v3.12.8

fixes #4644

.github/workflows/ufuzz.yml

@@ -32,6 +32,8 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install GNU Core Utilities
         if: ${{ startsWith(matrix.os, 'macos') }}
+        env:
+          HOMEBREW_NO_INSTALL_CLEANUP: 1
         shell: bash
         run: |
           brew install coreutils

README.md

@@ -769,6 +769,9 @@ to be `false` and all symbol names will be omitted.
 
 - `switches` (default: `true`) -- de-duplicate and remove unreachable `switch` branches
 
+- `templates` (default: `true`) -- compact template literals by embedding expressions
+  and/or converting to string literals, e.g. `` `foo ${42}` → "foo 42"``
+
 - `top_retain` (default: `null`) -- prevent specific toplevel functions and
   variables from `unused` removal (can be array, comma-separated, RegExp or
   function. Implies `toplevel`)
@@ -808,6 +811,8 @@ to be `false` and all symbol names will be omitted.
 - `varify` (default: `true`) -- convert block-scoped declaractions into `var`
   whenever safe to do so
 
+- `yields` (default: `true`) -- apply optimizations to `yield` expressions
+
 ## Mangle options
 
 - `eval` (default `false`) -- Pass `true` to mangle names visible in scopes
@@ -1254,3 +1259,25 @@ To allow for better optimizations, the compiler makes various assumptions:
   }()) => b)());
   ```
   UglifyJS may modify the input which in turn may suppress those errors.
+- Some arithmetic operations with `BigInt` may throw `TypeError`:
+  ```javascript
+  1n + 1;
+  // TypeError: can't convert BigInt to number
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.
+- Some versions of JavaScript will throw `SyntaxError` with the
+  following:
+  ```javascript
+  console.log(String.raw`\uFo`);
+  // SyntaxError: Invalid Unicode escape sequence
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.
+- Some versions of JavaScript will throw `SyntaxError` with the
+  following:
+  ```javascript
+  try {} catch (e) {
+      for (var e of []);
+  }
+  // SyntaxError: Identifier 'e' has already been declared
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.

lib/ast.js

@@ -113,7 +113,9 @@ var AST_Node = DEFNODE("Node", "start end", {
     walk: function(visitor) {
         visitor.visit(this);
     },
-    _validate: noop,
+    _validate: function() {
+        if (this.TYPE == "Node") throw new Error("should not instantiate AST_Node");
+    },
     validate: function() {
         var ctor = this.CTOR;
         do {
@@ -187,6 +189,9 @@ AST_Node.disable_validation = function() {
 
 var AST_Statement = DEFNODE("Statement", null, {
     $documentation: "Base class of all statements",
+    _validate: function() {
+        if (this.TYPE == "Statement") throw new Error("should not instantiate AST_Statement");
+    },
 });
 
 var AST_Debugger = DEFNODE("Debugger", null, {
@@ -215,7 +220,7 @@ function validate_expression(value, prop, multiple, allow_spread, allow_hole) {
     if (value instanceof AST_Destructured) throw new Error(prop + " cannot " + multiple + " AST_Destructured");
     if (value instanceof AST_Hole && !allow_hole) throw new Error(prop + " cannot " + multiple + " AST_Hole");
     if (value instanceof AST_Spread && !allow_spread) throw new Error(prop + " cannot " + multiple + " AST_Spread");
-    if (value instanceof AST_Statement && !is_function(value)) {
+    if (value instanceof AST_Statement && !(value instanceof AST_LambdaExpression)) {
         throw new Error(prop + " cannot " + multiple + " AST_Statement");
     }
     if (value instanceof AST_SymbolDeclaration) {
@@ -249,7 +254,7 @@ var AST_BlockScope = DEFNODE("BlockScope", "enclosed functions make_def parent_s
         enclosed: "[SymbolDef*/S] a list of all symbol definitions that are accessed from this scope or any subscopes",
         functions: "[Object/S] like `variables`, but only lists function declarations",
         parent_scope: "[AST_Scope?/S] link to the parent scope",
-        variables: "[Object/S] a map of name -> SymbolDef for all variables/functions defined in this scope",
+        variables: "[Object/S] a map of name ---> SymbolDef for all variables/functions defined in this scope",
     },
     clone: function(deep) {
         var node = this._clone(deep);
@@ -265,6 +270,7 @@ var AST_BlockScope = DEFNODE("BlockScope", "enclosed functions make_def parent_s
         return this.parent_scope.resolve();
     },
     _validate: function() {
+        if (this.TYPE == "BlockScope") throw new Error("should not instantiate AST_BlockScope");
         if (this.parent_scope == null) return;
         if (!(this.parent_scope instanceof AST_BlockScope)) throw new Error("parent_scope must be AST_BlockScope");
         if (!(this.resolve() instanceof AST_Scope)) throw new Error("must be contained within AST_Scope");
@@ -289,9 +295,10 @@ var AST_Block = DEFNODE("Block", "body", {
         });
     },
     _validate: function() {
+        if (this.TYPE == "Block") throw new Error("should not instantiate AST_Block");
         this.body.forEach(function(node) {
             if (!(node instanceof AST_Statement)) throw new Error("body must be AST_Statement[]");
-            if (is_function(node)) throw new Error("body cannot contain AST_Function");
+            if (node instanceof AST_LambdaExpression) throw new Error("body cannot contain AST_LambdaExpression");
         });
     },
 }, AST_BlockScope);
@@ -306,8 +313,9 @@ var AST_StatementWithBody = DEFNODE("StatementWithBody", "body", {
         body: "[AST_Statement] the body; this should always be present, even if it's an AST_EmptyStatement"
     },
     _validate: function() {
+        if (this.TYPE == "StatementWithBody") throw new Error("should not instantiate AST_StatementWithBody");
         if (!(this.body instanceof AST_Statement)) throw new Error("body must be AST_Statement");
-        if (is_function(this.body)) throw new Error("body cannot be AST_Function");
+        if (this.body instanceof AST_LambdaExpression) throw new Error("body cannot be AST_LambdaExpression");
     },
 }, AST_BlockScope);
 
@@ -346,7 +354,10 @@ var AST_LabeledStatement = DEFNODE("LabeledStatement", "label", {
 }, AST_StatementWithBody);
 
 var AST_IterationStatement = DEFNODE("IterationStatement", null, {
-    $documentation: "Internal class.  All loops inherit from it."
+    $documentation: "Internal class.  All loops inherit from it.",
+    _validate: function() {
+        if (this.TYPE == "IterationStatement") throw new Error("should not instantiate AST_IterationStatement");
+    },
 }, AST_StatementWithBody);
 
 var AST_DWLoop = DEFNODE("DWLoop", "condition", {
@@ -355,6 +366,7 @@ var AST_DWLoop = DEFNODE("DWLoop", "condition", {
         condition: "[AST_Node] the loop condition.  Should not be instanceof AST_Statement"
     },
     _validate: function() {
+        if (this.TYPE == "DWLoop") throw new Error("should not instantiate AST_DWLoop");
         must_be_expression(this, "condition");
     },
 }, AST_IterationStatement);
@@ -401,7 +413,7 @@ var AST_For = DEFNODE("For", "init condition step", {
         if (this.init != null) {
             if (!(this.init instanceof AST_Node)) throw new Error("init must be AST_Node");
             if (this.init instanceof AST_Statement
-                && !(this.init instanceof AST_Definitions || is_function(this.init))) {
+                && !(this.init instanceof AST_Definitions || this.init instanceof AST_LambdaExpression)) {
                 throw new Error("init cannot be AST_Statement");
             }
         }
@@ -410,11 +422,11 @@ var AST_For = DEFNODE("For", "init condition step", {
     },
 }, AST_IterationStatement);
 
-var AST_ForIn = DEFNODE("ForIn", "init object", {
-    $documentation: "A `for ... in` statement",
+var AST_ForEnumeration = DEFNODE("ForEnumeration", "init object", {
+    $documentation: "Base class for enumeration loops, i.e. `for ... in`, `for ... of` &  `for await ... of`",
     $propdoc: {
-        init: "[AST_Node] the `for/in` initialization code",
-        object: "[AST_Node] the object that we're looping through"
+        init: "[AST_Node] the assignment target during iteration",
+        object: "[AST_Node] the object to iterate over"
     },
     walk: function(visitor) {
         var node = this;
@@ -425,6 +437,7 @@ var AST_ForIn = DEFNODE("ForIn", "init object", {
         });
     },
     _validate: function() {
+        if (this.TYPE == "ForEnumeration") throw new Error("should not instantiate AST_ForEnumeration");
         if (this.init instanceof AST_Definitions) {
             if (this.init.definitions.length != 1) throw new Error("init must have single declaration");
         } else {
@@ -438,6 +451,18 @@ var AST_ForIn = DEFNODE("ForIn", "init object", {
     },
 }, AST_IterationStatement);
 
+var AST_ForIn = DEFNODE("ForIn", null, {
+    $documentation: "A `for ... in` statement",
+}, AST_ForEnumeration);
+
+var AST_ForOf = DEFNODE("ForOf", null, {
+    $documentation: "A `for ... of` statement",
+}, AST_ForEnumeration);
+
+var AST_ForAwaitOf = DEFNODE("ForAwaitOf", null, {
+    $documentation: "A `for await ... of` statement",
+}, AST_ForOf);
+
 var AST_With = DEFNODE("With", "expression", {
     $documentation: "A `with` statement",
     $propdoc: {
@@ -467,12 +492,15 @@ var AST_Scope = DEFNODE("Scope", "uses_eval uses_with", {
         return this.uses_eval || this.uses_with;
     },
     resolve: return_this,
+    _validate: function() {
+        if (this.TYPE == "Scope") throw new Error("should not instantiate AST_Scope");
+    },
 }, AST_Block);
 
 var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     $documentation: "The toplevel scope",
     $propdoc: {
-        globals: "[Object/S] a map of name -> SymbolDef for all undeclared names",
+        globals: "[Object/S] a map of name ---> SymbolDef for all undeclared names",
     },
     wrap: function(name) {
         var body = this.body;
@@ -517,8 +545,9 @@ var AST_Lambda = DEFNODE("Lambda", "argnames length_read rest uses_arguments", {
     $documentation: "Base class for functions",
     $propdoc: {
         argnames: "[(AST_DefaultValue|AST_Destructured|AST_SymbolFunarg)*] array of function arguments and/or destructured literals",
+        length_read: "[boolean/S] whether length property of this function is accessed",
         rest: "[(AST_Destructured|AST_SymbolFunarg)?] rest parameter, or null if absent",
-        uses_arguments: "[boolean/S] tells whether this function accesses the arguments array",
+        uses_arguments: "[boolean/S] whether this function accesses the arguments array",
     },
     each_argname: function(visit) {
         var tw = new TreeWalker(function(node) {
@@ -549,6 +578,7 @@ var AST_Lambda = DEFNODE("Lambda", "argnames length_read rest uses_arguments", {
         });
     },
     _validate: function() {
+        if (this.TYPE == "Lambda") throw new Error("should not instantiate AST_Lambda");
         this.argnames.forEach(function(node) {
             validate_destructured(node, function(node) {
                 if (!(node instanceof AST_SymbolFunarg)) throw new Error("argnames must be AST_SymbolFunarg[]");
@@ -567,12 +597,33 @@ var AST_Accessor = DEFNODE("Accessor", null, {
     },
 }, AST_Lambda);
 
+var AST_LambdaExpression = DEFNODE("LambdaExpression", "inlined", {
+    $documentation: "Base class for function expressions",
+    $propdoc: {
+        inlined: "[boolean/S] whether this function has been inlined",
+    },
+    _validate: function() {
+        if (this.TYPE == "LambdaExpression") throw new Error("should not instantiate AST_LambdaExpression");
+    },
+}, AST_Lambda);
+
 function is_arrow(node) {
-    return node instanceof AST_AsyncArrow || node instanceof AST_Arrow;
+    return node instanceof AST_Arrow || node instanceof AST_AsyncArrow;
 }
 
-function is_function(node) {
-    return is_arrow(node) || node instanceof AST_AsyncFunction || node instanceof AST_Function;
+function is_async(node) {
+    return node instanceof AST_AsyncArrow
+        || node instanceof AST_AsyncDefun
+        || node instanceof AST_AsyncFunction
+        || node instanceof AST_AsyncGeneratorDefun
+        || node instanceof AST_AsyncGeneratorFunction;
+}
+
+function is_generator(node) {
+    return node instanceof AST_AsyncGeneratorDefun
+        || node instanceof AST_AsyncGeneratorFunction
+        || node instanceof AST_GeneratorDefun
+        || node instanceof AST_GeneratorFunction;
 }
 
 function walk_lambda(node, tw) {
@@ -583,7 +634,7 @@ function walk_lambda(node, tw) {
     }
 }
 
-var AST_Arrow = DEFNODE("Arrow", "inlined value", {
+var AST_Arrow = DEFNODE("Arrow", "value", {
     $documentation: "An arrow function expression",
     $propdoc: {
         value: "[AST_Node?] simple return expression, or null if using function body.",
@@ -610,13 +661,9 @@ var AST_Arrow = DEFNODE("Arrow", "inlined value", {
             if (this.body.length) throw new Error("body must be empty if value exists");
         }
     },
-}, AST_Lambda);
+}, AST_LambdaExpression);
 
-function is_async(node) {
-    return node instanceof AST_AsyncArrow || node instanceof AST_AsyncDefun || node instanceof AST_AsyncFunction;
-}
-
-var AST_AsyncArrow = DEFNODE("AsyncArrow", "inlined value", {
+var AST_AsyncArrow = DEFNODE("AsyncArrow", "value", {
     $documentation: "An asynchronous arrow function expression",
     $propdoc: {
         value: "[AST_Node?] simple return expression, or null if using function body.",
@@ -643,9 +690,9 @@ var AST_AsyncArrow = DEFNODE("AsyncArrow", "inlined value", {
             if (this.body.length) throw new Error("body must be empty if value exists");
         }
     },
-}, AST_Lambda);
+}, AST_LambdaExpression);
 
