout: "undefined"
+}
+
+issue_4928_2: {
+    options = {
+        ie8: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        switch (42) {
+          case console:
+            var a = function f() {
+                f(a);
+            };
+          case 42:
+            var a = console.log("PASS");
+        }
+    }
+    expect: {
+        switch (42) {
+          case console:
+            var a = function f() {
+                f(a);
+            };
+          case 42:
+            a = console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+}

test/compress/imports.js

@@ -54,13 +54,22 @@ dynamic_nought: {
     expect_exact: "import(foo);"
 }
 
-import_meta: {
+import_meta_1: {
     input: {
         console.log(import.meta, import.meta.url);
     }
     expect_exact: "console.log(import.meta,import.meta.url);"
 }
 
+import_meta_2: {
+    input: {
+        import.meta.url.split("/").forEach(function(part, index) {
+            console.log(index, part);
+        });
+    }
+    expect_exact: 'import.meta.url.split("/").forEach(function(part,index){console.log(index,part)});'
+}
+
 same_quotes: {
     beautify = {
         beautify: true,

test/compress/join_vars.js

@@ -1024,7 +1024,7 @@ issue_3856: {
     expect_stdout: "undefined"
 }
 
-issue_3916: {
+issue_3916_1: {
     options = {
         join_vars: true,
     }
@@ -1044,8 +1044,8 @@ issue_3916: {
         var o = {
             p: "PASS",
             __proto__: 42,
-            q: "FAIL",
         };
+        o.q = "FAIL";
         o.__proto__ = {
             p: "FAIL",
             q: "PASS",
@@ -1056,6 +1056,62 @@ issue_3916: {
     expect_stdout: "object PASS true PASS"
 }
 
+issue_3916_2: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        var log = console.log, o = {};
+        o.p = "FAIL 1";
+        o.__proto__ = {
+            get p() {
+                return "FAIL 2";
+            },
+            set p(u) {
+                log("FAIL 3");
+            },
+            set q(v) {
+                log("PASS 1");
+            },
+            get q() {
+                return "PASS 3";
+            },
+        };
+        o.p = "PASS 2";
+        o.q = "FAIL 4";
+        log(o.p);
+        log(o.q);
+    }
+    expect: {
+        var log = console.log, o = {
+            p: "FAIL 1",
+            __proto__: {
+                get p() {
+                    return "FAIL 2";
+                },
+                set p(u) {
+                    log("FAIL 3");
+                },
+                set q(v) {
+                    log("PASS 1");
+                },
+                get q() {
+                    return "PASS 3";
+                },
+            },
+        };
+        o.p = "PASS 2";
+        o.q = "FAIL 4";
+        log(o.p);
+        log(o.q);
+    }
+    expect_stdout: [
+        "PASS 1",
+        "PASS 2",
+        "PASS 3",
+    ]
+}
+
 assign_var: {
     options = {
         join_vars: true,

test/compress/let.js

@@ -1506,3 +1506,43 @@ issue_4691: {
     expect_stdout: "PASS"
     node_version: ">=4"
 }
+
+issue_4848: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        "use strict";
+        function f(a) {
+            a(function() {
+                console.log(b);
+            });
+            if (!console)
+                return;
+            let b = "PASS";
+        }
+        var g;
+        f(function(h) {
+            g = h;
+        });
+        g();
+    }
+    expect: {
+        "use strict";
+        function f(a) {
+            a(function() {
+                console.log(b);
+            });
+            if (!console)
+                return;
+            let b = "PASS";
+        }
+        var g;
+        f(function(h) {
+            g = h;
+        });
+        g();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/loops.js

@@ -829,6 +829,18 @@ empty_for_in_prop_init: {
 }
 
 for_of: {
+    input: {
+        var a = [ "PASS", 42 ];
+        a.p = "FAIL";
+        for (a of (null, a))
+            console.log(a);
+    }
+    expect_exact: 'var a=["PASS",42];a.p="FAIL";for(a of(null,a))console.log(a);'
+    expect_stdout: true
+    node_version: ">=0.12"
+}
+
+for_async_of: {
     input: {
         var async = [ "PASS", 42 ];
         async.p = "FAIL";
@@ -837,7 +849,21 @@ for_of: {
     }
     expect_exact: 'var async=["PASS",42];async.p="FAIL";for(async of(null,async))console.log(async);'
     expect_stdout: true
-    node_version: ">=0.12"
+    node_version: ">=0.12 <16"
+}
+
+for_of_regexp: {
+    input: {
+        for (var a of /foo/);
+    }
+    expect_exact: "for(var a of/foo/);"
+}
+
+for_await_of_regexp: {
+    input: {
+        for await (var a of /foo/);
+    }
+    expect_exact: "for await(var a of/foo/);"
 }
 
 issue_3631_1: {

test/compress/numbers.js

@@ -104,6 +104,40 @@ parentheses_for_prototype_functions_galio: {
     expect_stdout: true
 }
 
+octal: {
+    beautify = {
+        beautify: true,
+    }
+    input: {
+        (function() {
+            console.log(052);
+            console.log(-052);
+
+            console.log(018);
+            console.log(-018);
+
+            console.log(052.toFixed(0));
+            console.log(-052.toFixed(0));
+
+            console.log(018..toFixed(0));
+            console.log(-018..toFixed(0));
+        })();
+    }
+    expect_exact: [
+        "(function() {",
+        "    console.log(42);",
+        "    console.log(-42);",
+        "    console.log(18);",
+        "    console.log(-18);",
+        "    console.log(42..toFixed(0));",
+        "    console.log(-42..toFixed(0));",
+        "    console.log(18..toFixed(0));",
+        "    console.log(-18..toFixed(0));",
+        "})();",
+    ]
+    expect_stdout: true
+}
+
 comparisons: {
     options = {
         comparisons: true,

