harmony-v3.0.23

... by teaching `collapse_vars` some new tricks.

fixes #2187

README.md

@@ -1,11 +1,11 @@
 uglify-es
 =========
 
-**uglify-es** is an ECMAScript 2015 parser, minifier, compressor and beautifier toolkit.
+**uglify-es** is an ECMAScript parser, minifier, compressor and beautifier toolkit for ES6+.
 
 #### Note:
-- **The `uglify-es` API and CLI is compatible with `uglify-js@3.x`.**
-- **`uglify-es` is not backwards compatible with the `uglify-js@2.x` API and CLI.**
+- **`uglify-es` is API/CLI compatible with `uglify-js@3`.**
+- **`uglify-es` is not backwards compatible with `uglify-js@2`.**
 
 Install
 -------
@@ -102,13 +102,14 @@ a double dash to prevent input files being used as option arguments:
                                 sequences.
     --config-file <file>        Read `minify()` options from JSON file.
     -d, --define <expr>[=value] Global definitions.
+    --ecma <version>            Specifiy ECMAScript release: 5, 6, 7 or 8.
     --ie8                       Support non-standard Internet Explorer 8.
                                 Equivalent to setting `ie8: true` in `minify()`
                                 for `compress`, `mangle` and `output` options.
                                 By default UglifyJS will not try to be IE-proof.
     --keep-fnames               Do not mangle/drop function names.  Useful for
                                 code relying on Function.prototype.name.
-    --name-cache                File to hold mangled name mappings.
+    --name-cache <file>         File to hold mangled name mappings.
     --self                      Build UglifyJS as a library (implies --wrap UglifyJS)
     --source-map [options]      Enable source map/specify source map options:
                                 `base`  Path to compute relative paths from input files.
@@ -380,7 +381,47 @@ var code = {
 var options = { toplevel: true };
 var result = UglifyJS.minify(code, options);
 console.log(result.code);
-// console.log(function(n,o){return n+o}(3,7));
+// console.log(3+7);
+```
+
+The `nameCache` option:
+```javascript
+var options = {
+    mangle: {
+        toplevel: true,
+    },
+    nameCache: {}
+};
+var result1 = UglifyJS.minify({
+    "file1.js": "function add(first, second) { return first + second; }"
+}, options);
+var result2 = UglifyJS.minify({
+    "file2.js": "console.log(add(1 + 2, 3 + 4));"
+}, options);
+console.log(result1.code);
+// function n(n,r){return n+r}
+console.log(result2.code);
+// console.log(n(3,7));
+```
+
+You may persist the name cache to the file system in the following way:
+```javascript
+var cacheFileName = "/tmp/cache.json";
+var options = {
+    mangle: {
+        properties: true,
+    },
+    nameCache: JSON.parse(fs.readFileSync(cacheFileName, "utf8"))
+};
+fs.writeFileSync("part1.js", UglifyJS.minify({
+    "file1.js": fs.readFileSync("file1.js", "utf8"),
+    "file2.js": fs.readFileSync("file2.js", "utf8")
+}, options).code, "utf8");
+fs.writeFileSync("part2.js", UglifyJS.minify({
+    "file3.js": fs.readFileSync("file3.js", "utf8"),
+    "file4.js": fs.readFileSync("file4.js", "utf8")
+}, options).code, "utf8");
+fs.writeFileSync(cacheFileName, JSON.stringify(options.nameCache), "utf8");
 ```
 
 An example of a combination of `minify()` options:
@@ -433,6 +474,9 @@ if (result.error) throw result.error;
 
 ## Minify options
 
+- `ecma` (default `undefined`) - pass `5`, `6`, `7` or `8` to override `parse`,
+  `compress` and `output` options.
+
 - `warnings` (default `false`) — pass `true` to return compressor warnings
   in `result.warnings`. Use the value `"verbose"` for more detailed warnings.
 
@@ -458,13 +502,19 @@ if (result.error) throw result.error;
 - `toplevel` (default `false`) - set to `true` if you wish to enable top level
   variable and function name mangling and to drop unused variables and functions.
 
+- `nameCache` (default `null`) - pass an empty object `{}` or a previously
+  used `nameCache` object if you wish to cache mangled variable and
+  property names across multiple invocations of `minify()`. Note: this is
+  a read/write property. `minify()` will read the name cache state of this
+  object and update it during minification so that it may be
+  reused or externally persisted by the user.
+
 - `ie8` (default `false`) - set to `true` to support IE8.
 
 ## Minify options structure
 
 ```javascript
 {
-    warnings: false,
     parse: {
         // parse options
     },
@@ -484,8 +534,11 @@ if (result.error) throw result.error;
     sourceMap: {
         // source map options
     },
+    ecma: 5, // specify one of: 5, 6, 7 or 8
+    nameCache: null, // or specify a name cache object
     toplevel: false,
     ie8: false,
+    warnings: false,
 }
 ```
 
@@ -539,6 +592,9 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 ## Parse options
 
 - `bare_returns` (default `false`) -- support top level `return` statements
+- `ecma` (default: `8`) -- specify one of `5`, `6`, `7` or `8`. Note: this setting
+  is not presently enforced except for ES8 optional trailing commas in function
+  parameter lists and calls with `ecma` `8`.
 - `html5_comments` (default `true`)
 - `shebang` (default `true`) -- support `#!command` as the first line
 
@@ -590,6 +646,10 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 
 - `evaluate` -- attempt to evaluate constant expressions
 
+- `arrows` (default `true`) -- convert ES5 style anonymous function expressions
+  to arrow functions if permissible by language semantics.
+  Note: `arrows` requires that the `ecma` compress option is set to `6` or greater.
+
 - `booleans` -- various optimizations for boolean context, for example `!!a
   ? b : c → a ? b : c`
 
@@ -678,6 +738,9 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
   annotation `/*@__PURE__*/` or `/*#__PURE__*/` immediately precedes the call. For
   example: `/*@__PURE__*/foo();`
 
+- `ecma` -- default `5`. Pass `6` or greater to enable `compress` options that
+  will transform ES5 code into smaller ES6+ equivalent forms.
+
 ## Mangle options
 
 - `reserved` (default `[]`). Pass an array of identifiers that should be
@@ -686,6 +749,8 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 - `toplevel` (default `false`). Pass `true` to mangle names declared in the
   top level scope.
 
+- `keep_classnames` (default `false`).  Pass `true` to not mangle class names.
+
 - `keep_fnames` (default `false`).  Pass `true` to not mangle function names.
   Useful for code relying on `Function.prototype.name`. See also: the `keep_fnames`
   [compress option](#compress-options).
@@ -749,9 +814,12 @@ can pass additional arguments that control the code output:
 - `comments` (default `false`) -- pass `true` or `"all"` to preserve all
   comments, `"some"` to preserve some comments, a regular expression string
   (e.g. `/^!/`) or a function.
-- `ecma` (default `5`) -- set output printing mode.  This will only change the
-  output in direct control of the beautifier.  Non-compatible features in the
-  abstract syntax tree will still be outputted as is.
+- `ecma` (default `5`) -- set output printing mode. Set `ecma` to `6` or
+  greater to emit shorthand object properties - i.e.: `{a}` instead of `{a: a}`.
+  The `ecma` option will only change the output in direct control of the
+  beautifier. Non-compatible features in the abstract syntax tree will still
+  be output as is. For example: an `ecma` setting of `5` will **not** convert
+  ES6+ code to ES5.
 - `indent_level` (default 4)
 - `indent_start` (default 0) -- prefix all lines by that many spaces
 - `inline_script` (default `false`) -- escape the slash in occurrences of

bin/uglifyjs

@@ -44,6 +44,7 @@ program.option("-o, --output <file>", "Output file (default STDOUT).");
 program.option("--comments [filter]", "Preserve copyright comments in the output.");
 program.option("--config-file <file>", "Read minify() options from JSON file.");
 program.option("-d, --define <expr>[=value]", "Global definitions.", parse_js("define"));
+program.option("--ecma <version>", "Specifiy ECMAScript release: 5, 6, 7 or 8.");
 program.option("--ie8", "Support non-standard Internet Explorer 8.");
 program.option("--keep-fnames", "Do not mangle/drop function names. Useful for code relying on Function.prototype.name.");
 program.option("--name-cache <file>", "File to hold mangled name mappings.");
@@ -73,6 +74,10 @@ if (!program.output && program.sourceMap && program.sourceMap.url != "inline") {
         options[name] = program[name];
     }
 });
+if ("ecma" in program) {
+    if (program.ecma != (program.ecma | 0)) fatal("ERROR: ecma must be an integer");
+    options.ecma = program.ecma | 0;
+}
 if (program.beautify) {
     options.output = typeof program.beautify == "object" ? program.beautify : {};
     if (!("beautify" in options.output)) {
@@ -106,17 +111,8 @@ if (program.mangleProps) {
     if (typeof options.mangle != "object") options.mangle = {};
     options.mangle.properties = program.mangleProps;
 }
-var cache;
 if (program.nameCache) {
-    cache = JSON.parse(read_file(program.nameCache, "{}"));
-    if (options.mangle) {
-        if (typeof options.mangle != "object") options.mangle = {};
-        options.mangle.cache = to_cache("vars");
-        if (options.mangle.properties) {
-            if (typeof options.mangle.properties != "object") options.mangle.properties = {};
-            options.mangle.properties.cache = to_cache("props");
-        }
-    }
+    options.nameCache = JSON.parse(read_file(program.nameCache, "{}"));
 }
 if (program.output == "ast") {
     options.output = {
@@ -266,9 +262,7 @@ function run() {
         print(result.code);
     }
     if (program.nameCache) {
-        fs.writeFileSync(program.nameCache, JSON.stringify(cache, function(key, value) {
-            return value instanceof UglifyJS.Dictionary ? value.toObject() : value;
-        }));
+        fs.writeFileSync(program.nameCache, JSON.stringify(options.nameCache));
     }
     if (result.timings) for (var phase in result.timings) {
         print_error("- " + phase + ": " + result.timings[phase].toFixed(3) + "s");
@@ -381,18 +375,6 @@ function parse_source_map() {
     }
 }
 
-function to_cache(key) {
-    if (cache[key]) {
-        cache[key].props = UglifyJS.Dictionary.fromObject(cache[key].props);
-    } else {
-        cache[key] = {
-            cname: -1,
-            props: new UglifyJS.Dictionary()
-        };
-    }
-    return cache[key];
-}
-
 function skip_key(key) {
     return skip_keys.indexOf(key) >= 0;
 }

lib/ast.js

@@ -345,7 +345,7 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
 var AST_Expansion = DEFNODE("Expansion", "expression", {
     $documentation: "An expandible argument, such as ...rest, a splat, such as [1,2,...all], or an expansion in a variable declaration, such as var [first, ...rest] = list",
     $propdoc: {
-        expression: "AST_Symbol the thing to be expanded"
+        expression: "[AST_Node] the thing to be expanded"
     },
     _walk: function(visitor) {
         var self = this;
@@ -446,7 +446,7 @@ var AST_PrefixedTemplateString = DEFNODE("PrefixedTemplateString", "template_str
 var AST_TemplateString = DEFNODE("TemplateString", "segments", {
     $documentation: "A template string literal",
     $propdoc: {
-        segments: "[AST_TemplateSegment|AST_Expression]* One or more segments, starting with AST_TemplateSegment. AST_Expression may follow AST_TemplateSegment, but each AST_Expression must be followed by AST_TemplateSegment."
+        segments: "[AST_Node*] One or more segments, starting with AST_TemplateSegment. AST_Node may follow AST_TemplateSegment, but each AST_Node must be followed by AST_TemplateSegment."
     },
     _walk: function(visitor) {
         return visitor._visit(this, function(){
@@ -629,11 +629,11 @@ var AST_Const = DEFNODE("Const", null, {
     $documentation: "A `const` statement"
 }, AST_Definitions);
 
-var AST_NameImport = DEFNODE("NameImport", "foreign_name name", {
-    $documentation: "The part of the import statement that imports names from a module.",
+var AST_NameMapping = DEFNODE("NameMapping", "foreign_name name", {
+    $documentation: "The part of the export/import statement that declare names from a module.",
     $propdoc: {
-        foreign_name: "[AST_SymbolImportForeign] The name being imported (as specified in the module)",
-        name: "[AST_SymbolImport] The name as it becomes available to this module."
+        foreign_name: "[AST_SymbolExportForeign|AST_SymbolImportForeign] The name being exported/imported (as specified in the module)",
+        name: "[AST_SymbolExport|AST_SymbolImport] The name as it is visible to this module."
     },
     _walk: function (visitor) {
         return visitor._visit(this, function() {
@@ -647,7 +647,7 @@ var AST_Import = DEFNODE("Import", "imported_name imported_names module_name", {
     $documentation: "An `import` statement",
     $propdoc: {
         imported_name: "[AST_SymbolImport] The name of the variable holding the module's default export.",
-        imported_names: "[AST_NameImport*] The names of non-default imported variables",
+        imported_names: "[AST_NameMapping*] The names of non-default imported variables",
         module_name: "[AST_String] String literal describing where this module came from",
     },
     _walk: function(visitor) {
@@ -656,7 +656,7 @@ var AST_Import = DEFNODE("Import", "imported_name imported_names module_name", {
                 this.imported_name._walk(visitor);
             }
             if (this.imported_names) {
-                this.imported_names.forEach(function (name_import) {
+                this.imported_names.forEach(function(name_import) {
                     name_import._walk(visitor);
                 });
             }
@@ -670,7 +670,7 @@ var AST_Export = DEFNODE("Export", "exported_definition exported_value is_defaul
     $propdoc: {
         exported_definition: "[AST_Defun|AST_Definitions|AST_DefClass?] An exported definition",
         exported_value: "[AST_Node?] An exported value",
-        exported_names: "[AST_NameImport*?] List of exported names",
+        exported_names: "[AST_NameMapping*?] List of exported names",
         module_name: "[AST_String?] Name of the file to load exports from",
         is_default: "[Boolean] Whether this is the default exported value of this module"
     },
@@ -682,6 +682,14 @@ var AST_Export = DEFNODE("Export", "exported_definition exported_value is_defaul
             if (this.exported_value) {
                 this.exported_value._walk(visitor);
             }
+            if (this.exported_names) {
+                this.exported_names.forEach(function(name_export) {
+                    name_export._walk(visitor);
+                });
+            }
+            if (this.module_name) {
+                this.module_name._walk(visitor);
+            }
         });
     }
 }, AST_Statement);
@@ -996,7 +1004,7 @@ var AST_SymbolCatch = DEFNODE("SymbolCatch", null, {
 }, AST_SymbolBlockDeclaration);
 
 var AST_SymbolImport = DEFNODE("SymbolImport", null, {
-    $documentation: "Symbol refering to an imported name",
+    $documentation: "Symbol referring to an imported name",
 }, AST_SymbolBlockDeclaration);
 
 var AST_SymbolImportForeign = DEFNODE("SymbolImportForeign", null, {
@@ -1018,6 +1026,14 @@ var AST_SymbolRef = DEFNODE("SymbolRef", null, {
     $documentation: "Reference to some symbol (not definition/declaration)",
 }, AST_Symbol);
 
+var AST_SymbolExport = DEFNODE("SymbolExport", null, {
+    $documentation: "Symbol referring to a name to export",
+}, AST_SymbolRef);
+
+var AST_SymbolExportForeign = DEFNODE("SymbolExportForeign", null, {
+    $documentation: "A symbol exported from this module, but it is used in the other module, and its real name is irrelevant for this module's purposes",
+}, AST_Symbol);
+
 var AST_LabelRef = DEFNODE("LabelRef", null, {
     $documentation: "Reference to a label symbol",
 }, AST_Symbol);

lib/compress.js

@@ -48,6 +48,7 @@ function Compressor(options, false_by_default) {
         return new Compressor(options, false_by_default);
     TreeTransformer.call(this, this.before, this.after);
     this.options = defaults(options, {
+        arrows        : !false_by_default,
         booleans      : !false_by_default,
         cascade       : !false_by_default,
         collapse_vars : !false_by_default,
@@ -93,12 +94,9 @@ function Compressor(options, false_by_default) {
     var global_defs = this.options["global_defs"];
     if (typeof global_defs == "object") for (var key in global_defs) {
         if (/^@/.test(key) && HOP(global_defs, key)) {
-            var ast = parse(global_defs[key]);
-            if (ast.body.length == 1 && ast.body[0] instanceof AST_SimpleStatement) {
-                global_defs[key.slice(1)] = ast.body[0].body;
-            } else throw new Error(string_template("Can't handle expression: {value}", {
-                value: global_defs[key]
-            }));
+            global_defs[key.slice(1)] = parse(global_defs[key], {
+                expression: true
+            });
         }
     }
     var pure_funcs = this.options["pure_funcs"];
@@ -125,13 +123,13 @@ function Compressor(options, false_by_default) {
         };
     }
     var toplevel = this.options["toplevel"];
-    if (typeof toplevel == "string") {
-        this.toplevel.funcs = /funcs/.test(toplevel);
-        this.toplevel.vars = /vars/.test(toplevel);
-    } else {
-        this.toplevel = toplevel ? return_true : return_false;
-        this.toplevel.funcs = this.toplevel.vars = toplevel;
-    }
+    this.toplevel = typeof toplevel == "string" ? {
+        funcs: /funcs/.test(toplevel),
+        vars: /vars/.test(toplevel)
+    } : {
+        funcs: toplevel,
+        vars: toplevel
+    };
     var sequences = this.options["sequences"];
     this.sequences_limit = sequences == 1 ? 800 : sequences | 0;
     this.warnings_produced = {};
@@ -140,11 +138,12 @@ function Compressor(options, false_by_default) {
 Compressor.prototype = new TreeTransformer;
 merge(Compressor.prototype, {
     option: function(key) { return this.options[key] },
-    toplevel: function(def) {
-        for (var i = 0, len = def.orig.length; i < len; i++)
+    exposed: function(def) {
+        if (def.export) return true;
+        if (def.global) for (var i = 0, len = def.orig.length; i < len; i++)
             if (!this.toplevel[def.orig[i] instanceof AST_SymbolDefun ? "funcs" : "vars"])
-                return false;
-        return true;
+                return true;
+        return false;
     },
     compress: function(node) {
         if (this.option("expression")) {
@@ -280,11 +279,11 @@ merge(Compressor.prototype, {
         var reduce_vars = rescan && compressor.option("reduce_vars");
         var safe_ids = Object.create(null);
         var suppressor = new TreeWalker(function(node) {
-            if (node instanceof AST_Symbol) {
-                var d = node.definition();
-                if (node instanceof AST_SymbolRef) d.references.push(node);
-                d.fixed = false;
-            }
+            if (!(node instanceof AST_Symbol)) return;
+            var d = node.definition();
+            if (!d) return;
+            if (node instanceof AST_SymbolRef) d.references.push(node);
+            d.fixed = false;
         });
         var tw = new TreeWalker(function(node, descend) {
             node._squeezed = false;
@@ -352,7 +351,7 @@ merge(Compressor.prototype, {
                 }
                 if (node instanceof AST_Defun) {
                     var d = node.name.definition();
-                    if (d.global && !compressor.toplevel(d) || safe_to_read(d)) {
+                    if (compressor.exposed(d) || safe_to_read(d)) {
                         d.fixed = false;
                     } else {
                         d.fixed = node;
@@ -364,7 +363,7 @@ merge(Compressor.prototype, {
                     safe_ids = save_ids;
                     return true;
                 }
-                if (node instanceof AST_Function || node instanceof AST_Arrow) {
+                if (is_func_expr(node)) {
                     push();
                     var iife;
                     if (!node.name
@@ -527,7 +526,7 @@ merge(Compressor.prototype, {
             def.escaped = false;
             if (def.scope.uses_eval) {
                 def.fixed = false;
-            } else if (!def.global || def.orig[0] instanceof AST_SymbolConst || compressor.toplevel(def)) {
+            } else if (def.orig[0] instanceof AST_SymbolConst || !compressor.exposed(def)) {
                 def.fixed = undefined;
             } else {
                 def.fixed = false;
@@ -557,8 +556,29 @@ merge(Compressor.prototype, {
         return fixed();
     });
 
+    AST_SymbolRef.DEFMETHOD("is_immutable", function() {
+        var orig = this.definition().orig;
+        return orig.length == 1 && orig[0] instanceof AST_SymbolLambda;
+    });
+
+    function is_func_expr(node) {
+        return node instanceof AST_Arrow || node instanceof AST_Function;
+    }
+
     function is_lhs_read_only(lhs) {
-        return lhs instanceof AST_SymbolRef && lhs.definition().orig[0] instanceof AST_SymbolLambda;
+        if (lhs instanceof AST_SymbolRef) return lhs.definition().orig[0] instanceof AST_SymbolLambda;
+        if (lhs instanceof AST_PropAccess) {
+            lhs = lhs.expression;
+            if (lhs instanceof AST_SymbolRef) {
+                if (lhs.is_immutable()) return false;
+                lhs = lhs.fixed_value();
+            }
+            if (!lhs) return true;
+            if (lhs instanceof AST_RegExp) return false;
+            if (lhs instanceof AST_Constant) return true;
+            return is_lhs_read_only(lhs);
+        }
+        return false;
     }
 
     function is_ref_of(ref, type) {
@@ -672,7 +692,9 @@ merge(Compressor.prototype, {
             node instanceof AST_DefClass ||
             node instanceof AST_Defun ||
             node instanceof AST_Let ||
-            node instanceof AST_Const
+            node instanceof AST_Const ||
+            node instanceof AST_Export ||
+            node instanceof AST_Import
         );
     }
 
@@ -727,15 +749,23 @@ merge(Compressor.prototype, {
             var candidates = [];
             var stat_index = statements.length;
             while (--stat_index >= 0) {
+                // Treat parameters as collapsible in IIFE, i.e.