-var AST_AsyncFunction = DEFNODE("AsyncFunction", "inlined name", {
+var AST_AsyncFunction = DEFNODE("AsyncFunction", "name", {
     $documentation: "An asynchronous function expression",
     $propdoc: {
         name: "[AST_SymbolLambda?] the name of this function",
@@ -655,9 +702,21 @@ var AST_AsyncFunction = DEFNODE("AsyncFunction", "inlined name", {
             if (!(this.name instanceof AST_SymbolLambda)) throw new Error("name must be AST_SymbolLambda");
         }
     },
-}, AST_Lambda);
+}, AST_LambdaExpression);
 
-var AST_Function = DEFNODE("Function", "inlined name", {
+var AST_AsyncGeneratorFunction = DEFNODE("AsyncGeneratorFunction", "name", {
+    $documentation: "An asynchronous generator function expression",
+    $propdoc: {
+        name: "[AST_SymbolLambda?] the name of this function",
+    },
+    _validate: function() {
+        if (this.name != null) {
+            if (!(this.name instanceof AST_SymbolLambda)) throw new Error("name must be AST_SymbolLambda");
+        }
+    },
+}, AST_LambdaExpression);
+
+var AST_Function = DEFNODE("Function", "name", {
     $documentation: "A function expression",
     $propdoc: {
         name: "[AST_SymbolLambda?] the name of this function",
@@ -667,36 +726,55 @@ var AST_Function = DEFNODE("Function", "inlined name", {
             if (!(this.name instanceof AST_SymbolLambda)) throw new Error("name must be AST_SymbolLambda");
         }
     },
+}, AST_LambdaExpression);
+
+var AST_GeneratorFunction = DEFNODE("GeneratorFunction", "name", {
+    $documentation: "A generator function expression",
+    $propdoc: {
+        name: "[AST_SymbolLambda?] the name of this function",
+    },
+    _validate: function() {
+        if (this.name != null) {
+            if (!(this.name instanceof AST_SymbolLambda)) throw new Error("name must be AST_SymbolLambda");
+        }
+    },
+}, AST_LambdaExpression);
+
+var AST_LambdaDefinition = DEFNODE("LambdaDefinition", "inlined name", {
+    $documentation: "Base class for function definitions",
+    $propdoc: {
+        inlined: "[boolean/S] whether this function has been inlined",
+        name: "[AST_SymbolDefun] the name of this function",
+    },
+    _validate: function() {
+        if (this.TYPE == "LambdaDefinition") throw new Error("should not instantiate AST_LambdaDefinition");
+        if (!(this.name instanceof AST_SymbolDefun)) throw new Error("name must be AST_SymbolDefun");
+    },
 }, AST_Lambda);
 
-function is_defun(node) {
-    return node instanceof AST_AsyncDefun || node instanceof AST_Defun;
-}
-
-var AST_AsyncDefun = DEFNODE("AsyncDefun", "inlined name", {
+var AST_AsyncDefun = DEFNODE("AsyncDefun", null, {
     $documentation: "An asynchronous function definition",
-    $propdoc: {
-        name: "[AST_SymbolDefun] the name of this function",
-    },
-    _validate: function() {
-        if (!(this.name instanceof AST_SymbolDefun)) throw new Error("name must be AST_SymbolDefun");
-    },
-}, AST_Lambda);
+}, AST_LambdaDefinition);
 
-var AST_Defun = DEFNODE("Defun", "inlined name", {
+var AST_AsyncGeneratorDefun = DEFNODE("AsyncGeneratorDefun", null, {
+    $documentation: "An asynchronous generator function definition",
+}, AST_LambdaDefinition);
+
+var AST_Defun = DEFNODE("Defun", null, {
     $documentation: "A function definition",
-    $propdoc: {
-        name: "[AST_SymbolDefun] the name of this function",
-    },
-    _validate: function() {
-        if (!(this.name instanceof AST_SymbolDefun)) throw new Error("name must be AST_SymbolDefun");
-    },
-}, AST_Lambda);
+}, AST_LambdaDefinition);
+
+var AST_GeneratorDefun = DEFNODE("GeneratorDefun", null, {
+    $documentation: "A generator function definition",
+}, AST_LambdaDefinition);
 
 /* -----[ JUMPS ]----- */
 
 var AST_Jump = DEFNODE("Jump", null, {
-    $documentation: "Base class for “jumps” (for now that's `return`, `throw`, `break` and `continue`)"
+    $documentation: "Base class for “jumps” (for now that's `return`, `throw`, `break` and `continue`)",
+    _validate: function() {
+        if (this.TYPE == "Jump") throw new Error("should not instantiate AST_Jump");
+    },
 }, AST_Statement);
 
 var AST_Exit = DEFNODE("Exit", "value", {
@@ -709,7 +787,10 @@ var AST_Exit = DEFNODE("Exit", "value", {
         visitor.visit(node, function() {
             if (node.value) node.value.walk(visitor);
         });
-    }
+    },
+    _validate: function() {
+        if (this.TYPE == "Exit") throw new Error("should not instantiate AST_Exit");
+    },
 }, AST_Jump);
 
 var AST_Return = DEFNODE("Return", null, {
@@ -738,6 +819,7 @@ var AST_LoopControl = DEFNODE("LoopControl", "label", {
         });
     },
     _validate: function() {
+        if (this.TYPE == "LoopControl") throw new Error("should not instantiate AST_LoopControl");
         if (this.label != null) {
             if (!(this.label instanceof AST_LabelRef)) throw new Error("label must be AST_LabelRef");
         }
@@ -772,7 +854,7 @@ var AST_If = DEFNODE("If", "condition alternative", {
         must_be_expression(this, "condition");
         if (this.alternative != null) {
             if (!(this.alternative instanceof AST_Statement)) throw new Error("alternative must be AST_Statement");
-            if (is_function(this.alternative)) throw new error("alternative cannot be AST_Function");
+            if (this.alternative instanceof AST_LambdaExpression) throw new error("alternative cannot be AST_LambdaExpression");
         }
     },
 }, AST_StatementWithBody);
@@ -801,6 +883,9 @@ var AST_Switch = DEFNODE("Switch", "expression", {
 
 var AST_SwitchBranch = DEFNODE("SwitchBranch", null, {
     $documentation: "Base class for `switch` branches",
+    _validate: function() {
+        if (this.TYPE == "SwitchBranch") throw new Error("should not instantiate AST_SwitchBranch");
+    },
 }, AST_Block);
 
 var AST_Default = DEFNODE("Default", null, {
@@ -889,6 +974,7 @@ var AST_Definitions = DEFNODE("Definitions", "definitions", {
         });
     },
     _validate: function() {
+        if (this.TYPE == "Definitions") throw new Error("should not instantiate AST_Definitions");
         if (this.definitions.length < 1) throw new Error("must have at least one definition");
     },
 }, AST_Statement);
@@ -1036,6 +1122,7 @@ var AST_PropAccess = DEFNODE("PropAccess", "expression property", {
         return p;
     },
     _validate: function() {
+        if (this.TYPE == "PropAccess") throw new Error("should not instantiate AST_PropAccess");
         must_be_expression(this, "expression");
     },
 });
@@ -1096,6 +1183,7 @@ var AST_Unary = DEFNODE("Unary", "operator expression", {
         });
     },
     _validate: function() {
+        if (this.TYPE == "Unary") throw new Error("should not instantiate AST_Unary");
         if (typeof this.operator != "string") throw new Error("operator must be string");
         must_be_expression(this, "expression");
     },
@@ -1183,6 +1271,27 @@ var AST_Await = DEFNODE("Await", "expression", {
     },
 });
 
+var AST_Yield = DEFNODE("Yield", "expression nested", {
+    $documentation: "A yield expression",
+    $propdoc: {
+        expression: "[AST_Node?] return value for iterator, or null if undefined",
+        nested: "[boolean] whether to iterate over expression as generator",
+    },
+    walk: function(visitor) {
+        var node = this;
+        visitor.visit(node, function() {
+            if (node.expression) node.expression.walk(visitor);
+        });
+    },
+    _validate: function() {
+        if (this.expression != null) {
+            must_be_expression(this, "expression");
+        } else if (this.nested) {
+            throw new Error("yield* must contain expression");
+        }
+    },
+});
+
 /* -----[ LITERALS ]----- */
 
 var AST_Array = DEFNODE("Array", "elements", {
@@ -1208,6 +1317,9 @@ var AST_Destructured = DEFNODE("Destructured", "rest", {
     $propdoc: {
         rest: "[(AST_Destructured|AST_SymbolDeclaration|AST_SymbolRef)?] rest parameter, or null if absent",
     },
+    _validate: function() {
+        if (this.TYPE == "Destructured") throw new Error("should not instantiate AST_Destructured");
+    },
 });
 
 function validate_destructured(node, check, allow_default) {
@@ -1319,6 +1431,7 @@ var AST_ObjectProperty = DEFNODE("ObjectProperty", "key value", {
         });
     },
     _validate: function() {
+        if (this.TYPE == "ObjectProperty") throw new Error("should not instantiate AST_ObjectProperty");
         if (typeof this.key != "string") {
             if (!(this.key instanceof AST_Node)) throw new Error("key must be string or AST_Node");
             must_be_expression(this, "key");
@@ -1356,6 +1469,7 @@ var AST_Symbol = DEFNODE("Symbol", "scope name thedef", {
         thedef: "[SymbolDef/S] the definition of this symbol"
     },
     _validate: function() {
+        if (this.TYPE == "Symbol") throw new Error("should not instantiate AST_Symbol");
         if (typeof this.name != "string") throw new Error("name must be string");
     },
 });
@@ -1418,8 +1532,39 @@ var AST_This = DEFNODE("This", null, {
     },
 }, AST_Symbol);
 
+var AST_Template = DEFNODE("Template", "expressions strings tag", {
+    $documentation: "A template literal, i.e. tag`str1${expr1}...strN${exprN}strN+1`",
+    $propdoc: {
+        expressions: "[AST_Node*] the placeholder expressions",
+        strings: "[string*] the raw text segments",
+        tag: "[AST_Node] tag function, or null if absent",
+    },
+    walk: function(visitor) {
+        var node = this;
+        visitor.visit(node, function() {
+            if (node.tag) node.tag.walk(visitor);
+            node.expressions.forEach(function(expr) {
+                expr.walk(visitor);
+            });
+        });
+    },
+    _validate: function() {
+        if (this.expressions.length + 1 != this.strings.length) {
+            throw new Error("malformed template with " + this.expressions.length + " placeholder(s) but " + this.strings.length + " text segment(s)");
+        }
+        must_be_expressions(this, "expressions");
+        this.strings.forEach(function(string) {
+            if (typeof string != "string") throw new Error("strings must contain string");
+        });
+        if (this.tag != null) must_be_expression(this, "tag");
+    },
+});
+
 var AST_Constant = DEFNODE("Constant", null, {
     $documentation: "Base class for all constants",
+    _validate: function() {
+        if (this.TYPE == "Constant") throw new Error("should not instantiate AST_Constant");
+    },
 });
 
 var AST_String = DEFNODE("String", "value quote", {
@@ -1440,6 +1585,19 @@ var AST_Number = DEFNODE("Number", "value", {
     },
     _validate: function() {
         if (typeof this.value != "number") throw new Error("value must be number");
+        if (!isFinite(this.value)) throw new Error("value must be finite");
+        if (this.value < 0) throw new Error("value cannot be negative");
+    },
+}, AST_Constant);
+
+var AST_BigInt = DEFNODE("BigInt", "value", {
+    $documentation: "A BigInt literal",
+    $propdoc: {
+        value: "[string] the numeric representation",
+    },
+    _validate: function() {
+        if (typeof this.value != "string") throw new Error("value must be string");
+        if (this.value[0] == "-") throw new Error("value cannot be negative");
     },
 }, AST_Constant);
 
@@ -1455,6 +1613,9 @@ var AST_RegExp = DEFNODE("RegExp", "value", {
 
 var AST_Atom = DEFNODE("Atom", null, {
     $documentation: "Base class for atoms",
+    _validate: function() {
+        if (this.TYPE == "Atom") throw new Error("should not instantiate AST_Atom");
+    },
 }, AST_Constant);
 
 var AST_Null = DEFNODE("Null", null, {
@@ -1484,6 +1645,9 @@ var AST_Infinity = DEFNODE("Infinity", null, {
 
 var AST_Boolean = DEFNODE("Boolean", null, {
     $documentation: "Base class for booleans",
+    _validate: function() {
+        if (this.TYPE == "Boolean") throw new Error("should not instantiate AST_Boolean");
+    },
 }, AST_Atom);
 
 var AST_False = DEFNODE("False", null, {

lib/output.js

@@ -673,7 +673,9 @@ function OutputStream(options) {
         }
     }
     PARENS(AST_AsyncFunction, needs_parens_function);
+    PARENS(AST_AsyncGeneratorFunction, needs_parens_function);
     PARENS(AST_Function, needs_parens_function);
+    PARENS(AST_GeneratorFunction, needs_parens_function);
 
     // same goes for an object literal, because otherwise it would be
     // interpreted as a block of code.
@@ -682,51 +684,69 @@ function OutputStream(options) {
     }
     PARENS(AST_Object, needs_parens_obj);
 
-    PARENS(AST_Unary, function(output) {
+    function needs_parens_unary(output) {
         var p = output.parent();
-        return (p instanceof AST_Call || p instanceof AST_PropAccess) && p.expression === this;
-    });
+        // (-x) ** y
+        if (p instanceof AST_Binary) return p.operator == "**" && p.left === this;
+        // (await x)(y)
+        // new (await x)
+        if (p instanceof AST_Call) return p.expression === this;
+        // (x++)[y]
+        // (typeof x).y
+        if (p instanceof AST_PropAccess) return p.expression === this;
+    }
+    PARENS(AST_Await, needs_parens_unary);
+    PARENS(AST_Unary, needs_parens_unary);
 