test/compress/optional-chains.js

@@ -0,0 +1,277 @@
+call: {
+    input: {
+        console.log?.(undefined?.(console.log("FAIL")));
+    }
+    expect_exact: 'console.log?.((void 0)?.(console.log("FAIL")));'
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+dot: {
+    input: {
+        console?.log((void 0)?.p);
+    }
+    expect_exact: "console?.log((void 0)?.p);"
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+dot_in: {
+    input: {
+        var o = { in: 42 };
+        console.log(o.in, o?.in);
+    }
+    expect_exact: "var o={in:42};console.log(o.in,o?.in);"
+    expect_stdout: "42 42"
+    node_version: ">=14"
+}
+
+sub: {
+    input: {
+        console?.["log"](null?.[console.log("FAIL")]);
+    }
+    expect_exact: 'console?.["log"](null?.[console.log("FAIL")]);'
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+ternary_decimal: {
+    input: {
+        null ? .42 : console.log("PASS");
+    }
+    expect_exact: 'null?.42:console.log("PASS");'
+    expect_stdout: "PASS"
+}
+
+assign_parentheses_call: {
+    input: {
+        var o = {};
+        ((() => o)?.()).p = "PASS";
+        console.log(o.p);
+    }
+    expect_exact: 'var o={};((()=>o)?.()).p="PASS";console.log(o.p);'
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+assign_parentheses_dot: {
+    input: {
+        (console?.log).name.p = console.log("PASS");
+    }
+    expect_exact: '(console?.log.name).p=console.log("PASS");'
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+assign_no_parentheses: {
+    input: {
+        console[console.log?.("PASS")] = 42;
+    }
+    expect_exact: 'console[console.log?.("PASS")]=42;'
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+unary_parentheses: {
+    input: {
+        var o = { p: 41 };
+        (function() {
+            return o;
+        }?.()).p++;
+        console.log(o.p);
+    }
+    expect_exact: "var o={p:41};(function(){return o}?.()).p++;console.log(o.p);"
+    expect_stdout: "42"
+    node_version: ">=14"
+}
+
+collapse_vars_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a;
+        A = 42;
+        a?.[42];
+        console.log(typeof A);
+    }
+    expect: {
+        var a;
+        A = 42;
+        a?.[42];
+        console.log(typeof A);
+    }
+    expect_stdout: "number"
+    node_version: ">=14"
+}
+
+collapse_vars_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a;
+        A = 42;
+        a?.(42);
+        console.log(typeof A);
+    }
+    expect: {
+        var a;
+        A = 42;
+        a?.(42);
+        console.log(typeof A);
+    }
+    expect_stdout: "number"
+    node_version: ">=14"
+}
+
+properties: {
+    options = {
+        evaluate: true,
+        properties: true,
+    }
+    input: {
+        var a;
+        console.log(a?.["FAIL"]);
+    }
+    expect: {
+        var a;
+        console.log(a?.FAIL);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+reduce_vars_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        null?.[a = 0];
+        console.log(a ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = 1;
+        null?.[a = 0];
+        console.log(a ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+reduce_vars_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        null?.(a = 0);
+        console.log(a ? "PASS" : "FAIL");
+    }
+    expect: {
+        var a = 1;
+        null?.(a = 0);
+        console.log(a ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+side_effects: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        var a;
+        a?.[a = "FAIL"];
+        console.log(a);
+    }
+    expect: {
+        var a;
+        a?.[a = "FAIL"];
+        console.log(a);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}
+
+trim_1: {
+    options = {
+        evaluate: true,
+        optional_chains: true,
+        reduce_vars: true,
+        unsafe: true,
+    }
+    input: {
+        (function(a, b) {
+            console?.log?.(a?.p, b?.[console.log("FAIL")]);
+        })?.({ p: "PASS" });
+    }
+    expect: {
+        (function(a, b) {
+            console?.log?.(a.p, void 0);
+        })({ p: "PASS" });
+    }
+    expect_stdout: "PASS undefined"
+    node_version: ">=14"
+}
+
+trim_2: {
+    options = {
+        evaluate: true,
+        optional_chains: true,
+        side_effects: true,
+    }
+    input: {
+        (void console.log("PASS"))?.[console.log("FAIL")];
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_4906: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        do {
+            var a = a?.[42];
+        } while (console.log("PASS"));
+    }
+    expect: {
+        do {} while (console.log("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=14"
+}
+
+issue_4928: {
+    options = {
+        ie8: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = a?.[function f() {
+            f(a);
+        }];
+        console.log(typeof f);
+    }
+    expect: {
+        var a = a?.[function f() {
+            f(a);
+        }];
+        console.log(typeof f);
+    }
+    expect_stdout: "undefined"
+    node_version: ">=14"
+}

test/compress/properties.js

@@ -1400,3 +1400,66 @@ object_super: {
     expect_stdout: "PASS"
     node_version: ">=4"
 }
+
+issue_4831_1: {
+    options = {
+        properties: true,
+    }
+    input: {
+        console.log({
+            f() {
+                return arguments;
+            },
+        }.f("PASS")[0]);
+    }
+    expect: {
+        console.log([
+            function() {
+                return arguments;
+            },
+        ][0]("PASS")[0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4831_2: {
+    options = {
+        properties: true,
+    }
+    input: {
+        var f = {
+            f() {
+                return arguments;
+            },
+        }.f;
+        console.log(f("PASS")[0]);
+    }
+    expect: {
+        var f = {
+            f() {
+                return arguments;
+            },
+        }.f;
+        console.log(f("PASS")[0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4888: {
+    options = {
+        properties: true,
+    }
+    input: {
+        console.log(typeof {
+            __proto__: 42,
+        }.__proto__);
+    }
+    expect: {
+        console.log(typeof {
+            __proto__: 42,
+        }.__proto__);
+    }
+    expect_stdout: "object"
+}

test/compress/pure_funcs.js

@@ -133,7 +133,7 @@ conditional: {
 relational: {
     options = {
         pure_funcs: [ "foo" ],
-        side_effects :true,
+        side_effects: true,
     }
     input: {
         foo() in new foo();
@@ -158,7 +158,7 @@ relational: {
 arithmetic: {
     options = {
         pure_funcs: [ "foo" ],
-        side_effects :true,
+        side_effects: true,
     }
     input: {
         foo() + foo();
@@ -183,7 +183,7 @@ arithmetic: {
 boolean_and: {
     options = {
         pure_funcs: [ "foo" ],
-        side_effects :true,
+        side_effects: true,
     }
     input: {
         foo() && foo();
@@ -208,7 +208,7 @@ boolean_and: {
 boolean_or: {
     options = {
         pure_funcs: [ "foo" ],
-        side_effects :true,
+        side_effects: true,
     }
     input: {
         foo() || foo();
@@ -233,7 +233,7 @@ boolean_or: {
 assign: {
     options = {
         pure_funcs: [ "foo" ],
-        side_effects :true,
+        side_effects: true,
     }
     input: {
         var a;
@@ -256,7 +256,7 @@ assign: {
 unary: {
     options = {
         pure_funcs: [ "foo" ],
-        side_effects :true,
+        side_effects: true,
     }
     input: {
         typeof foo();

test/compress/pure_getters.js

@@ -1564,3 +1564,103 @@ issue_4803: {
     }
     expect_stdout: "PASS"
 }
+
+nested_property_assignments_1: {
+    options = {
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var f;
+        ((f = function() {
+            console.log("FAIL");
+        }).p = f).q = console.log("PASS");
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+nested_property_assignments_2: {
+    options = {
+        pure_getters: "strict",
+        unused: true,
+    }
+    input: {
+        var o = {};
+        (function() {
+            var a;
+            (o.p = a = {}).q = "PASS";
+        })();
+        console.log(o.p.q);
+    }
+    expect: {
+        var o = {};
+        (function() {
+            (o.p = {}).q = "PASS";
+        })();
+        console.log(o.p.q);
+    }
+    expect_stdout: "PASS"
+}
+
+nested_property_assignments_3: {
+    options = {
+        collapse_vars: true,
+        pure_getters: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var o = { p: {} };
+        (function(a) {
+            console && a;
+            if (console) {
+                a = a.p;
+                a.q = a;
+            }
+        })(o);
+        console.log(o.p.q === o.p ? "PASS" : "FAIL");
+    }
+    expect: {
+        var o = { p: {} };
+        (function(a) {
+            console;
+            if (console)
+                (a = a.p).q = a;
+        })(o);
+        console.log(o.p.q === o.p ? "PASS" : "FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4939: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        ({
+            __proto__: {
+                get p() {
+                    console.log("PASS");
+                },
+            },
+        }).p;
+    }
+    expect: {
+        ({
+            __proto__: {
+                get p() {
+                    console.log("PASS");
+                },
+            },
+        }).p;
+    }
+    expect_stdout: "PASS"
+}