+                //   function(a, b){ ... }(x());
+                // would be translated into equivalent assignments:
+                //   var a = x(), b = undefined;
+                if (stat_index == 0 && compressor.option("unused")) extract_args();
+                // Find collapsible assignments
                 extract_candidates(statements[stat_index]);
                 while (candidates.length > 0) {
                     var candidate = candidates.pop();
                     var lhs = get_lhs(candidate);
                     if (!lhs || is_lhs_read_only(lhs)) continue;
+                    // Locate symbols which may execute code outside of scanning range
                     var lvalues = get_lvalues(candidate);
                     if (lhs instanceof AST_SymbolRef) lvalues[lhs.name] = false;
                     var side_effects = value_has_side_effects(candidate);
-                    var hit = false, abort = false, replaced = false;
+                    var hit = candidate.name instanceof AST_SymbolFunarg;
+                    var abort = false, replaced = false;
                     var tt = new TreeTransformer(function(node, descend) {
                         if (abort) return node;
                         // Skip nodes before `candidate` as quickly as possible
@@ -777,7 +807,7 @@ merge(Compressor.prototype, {
                             }
                             if (candidate instanceof AST_VarDef) {
                                 var def = candidate.name.definition();
-                                if (def.references.length == 1 && (!def.global || compressor.toplevel(def))) {
+                                if (def.references.length == 1 && !compressor.exposed(def)) {
                                     return maintain_this_binding(parent, node, candidate.value);
                                 }
                                 return make_node(AST_Assign, candidate, {
@@ -818,6 +848,58 @@ merge(Compressor.prototype, {
                 }
             }
 
+            function has_overlapping_symbol(fn, arg) {
+                var found = false;
+                arg.walk(new TreeWalker(function(node) {
+                    if (found) return true;
+                    if (node instanceof AST_SymbolRef && fn.variables.has(node.name)) {
+                        var s = node.definition().scope;
+                        if (s !== scope) while (s = s.parent_scope) {
+                            if (s === scope) return true;
+                        }
+                        found = true;
+                    }
+                }));
+                return found;
+            }
+
+            function extract_args() {
+                var iife, fn = compressor.self();
+                if (is_func_expr(fn)
+                    && !fn.name
+                    && !fn.uses_arguments
+                    && !fn.uses_eval
+                    && (iife = compressor.parent()) instanceof AST_Call
+                    && iife.expression === fn
+                    && all(iife.args, function(arg) {
+                        return !(arg instanceof AST_Expansion);
+                    })) {
+                    fn.argnames.forEach(function(sym, i) {
+                        if (sym instanceof AST_Expansion) {
+                            var elements = iife.args.slice(i);
+                            if (all(elements, function(arg) {
+                                return !has_overlapping_symbol(fn, arg);
+                            })) {
+                                candidates.push(make_node(AST_VarDef, sym, {
+                                    name: sym.expression,
+                                    value: make_node(AST_Array, iife, {
+                                        elements: elements
+                                    })
+                                }));
+                            }
+                        } else {
+                            var arg = iife.args[i];
+                            if (!arg) arg = make_node(AST_Undefined, sym);
+                            else if (has_overlapping_symbol(fn, arg)) arg = null;
+                            if (arg) candidates.push(make_node(AST_VarDef, sym, {
+                                name: sym,
+                                value: arg
+                            }));
+                        }
+                    });
+                }
+            }
+
             function extract_candidates(expr) {
                 if (expr instanceof AST_Assign && !expr.left.has_side_effects(compressor)
                     || expr instanceof AST_Unary && (expr.operator == "++" || expr.operator == "--")) {
@@ -838,8 +920,8 @@ merge(Compressor.prototype, {
             function get_lhs(expr) {
                 if (expr instanceof AST_VarDef && expr.name instanceof AST_SymbolDeclaration) {
                     var def = expr.name.definition();
-                    if (def.orig.length > 1
-                        || def.references.length == 1 && (!def.global || compressor.toplevel(def))) {
+                    if (def.orig.length > 1 && !(expr.name instanceof AST_SymbolFunarg)
+                        || def.references.length == 1 && !compressor.exposed(def)) {
                         return make_node(AST_SymbolRef, expr.name, expr.name);
                     }
                 } else {
@@ -881,6 +963,19 @@ merge(Compressor.prototype, {
             }
 
             function remove_candidate(expr) {
+                if (expr.name instanceof AST_SymbolFunarg) {
+                    var iife = compressor.parent(), argnames = compressor.self().argnames;
+                    var index = argnames.indexOf(expr.name);
+                    if (index < 0) {
+                        iife.args.length = Math.min(iife.args.length, argnames.length - 1);
+                    } else {
+                        var args = iife.args;
+                        if (args[index]) args[index] = make_node(AST_Number, args[index], {
+                            value: 0
+                        });
+                    }
+                    return true;
+                }
                 var found = false;
                 return statements[stat_index].transform(new TreeTransformer(function(node, descend, in_list) {
                     if (found) return node;
@@ -1299,6 +1394,7 @@ merge(Compressor.prototype, {
             return false;
         });
         def(AST_Function, return_false);
+        def(AST_Arrow, return_false);
         def(AST_UnaryPostfix, return_false);
         def(AST_UnaryPrefix, function() {
             return this.operator == "void";
@@ -1328,6 +1424,7 @@ merge(Compressor.prototype, {
         def(AST_SymbolRef, function(pure_getters) {
             if (this.is_undefined) return true;
             if (!is_strict(pure_getters)) return false;
+            if (this.is_immutable()) return false;
             var fixed = this.fixed_value();
             return !fixed || fixed._throw_on_access(pure_getters);
         });
@@ -1571,9 +1668,6 @@ merge(Compressor.prototype, {
         def(AST_Lambda, function(){
             throw def;
         });
-        def(AST_Arrow, function() {
-            throw def;
-        });
         def(AST_Class, function() {
             throw def;
         });
@@ -1627,8 +1721,7 @@ merge(Compressor.prototype, {
               case "typeof":
                 // Function would be evaluated to an array and so typeof would
                 // incorrectly return 'object'. Hence making is a special case.
-                if (e instanceof AST_Function ||
-                    e instanceof AST_Arrow) return typeof function(){};
+                if (is_func_expr(e)) return typeof function(){};
 
                 e = ev(e, compressor);
 
@@ -1800,6 +1893,9 @@ merge(Compressor.prototype, {
         def(AST_Function, function(){
             return basic_negation(this);
         });
+        def(AST_Arrow, function(){
+            return basic_negation(this);
+        });
         def(AST_UnaryPrefix, function(){
             if (this.operator == "!")
                 return this.expression;
@@ -2042,7 +2138,7 @@ merge(Compressor.prototype, {
     });
 
     OPT(AST_Block, function(self, compressor){
-        if (!(self.body instanceof AST_Node)) tighten_body(self.body, compressor);
+        tighten_body(self.body, compressor);
         return self;
     });
 
@@ -2081,14 +2177,14 @@ merge(Compressor.prototype, {
         var var_defs_by_id = new Dictionary();
         var initializations = new Dictionary();
         var destructuring_value = null;
-        var in_definition = false;
         // pass 1: find out which symbols are directly used in
         // this scope (not in nested scopes).
         var scope = this;
         var tw = new TreeWalker(function(node, descend){
             if (node !== self) {
                 if (node instanceof AST_Defun || node instanceof AST_DefClass) {
-                    if (!drop_funcs && scope === self) {
+                    var in_export = tw.parent() instanceof AST_Export;
+                    if (in_export || !drop_funcs && scope === self) {
                         var node_def = node.name.definition();
                         if (node_def.global && !(node_def.id in in_use_ids)) {
                             in_use_ids[node_def.id] = true;
@@ -2099,15 +2195,16 @@ merge(Compressor.prototype, {
                     return true; // don't go in nested scopes
                 }
                 if (node instanceof AST_Definitions && scope === self) {
+                    var in_export = tw.parent() instanceof AST_Export;
                     node.definitions.forEach(function(def){
                         if (def.name instanceof AST_SymbolVar) {
                             var_defs_by_id.add(def.name.definition().id, def);
                         }
-                        if (!drop_vars) {
+                        if (in_export || !drop_vars) {
                             def.name.walk(new TreeWalker(function(node) {
                                 if (node instanceof AST_SymbolDeclaration) {
                                     var def = node.definition();
-                                    if (def.global && !(def.id in in_use_ids)) {
+                                    if ((in_export || def.global) && !(def.id in in_use_ids)) {
                                         in_use_ids[def.id] = true;
                                         in_use.push(def);
                                     }
@@ -2118,9 +2215,7 @@ merge(Compressor.prototype, {
                             if (def.name instanceof AST_Destructuring) {
                                 var destructuring_cache = destructuring_value;
                                 destructuring_value = def.value;
-                                in_definition = true;
                                 def.walk(tw);
-                                in_definition = false;
                                 destructuring_value = destructuring_cache;
                             } else {
                                 initializations.add(def.name.name, def.value);
@@ -2156,46 +2251,8 @@ merge(Compressor.prototype, {
                     scope = save_scope;
                     return true;
                 }
-                if (node instanceof AST_Destructuring) {
-                    if (!in_definition) {
-                        return true;
-                    }
-                    for (var i = 0; i < node.names.length; i++) {
-                        if (node.names[i] instanceof AST_Destructuring) {
-                            node.names[i].walk(tw);
-                        }
-                        else if (node.names[i] instanceof AST_Expansion) {
-                            if (node.names[i].expression instanceof AST_Symbol) {
-                                initializations.add(node.names[i].expression.name, destructuring_value);
-                            } else if (node.names[i].expression instanceof AST_Destructuring) {
-                                node.names[i].expression.walk(tw);
-                            } else {
-                                throw new Error(string_template("Can't handle expansion of type: {type}", {
-                                    type: Object.getPrototypeOf(node.names[i].expression).TYPE
-                                }));
-                            }
-                        }
-                        else if (node.names[i] instanceof AST_ObjectKeyVal) {
-                            if (typeof node.names[i].key === "string") {
-                                initializations.add(node.names[i].key, destructuring_value);
-                            }
-                        }
-                        else if (node.names[i] instanceof AST_Symbol) {
-                            initializations.add(node.names[i].name, destructuring_value);
-                        }
-                        else if (node.names[i] instanceof AST_DefaultAssign) {
-                            continue;
-                        }
-                        else if (node.names[i] instanceof AST_Hole) {
-                            continue;
-                        }
-                        else {
-                            throw new Error(string_template("Unknown destructuring element of type: {type}", {
-                                type: Object.getPrototypeOf(node.names[i]).TYPE
-                            }));
-                        }
-                    }
-                    return true;
+                if (node.destructuring && destructuring_value) {
+                    initializations.add(node.name, destructuring_value);
                 }
             }
         });
@@ -2224,11 +2281,8 @@ merge(Compressor.prototype, {
         // pass 3: we should drop declarations not in_use
         var tt = new TreeTransformer(
             function before(node, descend, in_list) {
-                var parent = tt.parent();
                 if (!compressor.option("keep_fnames")
-                    && ((node instanceof AST_Function || node instanceof AST_ClassExpression) && node.name
-                        || (node instanceof AST_Defun || node instanceof AST_DefClass)
-                            && parent instanceof AST_Export && parent.is_default)) {
+                    && node.name && (node instanceof AST_Function || node instanceof AST_ClassExpression)) {
                     var def = node.name.definition();
                     // any declarations with same name will overshadow
                     // name of this anonymous function and can therefore
@@ -2263,7 +2317,7 @@ merge(Compressor.prototype, {
                         }
                     }
                 }
-                if ((node instanceof AST_Defun || node instanceof AST_DefClass) && !(parent instanceof AST_Export) && node !== self) {
+                if ((node instanceof AST_Defun || node instanceof AST_DefClass) && node !== self) {
                     var keep = (node.name.definition().id in in_use_ids) || !drop_funcs && node.name.definition().global;
                     if (!keep) {
                         compressor[node.name.unreferenced() ? "warn" : "info"]("Dropping unused function {name} [{file}:{line},{col}]", template(node.name));
@@ -2271,6 +2325,7 @@ merge(Compressor.prototype, {
                     }
                     return node;
                 }
+                var parent = tt.parent();
                 if (node instanceof AST_Definitions
                     && !(parent instanceof AST_ForIn && parent.init === node)
                     && (drop_vars || !(parent instanceof AST_Toplevel) && !(node instanceof AST_Var))) {
@@ -2587,7 +2642,7 @@ merge(Compressor.prototype, {
         def(AST_This, return_null);
         def(AST_Call, function(compressor, first_in_statement){
             if (!this.has_pure_annotation(compressor) && compressor.pure_funcs(this)) {
-                if (this.expression instanceof AST_Function
+                if (is_func_expr(this.expression)
                     && (!this.expression.name || !this.expression.name.definition().references.length)) {
                     var node = this.clone();
                     node.expression.process_expression(false, compressor);
@@ -2691,6 +2746,9 @@ merge(Compressor.prototype, {
             if (expr) merge_sequence(expressions, expr);
             return make_sequence(this, expressions);
         });
+        def(AST_Expansion, function(compressor, first_in_statement){
+            return this.expression.drop_side_effect_free(compressor, first_in_statement);
+        });
     })(function(node, func){
         node.DEFMETHOD("drop_side_effect_free", func);
     });
@@ -3106,15 +3164,31 @@ merge(Compressor.prototype, {
     OPT(AST_Call, function(self, compressor){
         var exp = self.expression;
         var fn = exp;
+        var simple_args = all(self.args, function(arg) {
+            return !(arg instanceof AST_Expansion);
+        });
         if (compressor.option("unused")
-            && (fn instanceof AST_Function
+            && simple_args
+            && (is_func_expr(fn)
                 || compressor.option("reduce_vars")
                     && fn instanceof AST_SymbolRef
-                    && (fn = fn.fixed_value()) instanceof AST_Function)
+                    && is_func_expr(fn = fn.fixed_value()))
             && !fn.uses_arguments
             && !fn.uses_eval) {
             var pos = 0, last = 0;
             for (var i = 0, len = self.args.length; i < len; i++) {
+                if (fn.argnames[i] instanceof AST_Expansion) {
+                    if (fn.argnames[i].expression.__unused) while (i < len) {
+                        var node = self.args[i++].drop_side_effect_free(compressor);
+                        if (node) {
+                            self.args[pos++] = node;
+                        }
+                    } else while (i < len) {
+                        self.args[pos++] = self.args[i++];
+                    }
+                    last = pos;
+                    break;
+                }
                 var trim = i >= fn.argnames.length;
                 if (trim || fn.argnames[i].__unused) {
                     var node = self.args[i].drop_side_effect_free(compressor);
@@ -3272,7 +3346,7 @@ merge(Compressor.prototype, {
             if (self.args.length == 0) return make_node(AST_Function, self, {
                 argnames: [],
                 body: []
-            });
+            }).optimize(compressor);
             if (all(self.args, function(x) {
                 return x instanceof AST_String;
             })) {
@@ -3280,7 +3354,7 @@ merge(Compressor.prototype, {
                 //   https://github.com/mishoo/UglifyJS2/issues/203
                 // if the code argument is a constant, then we can minify it.