     PARENS(AST_Sequence, function(output) {
         var p = output.parent();
-            // [ 1, (2, 3), 4 ] ==> [ 1, 3, 4 ]
+            // [ 1, (2, 3), 4 ] ---> [ 1, 3, 4 ]
         return p instanceof AST_Array
-            // () => (foo, bar)
+            // () ---> (foo, bar)
             || is_arrow(p) && p.value === this
             // await (foo, bar)
             || p instanceof AST_Await
-            // 1 + (2, 3) + 4 ==> 8
+            // 1 + (2, 3) + 4 ---> 8
             || p instanceof AST_Binary
             // new (foo, bar) or foo(1, (2, 3), 4)
             || p instanceof AST_Call
             // (false, true) ? (a = 10, b = 20) : (c = 30)
-            // ==> 20 (side effect, set a := 10 and b := 20)
+            // ---> 20 (side effect, set a := 10 and b := 20)
             || p instanceof AST_Conditional
-            // [ a = (1, 2) ] = [] ==> a == 2
+            // [ a = (1, 2) ] = [] ---> a == 2
             || p instanceof AST_DefaultValue
-            // { [(1, 2)]: 3 }[2] ==> 3
-            // { foo: (1, 2) }.foo ==> 2
+            // { [(1, 2)]: foo } = bar
+            // { 1: (2, foo) } = bar
             || p instanceof AST_DestructuredKeyVal
+            // for (foo of (bar, baz));
+            || p instanceof AST_ForOf
+            // { [(1, 2)]: 3 }[2] ---> 3
+            // { foo: (1, 2) }.foo ---> 2
             || p instanceof AST_ObjectProperty
-            // (1, {foo:2}).foo or (1, {foo:2})["foo"] ==> 2
+            // (1, {foo:2}).foo or (1, {foo:2})["foo"] ---> 2
             || p instanceof AST_PropAccess && p.expression === this
             // ...(foo, bar, baz)
             || p instanceof AST_Spread
             // !(foo, bar, baz)
             || p instanceof AST_Unary
-            // var a = (1, 2), b = a + a; ==> b == 4
-            || p instanceof AST_VarDef;
+            // var a = (1, 2), b = a + a; ---> b == 4
+            || p instanceof AST_VarDef
+            // yield (foo, bar)
+            || p instanceof AST_Yield;
     });
 
     PARENS(AST_Binary, function(output) {
         var p = output.parent();
         // await (foo && bar)
         if (p instanceof AST_Await) return true;
-        // this deals with precedence: 3 * (2 + 1)
+        // this deals with precedence:
+        //   3 * (2 + 1)
+        //   3 - (2 - 1)
+        //   (1 ** 2) ** 3
         if (p instanceof AST_Binary) {
             var po = p.operator, pp = PRECEDENCE[po];
             var so = this.operator, sp = PRECEDENCE[so];
-            return pp > sp || (pp == sp && this === p.right);
+            return pp > sp || (pp == sp && this === p[po == "**" ? "left" : "right"]);
         }
         // (foo && bar)()
         if (p instanceof AST_Call) return p.expression === this;
@@ -773,18 +793,16 @@ function OutputStream(options) {
         // (new foo)(bar)
         if (p instanceof AST_Call) return p.expression === this;
         // (new Date).getTime(), (new Date)["getTime"]()
-        return p instanceof AST_PropAccess;
+        if (p instanceof AST_PropAccess) return true;
+        // (new foo)`bar`
+        if (p instanceof AST_Template) return p.tag === this;
     });
 
     PARENS(AST_Number, function(output) {
+        if (!output.option("galio")) return false;
+        // https://github.com/mishoo/UglifyJS/pull/1009
         var p = output.parent();
-        if (p instanceof AST_PropAccess && p.expression === this) {
-            var value = this.value;
-                // https://github.com/mishoo/UglifyJS/issues/115
-            return value < 0
-                // https://github.com/mishoo/UglifyJS/pull/1009
-                || output.option("galio") && /^0/.test(make_num(value));
-        }
+        return p instanceof AST_PropAccess && p.expression === this && /^0/.test(make_num(this.value));
     });
 
     function needs_parens_assign_cond(self, output) {
@@ -799,6 +817,8 @@ function OutputStream(options) {
         if (p instanceof AST_Conditional) return p.condition === self;
         // (a = foo)["prop"] —or— (a = foo).prop
         if (p instanceof AST_PropAccess) return p.expression === self;
+        // (a = foo)`bar`
+        if (p instanceof AST_Template) return p.tag === self;
         // !(a = false) → true
         if (p instanceof AST_Unary) return true;
     }
@@ -807,8 +827,8 @@ function OutputStream(options) {
     });
     PARENS(AST_Assign, function(output) {
         if (needs_parens_assign_cond(this, output)) return true;
-        //  v8 parser bug   =>     workaround
-        // f([1], [a] = []) => f([1], ([a] = []))
+        //  v8 parser bug   --->     workaround
+        // f([1], [a] = []) ---> f([1], ([a] = []))
         if (output.option("v8")) return this.left instanceof AST_Destructured;
         // ({ p: a } = o);
         if (this.left instanceof AST_DestructuredObject) return needs_parens_obj(output);
@@ -819,15 +839,8 @@ function OutputStream(options) {
     PARENS(AST_Conditional, function(output) {
         return needs_parens_assign_cond(this, output);
     });
-
-    PARENS(AST_Await, function(output) {
-        var p = output.parent();
-        // new (await foo)
-        // (await foo)(bar)
-        if (p instanceof AST_Call) return p.expression === this;
-        // (await foo).prop
-        // (await foo)["prop"]
-        if (p instanceof AST_PropAccess) return p.expression === this;
+    PARENS(AST_Yield, function(output) {
+        return needs_parens_assign_cond(this, output);
     });
 
     /* -----[ PRINTERS ]----- */
@@ -969,20 +982,25 @@ function OutputStream(options) {
         output.space();
         force_statement(self.body, output);
     });
-    DEFPRINT(AST_ForIn, function(output) {
-        var self = this;
-        output.print("for");
-        output.space();
-        output.with_parens(function() {
-            self.init.print(output);
+    function print_for_enum(prefix, infix) {
+        return function(output) {
+            var self = this;
+            output.print(prefix);
             output.space();
-            output.print("in");
+            output.with_parens(function() {
+                self.init.print(output);
+                output.space();
+                output.print(infix);
+                output.space();
+                self.object.print(output);
+            });
             output.space();
-            self.object.print(output);
-        });
-        output.space();
-        force_statement(self.body, output);
-    });
+            force_statement(self.body, output);
+        };
+    }
+    DEFPRINT(AST_ForAwaitOf, print_for_enum("for await", "of"));
+    DEFPRINT(AST_ForIn, print_for_enum("for", "in"));
+    DEFPRINT(AST_ForOf, print_for_enum("for", "of"));
     DEFPRINT(AST_With, function(output) {
         var self = this;
         output.print("with");
@@ -1052,6 +1070,20 @@ function OutputStream(options) {
     }
     DEFPRINT(AST_AsyncDefun, print_async);
     DEFPRINT(AST_AsyncFunction, print_async);
+    function print_async_generator(output) {
+        output.print("async");
+        output.space();
+        output.print("function*");
+        print_lambda(this, output);
+    }
+    DEFPRINT(AST_AsyncGeneratorDefun, print_async_generator);
+    DEFPRINT(AST_AsyncGeneratorFunction, print_async_generator);
+    function print_generator(output) {
+        output.print("function*");
+        print_lambda(this, output);
+    }
+    DEFPRINT(AST_GeneratorDefun, print_generator);
+    DEFPRINT(AST_GeneratorFunction, print_generator);
 
     /* -----[ jumps ]----- */
     function print_jump(kind, prop) {
@@ -1203,7 +1235,7 @@ function OutputStream(options) {
                 def.print(output);
             });
             var p = output.parent();
-            if (p && p.init !== self || !(p instanceof AST_For || p instanceof AST_ForIn)) output.semicolon();
+            if (!(p instanceof AST_IterationStatement && p.init === self)) output.semicolon();
         };
     }
     DEFPRINT(AST_Const, print_definitinos("const"));
@@ -1230,7 +1262,7 @@ function OutputStream(options) {
             output.print("=");
             output.space();
             var p = output.parent(1);
-            var noin = p instanceof AST_For || p instanceof AST_ForIn;
+            var noin = p instanceof AST_For || p instanceof AST_ForEnumeration;
             parenthesize_for_noin(self.value, output, noin);
         }
     });
@@ -1351,6 +1383,13 @@ function OutputStream(options) {
         output.space();
         this.expression.print(output);
     });
+    DEFPRINT(AST_Yield, function(output) {
+        output.print(this.nested ? "yield*" : "yield");
+        if (this.expression) {
+            output.space();
+            this.expression.print(output);
+        }
+    });
 
     /* -----[ literals ]----- */
     DEFPRINT(AST_Array, function(output) {
@@ -1481,6 +1520,19 @@ function OutputStream(options) {
     DEFPRINT(AST_This, function(output) {
         output.print("this");
     });
+    DEFPRINT(AST_Template, function(output) {
+        var self = this;
+        if (self.tag) self.tag.print(output);
+        output.print("`");
+        for (var i = 0; i < self.expressions.length; i++) {
+            output.print(self.strings[i]);
+            output.print("${");
+            self.expressions[i].print(output);
+            output.print("}");
+        }
+        output.print(self.strings[i]);
+        output.print("`");
+    });
     DEFPRINT(AST_Constant, function(output) {
         output.print(this.value);
     });

lib/parse.js

@@ -81,6 +81,7 @@ var OPERATORS = makePredicate([
     "*",
     "/",
     "%",
+    "**",
     ">>",
     "<<",
     ">>>",
@@ -111,13 +112,18 @@ var OPERATORS = makePredicate([
 
 var NEWLINE_CHARS = "\n\r\u2028\u2029";
 var OPERATOR_CHARS = "+-*&%=<>!?|~^";
-var PUNC_BEFORE_EXPRESSION = "[{(,;:";
-var PUNC_CHARS = PUNC_BEFORE_EXPRESSION + ")}]";
+var PUNC_OPENERS = "[{(";
+var PUNC_SEPARATORS = ",;:";
+var PUNC_CLOSERS = ")}]";
+var PUNC_AFTER_EXPRESSION = PUNC_SEPARATORS + PUNC_CLOSERS;
+var PUNC_BEFORE_EXPRESSION = PUNC_OPENERS + PUNC_SEPARATORS;
+var PUNC_CHARS = PUNC_BEFORE_EXPRESSION + "`" + PUNC_CLOSERS;
 var WHITESPACE_CHARS = NEWLINE_CHARS + " \u00a0\t\f\u000b\u200b\u2000\u2001\u2002\u2003\u2004\u2005\u2006\u2007\u2008\u2009\u200a\u202f\u205f\u3000\uFEFF";
 var NON_IDENTIFIER_CHARS = makePredicate(characters("./'\"" + OPERATOR_CHARS + PUNC_CHARS + WHITESPACE_CHARS));
 
 NEWLINE_CHARS = makePredicate(characters(NEWLINE_CHARS));
 OPERATOR_CHARS = makePredicate(characters(OPERATOR_CHARS));
+PUNC_AFTER_EXPRESSION = makePredicate(characters(PUNC_AFTER_EXPRESSION));
 PUNC_BEFORE_EXPRESSION = makePredicate(characters(PUNC_BEFORE_EXPRESSION));
 PUNC_CHARS = makePredicate(characters(PUNC_CHARS));
 WHITESPACE_CHARS = makePredicate(characters(WHITESPACE_CHARS));
@@ -144,6 +150,43 @@ function is_identifier_string(str) {
     return /^[a-z_$][a-z0-9_$]*$/i.test(str);
 }
 
+function decode_escape_sequence(seq) {
+    switch (seq[0]) {
+      case "b": return "\b";
+      case "f": return "\f";
+      case "n": return "\n";
+      case "r": return "\r";
+      case "t": return "\t";
+      case "u":
+        var code;
+        if (seq.length == 5) {
+            code = seq.slice(1);
+        } else if (seq[1] == "{" && seq.slice(-1) == "}") {
+            code = seq.slice(2, -1);
+        } else {
+            return;
+        }
+        var num = parseInt(code, 16);
+        if (num < 0 || isNaN(num)) return;
+        if (num < 0x10000) return String.fromCharCode(num);
+        if (num > 0x10ffff) return;
+        return String.fromCharCode((num >> 10) + 0xd7c0) + String.fromCharCode((num & 0x03ff) + 0xdc00);
+      case "v": return "\u000b";
+      case "x":
+        if (seq.length != 3) return;
+        var num = parseInt(seq.slice(1), 16);
+        if (num < 0 || isNaN(num)) return;
+        return String.fromCharCode(num);
+      case "\r":
+      case "\n":
+        return "";
+      default:
+        if (seq == "0") return "\0";
+        if (seq[0] >= "0" && seq[0] <= "9") return;
+        return seq;
+    }
+}
+
 function parse_js_number(num) {
     var match;
     if (match = RE_BIN_NUMBER.exec(num)) return parseInt(match[1], 2);
@@ -190,7 +233,29 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         regex_allowed   : false,
         comments_before : [],
         directives      : {},
-        directive_stack : []
+        directive_stack : [],
+        read_template   : with_eof_error("Unterminated template literal", function(strings) {
+            var s = "";
+            for (;;) {
+                var ch = next(true, true);
+                switch (ch) {
+                  case "\\":
+                    ch += next(true, true);
+                    break;
+                  case "`":
+                    strings.push(s);
+                    return;
+                  case "$":
+                    if (peek() == "{") {
+                        next();
+                        strings.push(s);
+                        S.regex_allowed = true;
+                        return true;
+                    }
+                }
+                s += ch;
+            }
+        }),
     };
     var prev_was_dot = false;
 
@@ -280,9 +345,8 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
     }
 
     function read_while(pred) {
-        var ret = "", ch, i = 0;
-        while ((ch = peek()) && pred(ch, i++))
-            ret += next();
+        var ret = "", ch;
+        while ((ch = peek()) && pred(ch)) ret += next();
         return ret;
     }
 