test/compress/reduce_vars.js

@@ -7631,3 +7631,94 @@ issue_4568: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4937: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            while (console.log("PASS"));
+        }
+        do {
+            function g() {
+                f();
+            }
+        } while (!g);
+        f();
+    }
+    expect: {
+        function f() {
+            while (console.log("PASS"));
+        }
+        do {
+            function g() {
+                f();
+            }
+        } while (!g);
+        f();
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4943_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a, b = 1;
+        (function f() {
+            a = "foo";
+            b-- && f();
+            console.log(a);
+            a = "bar";
+        })();
+    }
+    expect: {
+        var a, b = 1;
+        (function f() {
+            a = "foo";
+            b-- && f();
+            console.log(a);
+            a = "bar";
+        })();
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}
+
+issue_4943_2: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a, b = 1;
+        (function f() {
+            a = "foo";
+            b-- && f();
+            console.log(a);
+            a = "bar";
+        })();
+    }
+    expect: {
+        var a, b = 1;
+        (function f() {
+            a = "foo";
+            b-- && f();
+            console.log(a);
+            a = "bar";
+        })();
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+}

test/compress/sandbox.js

@@ -172,3 +172,32 @@ issue_4054: {
     }
     expect_stdout: "{ p: [Setter] }"
 }
+
+issue_4811_1: {
+    input: {
+        for (var PASS in this);
+        console.log(PASS, this, {} < this);
+    }
+    expect: {
+        for (var PASS in this);
+        console.log(PASS, this, {} < this);
+    }
+    expect_stdout: "PASS [object global] true"
+}
+
+issue_4811_2: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        (async function() {});
+        for (var PASS in this);
+        console.log(PASS, this, {} < this);
+    }
+    expect: {
+        for (var PASS in this);
+        console.log(PASS, this, {} < this);
+    }
+    expect_stdout: "PASS [object global] true"
+    node_version: ">=8"
+}

test/compress/side_effects.js

@@ -198,6 +198,36 @@ global_fns: {
     ]
 }
 
+global_constructors: {
+    options = {
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        Map;
+        new Map(console.log("foo"));
+        Set;
+        new Set(console.log("bar"));
+        WeakMap;
+        new WeakMap(console.log("baz"));
+        WeakSet;
+        new WeakSet(console.log("moo"));
+    }
+    expect: {
+        console.log("foo");
+        console.log("bar");
+        console.log("baz");
+        console.log("moo");
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "baz",
+        "moo",
+    ]
+    node_version: ">=0.12"
+}
+
 unsafe_builtin_1: {
     options = {
         side_effects: true,

test/compress/spreads.js

@@ -1045,3 +1045,114 @@ issue_4614: {
     expect_stdout: true
     node_version: ">=6"
 }
+
+issue_4849: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        while (function() {
+            while (!console);
+        }(new function(a) {
+            console.log(typeof { ...a });
+        }(function() {})));
+    }
+    expect: {
+        while (function() {
+            while (!console);
+        }(function(a) {
+            console.log(typeof { ...function() {} });
+        }()));
+    }
+    expect_stdout: "object"
+    node_version: ">=8"
+}
+
+issue_4882_1: {
+    options = {
+        objects: true,
+        spreads: true,
+    }
+    input: {
+        var o = {
+            p: "PASS",
+            ... {
+                __proto__: {
+                    p: "FAIL 1",
+                    q: "FAIL 2",
+                },
+            },
+        };
+        console.log(o.p);
+        console.log(o.q);
+    }
+    expect: {
+        var o = {
+            p: "PASS",
+        };
+        console.log(o.p);
+        console.log(o.q);
+    }
+    expect_stdout: [
+        "PASS",
+        "undefined",
+    ]
+    node_version: ">=8"
+}
+
+issue_4882_2: {
+    options = {
+        objects: true,
+        spreads: true,
+    }
+    input: {
+        console.log(null == Object.getPrototypeOf({
+            ... {
+                __proto__: (console.log(42), null),
+            },
+        }) ? "FAIL" : "PASS");
+    }
+    expect: {
+        console.log(null == Object.getPrototypeOf({
+            ... {
+                __proto__: (console.log(42), null),
+            },
+        }) ? "FAIL" : "PASS");
+    }
+    expect_stdout: [
+        "42",
+        "PASS",
+    ]
+    node_version: ">=8"
+}
+
+issue_4882_3: {
+    options = {
+        objects: true,
+        spreads: true,
+    }
+    input: {
+        var o = {
+            __proto__: { p: 42 },
+            ... {
+                set __proto__(v) {},
+            },
+        };
+        console.log(o.__proto__ === Object.getPrototypeOf(o) ? "FAIL" : "PASS");
+        console.log(o.p);
+    }
+    expect: {
+        var o = {
+            __proto__: { p: 42 },
+            ["__proto__"]: void 0,
+        };
+        console.log(o.__proto__ === Object.getPrototypeOf(o) ? "FAIL" : "PASS");
+        console.log(o.p);
+    }
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=8"
+}

test/compress/templates.js

@@ -62,6 +62,23 @@ tag_parentheses_arrow: {
     node_version: ">=4"
 }
 
+tag_parentheses_binary: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var f = function() {
+            console.log("PASS");
+        } || console
+        f``;
+    }
+    expect_exact: '(function(){console.log("PASS")}||console)``;'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
 tag_parentheses_new: {
     input: {
         (new function() {
@@ -87,6 +104,21 @@ tag_parentheses_sequence: {
     node_version: ">=4"
 }
 