                 try {
-                    var code = "NaN(function(" + self.args.slice(0, -1).map(function(arg) {
+                    var code = "n(function(" + self.args.slice(0, -1).map(function(arg) {
                         return arg.value;
                     }).join(",") + "){" + self.args[self.args.length - 1].value + "})";
                     var ast = parse(code);
@@ -3289,27 +3363,36 @@ merge(Compressor.prototype, {
                     var comp = new Compressor(compressor.options);
                     ast = ast.transform(comp);
                     ast.figure_out_scope(mangle);
-                    ast.mangle_names();
+                    base54.reset();
+                    ast.compute_char_frequency(mangle);
+                    ast.mangle_names(mangle);
                     var fun;
                     ast.walk(new TreeWalker(function(node) {
                         if (fun) return true;
-                        if (node instanceof AST_Lambda) {
+                        if (is_func_expr(node)) {
                             fun = node;
                             return true;
                         }
                     }));
-                    var args = fun.argnames.map(function(arg, i) {
-                        return make_node(AST_String, self.args[i], {
-                            value: arg.print_to_string()
-                        });
-                    });
+                    if (fun.body instanceof AST_Node) {
+                        fun.body = [
+                            make_node(AST_Return, fun.body, {
+                                value: fun.body
+                            })
+                        ];
+                    }
                     var code = OutputStream();
                     AST_BlockStatement.prototype._codegen.call(fun, fun, code);
-                    code = code.toString().replace(/^\{|\}$/g, "");
-                    args.push(make_node(AST_String, self.args[self.args.length - 1], {
-                        value: code
-                    }));
-                    self.args = args;
+                    self.args = [
+                        make_node(AST_String, self, {
+                            value: fun.argnames.map(function(arg) {
+                                return arg.print_to_string();
+                            }).join(",")
+                        }),
+                        make_node(AST_String, self.args[self.args.length - 1], {
+                            value: code.get().replace(/^\{|\}$/g, "")
+                        })
+                    ];
                     return self;
                 } catch (ex) {
                     if (ex instanceof JS_Parse_Error) {
@@ -3321,85 +3404,67 @@ merge(Compressor.prototype, {
                 }
             }
         }
-        var stat = fn instanceof AST_Function && fn.body[0];
+        var stat = is_func_expr(fn) && fn.body;
+        if (stat instanceof AST_Node) {
+            stat = make_node(AST_Return, stat, {
+                value: stat
+            });
+        } else if (stat) {
+            stat = stat[0];
+        }
         if (compressor.option("inline") && stat instanceof AST_Return) {
             var value = stat.value;
             if (!value || value.is_constant_expression()) {
                 var args = self.args.concat(value || make_node(AST_Undefined, self));
-                return make_sequence(self, args).transform(compressor);
+                return make_sequence(self, args).optimize(compressor);
             }
         }
-        if (exp instanceof AST_Function && !exp.is_generator && !exp.async) {
+        if (is_func_expr(exp) && !exp.is_generator && !exp.async) {
             if (compressor.option("inline")
+                && simple_args
                 && !exp.name
-                && exp.body.length == 1
                 && !exp.uses_arguments
                 && !exp.uses_eval
+                && (exp.body instanceof AST_Node || exp.body.length == 1)
+                && all(exp.argnames, function(arg) {
+                    if (arg instanceof AST_Expansion) return arg.expression.__unused;
+                    return arg.__unused;
+                })
                 && !self.has_pure_annotation(compressor)) {
                 var value;
                 if (stat instanceof AST_Return) {
-                    value = stat.value.clone(true);
+                    value = stat.value;
                 } else if (stat instanceof AST_SimpleStatement) {
                     value = make_node(AST_UnaryPrefix, stat, {
                         operator: "void",
-                        expression: stat.body.clone(true)
+                        expression: stat.body
                     });
                 }
                 if (value) {
-                    var fn = exp.clone();
-                    fn.argnames = [];
-                    fn.body = [];
-                    if (exp.argnames.length > 0) {
-                        fn.body.push(make_node(AST_Var, self, {
-                            definitions: exp.argnames.map(function(sym, i) {
-                                var arg = self.args[i];
-                                return make_node(AST_VarDef, sym, {
-                                    name: sym,
-                                    value: arg ? arg.clone(true) : make_node(AST_Undefined, self)
-                                });
-                            })
-                        }));
-                    }
-                    if (self.args.length > exp.argnames.length) {
-                        fn.body.push(make_node(AST_SimpleStatement, self, {
-                            body: make_sequence(self, self.args.slice(exp.argnames.length).map(function(node) {
-                                return node.clone(true);
-                            }))
-                        }));
-                    }
-                    fn.body.push(make_node(AST_Return, self, {
-                        value: value
-                    }));
-                    var body = fn.transform(compressor).body;
-                    if (body.length == 0) return make_node(AST_Undefined, self);
-                    if (body.length == 1 && body[0] instanceof AST_Return) {
-                        value = body[0].value;
-                        if (!value) return make_node(AST_Undefined, self);
-                        var tw = new TreeWalker(function(node) {
-                            if (value === self) return true;
-                            if (node instanceof AST_SymbolRef) {
-                                var ref = node.scope.find_variable(node);
-                                if (ref && ref.scope.parent_scope === fn.parent_scope) {
-                                    value = self;
-                                    return true;
-                                }
-                            }
-                            if (node instanceof AST_This && !tw.find_parent(AST_Scope)) {
-                                value = self;
+                    var tw = new TreeWalker(function(node) {
+                        if (!value) return true;
+                        if (node instanceof AST_SymbolRef) {
+                            var ref = node.scope.find_variable(node);
+                            if (ref && ref.scope.parent_scope === fn.parent_scope) {
+                                value = null;
                                 return true;
                             }
-                        });
-                        value.walk(tw);
-                        if (value !== self) value = best_of(compressor, value, self);
-                    } else {
-                        value = self;
-                    }
-                    if (value !== self) return value;
+                        }
+                        if (node instanceof AST_This && !tw.find_parent(AST_Scope)) {
+                            value = null;
+                            return true;
+                        }
+                    });
+                    value.walk(tw);
+                }
+                if (value) {
+                    var args = self.args.concat(value);
+                    return make_sequence(self, args).optimize(compressor);
                 }
             }
-            if (compressor.option("side_effects") && all(exp.body, is_empty)) {
+            if (compressor.option("side_effects") && !(exp.body instanceof AST_Node) && all(exp.body, is_empty)) {
                 var args = self.args.concat(make_node(AST_Undefined, self));
-                return make_sequence(self, args).transform(compressor);
+                return make_sequence(self, args).optimize(compressor);
             }
         }
         if (compressor.option("drop_console")) {
@@ -3532,6 +3597,8 @@ merge(Compressor.prototype, {
                         || cdr instanceof AST_PropAccess
                         || cdr instanceof AST_Unary && !unary_side_effects(cdr.operator)) {
                         field = "expression";
+                    } else if (cdr instanceof AST_Conditional) {
+                        field = "condition";
                     } else {
                         expressions[++i] = expressions[j];
                         break;
@@ -4039,6 +4106,10 @@ merge(Compressor.prototype, {
         return self;
     });
 
+    OPT(AST_SymbolExport, function(self, compressor){
+        return self;
+    });
+
     OPT(AST_SymbolRef, function(self, compressor){
         var def = self.resolve_defines(compressor);
         if (def) {
@@ -4062,15 +4133,15 @@ merge(Compressor.prototype, {
             var d = self.definition();
             var fixed = self.fixed_value();
             if (fixed instanceof AST_Defun) {
-                d.fixed = fixed = make_node(AST_Function, fixed, fixed).clone(true);
+                d.fixed = fixed = make_node(AST_Function, fixed, fixed);
             }
             if (compressor.option("unused")
-                && fixed instanceof AST_Function
+                && is_func_expr(fixed)
                 && d.references.length == 1
                 && !(d.scope.uses_arguments && d.orig[0] instanceof AST_SymbolFunarg)
                 && !d.scope.uses_eval
                 && compressor.find_parent(AST_Scope) === fixed.parent_scope) {
-                return fixed;
+                return fixed.clone(true);
             }
             if (compressor.option("evaluate") && fixed) {
                 if (d.should_replace === undefined) {
@@ -4093,7 +4164,7 @@ merge(Compressor.prototype, {
                         }
                         var name_length = d.name.length;
                         var overhead = 0;
-                        if (compressor.option("unused") && (!d.global || compressor.toplevel(d))) {
+                        if (compressor.option("unused") && !compressor.exposed(d)) {
                             overhead = (name_length + 2 + value_length) / d.references.length;
                         }
                         d.should_replace = value_length <= name_length + overhead ? fn : false;
@@ -4504,13 +4575,37 @@ merge(Compressor.prototype, {
     });
 
     OPT(AST_Arrow, function(self, compressor){
-        if (self.body.length === 1 && self.body[0] instanceof AST_Return) {
+        if (!(self.body instanceof AST_Node)) tighten_body(self.body, compressor);
+        if (compressor.option("arrows")
+            && self.body.length == 1
+            && self.body[0] instanceof AST_Return) {
             var value = self.body[0].value;
             self.body = value ? value : [];
         }
         return self;
     });
 
+    OPT(AST_Function, function(self, compressor){
+        tighten_body(self.body, compressor);
+        if (compressor.option("arrows")
+            && compressor.option("ecma") >= 6
+            && !self.name
+            && !self.is_generator
+            && !self.uses_arguments
+            && !self.uses_eval) {
+            var has_special_symbol = false;
+            self.walk(new TreeWalker(function(node) {
+                if (has_special_symbol) return true;
+                if (node instanceof AST_Symbol && !node.definition()) {
+                    has_special_symbol = true;
+                    return true;
+                }
+            }));
+            if (!has_special_symbol) return make_node(AST_Arrow, self, self).optimize(compressor);
+        }
+        return self;
+    });
+
     OPT(AST_Class, function(self, compressor){
         // HACK to avoid compress failure.
         // AST_Class is not really an AST_Scope/AST_Block as it lacks a body.