@@ -292,16 +356,14 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
 
     function read_num(prefix) {
         var has_e = false, after_e = false, has_x = false, has_dot = prefix == ".";
-        var num = read_while(function(ch, i) {
+        var num = read_while(function(ch) {
             var code = ch.charCodeAt(0);
             switch (code) {
               case 120: case 88: // xX
                 return has_x ? false : (has_x = true);
               case 101: case 69: // eE
                 return has_x ? true : has_e ? false : (has_e = after_e = true);
-              case 45: // -
-                return after_e || (i == 0 && !prefix);
-              case 43: // +
+              case 43: case 45: // +-
                 return after_e;
               case (after_e = false, 46): // .
                 return (!has_dot && !has_x && !has_e) ? (has_dot = true) : false;
@@ -315,41 +377,29 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
             num = num.replace(has_x ? /([1-9a-f]|.0)_(?=[0-9a-f])/gi : /([1-9]|.0)_(?=[0-9])/gi, "$1");
         }
         var valid = parse_js_number(num);
-        if (!isNaN(valid)) return token("num", valid);
-        parse_error("Invalid syntax: " + num);
+        if (isNaN(valid)) parse_error("Invalid syntax: " + num);
+        if (has_dot || has_e || peek() != "n") return token("num", valid);
+        return token("bigint", num.toLowerCase() + next());
     }
 
     function read_escaped_char(in_string) {
-        var ch = next(true, in_string);
-        switch (ch.charCodeAt(0)) {
-          case 110: return "\n";
-          case 114: return "\r";
-          case 116: return "\t";
-          case 98:  return "\b";
-          case 118: return "\u000b";                            // \v
-          case 102: return "\f";
-          case 120: return String.fromCharCode(hex_bytes(2));   // \x
-          case 117:                                             // \u
-            if (peek() != "{") return String.fromCharCode(hex_bytes(4));
-            next();
-            var num = 0;
-            do {
-                var digit = parseInt(next(true), 16);
-                if (isNaN(digit)) parse_error("Invalid hex-character pattern in string");
-                num = num * 16 + digit;
-            } while (peek() != "}");
-            next();
-            if (num < 0x10000) return String.fromCharCode(num);
-            if (num > 0x10ffff) parse_error("Invalid character code: " + num);
-            return String.fromCharCode((num >> 10) + 0xd7c0) + String.fromCharCode((num & 0x03ff) + 0xdc00);
-          case 13:                                              // \r
-            // DOS newline
-            if (peek() == "\n") next(true, in_string);
-          case 10:  return "";                                  // \n
+        var seq = next(true, in_string);
+        if (seq >= "0" && seq <= "7") return read_octal_escape_sequence(seq);
+        if (seq == "u") {
+            var ch = next(true, in_string);
+            seq += ch;
+            if (ch != "{") {
+                seq += next(true, in_string) + next(true, in_string) + next(true, in_string);
+            } else do {
+                ch = next(true, in_string);
+                seq += ch;
+            } while (ch != "}");
+        } else if (seq == "x") {
+            seq += next(true, in_string) + next(true, in_string);
         }
-        if (ch >= "0" && ch <= "7")
-            return read_octal_escape_sequence(ch);
-        return ch;
+        var str = decode_escape_sequence(seq);
+        if (typeof str != "string") parse_error("Invalid escape sequence: \\" + seq);
+        return str;
     }
 
     function read_octal_escape_sequence(ch) {
@@ -368,17 +418,6 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
         return String.fromCharCode(parseInt(ch, 8));
     }
 
-    function hex_bytes(n) {
-        var num = 0;
-        for (; n > 0; --n) {
-            var digit = parseInt(next(true), 16);
-            if (isNaN(digit))
-                parse_error("Invalid hex-character pattern in string");
-            num = (num << 4) | digit;
-        }
-        return num;
-    }
-
     var read_string = with_eof_error("Unterminated string constant", function(quote_char) {
         var quote = next(), ret = "";
         for (;;) {
@@ -632,10 +671,11 @@ var PRECEDENCE = function(a, ret) {
     ["<", ">", "<=", ">=", "in", "instanceof"],
     [">>", "<<", ">>>"],
     ["+", "-"],
-    ["*", "/", "%"]
+    ["*", "/", "%"],
+    ["**"],
 ], {});
 
-var ATOMIC_START_TOKEN = makePredicate("atom num regexp string");
+var ATOMIC_START_TOKEN = makePredicate("atom bigint num regexp string");
 
 /* -----[ Parser ]----- */
 
@@ -658,6 +698,7 @@ function parse($TEXT, options) {
         in_directives : true,
         in_funarg     : -1,
         in_function   : 0,
+        in_generator  : false,
         in_loop       : 0,
         labels        : [],
         peeked        : null,
@@ -783,6 +824,7 @@ function parse($TEXT, options) {
             semicolon();
             return dir ? new AST_Directive(body) : new AST_SimpleStatement({ body: body });
           case "num":
+          case "bigint":
           case "regexp":
           case "operator":
           case "atom":
@@ -794,12 +836,17 @@ function parse($TEXT, options) {
                 if (is_token(peek(), "keyword", "function")) {
                     next();
                     next();
-                    return function_(AST_AsyncDefun);
+                    if (!is("operator", "*")) return function_(AST_AsyncDefun);
+                    next();
+                    return function_(AST_AsyncGeneratorDefun);
                 }
                 break;
               case "await":
                 if (S.in_async) return simple_statement();
                 break;
+              case "yield":
+                if (S.in_generator) return simple_statement();
+                break;
             }
             return is_token(peek(), "punc", ":")
                 ? labeled_statement()
@@ -815,6 +862,7 @@ function parse($TEXT, options) {
                 });
               case "[":
               case "(":
+              case "`":
                 return simple_statement();
               case ";":
                 S.in_directives = false;
@@ -869,7 +917,9 @@ function parse($TEXT, options) {
 
               case "function":
                 next();
-                return function_(AST_Defun);
+                if (!is("operator", "*")) return function_(AST_Defun);
+                next();
+                return function_(AST_GeneratorDefun);
 
               case "if":
                 next();
@@ -990,6 +1040,7 @@ function parse($TEXT, options) {
     }
 
     function for_() {
+        var await = is("name", "await") && next();
         expect("(");
         var init = null;
         if (!is("punc", ";")) {
@@ -1000,16 +1051,29 @@ function parse($TEXT, options) {
                 : is("keyword", "var")
                 ? (next(), var_(true))
                 : expression(true);
-            if (is("operator", "in")) {
+            var ctor;
+            if (await) {
+                expect_token("name", "of");
+                ctor = AST_ForAwaitOf;
+            } else if (is("operator", "in")) {
+                next();
+                ctor = AST_ForIn;
+            } else if (is("name", "of")) {
+                next();
+                ctor = AST_ForOf;
+            }
+            if (ctor) {
                 if (init instanceof AST_Definitions) {
                     if (init.definitions.length > 1) {
-                        token_error(init.start, "Only one variable declaration allowed in for..in loop");
+                        token_error(init.start, "Only one variable declaration allowed in for..in/of loop");
+                    }
+                    if (ctor !== AST_ForIn && init.definitions[0].value) {
+                        token_error(init.definitions[0].value.start, "No initializers allowed in for..of loop");
                     }
                 } else if (!(is_assignable(init) || (init = to_destructured(init)) instanceof AST_Destructured)) {
-                    token_error(init.start, "Invalid left-hand side in for..in loop");
+                    token_error(init.start, "Invalid left-hand side in for..in/of loop");
                 }
-                next();
-                return for_in(init);
+                return for_enum(ctor, init);
             }
         }
         return regular_for(init);
@@ -1029,10 +1093,10 @@ function parse($TEXT, options) {
         });
     }
 
-    function for_in(init) {
+    function for_enum(ctor, init) {
         var obj = expression();
         expect(")");
-        return new AST_ForIn({
+        return new ctor({
             init   : init,
             object : obj,
             body   : in_loop(statement)
@@ -1102,7 +1166,9 @@ function parse($TEXT, options) {
 
     function arrow(exprs, start, async) {
         var was_async = S.in_async;
+        var was_gen = S.in_generator;
         S.in_async = async;
+        S.in_generator = false;
         var was_funarg = S.in_funarg;
         S.in_funarg = S.in_function;
         var argnames = exprs.map(to_funarg);
@@ -1132,6 +1198,7 @@ function parse($TEXT, options) {
         --S.in_function;
         S.in_loop = loop;
         S.labels = labels;
+        S.in_generator = was_gen;
         S.in_async = was_async;
         return new (async ? AST_AsyncArrow : AST_Arrow)({
             start: start,
@@ -1145,15 +1212,15 @@ function parse($TEXT, options) {
 
     var function_ = function(ctor) {
         var was_async = S.in_async;
+        var was_gen = S.in_generator;
         var name;
-        if (ctor === AST_AsyncDefun) {
+        if (/Defun$/.test(ctor.TYPE)) {
             name = as_symbol(AST_SymbolDefun);
-            S.in_async = true;
-        } else if (ctor === AST_Defun) {
-            name = as_symbol(AST_SymbolDefun);
-            S.in_async = false;
+            S.in_async = /^Async/.test(ctor.TYPE);
+            S.in_generator = /Generator/.test(ctor.TYPE);
         } else {
-            S.in_async = ctor === AST_AsyncFunction;
+            S.in_async = /^Async/.test(ctor.TYPE);
+            S.in_generator = /Generator/.test(ctor.TYPE);
             name = as_symbol(AST_SymbolLambda, true);
         }
         if (name && ctor !== AST_Accessor && !(name instanceof AST_SymbolDeclaration))
@@ -1182,6 +1249,7 @@ function parse($TEXT, options) {
         --S.in_function;
         S.in_loop = loop;
         S.labels = labels;
+        S.in_generator = was_gen;
         S.in_async = was_async;
         return new ctor({
             name: name,
@@ -1361,6 +1429,9 @@ function parse($TEXT, options) {
           case "num":
             ret = new AST_Number({ start: tok, end: tok, value: tok.value });
             break;
+          case "bigint":
+            ret = new AST_BigInt({ start: tok, end: tok, value: tok.value });
+            break;
           case "string":
             ret = new AST_String({
                 start : tok,
@@ -1397,6 +1468,11 @@ function parse($TEXT, options) {
         var start = S.token;
         if (is("punc")) {
             switch (start.value) {
+              case "`":
+                var tmpl = template(null);
+                tmpl.start = start;
+                tmpl.end = prev();
+                return subscripts(tmpl, allow_calls);
               case "(":
                 next();
                 if (is("punc", ")")) {
@@ -1437,7 +1513,13 @@ function parse($TEXT, options) {
         }
         if (is("keyword", "function")) {
             next();
-            var func = function_(AST_Function);
+            var func;
+            if (is("operator", "*")) {
+                next();
+                func = function_(AST_GeneratorFunction);
+            } else {
+                func = function_(AST_Function);
+            }
             func.start = start;
             func.end = prev();
             return subscripts(func, allow_calls);
@@ -1448,12 +1530,18 @@ function parse($TEXT, options) {
             if (sym.name == "async") {
                 if (is("keyword", "function")) {
                     next();
-                    var func = function_(AST_AsyncFunction);
+                    var func;
+                    if (is("operator", "*")) {
+                        next();
+                        func = function_(AST_AsyncGeneratorFunction);
+                    } else {
+                        func = function_(AST_AsyncFunction);
+                    }
                     func.start = start;
                     func.end = prev();
                     return subscripts(func, allow_calls);
                 }
-                if (is("name")) {
+                if (is("name") && is_token(peek(), "punc", "=>")) {
                     start = S.token;
                     sym = _make_symbol(AST_SymbolRef, start);
                     next();
@@ -1523,6 +1611,21 @@ function parse($TEXT, options) {
             // allow trailing comma
             if (!options.strict && is("punc", "}")) break;
             var start = S.token;
+            if (is("operator", "*")) {
+                next();
+                var key = as_property_key();
+                var gen_start = S.token;
+                var gen = function_(AST_GeneratorFunction);
+                gen.start = gen_start;
+                gen.end = prev();
+                a.push(new AST_ObjectKeyVal({
+                    start: start,
+                    key: key,
+                    value: gen,
+                    end: prev(),
+                }));
+                continue;
+            }
             if (is("operator", "...")) {
                 next();
                 a.push(new AST_Spread({
@@ -1584,9 +1687,10 @@ function parse($TEXT, options) {
             }
             if (start.type == "name") switch (key) {
               case "async":
+                var is_gen = is("operator", "*") && next();
                 key = as_property_key();
                 var func_start = S.token;
-                var func = function_(AST_AsyncFunction);
+                var func = function_(is_gen ? AST_AsyncGeneratorFunction : AST_AsyncFunction);
                 func.start = func_start;
                 func.end = prev();
                 a.push(new AST_ObjectKeyVal({
@@ -1650,6 +1754,7 @@ function parse($TEXT, options) {
     function _make_symbol(type, token) {
         var name = token.value;
         if (name === "await" && S.in_async) unexpected(token);
+        if (name === "yield" && S.in_generator) unexpected(token);
         return new (name === "this" ? AST_This : type)({
             name: "" + name,
             start: token,
@@ -1767,6 +1872,23 @@ function parse($TEXT, options) {
         }
     }
 
+    function template(tag) {
+        var read = S.input.context().read_template;
+        var strings = [];
+        var expressions = [];
+        while (read(strings)) {
+            next();
+            expressions.push(expression());
+            if (!is("punc", "}")) unexpected();
+        }
+        next();
+        return new AST_Template({
+            expressions: expressions,
+            strings: strings,
+            tag: tag,
+        });
+    }
+
     var subscripts = function(expr, allow_calls) {
         var start = expr.start;
         if (is("punc", ".")) {
@@ -1800,15 +1922,51 @@ function parse($TEXT, options) {
             mark_pure(call);
             return subscripts(call, true);
         }
+        if (is("punc", "`")) {
+            var tmpl = template(expr);
+            tmpl.start = expr.start;
+            tmpl.end = prev();
+            return subscripts(tmpl, allow_calls);
+        }
         return expr;
     };
 
-    function maybe_unary() {
+    function maybe_unary(no_in) {
         var start = S.token;
+        if (S.in_async && is("name", "await")) {
+            if (S.in_funarg === S.in_function) croak("Invalid use of await in function argument");
+            S.input.context().regex_allowed = true;
+            next();
+            return new AST_Await({
+                start: start,
+                expression: maybe_unary(no_in),
+                end: prev(),
+            });
+        }
+        if (S.in_generator && is("name", "yield")) {
+            if (S.in_funarg === S.in_function) croak("Invalid use of yield in function argument");
+            S.input.context().regex_allowed = true;
+            next();
+            var exp = null;
+            var nested = false;
+            if (is("operator", "*")) {
+                next();
+                exp = maybe_assign(no_in);
+                nested = true;
+            } else if (is("punc") ? !PUNC_AFTER_EXPRESSION[S.token.value] : !can_insert_semicolon()) {
+                exp = maybe_assign(no_in);
+            }
+            return new AST_Yield({
+                start: start,
+                expression: exp,
+                nested: nested,
+                end: prev(),
+            });
+        }
         if (is("operator") && UNARY_PREFIX[start.value]) {
             next();
             handle_regexp();
-            var ex = make_unary(AST_UnaryPrefix, start, maybe_await());
+            var ex = make_unary(AST_UnaryPrefix, start, maybe_unary(no_in));
             ex.start = start;
             ex.end = prev();
             return ex;
@@ -1839,26 +1997,13 @@ function parse($TEXT, options) {
         return new ctor({ operator: op, expression: expr });
     }
 