+tag_parentheses_unary: {
+    input: {
+        var a;
+        try {
+            (~a)``;
+            (a++)``;
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_exact: 'var a;try{(~a)``;(a++)``}catch(e){console.log("PASS")}'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
 malformed_escape: {
     input: {
         (function(s) {
@@ -343,7 +375,7 @@ issue_4676: {
         reduce_vars: true,
         templates: true,
         toplevel: true,
-        unsafe:true,
+        unsafe: true,
         unused: true,
     }
     input: {
@@ -366,3 +398,24 @@ issue_4676: {
     expect_stdout: "PASS"
     node_version: ">=4"
 }
+
+issue_4931: {
+    options = {
+        evaluate: true,
+        templates: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(String.raw`${typeof A} ${"\r"}`);
+        console.log(String.raw`${"\\"} ${"`"}`);
+    }
+    expect: {
+        console.log(String.raw`${typeof A} ${"\r"}`);
+        console.log("\\ `");
+    }
+    expect_stdout: [
+        "undefined \r",
+        "\\ `",
+    ]
+    node_version: ">=4"
+}

test/compress/varify.js

@@ -523,3 +523,55 @@ default_init: {
     expect_stdout: "PASS"
     node_version: ">=4"
 }
+
+issue_4933_1: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+        varify: true,
+    }
+    input: {
+        console.log(f());
+        function f() {
+            var a;
+            for (console in a = [ f ]) {
+                const b = a;
+            }
+        }
+    }
+    expect: {
+        console.log(function f() {
+            var a;
+            for (console in a = [ f ]) {
+                const b = a;
+            }
+        }());
+    }
+    expect_stdout: "undefined"
+}
+
+issue_4933_2: {
+    options = {
+        passes: 2,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+        varify: true,
+    }
+    input: {
+        console.log(f());
+        function f() {
+            var a;
+            for (console in a = [ f ]) {
+                const b = a;
+            }
+        }
+    }
+    expect: {
+        console.log(function f() {
+            for (console in [ f ]);
+        }());
+    }
+    expect_stdout: "undefined"
+}

test/compress/yields.js

@@ -150,6 +150,27 @@ for_await_of: {
     node_version: ">=10"
 }
 
+comment_newline: {
+    beautify = {
+        comments: "all",
+    }
+    input: {
+        console.log(function*() {
+            yield (
+                /* */
+                "PASS"
+            );
+        }().next().value);
+    }
+    expect_exact: [
+        "console.log(function*(){",
+        "/* */",
+        'yield"PASS"}().next().value);',
+    ]
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
 collapse_vars_1: {
     options = {
         collapse_vars: true,

test/input/invalid/assign_4.js

@@ -1 +1 @@
-++null
+console.log(4 || (null = 4));

test/input/invalid/assign_5.js

@@ -0,0 +1 @@
+console.log(5 || ([]?.length ^= 5));

test/input/invalid/for-await.js

@@ -0,0 +1 @@
+for await (; console.log(42););

test/mocha/cli.js

@@ -427,16 +427,30 @@ describe("bin/uglifyjs", function() {
             done();
         });
     });
-    it("Should throw syntax error (++null)", function(done) {
+    it("Should throw syntax error (null = 4)", function(done) {
         var command = uglifyjscmd + " test/input/invalid/assign_4.js";
         exec(command, function(err, stdout, stderr) {
             assert.ok(err);
             assert.strictEqual(stdout, "");
             assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
-                "Parse error at test/input/invalid/assign_4.js:1,0",
-                "++null",
-                "^",
-                "ERROR: Invalid use of ++ operator",
+                "Parse error at test/input/invalid/assign_4.js:1,23",
+                "console.log(4 || (null = 4));",
+                "                       ^",
+                "ERROR: Invalid assignment",
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error ([]?.length ^= 5)", function(done) {
+        var command = uglifyjscmd + " test/input/invalid/assign_5.js";
+        exec(command, function(err, stdout, stderr) {
+            assert.ok(err);
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/assign_5.js:1,29",
+                "console.log(5 || ([]?.length ^= 5));",
+                "                             ^",
+                "ERROR: Invalid assignment",
             ].join("\n"));
             done();
         });
@@ -679,6 +693,20 @@ describe("bin/uglifyjs", function() {
             done();
         });
     });
+    it("Should throw syntax error (for-await)", function(done) {
+        var command = uglifyjscmd + " test/input/invalid/for-await.js";
+        exec(command, function(err, stdout, stderr) {
+            assert.ok(err);
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/for-await.js:1,11",
+                "for await (; console.log(42););",
+                "           ^",
+                "ERROR: Unexpected token: punc «;»",
+            ].join("\n"));
+            done();
+        });
+    });
     it("Should throw syntax error (switch defaults)", function(done) {
         var command = uglifyjscmd + " test/input/invalid/switch.js";
         exec(command, function(err, stdout, stderr) {

test/mocha/let.js

@@ -7,11 +7,11 @@ describe("let", function() {
         // Produce a lot of variables in a function and run it through mangle.
         var s = '"dddddeeeeelllllooooottttt"; function foo() {';
         for (var i = 0; i < 18000; i++) {
-            s += "var v" + i + "=0;";
+            s += "var v" + i + "=[];";
         }
         s += '}';
         var result = UglifyJS.minify(s, {
-            compress: false
+            compress: false,
         }).code;
 
         // Verify that select keywords and reserved keywords not produced

test/mocha/reduce.js

@@ -183,6 +183,24 @@ describe("test/reduce.js", function() {
             "// }",
         ].join("\n"));
     });
+    it("Should reduce `for (const ... in ...)` without invalid intermediate AST", function() {
+        if (semver.satisfies(process.version, "<4")) return;
+        var code = [
+            "var a = 0;",
+            "",
+            "for (const b in [ 1, 2, 3 ]) {",
+            "    a = +a + 1 - .2;",
+            "    console.log(a);",
+            "}",
+        ].join("\n");
+        var result = reduce_test(code, {
+            compress: {
+                unsafe_math: true,
+            },
+        });
+        if (result.error) throw result.error;
+        assert.deepEqual(result.warnings, []);
+    });
     it("Should reduce infinite loops with reasonable performance", function() {
         if (semver.satisfies(process.version, "<=0.10")) return;
         this.timeout(120000);
@@ -361,4 +379,39 @@ describe("test/reduce.js", function() {
         if (result.error) throw result.error;
         assert.strictEqual(result.code, read("test/input/reduce/destructured_catch.reduced.js"));
     });
+    it("Should not enumerate `toString` over global context", function() {
+        if (semver.satisfies(process.version, "<8")) return;
+        var code = [
+            "(async function() {});",
+            "for (var k in this);",
+            "console.log(k, 42 + this);",
+        ].join("\n");
+        var result = reduce_test(code, {
+            mangle: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, [
+            "// Can't reproduce test failure",
+            "// minify options: {",
+            '//   "mangle": false',
+            "// }",
+        ].join("\n"));
+    });
+    it("Should reduce object with method syntax without invalid intermediate AST", function() {
+        if (semver.satisfies(process.version, "<4")) return;
+        var code = [
+            "console.log({",
+            "    f() {",
+            "        return 1 - .8;",
+            "    },",
+            "}.f());",
+        ].join("\n");
+        var result = reduce_test(code, {
+            compress: {
+                unsafe_math: true,
+            },
+        });
+        if (result.error) throw result.error;
+        assert.deepEqual(result.warnings, []);
+    });
 });

test/mozilla-ast.js

@@ -5,23 +5,23 @@ var acorn = require("acorn");
 var ufuzz = require("./ufuzz");
 var UglifyJS = require("..");
 