lib/minify.js

@@ -27,14 +27,33 @@ function set_shorthand(name, options, keys) {
     }
 }
 
+function init_cache(cache) {
+    if (!cache) return;
+    if (!("cname" in cache)) cache.cname = -1;
+    if (!("props" in cache)) {
+        cache.props = new Dictionary();
+    } else if (!(cache.props instanceof Dictionary)) {
+        cache.props = Dictionary.fromObject(cache.props);
+    }
+}
+
+function to_json(cache) {
+    return {
+        cname: cache.cname,
+        props: cache.props.toObject()
+    };
+}
+
 function minify(files, options) {
     var warn_function = AST_Node.warn_function;
     try {
         options = defaults(options, {
             compress: {},
+            ecma: undefined,
             ie8: false,
             keep_fnames: false,
             mangle: {},
+            nameCache: null,
             output: {},
             parse: {},
             sourceMap: false,
@@ -46,13 +65,14 @@ function minify(files, options) {
         var timings = options.timings && {
             start: Date.now()
         };
+        set_shorthand("ecma", options, [ "parse", "compress", "output" ]);
         set_shorthand("ie8", options, [ "compress", "mangle", "output" ]);
         set_shorthand("keep_fnames", options, [ "compress", "mangle" ]);
         set_shorthand("toplevel", options, [ "compress", "mangle" ]);
         set_shorthand("warnings", options, [ "compress" ]);
         if (options.mangle) {
             options.mangle = defaults(options.mangle, {
-                cache: null,
+                cache: options.nameCache && (options.nameCache.vars || {}),
                 eval: false,
                 ie8: false,
                 keep_classnames: false,
@@ -62,6 +82,16 @@ function minify(files, options) {
                 safari10: false,
                 toplevel: false,
             }, true);
+            if (options.nameCache && options.mangle.properties) {
+                if (typeof options.mangle.properties != "object") {
+                    options.mangle.properties = {};
+                }
+                if (!("cache" in options.mangle.properties)) {
+                    options.mangle.properties.cache = options.nameCache.props || {};
+                }
+            }
+            init_cache(options.mangle.cache);
+            init_cache(options.mangle.properties.cache);
         }
         if (options.sourceMap) {
             options.sourceMap = defaults(options.sourceMap, {
@@ -155,6 +185,12 @@ function minify(files, options) {
                 }
             }
         }
+        if (options.nameCache && options.mangle) {
+            if (options.mangle.cache) options.nameCache.vars = to_json(options.mangle.cache);
+            if (options.mangle.properties && options.mangle.properties.cache) {
+                options.nameCache.props = to_json(options.mangle.properties.cache);
+            }
+        }
         if (timings) {
             timings.end = Date.now();
             result.timings = {

lib/output.js

@@ -533,6 +533,7 @@ function OutputStream(options) {
             use_asm = prev_use_asm;
         }
     });
+    AST_Node.DEFMETHOD("_print", AST_Node.prototype.print);
 
     AST_Node.DEFMETHOD("print_to_string", function(options){
         var s = OutputStream(options);
@@ -672,6 +673,12 @@ function OutputStream(options) {
                 && this.operator !== "--";
     });
 
+    PARENS(AST_Await, function(output){
+        var p = output.parent();
+        return p instanceof AST_PropAccess && p.expression === this
+            || p instanceof AST_Call && p.expression === this;
+    });
+
     PARENS(AST_Sequence, function(output){
         var p = output.parent();
         return p instanceof AST_Call                          // (foo, bar)() or foo(1, (2, 3), 4)
@@ -978,12 +985,12 @@ function OutputStream(options) {
     AST_Lambda.DEFMETHOD("_do_print", function(output, nokeyword){
         var self = this;
         if (!nokeyword) {
-            if (this.async) {
+            if (self.async) {
                 output.print("async");
                 output.space();
             }
             output.print("function");
-            if (this.is_generator) {
+            if (self.is_generator) {
                 output.star();
             }
             if (self.name) {
@@ -1039,6 +1046,10 @@ function OutputStream(options) {
             parent instanceof AST_Unary ||
             (parent instanceof AST_Call && self === parent.expression);
         if (needs_parens) { output.print("(") }
+        if (self.async) {
+            output.print("async");
+            output.space();
+        }
         if (self.argnames.length === 1 && self.argnames[0] instanceof AST_Symbol) {
             self.argnames[0].print(output);
         } else {
@@ -1053,9 +1064,9 @@ function OutputStream(options) {
         output.print('=>');
         output.space();
         if (self.body instanceof AST_Node) {
-            this.body.print(output);
+            self.body.print(output);
         } else {
-            print_bracketed(this.body, output);
+            print_bracketed(self.body, output);
         }
         if (needs_parens) { output.print(")") }
     });
@@ -1280,7 +1291,6 @@ function OutputStream(options) {
                     name_import.print(output);
                     if (i < self.imported_names.length - 1) {
                         output.print(",");
-                        output.space();
                     }
                 });
                 output.space();
@@ -1296,17 +1306,26 @@ function OutputStream(options) {
         output.semicolon();
     });
 
-    DEFPRINT(AST_NameImport, function(self, output) {
+    DEFPRINT(AST_NameMapping, function(self, output) {
+        var is_import = output.parent() instanceof AST_Import;
         var definition = self.name.definition();
         var names_are_different =
             (definition && definition.mangled_name || self.name.name) !==
             self.foreign_name.name;
         if (names_are_different) {
-            output.print(self.foreign_name.name);
+            if (is_import) {
+                output.print(self.foreign_name.name);
+            } else {
+                self.name.print(output);
+            }
             output.space();
             output.print("as");
             output.space();
-            self.name.print(output);
+            if (is_import) {
+                self.name.print(output);
+            } else {
+                output.print(self.foreign_name.name);
+            }
         } else {
             self.name.print(output);
         }
@@ -1320,24 +1339,20 @@ function OutputStream(options) {
             output.space();
         }
         if (self.exported_names) {
-            output.space();
-
             if (self.exported_names.length === 1 && self.exported_names[0].name.name === "*") {
                 self.exported_names[0].print(output);
             } else {
                 output.print("{");
-                self.exported_names.forEach(function (name_import, i) {
+                self.exported_names.forEach(function(name_export, i) {
                     output.space();
-                    name_import.print(output);
+                    name_export.print(output);
                     if (i < self.exported_names.length - 1) {
                         output.print(",");
-                        output.space();
                     }
                 });
                 output.space();
                 output.print("}");
             }
-            output.space();
         }
         else if (self.exported_value) {
             self.exported_value.print(output);

lib/parse.js

@@ -509,8 +509,11 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         }
         var content = "", raw = "", ch, tok;
         next(true, true);
-        while ((ch = next(true, true)) !== "`") {
-            if (ch === "$" && peek() === "{") {
+        while ((ch = next(true, true)) != "`") {
+            if (ch == "\r") {
+                if (peek() == "\n") ++S.pos;
+                ch = "\n";
+            } else if (ch == "$" && peek() == "{") {
                 next(true, true);
                 S.brace_counter++;
                 tok = token(begin ? "template_head" : "template_substitution", content);
@@ -521,7 +524,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
             }
 
             raw += ch;
-            if (ch === "\\") {
+            if (ch == "\\") {
                 var tmp = S.pos;
                 ch = read_escaped_char();
                 raw += S.text.substr(tmp, S.pos - tmp);
@@ -856,6 +859,7 @@ function parse($TEXT, options) {
 
     options = defaults(options, {
         bare_returns   : false,
+        ecma           : 8,
         expression     : false,
         filename       : null,
         html5_comments : true,
@@ -1229,9 +1233,12 @@ function parse($TEXT, options) {
             var is_in = is("operator", "in");
             var is_of = is("name", "of");
             if (is_in || is_of) {
-                if ((init instanceof AST_Definitions) &&
-                        init.definitions.length > 1)
-                    croak("Only one variable declaration allowed in for..in loop");
+                if (init instanceof AST_Definitions) {
+                    if (init.definitions.length > 1)
+                        croak("Only one variable declaration allowed in for..in loop", init.start.line, init.start.col, init.start.pos);
+                } else if (!(is_assignable(init) || (init = to_destructuring(init)) instanceof AST_Destructuring)) {
+                    croak("Invalid left-hand side in for..in loop", init.start.line, init.start.col, init.start.pos);
+                }
                 next();
                 if (is_in) {
                     return for_in(init);
@@ -1281,18 +1288,19 @@ function parse($TEXT, options) {
         });
     };
 
-    var arrow_function = function(start, argnames) {
+    var arrow_function = function(start, argnames, is_async) {
         if (S.token.nlb) {
             croak("Unexpected newline before arrow (=>)");
         }
 
         expect_token("arrow", "=>");
 
-        var body = _function_body(is("punc", "{"));
+        var body = _function_body(is("punc", "{"), false, is_async);
 
         return new AST_Arrow({
             start    : start,
             end      : body.end,
+            async    : is_async,
             argnames : argnames,
             body     : body
         });
@@ -1385,22 +1393,20 @@ function parse($TEXT, options) {
 
     function parameters() {
         var start = S.token;
-        var first = true;
         var params = [];
         var used_parameters = track_used_binding_identifiers(true, S.input.has_directive("use strict"));
 
         expect("(");
 
         while (!is("punc", ")")) {
-            if (first) {
-                first = false;
-            } else {
-                expect(",");
-            }
-
             var param = parameter(used_parameters);
             params.push(param);
 
+            if (!is("punc", ")")) {
+                expect(",");
+                if (is("punc", ")") && options.ecma < 8) unexpected();
+            }
+
             if (param instanceof AST_Expansion) {
                 break;
             }
@@ -1616,25 +1622,40 @@ function parse($TEXT, options) {
         }
     }
 
-    function params_or_seq_() {
-        var first = true;
+    function params_or_seq_(allow_arrows, maybe_sequence) {
+        var spread_token;
+        var invalid_sequence;
+        var trailing_comma;
         var a = [];
+        expect("(");
         while (!is("punc", ")")) {
-            if (first) first = false; else expect(",");
+            if (spread_token) unexpected(spread_token);
             if (is("expand", "...")) {
-                var spread_token = S.token;
+                spread_token = S.token;
+                if (maybe_sequence) invalid_sequence = S.token;
                 next();
                 a.push(new AST_Expansion({
                     start: prev(),
                     expression: expression(),
                     end: S.token,
                 }));
-                if (!is("punc", ")")) {
-                    unexpected(spread_token);
-                }
             } else {
                 a.push(expression());
             }
+            if (!is("punc", ")")) {
+                expect(",");
+                if (is("punc", ")")) {
+                    if (options.ecma < 8) unexpected();
+                    trailing_comma = prev();
+                    if (maybe_sequence) invalid_sequence = trailing_comma;
+                }
+            }
+        }
+        expect(")");
+        if (allow_arrows && is("arrow", "=>")) {
+            if (spread_token && trailing_comma) unexpected(trailing_comma);
+        } else if (invalid_sequence) {
+            unexpected(invalid_sequence);
         }
         return a;
     }
@@ -1882,7 +1903,7 @@ function parse($TEXT, options) {
         var newexp = expr_atom(false), args;
         if (is("punc", "(")) {
             next();
-            args = expr_list(")");
+            args = expr_list(")", options.ecma >= 8);
         } else {
             args = [];
         }
@@ -1989,21 +2010,24 @@ function parse($TEXT, options) {
         }
     }
 
-    var expr_atom = function(allow_calls) {
+    var expr_atom = function(allow_calls, allow_arrows) {
         if (is("operator", "new")) {
             return new_(allow_calls);
         }
         var start = S.token;
+        var async = is("name", "async") && as_atom_node();
         if (is("punc")) {
-            switch (start.value) {
+            switch (S.token.value) {
               case "(":
-                next();
-                var exprs = params_or_seq_();
-                expect(")");
-                if (is("arrow", "=>")) {
-                    return arrow_function(start, exprs.map(to_fun_args));
+                if (async && !allow_calls) break;
+                var exprs = params_or_seq_(allow_arrows, !async);
+                if (allow_arrows && is("arrow", "=>")) {
+                    return arrow_function(start, exprs.map(to_fun_args), !!async);
                 }
-                var ex = exprs.length == 1 ? exprs[0] : new AST_Sequence({
+                var ex = async ? new AST_Call({
+                    expression: async,
+                    args: exprs
+                }) : exprs.length == 1 ? exprs[0] : new AST_Sequence({
                     expressions: exprs
                 });
                 ex.start = start;
@@ -2014,23 +2038,25 @@ function parse($TEXT, options) {
               case "{":
                 return subscripts(object_or_destructuring_(), allow_calls);
             }
-            unexpected();
+            if (!async) unexpected();
         }
-        if (is("name", "async") && is_token(peek(), "keyword", "function")) {
+        if (allow_arrows && is("name") && is_token(peek(), "arrow")) {
+            var param = new AST_SymbolFunarg({
+                name: S.token.value,
+                start: start,
+                end: start,
+            });
             next();
-            next();
-            var func = function_(AST_Function, false, true);
-            func.start = start;
-            func.end = prev();
-            return subscripts(func, allow_calls);
+            return arrow_function(start, [param], !!async);
         }
         if (is("keyword", "function")) {
             next();
-            var func = function_(AST_Function);
+            var func = function_(AST_Function, false, !!async);
             func.start = start;
             func.end = prev();
             return subscripts(func, allow_calls);
         }
+        if (async) return subscripts(async, allow_calls);
         if (is("keyword", "class")) {
             next();
             var cls = class_(AST_ClassExpression);
@@ -2302,7 +2328,7 @@ function parse($TEXT, options) {
             next();
         }
 
-        imported_names = import_names(true);
+        imported_names = map_names(true);
 
         if (imported_names || imported_name) {
             expect_token("name", "from");
@@ -2326,26 +2352,40 @@ function parse($TEXT, options) {
         });
     }
 
-    function import_name() {
+    function map_name(is_import) {
+        function make_symbol(type) {
+            return new type({
+                name: as_property_name(),
+                start: prev(),
+                end: prev()
+            });
+        }
+
+        var foreign_type = is_import ? AST_SymbolImportForeign : AST_SymbolExportForeign;
+        var type = is_import ? AST_SymbolImport : AST_SymbolExport;
         var start = S.token;
         var foreign_name;
         var name;
 
-        if (peek().value === "as" && peek().type === "name") {
-            foreign_name = as_symbol(AST_SymbolImportForeign);
+        if (is_import) {
+            foreign_name = make_symbol(foreign_type);
+        } else {
+            name = make_symbol(type);
+        }
+        if (is("name", "as")) {
             next();  // The "as" word
-        }
-        name = as_symbol(AST_SymbolImport);
-
-        if (foreign_name === undefined) {
-            foreign_name = new AST_SymbolImportForeign({
-                name: name.name,
-                start: name.start,
-                end: name.end,
-            });
+            if (is_import) {
+                name = make_symbol(type);
+            } else {
+                foreign_name = make_symbol(foreign_type);
+            }
+        } else if (is_import) {
+            name = new type(foreign_name);
+        } else {
+            foreign_name = new foreign_type(name);
         }
 
-        return new AST_NameImport({
+        return new AST_NameMapping({
             start: start,
             foreign_name: foreign_name,
             name: name,
@@ -2353,26 +2393,26 @@ function parse($TEXT, options) {
         })
     }
 
-    function import_nameAsterisk(name) {
+    function map_nameAsterisk(is_import, name) {
+        var foreign_type = is_import ? AST_SymbolImportForeign : AST_SymbolExportForeign;
+        var type = is_import ? AST_SymbolImport : AST_SymbolExport;
         var start = S.token;
         var foreign_name;
-
-
         var end = prev();
 
-        name = name || new AST_SymbolImport({
+        name = name || new type({
             name: '*',
             start: start,
             end: end,
         });
 
-        foreign_name = new AST_SymbolImportForeign({
+        foreign_name = new foreign_type({
             name: '*',
             start: start,
             end: end,
         });
 
-        return new AST_NameImport({
+        return new AST_NameMapping({
             start: start,
             foreign_name: foreign_name,
             name: name,
@@ -2380,13 +2420,13 @@ function parse($TEXT, options) {
         })
     }
 
-    function import_names(allow_as) {
+    function map_names(is_import) {
         var names;
         if (is("punc", "{")) {
             next();
             names = [];
             while (!is("punc", "}")) {
-                names.push(import_name());
+                names.push(map_name(is_import));
                 if (is("punc", ",")) {
                     next();
                 }
@@ -2395,11 +2435,11 @@ function parse($TEXT, options) {
         } else if (is("operator", "*")) {
             var name;
             next();
-            if (allow_as && is("name", "as")) {
+            if (is_import && is("name", "as")) {
                 next();  // The "as" word
                 name = as_symbol(AST_SymbolImportForeign);
             }