-    function maybe_await() {
-        var start = S.token;
-        if (!(S.in_async && is("name", "await"))) return maybe_unary();
-        if (S.in_funarg === S.in_function) croak("Invalid use of await in function argument");
-        S.input.context().regex_allowed = true;
-        next();
-        return new AST_Await({
-            start: start,
-            expression: maybe_await(),
-            end: prev(),
-        });
-    }
-
     var expr_op = function(left, min_prec, no_in) {
         var op = is("operator") ? S.token.value : null;
         if (op == "in" && no_in) op = null;
         var prec = op != null ? PRECEDENCE[op] : null;
         if (prec != null && prec > min_prec) {
             next();
-            var right = expr_op(maybe_await(), prec, no_in);
+            var right = expr_op(maybe_unary(no_in), op == "**" ? prec - 1 : prec, no_in);
             return expr_op(new AST_Binary({
                 start    : left.start,
                 left     : left,
@@ -1871,7 +2016,7 @@ function parse($TEXT, options) {
     };
 
     function expr_ops(no_in) {
-        return expr_op(maybe_await(), 0, no_in);
+        return expr_op(maybe_unary(no_in), 0, no_in);
     }
 
     var maybe_conditional = function(no_in) {

lib/propmangle.js

@@ -228,7 +228,7 @@ function mangle_properties(ast, options) {
         var mangled = cache.get(name);
         if (!mangled) {
             if (debug) {
-                // debug mode: use a prefix and suffix to preserve readability, e.g. o.foo -> o._$foo$NNN_.
+                // debug mode: use a prefix and suffix to preserve readability, e.g. o.foo ---> o._$foo$NNN_.
                 var debug_mangled = "_$" + name + "$" + debug_suffix + "_";
                 if (can_mangle(debug_mangled)) mangled = debug_mangled;
             }

lib/scope.js

@@ -101,6 +101,14 @@ SymbolDef.prototype = {
 
 var unary_side_effects = makePredicate("delete ++ --");
 
+function is_lhs(node, parent) {
+    if (parent instanceof AST_Assign) return parent.left === node && node;
+    if (parent instanceof AST_DefaultValue) return parent.name === node && node;
+    if (parent instanceof AST_Destructured) return node;
+    if (parent instanceof AST_DestructuredKeyVal) return node;
+    if (parent instanceof AST_Unary) return unary_side_effects[parent.operator] && parent.expression;
+}
+
 AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
     options = defaults(options, {
         cache: null,
@@ -113,7 +121,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
     var next_def_id = 0;
     var scope = self.parent_scope = null;
     var tw = new TreeWalker(function(node, descend) {
-        if (is_defun(node)) {
+        if (node instanceof AST_LambdaDefinition) {
             node.name.walk(tw);
             walk_scope(function() {
                 node.argnames.forEach(function(argname) {
@@ -269,8 +277,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
                 sym = self.def_global(node);
             } else if (name == "arguments" && is_arguments(sym)) {
                 var parent = tw.parent();
-                if (parent instanceof AST_Assign && parent.left === node
-                    || parent instanceof AST_Unary && unary_side_effects[parent.operator]) {
+                if (is_lhs(node, parent)) {
                     sym.scope.uses_arguments = 3;
                 } else if (sym.scope.uses_arguments < 2
                     && !(parent instanceof AST_PropAccess && parent.expression === node)) {
@@ -432,7 +439,7 @@ AST_BlockScope.DEFMETHOD("find_variable", function(name) {
 
 AST_BlockScope.DEFMETHOD("def_function", function(symbol, init) {
     var def = this.def_variable(symbol, init);
-    if (!def.init || is_defun(def.init)) def.init = init;
+    if (!def.init || def.init instanceof AST_LambdaDefinition) def.init = init;
     this.functions.set(symbol.name, def);
     return def;
 });
@@ -441,7 +448,7 @@ AST_BlockScope.DEFMETHOD("def_variable", function(symbol, init) {
     var def = this.variables.get(symbol.name);
     if (def) {
         def.orig.push(symbol);
-        if (is_function(def.init)) def.init = init;
+        if (def.init instanceof AST_LambdaExpression) def.init = init;
     } else {
         def = this.make_def(symbol, init);
         this.variables.set(symbol.name, def);

lib/transform.js

@@ -82,7 +82,7 @@ TreeTransformer.prototype = new TreeWalker;
         if (self.step) self.step = self.step.transform(tw);
         self.body = self.body.transform(tw);
     });
-    DEF(AST_ForIn, function(self, tw) {
+    DEF(AST_ForEnumeration, function(self, tw) {
         self.init = self.init.transform(tw);
         self.object = self.object.transform(tw);
         self.body = self.body.transform(tw);
@@ -157,6 +157,9 @@ TreeTransformer.prototype = new TreeWalker;
     DEF(AST_Await, function(self, tw) {
         self.expression = self.expression.transform(tw);
     });
+    DEF(AST_Yield, function(self, tw) {
+        if (self.expression) self.expression = self.expression.transform(tw);
+    });
     DEF(AST_Dot, function(self, tw) {
         self.expression = self.expression.transform(tw);
     });
@@ -201,6 +204,10 @@ TreeTransformer.prototype = new TreeWalker;
         if (self.key instanceof AST_Node) self.key = self.key.transform(tw);
         self.value = self.value.transform(tw);
     });
+    DEF(AST_Template, function(self, tw) {
+        if (self.tag) self.tag = self.tag.transform(tw);
+        self.expressions = do_list(self.expressions, tw);
+    });
 })(function(node, descend) {
     node.DEFMETHOD("transform", function(tw, in_list) {
         var x, y;

lib/utils.js

@@ -255,6 +255,8 @@ function first_in_statement(stack, arrow) {
             if (p.expressions[0] === node) continue;
         } else if (p instanceof AST_Statement) {
             return p.body === node;
+        } else if (p instanceof AST_Template) {
+            if (p.tag === node) continue;
         } else if (p instanceof AST_UnaryPostfix) {
             if (p.expression === node) continue;
         }

package.json

@@ -3,7 +3,7 @@
   "description": "JavaScript parser, mangler/compressor and beautifier toolkit",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "3.12.5",
+  "version": "3.12.8",
   "engines": {
     "node": ">=0.8.0"
   },

test/compress.js

@@ -209,7 +209,7 @@ function reminify(orig_options, input_code, input_formatted, stdout) {
         } else {
             var toplevel = sandbox.has_toplevel(options);
             var expected = stdout[toplevel ? 1 : 0];
-            var actual = run_code(result.code, toplevel);
+            var actual = sandbox.run_code(result.code, toplevel);
             if (typeof expected != "string" && typeof actual != "string" && expected.name == actual.name) {
                 actual = expected;
             }
@@ -244,11 +244,6 @@ function reminify(orig_options, input_code, input_formatted, stdout) {
     return true;
 }
 
-function run_code(code, toplevel) {
-    var result = sandbox.run_code(code, toplevel);
-    return typeof result == "string" ? result.replace(/\u001b\[\d+m/g, "") : result;
-}
-
 function test_case(test) {
     log("    Running test [{name}]", { name: test.name });
     U.AST_Node.enable_validation();
@@ -380,7 +375,7 @@ function test_case(test) {
         }
     }
     if (test.expect_stdout && (!test.node_version || semver.satisfies(process.version, test.node_version))) {
-        var stdout = [ run_code(input_code), run_code(input_code, true) ];
+        var stdout = [ sandbox.run_code(input_code), sandbox.run_code(input_code, true) ];
         var toplevel = sandbox.has_toplevel({
             compress: test.options,
             mangle: test.mangle
@@ -409,7 +404,7 @@ function test_case(test) {
             });
             return false;
         }
-        actual = run_code(output_code, toplevel);
+        actual = sandbox.run_code(output_code, toplevel);
         if (!sandbox.same_stdout(test.expect_stdout, actual)) {
             log([
                 "!!! failed",

test/compress/arrays.js

@@ -13,9 +13,10 @@ holes_and_undefined: {
     }
 }
 
-constant_join: {
+constant_join_1: {
     options = {
         evaluate: true,
+        side_effects: true,
         strings: true,
         unsafe: true,
     }
@@ -57,7 +58,7 @@ constant_join: {
         var c5 = [ boo() + bar() + "foo", 1, 2, 3, "bar", bar() + "foo" ].join();
         var c6 = [ "1,2,,,foo,bar", baz() ].join();
         var d = "foo-3bar-baz";
-        var e = [].join(foo + bar);
+        var e = (foo, bar, "");
         var f = "";
         var g = "";
     }

test/compress/arrows.js

@@ -434,6 +434,62 @@ collapse_value: {
     node_version: ">=4"
 }
 
+collapse_property_lambda: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+    }
+    input: {
+        console.log(function f() {
+            f.g = () => 42;
+            return f.g();
+        }());
+    }
+    expect: {
+        console.log(function f() {
+            return (f.g = () => 42)();
+        }());
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+drop_return: {
+    options = {
+        arrows: true,
+        side_effects: true,
+    }
+    input: {
+        (a => {
+            while (!console);
+            return console.log(a);
+        })(42);
+    }
+    expect: {
+        (a => {
+            while (!console);
+            console.log(a);
+        })(42);
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+drop_value: {
+    options = {
+        arrows: true,
+        side_effects: true,
+    }
+    input: {
+        ((a, b) => a + b)(console.log(42));
+    }
+    expect: {
+        ((a, b) => {})(console.log(42));
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
 reduce_iife_1: {
     options = {
         evaluate: true,

test/compress/awaits.js

@@ -519,6 +519,160 @@ collapse_vars_3: {
     node_version: ">=8"
 }
 
+collapse_property_lambda: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+    }
+    input: {
+        (async function f() {
+            f.g = () => 42;
+            return f.g();
+        })().then(console.log);
+    }
+    expect: {
+        (async function f() {
+            return (f.g = () => 42)();
+        })().then(console.log);
+    }
+    expect_stdout: "42"
+    node_version: ">=8"
+}
+
+drop_return: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        (async function(a) {
+            while (!console);
+            return console.log(a);
+        })(42);
+    }
+    expect: {
+        (async function(a) {
+            while (!console);
+            console.log(a);
+        })(42);
+    }
+    expect_stdout: "42"
+    node_version: ">=8"
+}
+
+functions: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        !async function() {
+            var a = async function a() {
+                return a && "a";
+            };
+            var b = async function x() {
+                return !!x;
+            };
+            var c = async function(c) {
+                return c;
+            };
+            if (await c(await b(await a()))) {
+                var d = async function() {};
+                var e = async function y() {
+                    return typeof y;
+                };
+                var f = async function(f) {
+                    return f;
+                };
+                console.log(await a(await d()), await b(await e()), await c(await f(42)), typeof d, await e(), typeof f);
+            }
+        }();
+    }
+    expect: {
+        !async function() {
+            async function a() {
+                return a && "a";
+            }
+            async function b() {
+                return !!b;
+            }
+            var c = async function(c) {
+                return c;
+            };
+            if (await c(await b(await a()))) {
+                async function d() {}
+                async function e() {
+                    return typeof e;
+                }
+                var f = async function(f) {
+                    return f;
+                };
+                console.log(await a(await d()), await b(await e()), await c(await f(42)), typeof d, await e(), typeof f);
+            }
+        }();
+    }
+    expect_stdout: "a true 42 function function function"
+    node_version: ">=8"
+}
+
+functions_use_strict: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        !async function() {
+            var a = async function a() {
+                return a && "a";
+            };
+            var b = async function x() {
+                return !!x;
+            };
+            var c = async function(c) {
+                return c;
+            };
+            if (await c(await b(await a()))) {
+                var d = async function() {};
+                var e = async function y() {
+                    return typeof y;
+                };
+                var f = async function(f) {
+                    return f;
+                };
+                console.log(await a(await d()), await b(await e()), await c(await f(42)), typeof d, await e(), typeof f);
+            }
+        }();
+    }
+    expect: {
+        "use strict";
+        !async function() {
+            async function a() {
+                return a && "a";
+            }
+            async function b() {
+                return !!b;
+            }
+            var c = async function(c) {
+                return c;
+            };
+            if (await c(await b(await a()))) {
+                var d = async function() {};
+                var e = async function y() {
+                    return typeof y;
+                };
+                var f = async function(f) {
+                    return f;
+                };
+                console.log(await a(await d()), await b(await e()), await c(await f(42)), typeof d, await e(), typeof f);
+            }
+        }();
+    }
+    expect_stdout: "a true 42 function function function"
+    node_version: ">=8"
+}
+
 issue_4335_1: {
     options = {
         inline: true,
@@ -612,22 +766,32 @@ issue_4340: {
 call_expression: {
     input: {
         console.log(typeof async function(log) {
-            (await log)("FAIL");
+            (await log)("foo");
         }(console.log).then);
+        console.log("bar");
     }
-    expect_exact: 'console.log(typeof async function(log){(await log)("FAIL")}(console.log).then);'
-    expect_stdout: "function"
+    expect_exact: 'console.log(typeof async function(log){(await log)("foo")}(console.log).then);console.log("bar");'
+    expect_stdout: [
+        "function",
+        "bar",
+        "foo",
+    ]
     node_version: ">=8"
 }
 
 property_access_expression: {
     input: {
         console.log(typeof async function(con) {
-            (await con).log("FAIL");
+            (await con).log("foo");
         }(console).then);
+        console.log("bar");
     }
-    expect_exact: 'console.log(typeof async function(con){(await con).log("FAIL")}(console).then);'
-    expect_stdout: "function"
+    expect_exact: 'console.log(typeof async function(con){(await con).log("foo")}(console).then);console.log("bar");'
+    expect_stdout: [
+        "function",
+        "bar",
+        "foo",
+    ]
     node_version: ">=8"
 }
 