-function try_beautify(code) {
-    var beautified = UglifyJS.minify(code, {
+function beautify(ast) {
+    var beautified = UglifyJS.minify(ast, {
         compress: false,
         mangle: false,
         output: {
             beautify: true,
-            braces: true
-        }
+            braces: true,
+        },
+    });
+    if (beautified.error) return beautified;
+    return UglifyJS.minify(beautified.code, {
+        compress: false,
+        mangle: false,
+        output: {
+            ast: true,
+        },
     });
-    if (beautified.error) {
-        console.log("// !!! beautify failed !!!");
-        console.log(beautified.error.stack);
-        console.log(code);
-    } else {
-        console.log("// (beautified)");
-        console.log(beautified.code);
-    }
 }
 
 function validate(ast) {
@@ -35,16 +35,55 @@ function validate(ast) {
     return UglifyJS.minify(ast, {
         compress: false,
         mangle: false,
+        output: {
+            ast: true,
+        },
+        validate: true,
     });
 }
 
-function test(original, estree, description) {
-    var transformed = validate(UglifyJS.AST_Node.from_mozilla_ast(estree));
-    if (transformed.error || original !== transformed.code) {
+function patch_import(code) {
+    return code.replace(/\bimport\s*\{\s*\}\s*from\s*(['"])/g, "import$1")
+        .replace(/\b(import\b.*?)\s*,\s*\{\s*\}\s*(from\s*['"])/g, "$1 $2");
+}
+
+function equals(input, transformed) {
+    if (input.code === transformed.code) return true;
+    return patch_import(input.code) === patch_import(transformed.code);
+}
+
+function test(input, to_moz, description, skip_on_error, beautified) {
+    try {
+        var ast = UglifyJS.AST_Node.from_mozilla_ast(to_moz(input));
+    } catch (e) {
+        if (skip_on_error) return true;
+        console.log("//=============================================================");
+        console.log("//", description, "failed... round", round);
+        console.log(e);
+        console.log("// original code");
+        if (beautified === true) console.log("// (beautified)");
+        console.log(input.code);
+        return false;
+    }
+    var transformed = validate(ast);
+    if (transformed.error || !equals(input, transformed)) {
+        if (!beautified) {
+            beautified = beautify(input.ast);
+            if (!beautified.error) {
+                beautified.raw = beautified.code;
+                if (!test(beautified, to_moz, description, skip_on_error, true)) return false;
+            }
+        }
         console.log("//=============================================================");
         console.log("// !!!!!! Failed... round", round);
         console.log("// original code");
-        try_beautify(original);
+        if (beautified.error) {
+            console.log("// !!! beautify failed !!!");
+            console.log(beautified.error.stack);
+        } else if (beautified === true) {
+            console.log("// (beautified)");
+        }
+        console.log(input.raw);
         console.log();
         console.log();
         console.log("//-------------------------------------------------------------");
@@ -52,7 +91,15 @@ function test(original, estree, description) {
         if (transformed.error) {
             console.log(transformed.error.stack);
         } else {
-            try_beautify(transformed.code);
+            beautified = beautify(transformed.ast);
+            if (beautified.error) {
+                console.log("// !!! beautify failed !!!");
+                console.log(beautified.error.stack);
+                console.log(transformed.code);
+            } else {
+                console.log("// (beautified)");
+                console.log(beautified.code);
+            }
         }
         console.log("!!!!!! Failed... round", round);
         return false;
@@ -67,24 +114,33 @@ for (var round = 1; round <= num_iterations; round++) {
     process.stdout.write(round + " of " + num_iterations + "\r");
     var code = ufuzz.createTopLevelCode();
     minify_options.forEach(function(options) {
-        var input = options ? UglifyJS.minify(code, JSON.parse(options)).code : code;
-        var uglified = UglifyJS.minify(input, {
+        var ok = true;
+        var input = UglifyJS.minify(options ? UglifyJS.minify(code, JSON.parse(options)).code : code, {
             compress: false,
             mangle: false,
             output: {
-                ast: true
-            }
+                ast: true,
+            },
         });
-        var ok = test(uglified.code, uglified.ast.to_mozilla_ast(), "AST_Node.to_mozilla_ast()");
-        try {
-            ok = test(uglified.code, acorn.parse(input), "acorn.parse()") && ok;
-        } catch (e) {
+        input.raw = options ? input.code : code;
+        if (input.error) {
+            ok = false;
             console.log("//=============================================================");
-            console.log("// acorn parser failed... round", round);
-            console.log(e);
+            console.log("// minify() failed... round", round);
+            console.log(input.error);
             console.log("// original code");
-            console.log(input);
+            console.log(code);
         }
+        if (ok) ok = test(input, function(input) {
+            return input.ast.to_mozilla_ast();
+        }, "AST_Node.to_mozilla_ast()");
+        if (ok) ok = test(input, function(input) {
+            return acorn.parse(input.raw, {
+                ecmaVersion: "latest",
+                locations: true,
+                sourceType: "module",
+            });
+        }, "acorn.parse()", !ufuzz.verbose);
         if (!ok) process.exit(1);
     });
 }

test/reduce.js

@@ -132,6 +132,8 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 return;
             }
             if (parent instanceof U.AST_VarDef && parent.name === node) return;
+            // preserve class methods
+            if (parent instanceof U.AST_ClassMethod && parent.value === node) return;
             // preserve exports
             if (parent instanceof U.AST_ExportDeclaration) return;
             if (parent instanceof U.AST_ExportDefault) return;
@@ -147,6 +149,9 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
             if (parent instanceof U.AST_For && parent.init === node && node instanceof U.AST_Definitions) return node;
             // preserve for (xxx in/of ...)
             if (parent instanceof U.AST_ForEnumeration && parent.init === node) return node;
+            // preserve super(...)
+            if (node.TYPE == "Call" && node.expression instanceof U.AST_Super) return;
+            if (node instanceof U.AST_Super && parent.TYPE == "Call" && parent.expression === node) return node;
 
             // node specific permutations with no parent logic
 
@@ -316,10 +321,11 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 var expr;
                 switch ((node.start._permute * steps | 0) % 3) {
                   case 0:
-                    if (!(node.init instanceof U.AST_Definitions
-                        && node.init.definitions[0].name instanceof U.AST_Destructured)) {
-                        expr = node.init;
+                    if (node.init instanceof U.AST_Definitions) {
+                        if (node.init instanceof U.AST_Const) break;
+                        if (node.init.definitions[0].name instanceof U.AST_Destructured) break;
                     }
+                    expr = node.init;
                     break;
                   case 1:
                     expr = node.object;
@@ -484,23 +490,27 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
             CHANGED = true;
             return newNode;
         }, function(node, in_list) {
-            if (node instanceof U.AST_Sequence) {
+            if (node instanceof U.AST_Definitions) {
+                // remove empty var statement
+                if (node.definitions.length == 0) return in_list ? List.skip : new U.AST_EmptyStatement({
+                    start: {},
+                });
+            } else if (node instanceof U.AST_ObjectMethod) {
+                if (!/Function$/.test(node.value.TYPE)) return new U.AST_ObjectKeyVal({
+                    key: node.key,
+                    value: node.value,
+                    start: {},
+                });
+            } else if (node instanceof U.AST_Sequence) {
                 // expand single-element sequence
                 if (node.expressions.length == 1) return node.expressions[0];
-            }
-            else if (node instanceof U.AST_Try) {
+            } else if (node instanceof U.AST_Try) {
                 // expand orphaned try block
                 if (!node.bcatch && !node.bfinally) return new U.AST_BlockStatement({
                     body: node.body,
                     start: {},
                 });
             }
-            else if (node instanceof U.AST_Definitions) {
-                // remove empty var statement
-                if (node.definitions.length == 0) return in_list ? List.skip : new U.AST_EmptyStatement({
-                    start: {},
-                });
-            }
         });
 