-            names = [import_nameAsterisk(name)];
+            names = [map_nameAsterisk(is_import, name)];
         }
         return names;
     }
@@ -2407,72 +2447,60 @@ function parse($TEXT, options) {
     function export_() {
         var start = S.token;
         var is_default;
-        var exported_value;
-        var exported_definition;
         var exported_names;
 
         if (is("keyword", "default")) {
             is_default = true;
             next();
-        } else {
-            exported_names = import_names(false);
+        } else if (exported_names = map_names(false)) {
+            if (is("name", "from")) {
+                next();
 
-            if (exported_names) {
-                if (is("name", "from")) {
-                    next();
-
-                    var mod_str = S.token;
-                    if (mod_str.type !== 'string') {
-                        unexpected();
-                    }
-                    next();
-
-                    return new AST_Export({
-                        start: start,
-                        is_default: is_default,
-                        exported_names: exported_names,
-                        module_name: new AST_String({
-                            start: mod_str,
-                            value: mod_str.value,
-                            quote: mod_str.quote,
-                            end: mod_str,
-                        }),
-                        end: prev(),
-                    });
-                } else {
-                    return new AST_Export({
-                        start: start,
-                        is_default: is_default,
-                        exported_names: exported_names,
-                        end: prev(),
-                    });
+                var mod_str = S.token;
+                if (mod_str.type !== 'string') {
+                    unexpected();
                 }
+                next();
+
+                return new AST_Export({
+                    start: start,
+                    is_default: is_default,
+                    exported_names: exported_names,
+                    module_name: new AST_String({
+                        start: mod_str,
+                        value: mod_str.value,
+                        quote: mod_str.quote,
+                        end: mod_str,
+                    }),
+                    end: prev(),
+                });
+            } else {
+                return new AST_Export({
+                    start: start,
+                    is_default: is_default,
+                    exported_names: exported_names,
+                    end: prev(),
+                });
             }
         }
 
-        var is_definition = is("keyword", "var") || is("keyword", "let") || is("keyword", "const");
-        if (is_definition) {
-            if (is_default) unexpected();
-            exported_definition = statement();
-        } else if (is("keyword", "class")) {
-            var cls = expr_atom(false);
-            if (cls.name) {
-                cls.name = new AST_SymbolDefClass(cls.name);
-                exported_definition = new AST_DefClass(cls);
-            } else {
-                exported_value = cls;
-            }
-        } else if (is("keyword", "function")) {
-            var func = expr_atom(false);
-            if (func.name) {
-                func.name = new AST_SymbolDefun(func.name);
-                exported_definition = new AST_Defun(func);
-            } else {
-                exported_value = func;
-            }
-        } else {
+        var node;
+        var exported_value;
+        var exported_definition;
+        if (is("punc", "{")
+            || is_default
+                && (is("keyword", "class") || is("keyword", "function"))
+                && is_token(peek(), "punc")) {
             exported_value = expression(false);
             semicolon();
+        } else if ((node = statement()) instanceof AST_Definitions && is_default) {
+            unexpected(node.start);
+        } else if (node instanceof AST_Definitions || node instanceof AST_Defun || node instanceof AST_DefClass) {
+            exported_definition = node;
+        } else if (node instanceof AST_SimpleStatement) {
+            exported_value = node.body;
+        } else {
+            unexpected(node.start);
         }
 
         return new AST_Export({
@@ -2598,11 +2626,9 @@ function parse($TEXT, options) {
         return expr;
     };
 
-    var call_args = embed_tokens(function call_args() {
-        var first = true;
+    var call_args = embed_tokens(function _call_args() {
         var args = [];
         while (!is("punc", ")")) {
-            if (first) first = false; else expect(",");
             if (is("expand", "...")) {
                 next();
                 args.push(new AST_Expansion({
@@ -2612,12 +2638,16 @@ function parse($TEXT, options) {
             } else {
                 args.push(expression(false));
             }
+            if (!is("punc", ")")) {
+                expect(",");
+                if (is("punc", ")") && options.ecma < 8) unexpected();
+            }
         }
         next();
         return args;
     });
 
-    var maybe_unary = function(allow_calls) {
+    var maybe_unary = function(allow_calls, allow_arrows) {
         var start = S.token;
         if (start.type == "name" && start.value == "await") {
             if (is_in_async()) {
@@ -2635,8 +2665,9 @@ function parse($TEXT, options) {
             ex.end = prev();
             return ex;
         }
-        var val = expr_atom(allow_calls);
+        var val = expr_atom(allow_calls, allow_arrows);
         while (is("operator") && UNARY_POSTFIX(S.token.value) && !S.token.nlb) {
+            if (val instanceof AST_Arrow) unexpected();
             val = make_unary(AST_UnaryPostfix, S.token, val);
             val.start = start;
             val.end = S.token;
@@ -2684,7 +2715,7 @@ function parse($TEXT, options) {
     };
 
     function expr_ops(no_in) {
-        return expr_op(maybe_unary(true), 0, no_in);
+        return expr_op(maybe_unary(true, true), 0, no_in);
     };
 
     var maybe_conditional = function(no_in) {
@@ -2765,22 +2796,6 @@ function parse($TEXT, options) {
             }
         }
 
-        if (start.type == "punc" && start.value == "(" && peek().value == ")") {
-            next();
-            next();
-            return arrow_function(start, []);
-        }
-
-        if (is("name") && is_token(peek(), "arrow")) {
-            var param = new AST_SymbolFunarg({
-                name: start.value,
-                start: start,
-                end: start,
-            });
-            next();
-            return arrow_function(start, [param]);
-        }
-
         var left = maybe_conditional(no_in);
         var val = S.token.value;
 

lib/scope.js

@@ -85,7 +85,7 @@ SymbolDef.prototype = {
             if (options.ie8 && sym instanceof AST_SymbolLambda)
                 s = s.parent_scope;
             var def;
-            if (this.defun && (def = this.defun.variables.get(this.name))) {
+            if (def = this.redefined()) {
                 this.mangled_name = def.mangled_name || def.name;
             } else
                 this.mangled_name = s.next_mangled(options, this);
@@ -93,6 +93,9 @@ SymbolDef.prototype = {
                 cache.set(this.name, this.mangled_name);
             }
         }
+    },
+    redefined: function() {
+        return this.defun && this.defun.variables.get(this.name);
     }
 };
 
@@ -129,7 +132,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
             scope = save_scope;
             return true;
         }
-        if (node instanceof AST_Destructuring && node.is_array === false) {
+        if (node instanceof AST_Destructuring) {
             in_destructuring = node;  // These don't nest
             descend();
             in_destructuring = null;
@@ -223,10 +226,25 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
             }));
             node.thedef = sym;
         }
+        if (!(scope instanceof AST_Toplevel) && (node instanceof AST_Export || node instanceof AST_Import)) {
+            js_error(
+                node.TYPE + " statement may only appear at top level",
+                node.start.file,
+                node.start.line,
+                node.start.col,
+                node.start.pos
+            );
+        }
 
         function mark_export(def, level) {
+            if (in_destructuring) {
+                var i = 0;
+                do {
+                    level++;
+                } while (tw.parent(i++) !== in_destructuring);
+            }
             var node = tw.parent(level);
-            def.export = node instanceof AST_Export && !node.is_default;
+            def.export = node instanceof AST_Export;
         }
     });
     self.walk(tw);
@@ -245,8 +263,9 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
                     s.uses_eval = true;
                 }
             }
-            var sym = node.scope.find_variable(name);
-            if (!sym) {
+            var sym;
+            if (tw.parent() instanceof AST_NameMapping && tw.parent(1).module_name
+                || !(sym = node.scope.find_variable(name))) {
                 sym = self.def_global(node);
             } else if (sym.scope instanceof AST_Lambda && name == "arguments") {
                 sym.scope.uses_arguments = true;
@@ -255,6 +274,16 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options){
             node.reference(options);
             return true;
         }
+        // ensure mangling works if catch reuses a scope variable
+        var def;
+        if (node instanceof AST_SymbolCatch && (def = node.definition().redefined())) {
+            var s = node.scope;
+            while (s) {
+                push_uniq(s.enclosed, def);
+                if (s === def.scope) break;
+                s = s.parent_scope;
+            }
+        }
     });
     self.walk(tw);
 
@@ -421,7 +450,7 @@ AST_Function.DEFMETHOD("next_mangled", function(options, def){
 
 AST_Symbol.DEFMETHOD("unmangleable", function(options){
     var def = this.definition();
-    return def && def.unmangleable(options);
+    return !def || def.unmangleable(options);
 });
 
 // labels are always mangleable
@@ -526,113 +555,69 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options){
 
 AST_Toplevel.DEFMETHOD("compute_char_frequency", function(options){
     options = this._default_mangler_options(options);
-    var tw = new TreeWalker(function(node){
-        if (node instanceof AST_Constant)
-            base54.consider(node.print_to_string());
-        else if (node instanceof AST_Return)
-            base54.consider("return");
-        else if (node instanceof AST_Throw)
-            base54.consider("throw");
-        else if (node instanceof AST_Continue)
-            base54.consider("continue");
-        else if (node instanceof AST_Break)
-            base54.consider("break");
-        else if (node instanceof AST_Debugger)
-            base54.consider("debugger");
-        else if (node instanceof AST_Directive)
-            base54.consider(node.value);
-        else if (node instanceof AST_While)
-            base54.consider("while");
-        else if (node instanceof AST_Do)
-            base54.consider("do while");
-        else if (node instanceof AST_If) {
-            base54.consider("if");
-            if (node.alternative) base54.consider("else");
-        }
-        else if (node instanceof AST_Var)
-            base54.consider("var");
-        else if (node instanceof AST_Const)
-            base54.consider("const");
-        else if (node instanceof AST_Lambda)
-            base54.consider("function");
-        else if (node instanceof AST_For)
-            base54.consider("for");
-        else if (node instanceof AST_ForIn)
-            base54.consider("for in");
-        else if (node instanceof AST_Switch)
-            base54.consider("switch");
-        else if (node instanceof AST_Case)
-            base54.consider("case");
-        else if (node instanceof AST_Default)
-            base54.consider("default");
-        else if (node instanceof AST_With)
-            base54.consider("with");
-        else if (node instanceof AST_ObjectSetter)
-            base54.consider("set" + (typeof node.key === "string" ? node.key : ""));
-        else if (node instanceof AST_ObjectGetter)
-            base54.consider("get" + (typeof node.key === "string" ? node.key : ""));
-        else if (node instanceof AST_ObjectKeyVal && typeof node.key === "string")
-            base54.consider(node.key);
-        else if (node instanceof AST_ConciseMethod && typeof node.key === "string")
-            base54.consider(node.key);
-        else if (node instanceof AST_New)
-            base54.consider("new");
-        else if (node instanceof AST_This)
-            base54.consider("this");
-        else if (node instanceof AST_Super)
-            base54.consider("super");
-        else if (node instanceof AST_Try)
-            base54.consider("try");
-        else if (node instanceof AST_Catch)
-            base54.consider("catch");
-        else if (node instanceof AST_Finally)
-            base54.consider("finally");
-        else if (node instanceof AST_Yield)
-            base54.consider("yield");
-        else if (node instanceof AST_Await)
-            base54.consider("await");
-        else if (node instanceof AST_Symbol && node.unmangleable(options))
-            base54.consider(node.name);
-        else if (node instanceof AST_Unary || node instanceof AST_Binary)
-            base54.consider(node.operator);
-        else if (node instanceof AST_Dot)
-            base54.consider(node.property);
-    });
-    this.walk(tw);
+    try {
+        AST_Node.prototype.print = function(stream, force_parens) {
+            this._print(stream, force_parens);
+            if (this instanceof AST_Symbol && !this.unmangleable(options)) {
+                base54.consider(this.name, -1);
+            } else if (options.properties) {
+                if (this instanceof AST_Dot) {
+                    base54.consider(this.property, -1);
+                } else if (this instanceof AST_Sub) {
+                    skip_string(this.property);
+                }
+            }
+        };
+        base54.consider(this.print_to_string(), 1);
+    } finally {
+        AST_Node.prototype.print = AST_Node.prototype._print;
+    }
     base54.sort();
+
+    function skip_string(node) {
+        if (node instanceof AST_String) {
+            base54.consider(node.value, -1);
+        } else if (node instanceof AST_Conditional) {
+            skip_string(node.consequent);
+            skip_string(node.alternative);
+        } else if (node instanceof AST_Sequence) {
+            skip_string(node.expressions[node.expressions.length - 1]);
+        }
+    }
 });
 
 var base54 = (function() {
-    var string = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_0123456789";
+    var leading = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ$_".split("");
+    var digits = "0123456789".split("");
     var chars, frequency;
     function reset() {
         frequency = Object.create(null);
-        chars = string.split("").map(function(ch){ return ch.charCodeAt(0) });
-        chars.forEach(function(ch){ frequency[ch] = 0 });
+        leading.forEach(function(ch) {
+            frequency[ch] = 0;
+        });
+        digits.forEach(function(ch) {
+            frequency[ch] = 0;
+        });
     }
-    base54.consider = function(str){
+    base54.consider = function(str, delta) {
         for (var i = str.length; --i >= 0;) {
-            var code = str.charCodeAt(i);
-            if (code in frequency) ++frequency[code];
+            frequency[str[i]] += delta;
         }
     };
+    function compare(a, b) {
+        return frequency[b] - frequency[a];
+    }
     base54.sort = function() {
-        chars = mergeSort(chars, function(a, b){
-            if (is_digit(a) && !is_digit(b)) return 1;
-            if (is_digit(b) && !is_digit(a)) return -1;
-            return frequency[b] - frequency[a];
-        });
+        chars = mergeSort(leading, compare).concat(mergeSort(digits, compare));
     };
     base54.reset = reset;
     reset();
-    base54.get = function(){ return chars };
-    base54.freq = function(){ return frequency };
     function base54(num) {
         var ret = "", base = 54;
         num++;
         do {
             num--;
-            ret += String.fromCharCode(chars[num % base]);
+            ret += chars[num % base];
             num = Math.floor(num / base);
             base = 64;
         } while (num > 0);

lib/transform.js

@@ -243,9 +243,22 @@ TreeTransformer.prototype = new TreeWalker;
         self.expression = self.expression.transform(tw);
     });
 
-    _(AST_Export, function(self, tw){
+    _(AST_NameMapping, function(self, tw) {
+        self.foreign_name = self.foreign_name.transform(tw);
+        self.name = self.name.transform(tw);
+    });
+
+    _(AST_Import, function(self, tw) {
+        if (self.imported_name) self.imported_name = self.imported_name.transform(tw);
+        if (self.imported_names) do_list(self.imported_names, tw);
+        self.module_name = self.module_name.transform(tw);
+    });
+
+    _(AST_Export, function(self, tw) {
         if (self.exported_definition) self.exported_definition = self.exported_definition.transform(tw);
         if (self.exported_value) self.exported_value = self.exported_value.transform(tw);
+        if (self.exported_names) do_list(self.exported_names, tw);
+        if (self.module_name) self.module_name = self.module_name.transform(tw);
     });
 
     _(AST_TemplateString, function(self, tw) {

package.json

@@ -4,7 +4,7 @@
   "homepage": "https://github.com/mishoo/UglifyJS2/tree/harmony",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "3.0.18",
+  "version": "3.0.23",
   "engines": {
     "node": ">=0.8.0"
   },
@@ -40,5 +40,18 @@
   "scripts": {
     "test": "node test/run-tests.js"
   },
-  "keywords": ["uglify", "uglify-js", "uglify-es", "minify", "minifier", "es5", "es6", "es2015"]
+  "keywords": [
+    "uglify",
+    "uglify-js",
+    "uglify-es",
+    "minify",
+    "minifier",
+    "es5",
+    "es6",
+    "es2015",
+    "es2016",
+    "es2017",
+    "async",
+    "await"
+  ]
 }

test/compress/arrow.js

@@ -202,3 +202,341 @@ arrow_unused_toplevel: {
     expect_stdout: [ "0", "1", "2", "9" ]
     node_version: ">=6"
 }
+
+no_leading_parentheses: {
+    input: {
+        (x,y) => x(y);
+        async (x,y) => await x(y);
+    }
+    expect_exact: "(x,y)=>x(y);async(x,y)=>await x(y);"
+}
+
+async_identifiers: {
+    options = {
+        arrows: true,
+        ecma: 6,
+    }
+    input: {
+        var async = function(x){ console.log("async", x); };
+        var await = function(x){ console.log("await", x); };
+        async(1);
+        await(2);
+    }
+    expect: {
+        var async = x => { console.log("async", x); };
+        var await = x => { console.log("await", x); };
+        async(1);
+        await(2);
+    }
+    expect_stdout: [
+        "async 1",
+        "await 2",
+    ]
+    node_version: ">=4"
+}
+
+async_function_expression: {
+    options = {
+        arrows: true,
+        ecma: 6,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        var named = async function foo() {
+            await bar(1 + 0) + (2 + 0);
+        }
+        var anon = async function() {
+            await (1 + 0) + bar(2 + 0);
+        }
+    }
+    expect: {