@@ -685,20 +849,18 @@ reduce_iife_3: {
     input: {
         var a = "foo";
         (async function() {
-            console.log(a);
-            console.log(await a);
+            console.log(a, await a, a, await a);
         })();
         a = "bar";
     }
     expect: {
         var a = "foo";
         (async function() {
-            console.log(a);
-            console.log(await a);
+            console.log(a, await a, a, await a);
         })();
         a = "bar";
     }
-    expect_stdout: "foo"
+    expect_stdout: "foo foo bar bar"
     node_version: ">=8"
 }
 
@@ -995,3 +1157,92 @@ issue_4534: {
     expect_stdout: "PASS"
     node_version: ">=8"
 }
+
+issue_4581: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (async () => (A, a = "FAIL"))();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (async () => (A, a = "FAIL"))();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4595: {
+    options = {
+        awaits: true,
+        inline: true,
+    }
+    input: {
+        (async function() {
+            await async function f() {
+                console.log(f.length);
+            }();
+        })();
+    }
+    expect: {
+        (async function() {
+            await async function f() {
+                console.log(f.length);
+            }();
+        })();
+    }
+    expect_stdout: "0"
+    node_version: ">=8"
+}
+
+issue_4598: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        if (console.log("PASS")) {
+            async function f() {}
+        }
+    }
+    expect: {
+        async function f() {}
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4618: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function() {
+            var await = async function f() {
+                console || f();
+            };
+            console.log;
+            return await;
+        }());
+    }
+    expect: {
+        console.log(typeof function() {
+            var await = async function f() {
+                console || f();
+            };
+            console.log;
+            return await;
+        }());
+    }
+    expect_stdout: "function"
+    node_version: ">=8"
+}

test/compress/bigint.js

@@ -0,0 +1,62 @@
+arithmetic: {
+    input: {
+        console.log(((1n + 0x2n) * (0o3n - -4n)) >> (5n - 6n));
+    }
+    expect_exact: "console.log((1n+0x2n)*(0o3n- -4n)>>5n-6n);"
+    expect_stdout: "42n"
+    node_version: ">=10"
+}
+
+minus_dot: {
+    input: {
+        console.log(typeof -42n.toString(), typeof (-42n).toString());
+    }
+    expect_exact: "console.log(typeof-42n.toString(),typeof(-42n).toString());"
+    expect_stdout: "number string"
+    node_version: ">=10"
+}
+
+evaluate: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        console.log((0xDEAD_BEEFn).toString(16));
+    }
+    expect: {
+        console.log(0xdeadbeefn.toString(16));
+    }
+    expect_stdout: "deadbeef"
+    node_version: ">=10"
+}
+
+Number: {
+    options = {
+        unsafe: true,
+    }
+    input: {
+        console.log(Number(-0xfeed_dead_beef_badn));
+    }
+    expect: {
+        console.log(+("" + -0xfeed_dead_beef_badn));
+    }
+    expect_stdout: "-1148098955808013200"
+    node_version: ">=10"
+}
+
+issue_4590: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        A = 1;
+        0n || console.log("PASS");
+    }
+    expect: {
+        A = 1;
+        0n || console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=10"
+}

test/compress/collapse_vars.js

@@ -5608,6 +5608,7 @@ collapse_rhs_array: {
 collapse_rhs_boolean_1: {
     options = {
         collapse_vars: true,
+        evaluate: true,
     }
     input: {
         var a, b;
@@ -5633,6 +5634,7 @@ collapse_rhs_boolean_1: {
 collapse_rhs_boolean_2: {
     options = {
         collapse_vars: true,
+        evaluate: true,
     }
     input: {
         var a;
@@ -5667,6 +5669,7 @@ collapse_rhs_boolean_3: {
         booleans: true,
         collapse_vars: true,
         conditionals: true,
+        evaluate: true,
     }
     input: {
         var a, f, g, h, i, n, s, t, x, y;
@@ -5720,6 +5723,7 @@ collapse_rhs_function: {
 collapse_rhs_number: {
     options = {
         collapse_vars: true,
+        evaluate: true,
     }
     input: {
         var a, b;
@@ -5799,6 +5803,7 @@ collapse_rhs_regexp: {
 collapse_rhs_string: {
     options = {
         collapse_vars: true,
+        evaluate: true,
     }
     input: {
         var a, b;
@@ -5874,6 +5879,7 @@ collapse_rhs_this: {
 collapse_rhs_undefined: {
     options = {
         collapse_vars: true,
+        side_effects: true,
     }
     input: {
         var a, b;
@@ -8705,3 +8711,48 @@ collapse_or_assign: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4586_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = 42;
+        (function f(b) {
+            var b = a;
+            if (b === arguments[0])
+                console.log("PASS");
+        })(console);
+    }
+    expect: {
+        var a = 42;
+        (function f(b) {
+            var b = a;
+            if (b === arguments[0])
+                console.log("PASS");
+        })(console);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4586_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = 42;
+        (function f(b) {
+            b = a;
+            if (b === arguments[0])
+                console.log("PASS");
+        })(console);
+    }
+    expect: {
+        var a = 42;
+        (function f(b) {
+            if ((b = a) === arguments[0])
+                console.log("PASS");
+        })(console);
+    }
+    expect_stdout: "PASS"
+}

test/compress/default-values.js

@@ -161,6 +161,7 @@ process_boolean_returns: {
 collapse_value_1: {
     options = {
         collapse_vars: true,
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -169,7 +170,7 @@ collapse_value_1: {
         }());
     }
     expect: {
-        console.log(function(a) {
+        console.log(function() {
             return "PASS";
         }());
     }
@@ -180,6 +181,7 @@ collapse_value_1: {
 collapse_value_2: {
     options = {
         collapse_vars: true,
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -188,7 +190,7 @@ collapse_value_2: {
         })().log("PASS");
     }
     expect: {
-        (function(a) {
+        (function() {
             return console;
         })().log("PASS");
     }
@@ -554,8 +556,9 @@ drop_fargs: {
         "bar",
     ]
     expect_warnings: [
-        "WARN: Dropping unused function argument c [test/compress/default-values.js:1,61]",
+        "WARN: Dropping unused default argument c [test/compress/default-values.js:1,61]",
         "WARN: Side effects in default value of unused variable b [test/compress/default-values.js:1,37]",
+        "WARN: Dropping unused default argument assignment a [test/compress/default-values.js:1,29]",
     ]
     node_version: ">=6"
 }
@@ -1596,3 +1599,65 @@ issue_4548: {
     ]
     node_version: ">=6"
 }
+
+issue_4588_1_unused: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function(a = 42) {}.length);
+    }
+    expect: {
+        console.log(function(a = 0) {}.length);
+    }
+    expect_stdout: "0"
+    node_version: ">=6"
+}
+
+issue_4588_2_unused: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function(a, b = void 0, c, d = "foo") {}.length);
+    }
+    expect: {
+        console.log(function(a, b = 0, c, d) {}.length);
+    }
+    expect_stdout: "1"
+    expect_warnings: [
+        "WARN: Dropping unused default argument assignment d [test/compress/default-values.js:1,47]",
+        "WARN: Dropping unused default argument value b [test/compress/default-values.js:1,32]",
+    ]
+    node_version: ">=6"
+}
+
+issue_4588_1_evaluate: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(a = 42) {}.length);
+    }
+    expect: {
+        console.log(0);
+    }
+    expect_stdout: "0"
+    node_version: ">=6"
+}
+
+issue_4588_2_evaluate: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(a, b = void 0, c, d = "foo") {}.length);
+    }
+    expect: {
+        console.log(1);
+    }
+    expect_stdout: "1"
+    node_version: ">=6"
+}

test/compress/destructured.js

@@ -2487,3 +2487,72 @@ issue_4554: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_4584: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        try {
+            (function f({
+                [console.log(a = "FAIL")]: a,
+            }) {})(0);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            (function f({
+                [console.log(a = "FAIL")]: a,
+            }) {})(0);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4608_1: {
+    options = {
+        arguments: true,
+        keep_fargs: false,
+    }
+    input: {
+        (function() {
+            [ arguments ] = [ "foo" ];
+            console.log(arguments[0]);
+        })();
+    }
+    expect: {
+        (function() {
+            [ arguments ] = [ "foo" ];
+            console.log(arguments[0]);
+        })();
+    }
+    expect_stdout: "f"
+    node_version: ">=6"
+}
+
+issue_4608_2: {
+    options = {
+        arguments: true,
+        reduce_vars: true,
+    }
+    input: {
+        (function(a) {
+            [ arguments ] = [ "foo" ];
+            console.log(arguments[0]);
+        })();
+    }
+    expect: {
+        (function(a) {
+            [ arguments ] = [ "foo" ];
+            console.log(arguments[0]);
+        })();
+    }
+    expect_stdout: "f"
+    node_version: ">=6"
+}

test/compress/drop-unused.js

@@ -2138,6 +2138,7 @@ issue_3497: {
 issue_3515_1: {
     options = {
         collapse_vars: true,
+        evaluate: true,
         reduce_vars: true,
         unused: true,
     }
@@ -2189,6 +2190,7 @@ issue_3515_2: {
 issue_3515_3: {
     options = {
         collapse_vars: true,
+        evaluate: true,
         unused: true,
     }
     input: {
@@ -2256,6 +2258,7 @@ function_assign: {
 issue_3598: {
     options = {
         collapse_vars: true,
+        evaluate: true,
         reduce_vars: true,
         unused: true,
     }

test/compress/evaluate.js

@@ -703,6 +703,7 @@ prototype_function: {
         var g = 0();
         var h = 0();
     }
+    expect_stdout: true
 }
 
 call_args: {
@@ -2800,7 +2801,7 @@ operator_in: {
         console.log("PASS" in { });
         console.log("FAIL" in { });
         console.log("toString" in { });
-        console.log(true);
+        console.log("toString" in { toString: 3 });
     }
     expect_stdout: [
         "true",

test/compress/exponentiation.js

@@ -0,0 +1,58 @@
+precedence_1: {
+    input: {
+        console.log(-4 ** 3 ** 2);
+    }
+    expect_exact: "console.log((-4)**3**2);"
+    expect_stdout: "-262144"
+    node_version: ">=8"
+}
+
+precedence_2: {
+    input: {
+        console.log(-4 ** (3 ** 2));
+    }
+    expect_exact: "console.log((-4)**3**2);"
+    expect_stdout: "-262144"
+    node_version: ">=8"
+}
+
+precedence_3: {
+    input: {
+        console.log(-(4 ** 3) ** 2);
+    }
+    expect_exact: "console.log((-(4**3))**2);"
+    expect_stdout: "4096"
+    node_version: ">=8"
+}
+
+precedence_4: {
+    input: {
+        console.log((-4 ** 3) ** 2);
+    }
+    expect_exact: "console.log(((-4)**3)**2);"
+    expect_stdout: "4096"
+    node_version: ">=8"
+}
+
+await: {
+    input: {
+        (async a => a * await a ** ++a % a)(2).then(console.log);
+    }
+    expect_exact: "(async a=>a*(await a)**++a%a)(2).then(console.log);"
+    expect_stdout: "1"
+    node_version: ">=8"
+}
+
+evaluate: {
+    options = {
+        evaluate: true,
+    }
+    input: {
+        console.log(1 + 2 ** 3 - 4);
+    }
+    expect: {
+        console.log(5);
+    }
+    expect_stdout: "5"
+    node_version: ">=8"
+}

test/compress/functions.js

@@ -5283,3 +5283,127 @@ issue_4471: {
         "PASS",
     ]
 }
+
+issue_4612_1: {
+    options = {
+        evaluate: true,
+        inline: true,
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            function f() {
+                return g();
+            }
+            function g(a) {
+                return a || f();
+            }
+            return g("PASS");
+        }());
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4612_2: {
+    options = {
+        evaluate: true,
+        inline: true,
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            function fn() {
+                return h();
+            }
+            function g() {
+                return fn();
+            }
+            function h(a) {
+                return a || fn();
+            }
+            return h("PASS");
+        }());
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4612_3: {
+    options = {
+        inline: true,
+        reduce_vars: true,
+    }
+    input: {
+        console.log(typeof function() {
+            return g();
+            function f() {
+                return g;
+            }
+            function g() {
+                {
+                    return f;
+                }
+            }
+        }());
+    }
+    expect: {
+        console.log(typeof function() {
+            return g();
+            function f() {
+                return g;
+            }
+            function g() {
+                return f;
+            }
+        }());
+    }
+    expect_stdout: "function"
+}
+
+issue_4612_4: {
+    options = {
+        booleans: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        console.log(function() {
+            function f() {
+                return h();
+            }
+            function g() {
+                {
+                    return h();
+                }
+            }
+            function h() {
+                {
+                    return g();
+                }
+            }
+        }());
+    }
+    expect: {
+        console.log(function() {
+            function f() {
+                return h();
+            }
+            function g() {
+                return h();
+            }
+            function h() {
+                return g();
+            }
+        }());
+    }
+    expect_stdout: "undefined"
+}

test/compress/issue-269.js

@@ -17,7 +17,7 @@ issue_269_1: {
     expect: {
         var x = {};
         console.log(
-            x + "", +x, !!x,
+            "" + x, +("" + x), !!x,
             "", 0, false
         );
     }

test/compress/join_vars.js

@@ -1055,3 +1055,75 @@ issue_3916: {
     }
     expect_stdout: "object PASS true PASS"
 }
+
+assign_var: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        b = "foo";
+        var a = [ , "bar" ];
+        console.log(b);
+        for (var b in a)
+            console.log(b, a[b]);
+    }
+    expect: {
+        var b = "foo", a = [ , "bar" ], b;
+        console.log(b);
+        for (b in a)
+            console.log(b, a[b]);
+    }
+    expect_stdout: [
+        "foo",
+        "1 bar",
+    ]
+}
+
+assign_for_var: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        i = "foo",
+        a = new Array(i, "bar");
+        for (var i = 2; --i >= 0;) {
+            console.log(a[i]);
+            for (var a in i);
+        }
+    }
+    expect: {
+        for (var i = "foo", a = new Array(i, "bar"), i = 2; --i >= 0;) {
+            console.log(a[i]);
+            for (var a in i);
+        }
+    }
+    expect_stdout: [
+        "bar",
+        "foo",
+    ]
+}
+
+assign_sequence_var: {
+    options = {
+        join_vars: true,
+    }
+    input: {
+        var a = 0, b = 1;
+        console.log(a),
+        a++,
+        b = 2;
+        var c = 3;
+        console.log(a, b, c);
+    }
+    expect: {
+        var a = 0, b = 1;
+        console.log(a),
+        a++;
+        var b = 2, c = 3;
+        console.log(a, b, c);
+    }
+    expect_stdout: [
+        "0",
+        "1 2 3",
+    ]
+}