         var diff_error_message;

test/release/install.sh

@@ -1,3 +1,24 @@
+echo "::group::GitHub Environment Variables"
+echo "CI: $CI"
+echo "GITHUB_WORKFLOW: $GITHUB_WORKFLOW"
+echo "GITHUB_RUN_ID: $GITHUB_RUN_ID"
+echo "GITHUB_RUN_NUMBER: $GITHUB_RUN_NUMBER"
+echo "GITHUB_ACTION: $GITHUB_ACTION"
+echo "GITHUB_ACTIONS: $GITHUB_ACTIONS"
+echo "GITHUB_ACTOR: $GITHUB_ACTOR"
+echo "GITHUB_REPOSITORY: $GITHUB_REPOSITORY"
+echo "GITHUB_EVENT_NAME: $GITHUB_EVENT_NAME"
+echo "GITHUB_EVENT_PATH: $GITHUB_EVENT_PATH"
+echo "GITHUB_WORKSPACE: $GITHUB_WORKSPACE"
+echo "GITHUB_SHA: $GITHUB_SHA"
+echo "GITHUB_REF: $GITHUB_REF"
+echo "GITHUB_HEAD_REF: $GITHUB_HEAD_REF"
+echo "GITHUB_BASE_REF: $GITHUB_BASE_REF"
+echo "GITHUB_SERVER_URL: $GITHUB_SERVER_URL"
+echo "GITHUB_API_URL: $GITHUB_API_URL"
+echo "GITHUB_GRAPHQL_URL: $GITHUB_GRAPHQL_URL"
+echo "::endgroup::"
+
 if command -v timeout &> /dev/null; then NATIVE=1; fi
 timeout() {
     T=$1

test/release/rollup-ts.sh

@@ -6,18 +6,22 @@ UGLIFY_OPTIONS=$@
 minify_in_situ() {
     ARGS="$UGLIFY_OPTIONS --validate --in-situ"
     DIRS="$1"
+    echo '> esbuild' $DIRS
+    for i in `find $DIRS -type f -name '*.ts' | grep -v '\.d\.ts'`
+    do
+        echo "$i"
+        CODE=`cat "$i"`
+        node_modules/.bin/esbuild --loader=ts --target=esnext > "$i" <<EOF
+$CODE
+EOF
+        ARGS="$ARGS $i"
+    done
     echo '> uglify-js' $DIRS $UGLIFY_OPTIONS
     for i in `find $DIRS -type f -name '*.js'`
     do
         ARGS="$ARGS $i"
     done
     uglify-js $ARGS
-    for i in `find $DIRS -type f -name '*.ts' | grep -v '\.d\.ts'`
-    do
-        echo "$i"
-        node_modules/.bin/esbuild --loader=ts --target=node14 < "$i" \
-            | uglify-js $UGLIFY_OPTIONS -o "$i"
-    done
 }
 
 rm -rf tmp/rollup \

test/release/sucrase.sh

@@ -6,6 +6,16 @@ UGLIFY_OPTIONS=$@
 minify_in_situ() {
     ARGS="$UGLIFY_OPTIONS --validate --in-situ"
     DIRS="$1"
+    echo '> esbuild' $DIRS
+    for i in `find $DIRS -type f -name '*.ts' | grep -v '\.d\.ts'`
+    do
+        echo "$i"
+        CODE=`cat "$i"`
+        node_modules/.bin/esbuild --loader=ts --target=esnext > "$i" <<EOF
+$CODE
+EOF
+        ARGS="$ARGS $i"
+    done
     echo '> uglify-js' $DIRS $UGLIFY_OPTIONS
     for i in `find $DIRS -type f -name '*.js'`
     do
@@ -16,12 +26,6 @@ minify_in_situ() {
         ARGS="$ARGS $i"
     done
     uglify-js $ARGS
-    for i in `find $DIRS -type f -name '*.ts' | grep -v '\.d\.ts'`
-    do
-        echo "$i"
-        node_modules/.bin/esbuild --loader=ts --target=node14 < "$i" \
-            | uglify-js $UGLIFY_OPTIONS -o "$i"
-    done
 }
 
 rm -rf tmp/sucrase \

test/release/web-tooling-benchmark.sh

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-alias uglify-js="node --max-old-space-size=4096 $PWD/bin/uglifyjs"
+alias uglify-js="node --max-old-space-size=8192 $PWD/bin/uglifyjs"
 UGLIFY_OPTIONS=$@
 
 minify_in_situ() {
@@ -23,6 +23,17 @@ rm -rf tmp/web-tooling-benchmark \
 +++ b/package.json
 @@ -12 +11,0 @@
 -    "postinstall": "npm run build:terser-bundled && npm run build:uglify-js-bundled && npm run build",
+--- a/src/bootstrap.js
++++ b/src/bootstrap.js
+@@ -6 +6 @@ const gmean = require("compute-gmean");
+-const package = require("../package.json");
++const package_json = require("../package.json");
+@@ -65 +65 @@ function initialize() {
+-  document.title = \`Web Tooling Benchmark v\${package.version}\`;
++  document.title = \`Web Tooling Benchmark v\${package_json.version}\`;
+@@ -68 +68 @@ function initialize() {
+-  versionDiv.innerHTML = \`v\${package.version}\`;
++  versionDiv.innerHTML = \`v\${package_json.version}\`;
 --- a/src/cli-flags-helper.js
 +++ b/src/cli-flags-helper.js
 @@ -7 +6,0 @@ const targetList = new Set([

test/sandbox.js

@@ -55,6 +55,8 @@ exports.patch_module_statements = function(code) {
         if (!header) return "";
         if (header.length == 1) return "0, " + header;
         return header.slice(0, -1) + " _" + ++count + header.slice(-1);
+    }).replace(/\bimport\.meta\b/g, function() {
+        return '({ url: "https://example.com/path/index.html" })';
     }).replace(/\bimport\b(?:\s*([^('"]+)\bfrom\b)?\s*(['"]).*?\2(?:$|\n|;)/g, function(match, symbols) {
         if (symbols) {
             if (!/^[{*]/.test(symbols)) symbols = "default:" + symbols;
@@ -200,9 +202,13 @@ function setup(global, builtins, setup_log, setup_tty) {
     });
     Object.defineProperties(global, props);
     // for Node.js v8+
-    global.toString = function() {
-        return "[object global]";
-    };
+    if (global.toString !== Object.prototype.toString) {
+        global.__proto__ = Object.defineProperty(Object.create(global.__proto__), "toString", {
+            value: function() {
+                return "[object global]";
+            },
+        });
+    }
 