+        var named = async function foo() {
+            await bar(1);
+        };
+        var anon = async () => {
+            await 1, bar(2);
+        };
+    }
+}
+
+issue_27: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        ecma: 6,
+        unused: true,
+    }
+    input: {
+        (function(jQuery) {
+            var $;
+            $ = jQuery;
+            $("body").addClass("foo");
+        })(jQuery);
+    }
+    expect: {
+        (jQuery => {
+            jQuery("body").addClass("foo");
+        })(jQuery);
+    }
+}
+
+issue_2105_1: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        ecma: 6,
+        inline: true,
+        passes: 3,
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        !function(factory) {
+            factory();
+        }( function() {
+            return function(fn) {
+                fn()().prop();
+            }( function() {
+                function bar() {
+                    var quux = function() {
+                        console.log("PASS");
+                    }, foo = function() {
+                        console.log;
+                        quux();
+                    };
+                    return { prop: foo };
+                }
+                return bar;
+            } );
+        });
+    }
+    expect: {
+        (() => {
+            var quux = () => {
+                console.log("PASS");
+            };
+            return {
+                prop: () => {
+                    console.log;
+                    quux();
+                }
+            };
+        })().prop();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_2105_2: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        passes: 2,
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        ((factory) => {
+            factory();
+        })( () => {
+            return ((fn) => {
+                fn()().prop();
+            })( () => {
+                let bar = () => {
+                    var quux = () => {
+                        console.log("PASS");
+                    }, foo = () => {
+                        console.log;
+                        quux();
+                    };
+                    return { prop: foo };
+                };
+                return bar;
+            } );
+        });
+    }
+    expect: {
+        (() => {
+            var quux = () => {
+                console.log("PASS");
+            };
+            return {
+                prop: () => {
+                    console.log;
+                    quux();
+                }
+            };
+        })().prop();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_2136_2: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        ecma: 6,
+        inline: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        function f(x) {
+            console.log(x);
+        }
+        !function(a, ...b) {
+            f(b[0]);
+        }(1, 2, 3);
+    }
+    expect: {
+        function f(x) {
+            console.log(x);
+        }
+        f([2,3][0]);
+    }
+    expect_stdout: "2"
+    node_version: ">=6"
+}
+
+issue_2136_3: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        ecma: 6,
+        evaluate: true,
+        inline: true,
+        passes: 3,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        function f(x) {
+            console.log(x);
+        }
+        !function(a, ...b) {
+            f(b[0]);
+        }(1, 2, 3);
+    }
+    expect: {
+        console.log(2);
+    }
+    expect_stdout: "2"
+    node_version: ">=6"
+}
+
+call_args: {
+    options = {
+        arrows: true,
+        ecma: 6,
+        evaluate: true,
+        inline: true,
+        reduce_vars: true,
+    }
+    input: {
+        const a = 1;
+        console.log(a);
+        +function(a) {
+            return a;
+        }(a);
+    }
+    expect: {
+        const a = 1;
+        console.log(1);
+        +(1, 1);
+    }
+    expect_stdout: true
+}
+
+call_args_drop_param: {
+    options = {
+        arrows: true,
+        ecma: 6,
+        evaluate: true,
+        inline: true,
+        keep_fargs: false,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        const a = 1;
+        console.log(a);
+        +function(a) {
+            return a;
+        }(a, b);
+    }
+    expect: {
+        const a = 1;
+        console.log(1);
+        +(b, 1);
+    }
+    expect_stdout: true
+}
+
+issue_485_crashing_1530: {
+    options = {
+        arrows: true,
+        conditionals: true,
+        dead_code: true,
+        ecma: 6,
+        evaluate: true,
+        inline: true,
+    }
+    input: {
+        (function(a) {
+            if (true) return;
+            var b = 42;
+        })(this);
+    }
+    expect: {
+        this, void 0;
+    }
+}
+
+issue_2084: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        conditionals: true,
+        ecma: 6,
+        evaluate: true,
+        inline: true,
+        passes: 2,
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var c = 0;
+        !function() {
+            !function(c) {
+                c = 1 + c;
+                var c = 0;
+                function f14(a_1) {
+                    if (c = 1 + c, 0 !== 23..toString())
+                        c = 1 + c, a_1 && (a_1[0] = 0);
+                }
+                f14();
+            }(-1);
+        }();
+        console.log(c);
+    }
+    expect: {
+        var c = 0;
+        ((c) => {
+            c = 1 + c,
+            c = 1 + (c = 0),
+            0 !== 23..toString() && (c = 1 + c);
+        })(-1),
+        console.log(c);
+    }
+    expect_stdout: "0"
+    node_version: ">=4"
+}

test/compress/async.js

@@ -6,6 +6,22 @@ await_precedence: {
     expect_exact: "async function f1(){await x+y}async function f2(){await(x+y)}"
 }
 
+await_precedence_prop: {
+    input: {
+        async function f1(){ return (await foo()).bar; }
+        async function f2(){ return (await foo().bar); }
+    }
+    expect_exact: "async function f1(){return(await foo()).bar}async function f2(){return await foo().bar}"
+}
+
+await_precedence_call: {
+    input: {
+        async function f3(){ return (await foo())(); }
+        async function f4(){ return await (foo()()); }
+    }
+    expect_exact: "async function f3(){return(await foo())()}async function f4(){return await foo()()}"
+}
+
 async_function_declaration: {
     options = {
         side_effects: true,
@@ -167,14 +183,14 @@ async_inline: {
 
 async_identifiers: {
     input: {
-        let async = function(x){ console.log("async", x); };
-        let await = function(x){ console.log("await", x); };
+        var async = function(x){ console.log("async", x); };
+        var await = function(x){ console.log("await", x); };
         async(1);
         await(2);
     }
     expect: {
-        let async = function(x){ console.log("async", x); };
-        let await = function(x){ console.log("await", x); };
+        var async = function(x){ console.log("async", x); };
+        var await = function(x){ console.log("await", x); };
         async(1);
         await(2);
     }
@@ -182,7 +198,6 @@ async_identifiers: {
         "async 1",
         "await 2",
     ]
-    node_version: ">=8"
 }
 
 async_shorthand_property: {
@@ -230,16 +245,50 @@ async_shorthand_property: {
     node_version: ">=4"
 }
 
-/* FIXME: add test when supported by parser
 async_arrow: {
     input: {
         let a1 = async x => await foo(x);
         let a2 = async () => await bar();
         let a3 = async (x) => await baz(x);
         let a4 = async (x, y) => { await far(x, y); }
-        let a5 = async ({x = [1], y: z = 2}) => { await wow(x, y); }
+        let a5 = async ({x = [1], y: z = 2}) => { await wow(x, z); }
     }
     expect: {
+        let a1 = async x => await foo(x);
+        let a2 = async () => await bar();
+        let a3 = async (x) => await baz(x);
+        let a4 = async (x, y) => { await far(x, y); }
+        let a5 = async ({x = [1], y: z = 2}) => { await wow(x, z); }
     }
 }
-*/
+
+async_arrow_wait: {
+    input: {
+        var a = async (x, y) => await x(y);
+    }
+    expect_exact: "var a=async(x,y)=>await x(y);"
+}
+
+async_arrow_iife: {
+    input: {
+        (async () => {
+            await fetch({});
+        })();
+    }
+    expect_exact: "(async()=>{await fetch({})})();"
+}
+
+async_arrow_iife_negate_iife: {
+    options = {
+        negate_iife: true,
+    }
+    input: {
+        (async () => {
+            await fetch();
+        })();
+        (() => {
+            plain();
+        })();
+    }
+    expect_exact: "(async()=>{await fetch()})();(()=>{plain()})();"
+}

test/compress/block-scope.js

@@ -104,34 +104,36 @@ regression_block_scope_resolves: {
     };
     input: {
         (function () {
-            if(1) {
+            if (1) {
                 let x;
-                const y;
+                const y = 1;
                 class Zee {};
             }
-            if(1) {
+            if (1) {
                 let ex;
-                const why;
+                const why = 2;
                 class Zi {};
             }
-            console.log(x, y, Zee, ex, why, Zi);
+            console.log(typeof x, typeof y, typeof Zee, typeof ex, typeof why, typeof Zi);
         }());
     }
     expect: {
         (function () {
             if (1) {
-                let o;
-                const n;
-                class c {};
+                let e;
+                const o = 1;
+                class t {};
             }
             if (1) {
-                let o;
-                const n;
-                class c {};
+                let e;
+                const o = 2;
+                class t {};
             }
-            console.log(x, y, Zee, ex, why, Zi);
+            console.log(typeof x, typeof y, typeof Zee, typeof ex, typeof why, typeof Zi);
         }());
     }
+    expect_stdout: "undefined undefined undefined undefined undefined undefined"
+    node_version: ">=6"
 }
 
 switch_block_scope_mangler: {
@@ -153,25 +155,37 @@ switch_block_scope_mangler: {
                     console.log(cat);
             }
         };
+        fn(1);
+        fn(2);
+        fn(3);
     }
     expect: {
-        var fn = function(o) {
-            switch (o) {
+        var fn = function(e) {
+            switch (e) {
               case 1:
-                let e = o + 1
-                let c = o + 4;
-                console.log(e, c);
+                let l = e + 1
+                let o = e + 4;
+                console.log(l, o);
                 break;
 
               case 2:
-                let l = o + 2;
-                console.log(l);
+                let n = e + 2;
+                console.log(n);
                 break;
 
               default:
-                let a = o + 3;
-                console.log(a);
+                let c = e + 3;
+                console.log(c);
             }
         };
+        fn(1);
+        fn(2);
+        fn(3);
     }
+    expect_stdout: [
+        "2 5",
+        "4",
+        "6",
+    ]
+    node_version: ">=6"
 }

test/compress/collapse_vars.js

@@ -2077,10 +2077,10 @@ chained_3: {
     }
     expect: {
         console.log(function(a, b) {
-            var c = a, c = b;
+            var c = 1, c = b;
             b++;
             return c;
-        }(1, 2));
+        }(0, 2));
     }
     expect_stdout: "2"
 }
@@ -2330,3 +2330,73 @@ reassign_const_2: {
     }
     expect_stdout: true
 }
+
+issue_2187_1: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = 1;
+        !function(foo) {
+            foo();
+            var a = 2;
+            console.log(a);
+        }(function() {
+            console.log(a);
+        });
+    }
+    expect: {
+        var a = 1;
+        !function(foo) {
+            foo();
+            var a = 2;
+            console.log(a);
+        }(function() {
+            console.log(a);
+        });
+    }
+    expect_stdout: [
+        "1",
+        "2",
+    ]
+}
+
+issue_2187_2: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var b = 1;
+        console.log(function(a) {
+            return a && ++b;
+        }(b--));
+    }
+    expect: {
+        var b = 1;
+        console.log(function(a) {
+            return b-- && ++b;
+        }());
+    }
+    expect_stdout: "1"
+}
+
+issue_2187_3: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        unused: true,
+    }
+    input: {
+        var b = 1;
+        console.log(function(a) {
+            return a && ++b;
+        }(b--));
+    }
+    expect: {
+        var b = 1;
+        console.log(b-- && ++b);
+    }
+    expect_stdout: "1"
+}

test/compress/destructuring.js

@@ -425,8 +425,8 @@ mangle_destructuring_decl: {
     expect: {
         function test(t) {
             let e = t.a || { e: 7, n: 8 };
-            let {t: n,  e: o,  n: s,  s: a = 9,  o: c,  r: l} = e;
-            console.log(n, o, s, a, c, l);
+            let {t: n,  e: o,  n: s,  s: l = 9,  o: a,  r: c} = e;
+            console.log(n, o, s, l, a, c);
         }
         test({ a: { t: 1, e: 2, n: 3, s: 4, o: 5, r: 6 } });
         test({});
@@ -462,15 +462,15 @@ mangle_destructuring_assign_toplevel_true: {
         test({});
     }
     expect: {
-        function n(n) {
-            let t, a, c;
-            let l = n.a || { e: 7, n: 8 };
-            ({t: o,  e,  n: s,  s: t = 9,  o: a,  r: c} = l);
-            console.log(o, e, s, t, a, c);
+        function e(e) {
+            let l, s, a;
+            let c = e.a || { e: 7, n: 8 };
+            ({t: n,  e: o,  n: t,  s: l = 9,  o: s,  r: a} = c);
+            console.log(n, o, t, l, s, a);
         }
-        let o, e, s;
-        n({ a: { t: 1, e: 2, n: 3, s: 4, o: 5, r: 6 } });
-        n({});
+        let n, o, t;
+        e({ a: { t: 1, e: 2, n: 3, s: 4, o: 5, r: 6 } });
+        e({});
     }
     expect_stdout: [
         "1 2 3 4 5 6",
@@ -504,10 +504,10 @@ mangle_destructuring_assign_toplevel_false: {
     }
     expect: {
         function test(o) {
-            let s, a, c;
-            let l = o.a || { e: 7, n: 8 };
-            ({t,  e,  n,  s = 9,  o: a,  r: c} = l);
-            console.log(t, e, n, s, a, c);
+            let s, l, a;
+            let c = o.a || { e: 7, n: 8 };
+            ({t,  e,  n,  s = 9,  o: l,  r: a} = c);
+            console.log(t, e, n, s, l, a);
         }
         let t, e, n;
         test({ a: { t: 1, e: 2, n: 3, s: 4, o: 5, r: 6 } });
@@ -588,8 +588,8 @@ arrow_func_with_destructuring_args: {
         })({bar: 5 - 0}, [, 6]);
     }
     expect: {
-        (({foo: o = 1, bar: n = 2}, [a = 3, b = 4]) => {
-            console.log(o, n, a, b);
+        (({foo: o = 1, bar: a = 2}, [b = 3, l = 4]) => {
+            console.log(o, a, b, l);
         })({bar: 5}, [, 6]);
     }
     expect_stdout: "1 5 3 6"
@@ -639,3 +639,23 @@ issue_2044_ecma_6_beautify: {
     }
     expect_exact: "({x: a = 1, y = 2 + b, z = 3 - c} = obj);"
 }
+
+issue_2140: {
+    options = {
+        unused: true,
+    }
+    input: {
+        !function() {
+            var t = {};
+            console.log(([t.a] = [42])[0]);
+        }();
+    }
+    expect: {
+        !function() {
+            var t = {};
+            console.log(([t.a] = [42])[0]);
+        }();
+    }
+    expect_stdout: "42"
+    node_version: ">=6"
+}

test/compress/drop-unused.js

@@ -1299,6 +1299,7 @@ issue_2105: {
     options = {
         collapse_vars: true,
         inline: true,
+        passes: 3,
         reduce_vars: true,
         side_effects: true,
         unused: true,
@@ -1324,7 +1325,7 @@ issue_2105: {
         });
     }
     expect: {
-        !void function() {
+        (function() {
             var quux = function() {
                 console.log("PASS");
             };
@@ -1334,7 +1335,95 @@ issue_2105: {
                     quux();
                 }
             };
-        }().prop();
+        })().prop();
     }
     expect_stdout: "PASS"
 }
+
+issue_2136_1: {
+    options = {
+        inline: true,
+        unused: true,
+    }
+    input: {
+        !function(a, ...b) {
+            console.log(b);
+        }();
+    }
+    expect: {
+        !function(a, ...b) {
+            console.log(b);
+        }();
+    }
+    expect_stdout: "[]"
+    node_version: ">=6"
+}
+
+issue_2136_2: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        function f(x) {
+            console.log(x);
+        }
+        !function(a, ...b) {
+            f(b[0]);
+        }(1, 2, 3);
+    }
+    expect: {
+        function f(x) {
+            console.log(x);
+        }
+        f([2,3][0]);
+    }
+    expect_stdout: "2"
+    node_version: ">=6"
+}
+
+issue_2136_3: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        inline: true,
+        passes: 3,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        function f(x) {
+            console.log(x);
+        }
+        !function(a, ...b) {
+            f(b[0]);
+        }(1, 2, 3);
+    }
+    expect: {
+        console.log(2);
+    }
+    expect_stdout: "2"
+    node_version: ">=6"
+}
+
+issue_2163: {
+    options = {
+        pure_funcs: [ "pure" ],
+        side_effects: true,
+    }
+    input: {
+        var c;
+        /*@__PURE__*/f(...a);
+        pure(b, ...c);
+    }
+    expect: {
+        var c;
+        a;
+        b;
+    }
+}

test/compress/export.js

@@ -0,0 +1,228 @@
+issue_2038_1: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        export var V = 1;
+        export let L = 2;
+        export const C = 3;
+    }
+    expect: {
+        export var V = 1;
+        export let L = 2;
+        export const C = 3;
+    }
+}
+
+issue_2038_2: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        let LET = 1;
+        const CONST = 2;
+        var VAR = 3;
+        export { LET, CONST, VAR };
+    }
+    expect: {
+        let t = 1;
+        const e = 2;
+        var o = 3;
+        export { t as LET, e as CONST, o as VAR };
+    }
+}
+
+issue_2126: {
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        import { foo as bar, cat as dog } from "stuff";
+        console.log(bar, dog);
+        export { bar as qux };
+        export { dog };
+    }
+    expect: {
+        import { foo as o, cat as s } from "stuff";
+        console.log(o, s);
+        export { o as qux };
+        export { s as dog };
+    }
+}
+
+beautify: {
+    beautify = {
+        beautify: true,
+    }
+    input: {
+        export { A as B, C as D };
+    }
+    expect_exact: "export { A as B, C as D };"
+}
+
+issue_2131: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function no() {
+            console.log(42);
+        }
+        function go() {
+            console.log(42);
+        }
+        var X = 1, Y = 2;
+        export function main() {
+            go(X);
+        };
+    }
+    expect: {
+        function go() {
+            console.log(42);
+        }
+        var X = 1;
+        export function main() {
+            go(X);
+        };
+    }
+}
+
+issue_2129: {
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        export const { keys } = Object;
+    }
+    expect: {
+        export const { keys } = Object;
+    }
+}
+
+async_func: {
+    options = {
+        keep_fargs: false,
+        unused: true,
+    }
+    input: {
+        export async function Foo(x){};
+    }
+    expect: {
+        export async function Foo(){};
+    }
+}
+
+issue_2134_1: {
+    options = {
+        keep_fargs: false,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        export function Foo(x){};
+        Foo.prototype = {};
+    }
+    expect: {
+        export function Foo(){};
+        Foo.prototype = {};
+    }
+}
+
+issue_2134_2: {
+    options = {