test/compress/loops.js

@@ -828,6 +828,21 @@ empty_for_in_prop_init: {
     ]
 }
 
+for_of: {
+    input: {
+        var async = [ "PASS", 42 ];
+        async.p = "FAIL";
+        for (async of (null, async))
+            console.log(async);
+    }
+    expect_exact: 'var async=["PASS",42];async.p="FAIL";for(async of(null,async))console.log(async);'
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=0.12"
+}
+
 issue_3631_1: {
     options = {
         dead_code: true,

test/compress/merge_vars.js

@@ -3183,3 +3183,32 @@ issue_4257: {
         "1",
     ]
 }
+
+issue_4628: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        (function() {
+            try {
+                console;
+            } finally {
+                var b = a;
+            }
+            for (var a in "foo");
+            console.log(b);
+        })();
+    }
+    expect: {
+        (function() {
+            try {
+                console;
+            } finally {
+                var b = a;
+            }
+            for (var a in "foo");
+            console.log(b);
+        })();
+    }
+    expect_stdout: "undefined"
+}

test/compress/numbers.js

@@ -338,7 +338,7 @@ evaluate_3: {
         console.log(1 + Number(x) + 2);
     }
     expect: {
-        console.log(+x + 3);
+        console.log(+("" + x) + 3);
     }
 }
 

test/compress/pure_getters.js

@@ -248,6 +248,35 @@ issue_2110_2: {
     expect_stdout: "function"
 }
 
+issue_2110_3: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        reduce_vars: true,
+    }
+    input: {
+        function g() {
+            return this;
+        }
+        console.log(typeof function() {
+            function f() {}
+            f.g = g;
+            return f.g();
+        }());
+    }
+    expect: {
+        function g() {
+            return this;
+        }
+        console.log(typeof function() {
+            function f() {}
+            f.g = g;
+            return f.g();
+        }());
+    }
+    expect_stdout: "function"
+}
+
 set_immutable_1: {
     options = {
         collapse_vars: true,
@@ -979,6 +1008,7 @@ collapse_vars_2_strict: {
 collapse_rhs_true: {
     options = {
         collapse_vars: true,
+        evaluate: true,
         pure_getters: true,
     }
     input: {
@@ -1015,6 +1045,7 @@ collapse_rhs_true: {
 collapse_rhs_false: {
     options = {
         collapse_vars: true,
+        evaluate: true,
         pure_getters: false,
     }
     input: {
@@ -1051,6 +1082,7 @@ collapse_rhs_false: {
 collapse_rhs_strict: {
     options = {
         collapse_vars: true,
+        evaluate: true,
         pure_getters: "strict",
     }
     input: {
@@ -1087,6 +1119,7 @@ collapse_rhs_strict: {
 collapse_rhs_setter: {
     options = {
         collapse_vars: true,
+        evaluate: true,
         pure_getters: "strict",
     }
     input: {

test/compress/reduce_vars.js

@@ -2460,6 +2460,7 @@ delay_def: {
         evaluate: true,
         reduce_funcs: true,
         reduce_vars: true,
+        side_effects: true,
         unused: true,
     }
     input: {

test/compress/rests.js

@@ -663,3 +663,103 @@ issue_4562: {
     expect_stdout: "f"
     node_version: ">=6"
 }
+
+issue_4575: {
+    options = {
+        collapse_vars: true,
+        ie8: true,
+        reduce_vars: true,
+        rests: true,
+        unused: true,
+    }
+    input: {
+        A = "PASS";
+        (function() {
+            var a = 0, b = a;
+            var c = function a(...b) {
+                A;
+                var d = A;
+                console.log(d, b.length);
+            }();
+        })();
+    }
+    expect: {
+        A = "PASS";
+        (function() {
+            (function(b) {
+                A;
+                var d = A;
+                console.log(d, b.length);
+            })([]);
+        })();
+    }
+    expect_stdout: "PASS 0"
+    node_version: ">=6"
+}
+
+issue_4621: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        (function f(a, ...{
+            [console.log(a)]: b,
+        }) {})("PASS");
+    }
+    expect: {
+        (function f(a, ...{
+            [console.log(a)]: b,
+        }) {})("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4644_1: {
+    options = {
+        evaluate: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function f(b, ...{
+            [a = "PASS"]: c,
+        }) {
+            return b;
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function f(b, ...{
+            [a = "PASS"]: c,
+        }) {
+            return b;
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4644_2: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(...a) {
+            return a[1];
+        }("FAIL", "PASS"), function(...b) {
+            return b.length;
+        }(), function(c, ...d) {
+            return d[0];
+        }("FAIL"));
+    }
+    expect: {
+        console.log("PASS", 0, function(c, ...d) {
+            return d[0];
+        }("FAIL"));
+    }
+    expect_stdout: "PASS 0 undefined"
+    node_version: ">=6"
+}

test/compress/sandbox.js

@@ -13,6 +13,23 @@ console_log: {
     ]
 }
 
+console_log_console: {
+    input: {
+        var log = console.log;
+        log(console);
+        log(typeof console.log);
+    }
+    expect: {
+        var log = console.log;
+        log(console);
+        log(typeof console.log);
+    }
+    expect_stdout: [
+        "{ log: 'function(){}' }",
+        "function",
+    ]
+}
+
 typeof_arguments: {
     options = {
         evaluate: true,
@@ -81,6 +98,63 @@ log_global: {
     expect_stdout: "[object global]"
 }
 
+log_nested: {
+    options = {
+        unused: true,
+    }
+    input: {
+        var o = { p: 42 };
+        for (var i = 0; i < 10; i++)
+            o = {
+                p: o,
+                q: function foo() {},
+            };
+        console.log(o);
+    }
+    expect: {
+        var o = { p: 42 };
+        for (var i = 0; i < 10; i++)
+            o = {
+                p: o,
+                q: function() {},
+            };
+        console.log(o);
+    }
+    expect_stdout: true
+}
+
+timers: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var count = 0, interval = 1000, duration = 3210;
+        var timer = setInterval(function() {
+            console.log(++count);
+        }, interval);
+        setTimeout(function() {
+            clearInterval(timer);
+        }, duration);
+    }
+    expect: {
+        var count = 0;
+        var timer = setInterval(function() {
+            console.log(++count);
+        }, 1000);
+        setTimeout(function() {
+            clearInterval(timer);
+        }, 3210);
+    }
+    expect_stdout: [
+        "1",
+        "2",
+        "3",
+    ]
+    node_version: ">=0.12"
+}
+
 issue_4054: {
     input: {
         console.log({

test/compress/spreads.js

@@ -918,3 +918,32 @@ issue_4560_3: {
     expect_stdout: "PASS"
     node_version: ">=6"
 }
+
+issue_4614: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        try {
+            (function(...[]) {
+                var arguments;
+                arguments[0];
+            })();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            (function(...[]) {
+                var arguments;
+                arguments[0];
+            })();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}

test/compress/templates.js

@@ -0,0 +1,300 @@
+simple: {
+    input: {
+        console.log(`foo
+        bar\nbaz`);
+    }
+    expect_exact: "console.log(`foo\n        bar\\nbaz`);"
+    expect_stdout: [
+        "foo",
+        "        bar",
+        "baz",
+    ]
+    node_version: ">=4"
+}
+
+placeholder: {
+    input: {
+        console.log(`foo ${ function(a, b) {
+            return a * b;
+        }(6, 7) }`);
+    }
+    expect_exact: "console.log(`foo ${function(a,b){return a*b}(6,7)}`);"
+    expect_stdout: "foo 42"
+    node_version: ">=4"
+}
+
+nested: {
+    input: {
+        console.log(`P${`A${"S"}`}S`);
+    }
+    expect_exact: 'console.log(`P${`A${"S"}`}S`);'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+tagged: {
+    input: {
+        console.log(String.raw`foo\nbar`);
+    }
+    expect_exact: "console.log(String.raw`foo\\nbar`);"
+    expect_stdout: "foo\\nbar"
+    node_version: ">=4"
+}
+
+tagged_chain: {
+    input: {
+        function f(strings) {
+            return strings.join("") || f;
+        }
+        console.log(f```${42}``pass`.toUpperCase());
+    }
+    expect_exact: 'function f(strings){return strings.join("")||f}console.log(f```${42}``pass`.toUpperCase());'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+tag_parenthesis_arrow: {
+    input: {
+        console.log((s => s.raw[0])`\tPASS`.slice(2));
+    }
+    expect_exact: "console.log((s=>s.raw[0])`\\tPASS`.slice(2));"
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+tag_parenthesis_new: {
+    input: {
+        (new function() {
+            return console.log;
+        })`foo`;
+    }
+    expect_exact: "(new function(){return console.log})`foo`;"
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+malformed_escape: {
+    input: {
+        (function(s) {
+            s.forEach((c, i) => console.log(i, c, s.raw[i]));
+            return () => console.log(arguments);
+        })`\uFo${42}`();
+    }
+    expect_exact: "(function(s){s.forEach((c,i)=>console.log(i,c,s.raw[i]));return()=>console.log(arguments)})`\\uFo${42}`();"
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+evaluate: {
+    options = {
+        evaluate: true,
+        templates: false,
+    }
+    input: {
+        console.log(`foo ${ function(a, b) {
+            return a * b;
+        }(6, 7) }`);
+    }
+    expect: {
+        console.log(`foo ${42}`);
+    }
+    expect_stdout: "foo 42"
+    node_version: ">=4"
+}
+
+evaluate_templates: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`foo ${ function(a, b) {
+            return a * b;
+        }(6, 7) }`);
+    }
+    expect: {
+        console.log("foo 42");
+    }
+    expect_stdout: "foo 42"
+    node_version: ">=4"
+}
+
+partial_evaluate: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`${6 * 7} foo ${console ? `PA` + "SS" : `FA` + `IL`}`);
+    }
+    expect: {
+        console.log(`42 foo ${console ? "PASS" : "FAIL"}`);
+    }
+    expect_stdout: "42 foo PASS"
+    node_version: ">=4"
+}
+
+malformed_evaluate_1: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`\67 ${6 * 7}`);
+    }
+    expect: {
+        console.log(`\67 42`);
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+malformed_evaluate_2: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`\u0${0}b${5}`);
+    }
+    expect: {
+        console.log(`\u0${0}b5`);
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+malformed_evaluate_3: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`\u${0}b${5}`);
+    }
+    expect: {
+        console.log(`\u0b5`);
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+malformed_evaluate_4: {
+    options = {
+        evaluate: true,
+        templates: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(String.raw`\u0${0}b${5}`);
+    }
+    expect: {
+        console.log("\\u00b5");
+    }
+    expect_stdout: "\\u00b5"
+    node_version: ">=8"
+}
+
+unsafe_evaluate: {
+    options = {
+        evaluate: true,
+        templates: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(String.raw`\uFo`);
+    }
+    expect: {
+        console.log("\\uFo");
+    }
+    expect_stdout: "\\uFo"
+    node_version: ">=8"
+}
+
+side_effects: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        `42`;
+        `${console.log("foo")}`;
+        console.log`\nbar`;
+    }
+    expect: {
+        console.log("foo");
+        console.log`\nbar`;
+    }
+    expect_stdout: true
+    node_version: ">=4"
+}
+
+unsafe_side_effects: {
+    options = {
+        side_effects: true,
+        unsafe: true,
+    }
+    input: {
+        `42`;
+        `${console.log("foo")}`;
+        String.raw`\nbar`;
+    }
+    expect: {
+        console.log("foo");
+    }
+    expect_stdout: "foo"
+    node_version: ">=4"
+}
+
+issue_4604: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = 0, log = console.log;
+        a = "FAIL";
+        (function() {
+            a = "PASS";
+        })``;
+        log(a);
+    }
+    expect: {
+        var a = 0, log = console.log;
+        a = "FAIL";
+        (function() {
+            a = "PASS";
+        })``;
+        log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4606: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`${typeof A} ${"\r"} ${"\\"} ${"`"}`);
+    }
+    expect: {
+        console.log(`${typeof A} \r \\ \``);
+    }
+    expect_stdout: "undefined \r \\ `"
+    node_version: ">=4"
+}
+
+issue_4630: {
+    options = {
+        evaluate: true,
+        templates: true,
+    }
+    input: {
+        console.log(`${/PASS/}`);
+    }
+    expect: {
+        console.log("/PASS/");
+    }
+    expect_stdout: "/PASS/"
+    node_version: ">=4"
+}