     function self() {
         return this;
@@ -216,7 +222,7 @@ function setup(global, builtins, setup_log, setup_tty) {
             if (arg === global) return "[object global]";
             if (/Error$/.test(arg.name)) return arg.toString();
             if (typeof arg.then == "function") return "[object Promise]";
-            arg.constructor.toString();
+            if (arg.constructor) arg.constructor.toString();
             var index = cache.original.indexOf(arg);
             if (index >= 0) return cache.replaced[index];
             if (--cache.level < 0) return "[object Object]";

test/ufuzz/index.js

@@ -149,8 +149,10 @@ var SUPPORT = function(matrix) {
     for_of: "for (var a of []);",
     generator: "function* f(){}",
     let: "let a;",
+    logical_assignment: "[].p ??= 0;",
     new_target: "function f() { new.target; }",
     nullish: "0 ?? 0",
+    optional_chaining: "0?.p",
     rest: "var [...a] = [];",
     rest_object: "var {...a} = {};",
     spread: "[...[]];",
@@ -203,12 +205,20 @@ var VALUES = [
     '"function"',
     "this",
 ];
+VALUES = VALUES.concat(VALUES);
+VALUES = VALUES.concat(VALUES);
+VALUES = VALUES.concat(VALUES);
 if (SUPPORT.bigint) VALUES = VALUES.concat([
     "(!0o644n)",
     "([3n][0] > 2)",
     "(-42n).toString()",
     "Number(0XDEADn << 16n | 0xbeefn)",
 ]);
+VALUES = VALUES.concat(VALUES);
+VALUES = VALUES.concat(VALUES);
+VALUES = VALUES.concat(VALUES);
+VALUES = VALUES.concat(VALUES);
+VALUES.push("import.meta");
 
 var BINARY_OPS = [
     " + ", // spaces needed to disambiguate with ++ cases (could otherwise cause syntax errors)
@@ -262,10 +272,13 @@ ASSIGNMENTS = ASSIGNMENTS.concat([
     ">>=",
     ">>>=",
 ]);
-if (SUPPORT.exponentiation) {
-    ASSIGNMENTS = ASSIGNMENTS.concat(ASSIGNMENTS);
-    ASSIGNMENTS.push("**=");
-}
+ASSIGNMENTS = ASSIGNMENTS.concat(ASSIGNMENTS);
+if (SUPPORT.exponentiation) ASSIGNMENTS.push("**=");
+if (SUPPORT.logical_assignment) ASSIGNMENTS = ASSIGNMENTS.concat([
+    "&&=",
+    "||=",
+    "??=",
+]);
 
 var UNARY_SAFE = [
     "+",
@@ -343,6 +356,7 @@ var block_vars = [];
 var lambda_vars = [];
 var unique_vars = [];
 var classes = [];
+var allow_this = true;
 var async = false;
 var has_await = false;
 var export_default = false;
@@ -389,6 +403,7 @@ function createTopLevelCode() {
     lambda_vars.length = 0;
     unique_vars.length = 0;
     classes.length = 0;
+    allow_this = true;
     async = false;
     has_await = false;
     export_default = false;
@@ -433,9 +448,9 @@ function addTrailingComma(list) {
 
 function createParams(was_async, was_generator, noDuplicate) {
     var save_async = async;
-    if (was_async) async = true;
+    if (!async) async = was_async;
     var save_generator = generator;
-    if (was_generator) generator = true;
+    if (!generator) generator = was_generator;
     var len = unique_vars.length;
     var params = [];
     for (var n = rng(4); --n >= 0;) {
@@ -557,9 +572,9 @@ function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was
     function createName() {
         unique_vars.push("a", "b", "c", "undefined", "NaN", "Infinity");
         var save_async = async;
-        if (was_async) async = true;
+        if (!async) async = was_async;
         var save_generator = generator;
-        if (was_generator) generator = true;
+        if (!generator) generator = was_generator;
         var name = createVarName(MANDATORY);
         generator = save_generator;
         async = save_async;
@@ -970,8 +985,17 @@ function createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn
         var label = createLabel(canBreak, canContinue);
         canBreak = label.break || enableLoopControl(canBreak, CAN_BREAK);
         canContinue = label.continue || enableLoopControl(canContinue, CAN_CONTINUE);
-        var key = rng(10) ? "key" + loop : getVarName(NO_CONST);
         var of = SUPPORT.for_of && rng(20) == 0;
+        var key;
+        if (rng(10)) {
+            key = "key" + loop;
+        } else if (bug_for_of_async && of) {
+            addAvoidVar("async");
+            key = getVarName(NO_CONST);
+            removeAvoidVar("async");
+        } else {
+            key = getVarName(NO_CONST);
+        }
         var init = "";
         if (!/^key/.test(key)) {
             if (!(of && bug_for_of_var) && rng(10) == 0) init = "var ";
@@ -1167,7 +1191,7 @@ function createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn
 
 function createSwitchParts(recurmax, n, canThrow, canBreak, canContinue, cannotReturn, stmtDepth) {
     var hadDefault = false;
-    var s = [""];
+    var s = [ "" ];
     canBreak = enableLoopControl(canBreak, CAN_BREAK);
     while (n-- > 0) {
         //hadDefault = n > 0; // disables weird `default` clause positioning (use when handling destabilizes)
@@ -1466,12 +1490,16 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
         return createValue() + " in " + createObjectLiteral(recurmax, stmtDepth, canThrow);
       case p++:
         var name = getVarName();
-        var s = name + "[" + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + "]";
-        return canThrow && rng(20) == 0 ? s : name + " && " + s;
+        var prop = "[" + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + "]";
+        if (SUPPORT.optional_chaining && rng(50) == 0) return name + "?." + prop;
+        if (canThrow && rng(20) == 0) return name + prop;
+        return name + " && " + name + prop;
       case p++:
         var name = getVarName();
-        var s = name + "." + getDotKey();
-        return canThrow && rng(20) == 0 ? s : name + " && " + s;
+        var prop = getDotKey();
+        if (SUPPORT.optional_chaining && rng(50) == 0) return name + "?." + prop;
+        if (canThrow && rng(20) == 0) return name + "." + prop;
+        return name + " && " + name + "." + prop;
       case p++:
       case p++:
         var name = getVarName();
@@ -1513,7 +1541,16 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
             name = rng(3) == 0 ? getVarName() : "f" + rng(funcs + 2);
         } while (name in called && !called[name]);
         called[name] = true;
-        return mayDefer("typeof " + name + ' == "function" && --_calls_ >= 0 && ' + name + createArgs(recurmax, stmtDepth, canThrow));
+        var args = createArgs(recurmax, stmtDepth, canThrow);
+        var call = "typeof " + name + ' == "function" && --_calls_ >= 0 && ' + name + args;
+        if (canThrow) {
+            if (SUPPORT.optional_chaining && args[0] != "`" && rng(50) == 0) {
+                call = "--_calls_ >= 0 && " + name + "?." + args;
+            } else if (rng(20) == 0) {
+                call = "--_calls_ >= 0 && " + name + args;
+            }
+        }
+        return mayDefer(call);
     }
     _createExpression.N = p;
     return _createExpression(recurmax, noComma, stmtDepth, canThrow);
@@ -1598,6 +1635,10 @@ var KEYS = [
     "1.5",
     "3",
 ].concat(SAFE_KEYS);
+SAFE_KEYS = SAFE_KEYS.concat(SAFE_KEYS);
+SAFE_KEYS = SAFE_KEYS.concat(SAFE_KEYS);
+SAFE_KEYS = SAFE_KEYS.concat(SAFE_KEYS);
+SAFE_KEYS.push("__proto__");
 