+        keep_fargs: false,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        export async function Foo(x){};
+        Foo.prototype = {};
+    }
+    expect: {
+        export async function Foo(){};
+        Foo.prototype = {};
+    }
+}
+
+redirection: {
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        let foo = 1, bar = 2;
+        export { foo as delete };
+        export { bar as default };
+        export { foo as var } from "module.js";
+    }
+    expect: {
+        let e = 1, o = 2;
+        export { e as delete };
+        export { o as default };
+        export { foo as var } from "module.js";
+    }
+}
+
+keyword_invalid_1: {
+    input: {
+        export { default };
+    }
+    expect: {
+        export { default };
+    }
+}
+
+keyword_invalid_2: {
+    input: {
+        export { default as Alias };
+    }
+    expect: {
+        export { default as Alias };
+    }
+}
+
+keyword_invalid_3: {
+    input: {
+        export { default as default };
+    }
+    expect: {
+        export { default as default };
+    }
+}
+
+keyword_valid_1: {
+    input: {
+        export { default } from "module.js";
+    }
+    expect: {
+        export { default } from "module.js";
+    }
+}
+
+keyword_valid_2: {
+    input: {
+        export { default as Alias } from "module.js";
+    }
+    expect: {
+        export { default as Alias } from "module.js";
+    }
+}
+
+keyword_valid_3: {
+    input: {
+        export { default as default } from "module.js";
+    }
+    expect: {
+        export { default as default } from "module.js";
+    }
+}

test/compress/functions.js

@@ -265,7 +265,7 @@ issue_203: {
     }
     expect: {
         var m = {};
-        var fn = Function("a", "b", "b.exports=42");
+        var fn = Function("n,o", "o.exports=42");
         fn(null, m, m.exports);
         console.log(m.exports);
     }
@@ -468,11 +468,9 @@ issue_2114_1: {
     }
     expect: {
         var c = 0;
-        !function() {
-            0;
-        }((c += 1, c = 1 + c, function() {
+        c = 1 + (c += 1), function() {
             var b = void (b && (b.b += (c += 1, 0)));
-        }()));
+        }();
         console.log(c);
     }
     expect_stdout: "2"

test/compress/global_defs.js

@@ -174,3 +174,24 @@ issue_1986: {
         console.log(42);
     }
 }
+
+issue_2167: {
+    options = {
+        conditionals: true,
+        dead_code: true,
+        evaluate: true,
+        global_defs: {
+            "@isDevMode": "function(){}",
+        },
+        side_effects: true,
+    }
+    input: {
+        if (isDevMode()) {
+            greetOverlord();
+        }
+        doWork();
+    }
+    expect: {
+        doWork();
+    }
+}

test/compress/harmony.js

@@ -16,9 +16,12 @@ typeof_arrow_functions: {
         evaluate: true
     }
     input: {
-        var foo = typeof (x) => null;
+        var foo = typeof (x => null);
+        console.log(foo);
     }
-    expect_exact: "var foo=\"function\";"
+    expect_exact: "var foo=\"function\";console.log(foo);"
+    expect_stdout: "function"
+    node_version: ">=4"
 }
 
 classes: {
@@ -60,15 +63,15 @@ class_name_can_be_mangled: {
         function x() {
             class Foo {
             }
-            var class1 = Foo
-            var class2 = class Bar {}
+            var class1 = Foo;
+            var class2 = class Bar {};
         }
     }
     expect: {
         function x() {
             class a { }
-            var n = a
-            var r = class a {}
+            var s = a;
+            var c = class a {};
         }
     }
 }
@@ -287,12 +290,12 @@ import_statement_mangling: {
         Whatever();
     }
     expect: {
-        import l from "foo";
-        import e, {Food as o} from "lel";
+        import o from "foo";
+        import m, {Food as r} from "lel";
         import {What as f} from "lel";
-        l();
-        e();
         o();
+        m();
+        r();
         f();
     }
 }
@@ -466,10 +469,10 @@ issue_1898: {
     expect: {
         class Foo {
             bar() {
-                for (const n of [ 6, 5 ])
+                for (const f of [ 6, 5 ])
                     for (let r of [ 4, 3 ])
                         for (var o of [ 2, 1 ])
-                            console.log(n, r, o);
+                            console.log(f, r, o);
             }
         }
         new Foo().bar();
@@ -494,9 +497,9 @@ issue_1753: {
     expect: {
         class SomeClass {
             constructor(r) {
-                let a = [];
-                for (let s = 0; s < 6; s++)
-                    a.push({
+                let s = [];
+                for (let a = 0; a < 6; a++)
+                    s.push({
                         mainDrawNumbers: [],
                         extraDrawNumbers: []
                     });
@@ -523,9 +526,9 @@ issue_1753_disable: {
     expect: {
         class SomeClass {
             constructor(r) {
-                let a = [];
+                let s = [];
                 for (let r = 0; r < 6; r++)
-                    a.push({
+                    s.push({
                         mainDrawNumbers: [],
                         extraDrawNumbers: []
                     });
@@ -664,3 +667,31 @@ class_expression_statement_unused_toplevel: {
     }
     expect_exact: ""
 }
+
+export_default_function_decl: {
+    options = {
+        toplevel: true,
+        passes: 3,
+        unused: true,
+    }
+    input: {
+        // do not drop "unused" exports
+        export default function Foo() {};
+        export function Far() {};
+    }
+    expect_exact: "export default function Foo(){};export function Far(){};"
+}
+
+export_default_class_decl: {
+    options = {
+        toplevel: true,
+        passes: 3,
+        unused: true,
+    }
+    input: {
+        // do not drop "unused" exports
+        export default class Car {};
+        export class Cab {};
+    }
+    expect_exact: "export default class Car{};export class Cab{};"
+}

test/compress/issue-1321.js

@@ -10,9 +10,9 @@ issue_1321_no_debug: {
     }
     expect: {
         var x = {};
-        x.b = 1;
-        x["a"] = 2 * x.b;
-        console.log(x.b, x["a"]);
+        x.o = 1;
+        x["a"] = 2 * x.o;
+        console.log(x.o, x["a"]);
     }
     expect_stdout: true
 }
@@ -30,9 +30,9 @@ issue_1321_debug: {
     }
     expect: {
         var x = {};
-        x.a = 1;
-        x["_$foo$_"] = 2 * x.a;
-        console.log(x.a, x["_$foo$_"]);
+        x.o = 1;
+        x["_$foo$_"] = 2 * x.o;
+        console.log(x.o, x["_$foo$_"]);
     }
     expect_stdout: true
 }
@@ -49,9 +49,9 @@ issue_1321_with_quoted: {
     }
     expect: {
         var x = {};
-        x.a = 1;
-        x["b"] = 2 * x.a;
-        console.log(x.a, x["b"]);
+        x.o = 1;
+        x["x"] = 2 * x.o;
+        console.log(x.o, x["x"]);
     }
     expect_stdout: true
 }

test/compress/issue-1466.js

@@ -33,8 +33,8 @@ same_variable_in_multiple_for_loop: {
             console.log(o, l);
             for (let o = 0; o < 2; o++) {
                 console.log(o, l);
-                let c = 2;
-                console.log(c);
+                let e = 2;
+                console.log(e);
             }
         }
     }
@@ -114,12 +114,12 @@ same_variable_in_multiple_forIn: {
     }
     expect: {
         var test = [ "a", "b", "c" ];
-        for (let o in test) {
-            console.log(o);
-            let e;
-            e = [ "e", "f", "g" ];
-            for (let o in test)
-                console.log(o);
+        for (let e in test) {
+            console.log(e);
+            let t;
+            t = [ "e", "f", "g" ];
+            for (let e in test)
+                console.log(e);
         }
     }
     expect_stdout: true
@@ -160,8 +160,8 @@ different_variable_in_multiple_for_loop: {
             console.log(o, l);
             for (let o = 0; o < 2; o++) {
                 console.log(o, l);
-                let c = 2;
-                console.log(c);
+                let e = 2;
+                console.log(e);
             }
         }
     }
@@ -241,12 +241,12 @@ different_variable_in_multiple_forIn: {
     }
     expect: {
         var test = [ "a", "b", "c" ];
-        for (let o in test) {
-            console.log(o);
-            let e;
-            e = [ "e", "f", "g" ];
-            for (let o in test)
-                console.log(o);
+        for (let e in test) {
+            console.log(e);
+            let t;
+            t = [ "e", "f", "g" ];
+            for (let e in test)
+                console.log(e);
         }
     }
     expect_stdout: true
@@ -281,10 +281,10 @@ more_variable_in_multiple_for: {
     }
     expect: {
         for (let o = 9, l = 0; l < 20; l += o) {
-            let c = o++ + l;
-            console.log(o, c, l);
-            for (let l = c, e = c * c, f = 0; f < 10; f++)
-                console.log(o, c, e, l, f);
+            let e = o++ + l;
+            console.log(o, e, l);
+            for (let l = e, t = e * e, c = 0; c < 10; c++)
+                console.log(o, e, t, l, c);
         }
     }
     expect_stdout: true

test/compress/issue-1770.js

@@ -82,7 +82,7 @@ numeric_literal: {
         '    42: 2,',
         '    "42": 3,',
         '    37: 4,',
-        '    a: 5,',
+        '    o: 5,',
         '    1e42: 6,',
         '    b: 7,',
         '    "1e+42": 8',
@@ -92,7 +92,7 @@ numeric_literal: {
         '',
         'console.log(obj[42], obj["42"]);',
         '',
-        'console.log(obj[37], obj["a"], obj[37], obj["37"]);',
+        'console.log(obj[37], obj["o"], obj[37], obj["37"]);',
         '',
         'console.log(obj[1e42], obj["b"], obj["1e+42"]);',
     ]

test/compress/issue-2001.js

@@ -45,7 +45,7 @@ export_default_func_1: {
     input: {
         export default function f(){};
     }
-    expect_exact: "export default function(){};"
+    expect_exact: "export default function f(){};"
 }
 
 export_default_func_2: {
@@ -58,7 +58,7 @@ export_default_func_2: {
     input: {
         export default function f(){}(1);
     }
-    expect_exact: "export default function(){};1;"
+    expect_exact: "export default function f(){};1;"
 }
 
 export_default_func_3: {
@@ -71,7 +71,7 @@ export_default_func_3: {
     input: {
         export default function f(){}(1);
     }
-    expect_exact: "export default function(){};"
+    expect_exact: "export default function f(){};"
 }
 
 export_class_1: {
@@ -121,7 +121,7 @@ export_default_class_1: {
     input: {
         export default class C {};
     }
-    expect_exact: "export default class{};"
+    expect_exact: "export default class C{};"
 }
 
 export_default_class_2: {
@@ -134,7 +134,7 @@ export_default_class_2: {
     input: {
         export default class C {}(1);
     }
-    expect_exact: "export default class{};1;"
+    expect_exact: "export default class C{};1;"
 }
 
 export_default_class_3: {
@@ -147,7 +147,7 @@ export_default_class_3: {
     input: {
         export default class C {}(1);
     }
-    expect_exact: "export default class{};"
+    expect_exact: "export default class C{};"
 }
 
 export_mangle_1: {
@@ -159,7 +159,7 @@ export_mangle_1: {
             return one - two;
         };
     }
-    expect_exact: "export function foo(n,o){return n-o};"
+    expect_exact: "export function foo(o,n){return o-n};"
 }
 
 export_mangle_2: {
@@ -171,7 +171,7 @@ export_mangle_2: {
             return one - two;
         };
     }
-    expect_exact: "export default function n(n,r){return n-r};"
+    expect_exact: "export default function foo(o,t){return o-t};"
 }
 
 export_mangle_3: {
@@ -189,7 +189,7 @@ export_mangle_3: {
             }
         };
     }
-    expect_exact: "export class C{go(n,r){return n-r+n}};"
+    expect_exact: "export class C{go(r,e){return r-e+r}};"
 }
 
 export_mangle_4: {
@@ -207,7 +207,7 @@ export_mangle_4: {
             }
         };
     }
-    expect_exact: "export default class n{go(n,r){return n-r+n}};"
+    expect_exact: "export default class C{go(e,r){return e-r+e}};"
 }
 
 export_mangle_5: {
@@ -221,7 +221,7 @@ export_mangle_5: {
             }
         };
     }
-    expect_exact: "export default{prop:function(n,r){return n-r}};"
+    expect_exact: "export default{prop:function(r,t){return r-t}};"
 }
 
 export_mangle_6: {
@@ -232,7 +232,7 @@ export_mangle_6: {
         var baz = 2;
         export let foo = 1, bar = baz;
     }
-    expect_exact: "var a=2;export let foo=1,bar=a;"
+    expect_exact: "var o=2;export let foo=1,bar=o;"
 }
 
 export_toplevel_1: {
@@ -247,7 +247,7 @@ export_toplevel_1: {
     }
     expect: {
         export function g(){};
-        export default function(){};
+        export default function h(){};
     }
 }
 
@@ -263,7 +263,7 @@ export_toplevel_2: {
     }
     expect: {
         export class B {};
-        export default class {};
+        export default class C {};
     }
 }
 

test/compress/issue-203.js

@@ -8,7 +8,7 @@ compress_new_function: {
         new Function("aa, bb", 'return aa;');
     }
     expect: {
-        Function("a", "b", "return a");
+        Function("n,r", "return n");
     }
 }
 
@@ -27,8 +27,30 @@ compress_new_function_with_destruct: {
         new Function("[[aa]], [{bb}]", 'return aa;');
     }
     expect: {
-        Function("a", "[b]", "return a");
-        Function("a", "{bb:b}", "return a");
-        Function("[[a]]", "[{bb:b}]", 'return a');
+        Function("n,[r]", "return n");
+        Function("n,{bb:b}", "return n");
+        Function("[[n]],[{bb:b}]", "return n");
+    }
+}
+
+compress_new_function_with_destruct_arrows: {
+    options = {
+        arrows: true,
+        unsafe: true,
+        unsafe_Func: true,
+        ecma: 6
+    }
+    beautify = {
+        ecma: 6
+    }
+    input: {
+        new Function("aa, [bb]", 'return aa;');
+        new Function("aa, {bb}", 'return aa;');
+        new Function("[[aa]], [{bb}]", 'return aa;');
+    }
+    expect: {
+        Function("n,[a]", "return n");
+        Function("b,{bb:n}", "return b");
+        Function("[[b]],[{bb:n}]", "return b");
     }
 }

test/compress/issue-281.js

@@ -419,7 +419,7 @@ wrap_iife_in_return_call: {
     expect_exact: '(void console.log("test"))();'
 }
 
-pure_annotation: {
+pure_annotation_1: {
     options = {
         inline: true,
         side_effects: true,
@@ -432,6 +432,20 @@ pure_annotation: {
     expect_exact: ""
 }
 
+pure_annotation_2: {
+    options = {
+        collapse_vars: true,
+        inline: true,
+        side_effects: true,
+    }
+    input: {
+        /*@__PURE__*/(function(n) {
+            console.log("hello", n);
+        }(42));
+    }
+    expect_exact: ""
+}
+
 drop_fargs: {
     options = {
         cascade: true,
@@ -449,9 +463,7 @@ drop_fargs: {
     }
     expect: {
         var a = 1;
-        !function() {
-            a++;
-        }(++a && a.var);
+        ++a && a.var, a++;
         console.log(a);
     }
     expect_stdout: "3"
@@ -474,9 +486,7 @@ keep_fargs: {
     }
     expect: {
         var a = 1;
-        !function(a_1) {
-            a++;
-        }(++a && a.var);
+        ++a && a.var, a++;
         console.log(a);
     }
     expect_stdout: "3"

test/compress/issue-747.js

@@ -1,37 +1,41 @@
 dont_reuse_prop: {
     mangle_props = {
         regex: /asd/
-    };
-
+    }
     input: {
+        "aaaaaaaaaabbbbb";
         var obj = {};
         obj.a = 123;
         obj.asd = 256;
         console.log(obj.a);
     }
     expect: {
+        "aaaaaaaaaabbbbb";
         var obj = {};
         obj.a = 123;
         obj.b = 256;
         console.log(obj.a);
     }
+    expect_stdout: "123"
 }
 
 unmangleable_props_should_always_be_reserved: {
     mangle_props = {
         regex: /asd/
-    };
-
+    }
     input: {
+        "aaaaaaaaaabbbbb";
         var obj = {};
         obj.asd = 256;
         obj.a = 123;
         console.log(obj.a);
     }
     expect: {
+        "aaaaaaaaaabbbbb";
         var obj = {};
         obj.b = 256;
         obj.a = 123;
         console.log(obj.a);
     }
-}
+    expect_stdout: "123"
+}

test/compress/object.js

@@ -105,7 +105,7 @@ getter_setter_mangler: {
             };
         }
     }
-    expect_exact: "function f(n,t){return{get:n,set:t,get g(){},set s(n){},c,a:1,m(){}}}"
+    expect_exact: "function f(t,e){return{get:t,set:e,get g(){},set s(t){},c,a:1,m(){}}}"
 }
 
 use_shorthand_opportunity: {
@@ -297,7 +297,7 @@ concise_methods_and_mangle_props: {
     expect: {
         function x() {
             obj = {
-                a() { return 1; }
+                o() { return 1; }
             }
         }
     }

test/compress/parameters.js

@@ -1,4 +1,7 @@
 arrow_functions: {
+    options = {
+        arrows: true,
+    }
     input: {
         (a) => b;  // 1 args
         (a, b) => c;  // n args
@@ -13,6 +16,9 @@ arrow_functions: {
 }
 
 arrow_return: {
+    options = {
+        arrows: true,
+    }
     input: {
         () => {};
         () => { return; };

test/compress/properties.js

@@ -135,11 +135,11 @@ mangle_properties: {
         a['run']({color: "blue", foo: "baz"});
     }
     expect: {
-        a["a"] = "bar";
-        a.b = "red";
-        x = {c: 10};
-        a.d(x.c, a.a);
-        a['d']({b: "blue", a: "baz"});
+        a["o"] = "bar";
+        a.a = "red";
+        x = {r: 10};
+        a.b(x.r, a.o);
+        a['b']({a: "blue", o: "baz"});
     }
 }
 
@@ -178,16 +178,16 @@ mangle_unquoted_properties: {
         function f1() {
             a["foo"] = "bar";
             a.color = "red";
-            a.b = 2;
-            x = {"bar": 10, c: 7};
-            a.c = 9;
+            a.o = 2;
+            x = {"bar": 10, f: 7};
+            a.f = 9;
         }
         function f2() {
             a.foo = "bar";
             a['color'] = "red";
-            x = {bar: 10, c: 7};
-            a.c = 9;
-            a.b = 3;
+            x = {bar: 10, f: 7};
+            a.f = 9;
+            a.o = 3;
         }
     }
 }

test/compress/pure_getters.js

@@ -241,3 +241,147 @@ issue_2110_2: {
     }
     expect_stdout: "function"
 }
+
+set_immutable_1: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 1;
+        a.foo += "";
+        if (a.foo) console.log("FAIL");
+        else console.log("PASS");
+    }
+    expect: {
+        1..foo += "";
+        if (1..foo) console.log("FAIL");
+        else console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+set_immutable_2: {
+    options = {
+        cascade: true,
+        conditionals: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        var a = 1;
+        a.foo += "";
+        if (a.foo) console.log("FAIL");
+        else console.log("PASS");
+    }
+    expect: {
+        var a = 1;
+        a.foo += "", a.foo ? console.log("FAIL") : console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+set_immutable_3: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        var a = 1;
+        a.foo += "";
+        if (a.foo) console.log("FAIL");
+        else console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        1..foo += "";
+        if (1..foo) console.log("FAIL");
+        else console.log("PASS");
+    }
+    expect_stdout: true
+}
+
+set_immutable_4: {
+    options = {
+        cascade: true,
+        conditionals: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        "use strict";
+        var a = 1;
+        a.foo += "";
+        if (a.foo) console.log("FAIL");
+        else console.log("PASS");
+    }
+    expect: {
+        "use strict";
+        var a = 1;
+        a.foo += "", a.foo ? console.log("FAIL") : console.log("PASS");
+    }
+    expect_stdout: true
+}
+
+set_mutable_1: {
+    options = {
+        collapse_vars: true,
+        evaluate: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        !function a() {