 function getDotKey(assign) {
     var key;
@@ -1692,6 +1733,8 @@ function createObjectFunction(recurmax, stmtDepth, canThrow, internal, isClazz)
         fn = function(defns) {
             if (generator) name = "*" + name;
             if (async) name = "async "+ name;
+            var save_allow = allow_this;
+            if (internal == "super") allow_this = false;
             s = [
                 name + "(" + createParams(save_async, save_generator, NO_DUPLICATE) + "){",
                 strictMode(),
@@ -1699,6 +1742,7 @@ function createObjectFunction(recurmax, stmtDepth, canThrow, internal, isClazz)
             ];
             s.push(_createStatements(2, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CANNOT_RETURN, stmtDepth));
             if (internal == "super") s.push("super" + createArgs(recurmax, stmtDepth, canThrow, NO_TEMPLATE) + ";");
+            allow_this = save_allow;
             if (/^(constructor|super)$/.test(internal) || rng(10) == 0) for (var i = rng(4); --i >= 0;) {
                 s.push(rng(2) ? createSuperAssignment(recurmax, stmtDepth, canThrow) : createThisAssignment(recurmax, stmtDepth, canThrow));
             }
@@ -1715,8 +1759,9 @@ function createObjectFunction(recurmax, stmtDepth, canThrow, internal, isClazz)
 
 function createObjectLiteral(recurmax, stmtDepth, canThrow) {
     recurmax--;
-    var obj = ["({"];
+    var obj = [ "({" ];
     var offset = SUPPORT.spread_object ? 0 : SUPPORT.computed_key ? 2 : 4;
+    var has_proto = false;
     for (var i = rng(6); --i >= 0;) switch (offset + rng(50 - offset)) {
       case 0:
         obj.push("..." + getVarName() + ",");
@@ -1732,7 +1777,12 @@ function createObjectLiteral(recurmax, stmtDepth, canThrow) {
         obj.push(createObjectFunction(recurmax, stmtDepth, canThrow) + ",");
         break;
       default:
-        obj.push(createObjectKey(recurmax, stmtDepth, canThrow) + ": " + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + ",");
+        if (has_proto || rng(200)) {
+            obj.push(createObjectKey(recurmax, stmtDepth, canThrow) + ": " + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + ",");
+        } else {
+            obj.push("__proto__: " + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + " || {},");
+            has_proto = true;
+        }
         break;
     }
     obj.push("})");
@@ -1775,7 +1825,7 @@ function createClassLiteral(recurmax, stmtDepth, canThrow, name) {
         if (SUPPORT.class_field && rng(2)) {
             s += internal || createObjectKey(recurmax, stmtDepth, canThrow);
             if (rng(5)) {
-                async = false;
+                async = bug_async_class_await && fixed && 0;
                 generator = false;
                 s += " = " + createExpression(recurmax, NO_COMMA, stmtDepth, fixed ? canThrow : CANNOT_THROW);
                 generator = save_generator;
@@ -1929,7 +1979,7 @@ function createValue() {
     var v;
     do {
         v = VALUES[rng(VALUES.length)];
-    } while (v == "new.target" && rng(200));
+    } while (v == "new.target" && rng(200) || !allow_this && v == "this");
     return v;
 }
 
@@ -1979,7 +2029,7 @@ function isBannedKeyword(name) {
       case "arguments":
         return in_class;
       case "await":
-        return async;
+        return async !== false;
       case "yield":
         return generator || in_class;
     }
@@ -2024,6 +2074,7 @@ function createVarName(maybe, dontStore) {
 if (require.main !== module) {
     exports.createTopLevelCode = createTopLevelCode;
     exports.num_iterations = num_iterations;
+    exports.verbose = verbose;
     return;
 }
 
@@ -2202,8 +2253,7 @@ function log(options) {
 function sort_globals(code) {
     var globals = run_code("throw Object.keys(this).sort(" + function(global) {
         return function(m, n) {
-            return (n == "toString") - (m == "toString")
-                || (typeof global[n] == "function") - (typeof global[m] == "function")
+            return (typeof global[n] == "function") - (typeof global[m] == "function")
                 || (m < n ? -1 : m > n ? 1 : 0);
         };
     } + "(this));" + code);
@@ -2253,7 +2303,7 @@ function is_error_in(ex) {
 }
 
 function is_error_spread(ex) {
-    return ex.name == "TypeError" && /Found non-callable @@iterator| is not iterable| is not a function/.test(ex.message);
+    return ex.name == "TypeError" && /Found non-callable @@iterator| is not iterable| not a function/.test(ex.message);
 }
 
 function is_error_recursion(ex) {
@@ -2372,6 +2422,8 @@ if (SUPPORT.arrow && SUPPORT.async && SUPPORT.rest && typeof sandbox.run_code("a
         return ex.name == "SyntaxError" && ex.message == "Rest parameter must be last formal parameter";
     };
 }
+var bug_async_class_await = SUPPORT.async && SUPPORT.class_field && typeof sandbox.run_code("var await; async function f() { class A { static p = await; } }") != "string";
+var bug_for_of_async = SUPPORT.for_await_of && typeof sandbox.run_code("var async; for (async of []);") != "string";
 var bug_for_of_var = SUPPORT.for_of && SUPPORT.let && typeof sandbox.run_code("try {} catch (e) { for (var e of []); }") != "string";
 if (SUPPORT.destructuring && typeof sandbox.run_code("console.log([ 1 ], {} = 2);") != "string") {
     beautify_options.output.v8 = true;

tools/node.js

@@ -56,6 +56,9 @@ if (+process.env["UGLIFY_BUG_REPORT"]) exports.minify = function(files, options)
 
 function describe_ast() {
     var out = OutputStream({ beautify: true });
+    doitem(AST_Node);
+    return out.get() + "\n";
+
     function doitem(ctor) {
         out.print("AST_" + ctor.TYPE);
         var props = ctor.SELF_PROPS.filter(function(prop) {
@@ -86,9 +89,7 @@ function describe_ast() {
                 });
             });
         }
-    };
-    doitem(AST_Node);
-    return out + "\n";
+    }
 }
 
 function infer_options(options) {