+            a.foo += "";
+            if (a.foo) console.log("PASS");
+            else console.log("FAIL");
+        }();
+    }
+    expect: {
+        !function a() {
+            if (a.foo += "") console.log("PASS");
+            else console.log("FAIL");
+        }();
+    }
+    expect_stdout: "PASS"
+}
+
+set_mutable_2: {
+    options = {
+        cascade: true,
+        conditionals: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+        sequences: true,
+        side_effects: true,
+    }
+    input: {
+        !function a() {
+            a.foo += "";
+            if (a.foo) console.log("PASS");
+            else console.log("FAIL");
+        }();
+    }
+    expect: {
+        !function a() {
+            (a.foo += "") ? console.log("PASS") : console.log("FAIL");
+        }();
+    }
+    expect_stdout: "PASS"
+}

test/compress/reduce_vars.js

@@ -2625,3 +2625,28 @@ issue_2090_2: {
     expect_stdout: "1"
     node_version: ">=4"
 }
+
+for_in_prop: {
+    options = {
+        reduce_vars: true,
+    }
+    input: {
+        var a = {
+            foo: function() {
+                for (this.b in [1, 2]);
+            }
+        };
+        a.foo();
+        console.log(a.b);
+    }
+    expect: {
+        var a = {
+            foo: function() {
+                for (this.b in [1, 2]);
+            }
+        };
+        a.foo();
+        console.log(a.b);
+    }
+    expect_stdout: "1"
+}

test/compress/screw-ie8.js

@@ -255,3 +255,73 @@ issue_1586_2: {
     }
     expect_exact: "function f(){try{x()}catch(c){console.log(c.message)}}"
 }
+
+issue_2120_1: {
+    mangle = {
+        ie8: false,
+    }
+    input: {
+        "aaaaaaaa";
+        var a = 1, b = "FAIL";
+        try {
+            throw 1;
+        } catch (c) {
+            try {
+                throw 0;
+            } catch (a) {
+                if (c) b = "PASS";
+            }
+        }
+        console.log(b);
+    }
+    expect: {
+        "aaaaaaaa";
+        var a = 1, b = "FAIL";
+        try {
+            throw 1;
+        } catch (t) {
+            try {
+                throw 0;
+            } catch (a) {
+                if (t) b = "PASS";
+            }
+        }
+        console.log(b);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_2120_2: {
+    mangle = {
+        ie8: true,
+    }
+    input: {
+        "aaaaaaaa";
+        var a = 1, b = "FAIL";
+        try {
+            throw 1;
+        } catch (c) {
+            try {
+                throw 0;
+            } catch (a) {
+                if (c) b = "PASS";
+            }
+        }
+        console.log(b);
+    }
+    expect: {
+        "aaaaaaaa";
+        var a = 1, b = "FAIL";
+        try {
+            throw 1;
+        } catch (c) {
+            try {
+                throw 0;
+            } catch (a) {
+                if (c) b = "PASS";
+            }
+        }
+        console.log(b);
+    }
+    expect_stdout: "PASS"
+}

test/input/invalid/export_1.js

@@ -0,0 +1,3 @@
+{
+    export var V = 1;
+}

test/input/invalid/export_2.js

@@ -0,0 +1 @@
+export class{};

test/input/invalid/export_3.js

@@ -0,0 +1 @@
+export function(){};

test/input/invalid/for-in_1.js

@@ -0,0 +1,4 @@
+var a, b = [1, 2];
+for (1, 2, a in b) {
+    console.log(a, b[a]);
+}

test/input/invalid/for-in_2.js

@@ -0,0 +1,4 @@
+var c = [1, 2];
+for (var a, b in c) {
+    console.log(a, c[a]);
+}

test/input/invalid/import.js

@@ -0,0 +1,3 @@
+{
+    import A from "B";
+}

test/input/invalid/sequence.js

@@ -0,0 +1 @@
+(a, ...b);

test/mocha/arrow.js

@@ -62,23 +62,20 @@ describe("Arrow functions", function() {
         }
     });
     it("Should not accept arrow functions in the middle or end of an expression", function() {
-        var tests = [
+        [
+            "0 + x => 0",
+            "0 + async x => 0",
             "typeof x => 0",
-            "0 + x => 0"
-        ];
-        var test = function(code) {
-            return function() {
+            "typeof async x => 0",
+            "typeof (x) => null",
+            "typeof async (x) => null",
+        ].forEach(function(code) {
+            assert.throws(function() {
                 uglify.parse(code);
-            }
-        }
-        var error = function(e) {
-            return e instanceof uglify.JS_Parse_Error &&
-                e.message === "Unexpected token: arrow (=>)";
-        }
-
-        for (var i = 0; i < tests.length; i++) {
-            assert.throws(test(tests[i]), error);
-        }
+            }, function(e) {
+                return e instanceof uglify.JS_Parse_Error && /^Unexpected /.test(e.message);
+            }, code);
+        });
     });
 
     it("Should parse a function containing default assignment correctly", function() {

test/mocha/cli.js

@@ -1,6 +1,7 @@
 var assert = require("assert");
 var exec = require("child_process").exec;
 var readFileSync = require("fs").readFileSync;
+var semver = require("semver");
 
 function read(path) {
     return readFileSync(path, "utf8");
@@ -9,9 +10,11 @@ function read(path) {
 describe("bin/uglifyjs", function () {
     var uglifyjscmd = '"' + process.argv[0] + '" bin/uglifyjs';
     it("should produce a functional build when using --self", function (done) {
-        this.timeout(30000);
+        this.timeout(60000);
 
-        var command = uglifyjscmd + ' --self -cm --wrap WrappedUglifyJS';
+        var command = uglifyjscmd + ' --self -mc ecma=';
+        command += semver.satisfies(process.version, ">=4") ? "6" : "5";
+        command += ',passes=3,keep_fargs=false,unsafe --wrap WrappedUglifyJS';
 
         exec(command, function (err, stdout) {
             if (err) throw err;
@@ -533,6 +536,111 @@ describe("bin/uglifyjs", function () {
             done();
         });
     });
+    it("Should throw syntax error (block-level export)", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/export_1.js -m';
+
+        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/export_1.js:2,4",
+                "    export var V = 1;",
+                "    ^",
+                "ERROR: Export statement may only appear at top level"
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (block-level import)", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/import.js -m';
+
+        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/import.js:2,4",
+                '    import A from "B";',
+                "    ^",
+                "ERROR: Import statement may only appear at top level"
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (anonymous class)", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/export_2.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/export_2.js:1,12",
+                "export class{};",
+                "            ^",
+                "ERROR: Unexpected token: punc ({)"
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (anonymous function)", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/export_3.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/export_3.js:1,15",
+                "export function(){};",
+                "               ^",
+                "ERROR: Unexpected token: punc (()"
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (spread in sequence)", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/sequence.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/sequence.js:1,4",
+                "(a, ...b);",
+                "    ^",
+                "ERROR: Unexpected token: expand (...)"
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (for-in init)", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/for-in_1.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-in_1.js:2,5",
+                "for (1, 2, a in b) {",
+                "     ^",
+                "ERROR: Invalid left-hand side in for..in loop"
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (for-in var)", function(done) {
+        var command = uglifyjscmd + ' test/input/invalid/for-in_2.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-in_2.js:2,5",
+                "for (var a, b in c) {",
+                "     ^",
+                "ERROR: Only one variable declaration allowed in for..in loop"
+            ].join("\n"));
+            done();
+        });
+    });
     it("Should handle literal string as source map input", function(done) {
         var command = [
             uglifyjscmd,

test/mocha/export.js

@@ -2,8 +2,7 @@ var assert = require("assert");
 var uglify = require("../node");
 
 describe("Export", function() {
-    it ("Should parse export directives", function() {
-
+    it("Should parse export directives", function() {
         var inputs = [
             ['export * from "a.js"', ['*'], "a.js"],
             ['export {A} from "a.js"', ['A'], "a.js"],
@@ -12,17 +11,17 @@ describe("Export", function() {
             ['export {A, B} from "a.js"', ['A', 'B'], "a.js"],
         ];
 
-        var test = function(code) {
+        function test(code) {
             return uglify.parse(code);
-        };
+        }
 
-        var extractNames = function(symbols) {
+        function extractNames(symbols) {
             var ret = [];
             for (var i = 0; i < symbols.length; i++) {
-                ret.push(symbols[i].name.name)
+                ret.push(symbols[i].foreign_name.name);
             }
             return ret;
-        };
+        }
 
         for (var i = 0; i < inputs.length; i++) {
             var ast = test(inputs[i][0]);
@@ -34,7 +33,7 @@ describe("Export", function() {
             assert(st instanceof uglify.AST_Export);
             var actualNames = extractNames(st.exported_names);
             assert.deepEqual(actualNames, names);
-            assert.equal(st.module_name.value, filename)
+            assert.equal(st.module_name.value, filename);
         }
-    })
-});
+    });
+});

test/mocha/function.js

@@ -191,15 +191,51 @@ describe("Function", function() {
         ];
         var test = function(code) {
             return function() {
-                uglify.parse(code);
+                uglify.parse(code, { ecma: 5 });
             }
         }
         var error = function(e) {
-            return e instanceof uglify.JS_Parse_Error &&
-                e.message === "Invalid function parameter";
+            return e instanceof uglify.JS_Parse_Error;
         }
         for (var i = 0; i < tests.length; i++) {
-            assert.throws(test(tests[i]), error);
+            assert.throws(test(tests[i]), error, tests[i]);
+        }
+    });
+    it("Should accept trailing commas only for ES8", function() {
+        [
+            "new Foo(a, );",
+            "async(...[1, 2], );",
+            "console.log(...[1, 2], );",
+            "!function(a, b, ){ console.log(a + b); }(3, 4, );",
+        ].forEach(function(code) {
+            uglify.parse(code, { ecma: 8 });
+            assert.throws(function() {
+                uglify.parse(code, { ecma: 6 });
+            }, function(e) {
+                return e instanceof uglify.JS_Parse_Error;
+            }, code);
+        });
+    });
+    it("Should not accept invalid trailing commas", function() {
+        var tests = [
+            "f(, );",
+            "(, ) => {};",
+            "(...p, ) => {};",
+            "function f(, ) {}",
+            "function f(...p, ) {}",
+            "function foo(a, b, , ) {}",
+            'console.log("hello", , );',
+        ];
+        var test = function(code) {
+            return function() {
+                uglify.parse(code, { ecma: 8 });
+            }
+        }
+        var error = function(e) {
+            return e instanceof uglify.JS_Parse_Error;
+        }
+        for (var i = 0; i < tests.length; i++) {
+            assert.throws(test(tests[i]), error, tests[i]);
         }
     });
     it("Should not accept an initializer when parameter is a rest parameter", function() {

test/mocha/glob.js

@@ -26,12 +26,12 @@ describe("bin/uglifyjs with input file globs", function() {
         });
     });
     it("bin/uglifyjs with multiple input file globs.", function(done) {
-        var command = uglifyjscmd + ' "test/input/issue-1242/???.es5" "test/input/issue-1242/*.js" -mc toplevel';
+        var command = uglifyjscmd + ' "test/input/issue-1242/???.es5" "test/input/issue-1242/*.js" -mc toplevel,passes=2';
 
         exec(command, function(err, stdout) {
             if (err) throw err;
 
-            assert.strictEqual(stdout, 'var print=console.log.bind(console);print("qux",9,6),print("Foo:",2*11);\n');
+            assert.strictEqual(stdout, 'var print=console.log.bind(console);print("qux",9,6),print("Foo:",22);\n');
             done();
         });
     });

test/mocha/let.js

@@ -2,29 +2,37 @@ var Uglify = require('../../');
 var assert = require("assert");
 
 describe("let", function() {
-    it("Should not produce `let` as a variable name in mangle", function(done) {
+    it("Should not produce reserved keywords as variable name in mangle", function(done) {
         this.timeout(10000);
 
         // Produce a lot of variables in a function and run it through mangle.
-        var s = '"use strict"; function foo() {';
-        for (var i = 0; i < 21000; ++i) {
+        var s = '"dddddeeeeelllllooooottttt"; function foo() {';
+        for (var i = 0; i < 18000; i++) {
             s += "var v" + i + "=0;";
         }
         s += '}';
         var result = Uglify.minify(s, {compress: false});
 
         // Verify that select keywords and reserved keywords not produced
-        assert.strictEqual(result.code.indexOf("var let="), -1);
-        assert.strictEqual(result.code.indexOf("var do="), -1);
-        assert.strictEqual(result.code.indexOf("var var="), -1);
+        [
+            "do",
+            "let",
+            "var",
+        ].forEach(function(name) {
+            assert.strictEqual(result.code.indexOf("var " + name + "="), -1);
+        });
 
         // Verify that the variable names that appeared immediately before
-        // and after the erroneously generated `let` variable name still exist
+        // and after the erroneously generated variable name still exist
         // to show the test generated enough symbols.
-        assert(result.code.indexOf("var ket=") >= 0);
-        assert(result.code.indexOf("var met=") >= 0);
+        [
+            "to", "eo",
+            "eet", "fet",
+            "rar", "oar",
+        ].forEach(function(name) {
+            assert.ok(result.code.indexOf("var " + name + "=") >= 0);
+        });
 
         done();
     });
 });
-

test/mocha/minify.js

@@ -1,6 +1,7 @@
 var Uglify = require('../../');
 var assert = require("assert");
 var readFileSync = require("fs").readFileSync;
+var run_code = require("../sandbox").run_code;
 
 function read(path) {
     return readFileSync(path, "utf8");
@@ -20,6 +21,58 @@ describe("minify", function() {
         assert.strictEqual(result.code, "alert(2);");
     });
 
+    it("Should work with mangle.cache", function() {
+        var cache = {};
+        var original = "";
+        var compressed = "";
+        [
+            "bar.es5",
+            "baz.es5",
+            "foo.es5",
+            "qux.js",
+        ].forEach(function(file) {
+            var code = read("test/input/issue-1242/" + file);
+            var result = Uglify.minify(code, {
+                mangle: {
+                    cache: cache,
+                    toplevel: true
+                }
+            });
+            if (result.error) throw result.error;
+            original += code;
+            compressed += result.code;
+        });
+        assert.strictEqual(JSON.stringify(cache).slice(0, 20), '{"cname":5,"props":{');
+        assert.strictEqual(compressed, 'function n(n){return 3*n}function r(n){return n/2}function c(o){l("Foo:",2*o)}var l=console.log.bind(console);var f=n(3),i=r(12);l("qux",f,i),c(11);');
+        assert.strictEqual(run_code(compressed), run_code(original));
+    });
+
+    it("Should work with nameCache", function() {
+        var cache = {};
+        var original = "";
+        var compressed = "";
+        [
+            "bar.es5",
+            "baz.es5",
+            "foo.es5",
+            "qux.js",
+        ].forEach(function(file) {
+            var code = read("test/input/issue-1242/" + file);
+            var result = Uglify.minify(code, {
+                mangle: {
+                    toplevel: true
+                },
+                nameCache: cache
+            });
+            if (result.error) throw result.error;
+            original += code;
+            compressed += result.code;
+        });
+        assert.strictEqual(JSON.stringify(cache).slice(0, 28), '{"vars":{"cname":5,"props":{');
+        assert.strictEqual(compressed, 'function n(n){return 3*n}function r(n){return n/2}function c(o){l("Foo:",2*o)}var l=console.log.bind(console);var f=n(3),i=r(12);l("qux",f,i),c(11);');
+        assert.strictEqual(run_code(compressed), run_code(original));
+    });
+
     describe("keep_quoted_props", function() {
         it("Should preserve quotes in object literals", function() {
             var js = 'var foo = {"x": 1, y: 2, \'z\': 3};';
@@ -212,7 +265,7 @@ describe("minify", function() {
             });
             var err = result.error;
             assert.ok(err instanceof Error);
-            assert.strictEqual(err.stack.split(/\n/)[0], "Error: Can't handle expression: debugger");
+            assert.strictEqual(err.stack.split(/\n/)[0], "SyntaxError: Unexpected token: keyword (debugger)");
         });
         it("should skip inherited properties", function() {
             var foo = Object.create({ skip: this });

test/mocha/template-string.js

@@ -30,4 +30,13 @@ describe("Template string", function() {
             assert.throws(exec(tests[i]), fail, tests[i]);
         }
     });
+    it("Should process all line terminators as LF", function() {
+        [
+            "`a\rb`",
+            "`a\nb`",
+            "`a\r\nb`",
+        ].forEach(function(code) {
+            assert.strictEqual(uglify.parse(code).print_to_string(), "`a\\nb`;");
+        });
+    });
 });

test/run-tests.js

@@ -86,7 +86,6 @@ function run_compress_tests() {
         log_start_file(file);
         function test_case(test) {
             log_test(test.name);
-            U.base54.reset();
             var output_options = test.beautify || {};
             var expect;
             if (test.expect) {
@@ -101,9 +100,6 @@ function run_compress_tests() {
                 quote_style: 3,
                 keep_quoted_props: true
             });
-            if (test.mangle_props) {
-                input = U.mangle_properties(input, test.mangle_props);
-            }
             var options = U.defaults(test.options, {
                 warnings: false
             });
@@ -118,10 +114,16 @@ function run_compress_tests() {
             var cmp = new U.Compressor(options, true);
             var output = cmp.compress(input);
             output.figure_out_scope(test.mangle);
-            if (test.mangle) {
+            if (test.mangle || test.mangle_props) {
+                U.base54.reset();
                 output.compute_char_frequency(test.mangle);
+            }
+            if (test.mangle) {
                 output.mangle_names(test.mangle);
             }
+            if (test.mangle_props) {
+                output = U.mangle_properties(output, test.mangle_props);
+            }
             output = make_code(output, output_options);
             if (expect != output) {
                 log("!!! failed\n---INPUT---\n{input}\n---OUTPUT---\n{output}\n---EXPECTED---\n{expected}\n\n", {