test/compress/yields.js

@@ -0,0 +1,952 @@
+binary: {
+    input: {
+        var a = function*() {
+            console.log(6 * (yield "PA" + "SS"));
+        }();
+        console.log(a.next("FAIL").value);
+        console.log(a.next(7).done);
+    }
+    expect_exact: 'var a=function*(){console.log(6*(yield"PA"+"SS"))}();console.log(a.next("FAIL").value);console.log(a.next(7).done);'
+    expect_stdout: [
+        "PASS",
+        "42",
+        "true",
+    ]
+    node_version: ">=4"
+}
+
+empty_yield: {
+    input: {
+        var a = function*() {
+            yield;
+            console.log(yield);
+            yield
+            "FAIL 1";
+        }();
+        console.log(a.next("FAIL 2").value);
+        console.log(a.next("FAIL 3").value);
+        console.log(a.next("PASS").value);
+        console.log(a.next("FAIL 4").done);
+    }
+    expect_exact: 'var a=function*(){yield;console.log(yield);yield;"FAIL 1"}();console.log(a.next("FAIL 2").value);console.log(a.next("FAIL 3").value);console.log(a.next("PASS").value);console.log(a.next("FAIL 4").done);'
+    expect_stdout: [
+        "undefined",
+        "undefined",
+        "PASS",
+        "undefined",
+        "true",
+    ]
+    node_version: ">=4"
+}
+
+empty_yield_conditional: {
+    input: {
+        var a = function*() {
+            console.log((yield) ? yield : yield);
+        }();
+        console.log(a.next("FAIL 1").value);
+        console.log(a.next("FAIL 2").value);
+        console.log(a.next("PASS").value);
+        console.log(a.next("FAIL 3").done);
+    }
+    expect_exact: 'var a=function*(){console.log((yield)?yield:yield)}();console.log(a.next("FAIL 1").value);console.log(a.next("FAIL 2").value);console.log(a.next("PASS").value);console.log(a.next("FAIL 3").done);'
+    expect_stdout: [
+        "undefined",
+        "undefined",
+        "PASS",
+        "undefined",
+        "true",
+    ]
+    node_version: ">=4"
+}
+
+nested_yield: {
+    input: {
+        console.log(function*() {
+            (yield*
+            f())
+            function* f() {
+                return "FAIL";
+            }
+            yield*
+            f();
+            yield *f();
+        }().next().value || "PASS");
+    }
+    expect_exact: 'console.log(function*(){yield*f();function*f(){return"FAIL"}yield*f();yield*f()}().next().value||"PASS");'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+pause_resume: {
+    input: {
+        function* f() {
+            console.log(yield "PASS");
+        }
+        var a = f();
+        console.log(a.next("FAIL").value);
+        console.log(a.next(42).done);
+    }
+    expect_exact: 'function*f(){console.log(yield"PASS")}var a=f();console.log(a.next("FAIL").value);console.log(a.next(42).done);'
+    expect_stdout: [
+        "PASS",
+        "42",
+        "true",
+    ]
+    node_version: ">=4"
+}
+
+arrow_yield: {
+    input: {
+        yield = "PASS";
+        console.log(function*() {
+            return () => yield || "FAIL";
+        }().next().value());
+    }
+    expect_exact: 'yield="PASS";console.log(function*(){return()=>yield||"FAIL"}().next().value());'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+for_of: {
+    input: {
+        function* f() {
+            if (yield "PASS") yield "FAIL 1";
+            yield 42;
+            return "FAIL 2";
+        }
+        for (var a of f())
+            console.log(a);
+    }
+    expect_exact: 'function*f(){if(yield"PASS")yield"FAIL 1";yield 42;return"FAIL 2"}for(var a of f())console.log(a);'
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=4"
+}
+
+for_await_of: {
+    input: {
+        async function* f() {
+            if (yield "PASS") yield "FAIL 1";
+            yield {
+                then: function(r) {
+                    r(42);
+                },
+            };
+            return "FAIL 2";
+        }
+        (async function(a) {
+            for await (a of f())
+                console.log(a);
+        })();
+    }
+    expect_exact: 'async function*f(){if(yield"PASS")yield"FAIL 1";yield{then:function(r){r(42)}};return"FAIL 2"}(async function(a){for await(a of f())console.log(a)})();'
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=10"
+}
+
+collapse_vars_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function*() {
+            a = "PASS";
+            yield 42;
+            return "PASS";
+        })().next();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function*() {
+            a = "PASS";
+            yield 42;
+            return "PASS";
+        })().next();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+collapse_vars_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function*() {
+            yield (a = "PASS");
+            return "PASS";
+        })().next();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function*() {
+            yield (a = "PASS");
+            return "PASS";
+        })().next();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+collapse_vars_3: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        (function*() {
+            yield (a = "PASS", 42);
+            return "PASS";
+        })().next();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (function*() {
+            yield (a = "PASS", 42);
+            return "PASS";
+        })().next();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+collapse_vars_4: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = "FAIL";
+        var b = function*(c) {
+            return c;
+        }(a = "PASS");
+        console.log(a, b.next().done);
+    }
+    expect: {
+        var a = "FAIL";
+        var b = function*(c) {
+            return c;
+        }(a = "PASS");
+        console.log(a, b.next().done);
+    }
+    expect_stdout: "PASS true"
+    node_version: ">=4"
+}
+
+collapse_property_lambda: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+    }
+    input: {
+        console.log(function* f() {
+            f.g = () => 42;
+            return f.g();
+        }().next().value);
+    }
+    expect: {
+        console.log(function* f() {
+            return (f.g = () => 42)();
+        }().next().value);
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+defun_name: {
+    input: {
+        function* yield() {
+            console.log("PASS");
+        }
+        yield().next();
+    }
+    expect: {
+        function* yield() {
+            console.log("PASS");
+        }
+        yield().next();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+drop_fname: {
+    rename = true
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        function* yield() {
+            console.log("PASS");
+        }
+        yield().next();
+    }
+    expect: {
+        (function*() {
+            console.log("PASS");
+        })().next();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+keep_fname: {
+    options = {
+        keep_fnames: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function* yield() {
+            console.log("PASS");
+        }
+        yield().next();
+    }
+    expect: {
+        function* yield() {
+            console.log("PASS");
+        }
+        yield().next();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+evaluate: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = function*() {}();
+        console.log(typeof a);
+    }
+    expect: {
+        var a = function*() {}();
+        console.log(typeof a);
+    }
+    expect_stdout: "object"
+    node_version: ">=4"
+}
+
+functions: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        !function*() {
+            var a = function* a() {
+                return a && "a";
+            };
+            var b = function* x() {
+                return !!x;
+            };
+            var c = function*(c) {
+                return c;
+            };
+            if (yield* c(yield* b(yield* a()))) {
+                var d = function*() {};
+                var e = function* y() {
+                    return typeof y;
+                };
+                var f = function*(f) {
+                    return f;
+                };
+                console.log(yield* a(yield* d()), yield* b(yield* e()), yield* c(yield* f(42)), typeof d, yield* e(), typeof f);
+            }
+        }().next();
+    }
+    expect: {
+        !function*() {
+            function* a() {
+                return a && "a";
+            }
+            function* b() {
+                return !!b;
+            }
+            var c = function*(c) {
+                return c;
+            };
+            if (yield* c(yield* b(yield* a()))) {
+                function* d() {}
+                function* e() {
+                    return typeof e;
+                }
+                var f = function*(f) {
+                    return f;
+                };
+                console.log(yield* a(yield* d()), yield* b(yield* e()), yield* c(yield* f(42)), typeof d, yield* e(), typeof f);
+            }
+        }().next();
+    }
+    expect_stdout: "a true 42 function function function"
+    node_version: ">=4"
+}
+
+functions_use_strict: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        !function*() {
+            var a = function* a() {
+                return a && "a";
+            };
+            var b = function* x() {
+                return !!x;
+            };
+            var c = function*(c) {
+                return c;
+            };
+            if (yield* c(yield* b(yield* a()))) {
+                var d = function*() {};
+                var e = function* y() {
+                    return typeof y;
+                };
+                var f = function*(f) {
+                    return f;
+                };
+                console.log(yield* a(yield* d()), yield* b(yield* e()), yield* c(yield* f(42)), typeof d, yield* e(), typeof f);
+            }
+        }().next();
+    }
+    expect: {
+        "use strict";
+        !function*() {
+            function* a() {
+                return a && "a";
+            }
+            function* b() {
+                return !!b;
+            }
+            var c = function*(c) {
+                return c;
+            };
+            if (yield* c(yield* b(yield* a()))) {
+                var d = function*() {};
+                var e = function* y() {
+                    return typeof y;
+                };
+                var f = function*(f) {
+                    return f;
+                };
+                console.log(yield* a(yield* d()), yield* b(yield* e()), yield* c(yield* f(42)), typeof d, yield* e(), typeof f);
+            }
+        }().next();
+    }
+    expect_stdout: "a true 42 function function function"
+    node_version: ">=4"
+}
+
+negate_iife: {
+    options = {
+        negate_iife: true,
+        side_effects: true,
+    }
+    input: {
+        (function*(a) {
+            console.log(a);
+        })("PASS").next();
+    }
+    expect: {
+        !function*(a) {
+            console.log(a);
+        }("PASS").next();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+reduce_iife_1: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function*(a) {
+            yield a;
+        }(42).next().value);
+    }
+    expect: {
+        console.log(function*(a) {
+            yield 42;
+        }().next().value);
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+reduce_iife_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function*() {
+            a = "FAIL";
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (function*() {
+            a = "FAIL";
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+reduce_single_use_defun: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function* f(a) {
+            console.log(a);
+        }
+        f("PASS").next();
+    }
+    expect: {
+        (function*(a) {
+            console.log(a);
+        })("PASS").next();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+reduce_tagged: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function* f() {
+            function g() {
+                h`foo`;
+            }
+            g();
+            function h(s) {
+                console.log(s[0]);
+            }
+            h([ "bar" ]);
+        }
+        f().next();
+    }
+    expect: {
+        function* f() {
+            (function() {
+                h`foo`;
+            })();
+            function h(s) {
+                console.log(s[0]);
+            }
+            h([ "bar" ]);
+        }
+        f().next();
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=4"
+}
+
+reduce_tagged_async: {
+    options = {
+        reduce_funcs: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        async function* f() {
+            function g() {
+                h`foo`;
+            }
+            g();
+            function h(s) {
+                console.log(s[0]);
+            }
+            h([ "bar" ]);
+        }
+        f().next();
+    }
+    expect: {
+        async function* f() {
+            (function() {
+                h`foo`;
+            })();
+            function h(s) {
+                console.log(s[0]);
+            }
+            h([ "bar" ]);
+        }
+        f().next();
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=10"
+}
+
+lift_sequence: {
+    options = {
+        sequences: true,
+        yields: true,
+    }
+    input: {
+        console.log(function*() {
+            yield (console, "PASS");
+        }().next().value);
+    }
+    expect: {
+        console.log(function*() {
+            console, yield "PASS";
+        }().next().value);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+inline_nested_yield: {
+    options = {
+        inline: true,
+        sequences: true,
+        yields: true,
+    }
+    input: {
+        var a = function*() {
+            yield* function*() {
+                yield "foo";
+                return "FAIL";
+            }();
+        }(), b;
+        do {
+            b = a.next();
+            console.log(b.value);
+        } while (!b.done);
+    }
+    expect: {
+        var a = function*() {
+            yield "foo",
+            "FAIL";
+        }(), b;
+        do {
+            b = a.next(),
+            console.log(b.value);
+        } while (!b.done);
+    }
+    expect_stdout: [
+        "foo",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+drop_body: {
+    options = {
+        side_effects: true,
+        yields: true,
+    }
+    input: {
+        (function*([ , a = console.log("foo") ]) {
+            console.log("bar");
+        })([ console.log("baz") ]);
+    }
+    expect: {
+        [ [ , 0[0] = console.log("foo") ] ] = [ [ console.log("baz") ] ];
+    }
+    expect_stdout: [
+        "baz",
+        "foo",
+    ]
+    node_version: ">=6"
+}
+
+drop_unused_call: {
+    options = {
+        inline: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+        yields: true,
+    }
+    input: {
+        var a = function*(){}(console.log("PASS"));
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4454_1: {
+    rename = false
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        function f(a) {
+            (function*(b = console.log(a)) {})();
+            var yield = 42..toString();
+            console.log(yield);
+        }
+        f("PASS");
+    }
+    expect: {
+        function f(a) {
+            (function*(b = console.log(a)) {})();
+            var yield = 42..toString();
+            console.log(yield);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=6"
+}
+
+issue_4454_2: {
+    rename = true
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        function f(a) {
+            (function*(b = console.log(a)) {})();
+            var yield = 42..toString();
+            console.log(yield);
+        }
+        f("PASS");
+    }
+    expect: {
+        function f(b) {
+            (function*(c = console.log(b)) {})();
+            var b = 42..toString();
+            console.log(b);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=6"
+}
+
+issue_4618: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function() {
+            var yield = function* f() {
+                console || f();
+            };
+            console.log;
+            return yield;
+        }());
+    }
+    expect: {
+        console.log(typeof function() {
+            var yield = function* f() {
+                console || f();
+            };
+            console.log;
+            return yield;
+        }());
+    }
+    expect_stdout: "function"
+    node_version: ">=4"
+}
+
+issue_4623: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        if (console ? function*() {} : 0)
+            console.log("PASS");
+    }
+    expect: {
+        (console ? function*() {} : 0) && console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4633: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = function*() {
+            (function(log) {
+                log(typeof this);
+            })(yield "PASS");
+        }();
+        console.log(a.next().value);
+        a.next(console.log);
+    }
+    expect: {
+        var a = function*() {
+            (function(log) {
+                log(typeof this);
+            })(yield "PASS");
+        }();
+        console.log(a.next().value);
+        a.next(console.log);
+    }
+    expect_stdout: [
+        "PASS",
+        "object",
+    ]
+    node_version: ">=4"
+}
+
+issue_4639_1: {
+    options = {
+        inline: true,
+    }
+    input: {
+        console.log(function*() {
+            return function() {
+                return yield => "PASS";
+            }();
+        }().next().value());
+    }
+    expect: {
+        console.log(function*() {
+            return function() {
+                return yield => "PASS";
+            }();
+        }().next().value());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4639_2: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (function*() {
+            console.log(function() {
+                return typeof yield;
+            }());
+        })().next();
+    }
+    expect: {
+        (function*() {
+            console.log(function() {
+                return typeof yield;
+            }());
+        })().next();
+    }
+    expect_stdout: "undefined"
+    node_version: ">=4"
+}
+
+issue_4641_1: {
+    options = {
+        sequences: true,
+    }
+    input: {
+        console.log(typeof async function*() {
+            try {
+                console.log("foo");
+                return;
+            } finally {
+                console.log("bar");
+            }
+        }().next().then);
+    }
+    expect: {
+        console.log(typeof async function*() {
+            try {
+                console.log("foo");
+                return;
+            } finally {
+                console.log("bar");
+            }
+        }().next().then);
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+        "function",
+    ]
+    node_version: ">=10"
+}
+
+issue_4641_2: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        console.log(typeof async function*() {
+            try {
+                return void "FAIL";
+            } finally {
+                console.log("PASS");
+            }
+        }().next().then);
+    }
+    expect: {
+        console.log(typeof async function*() {
+            try {
+                return void 0;
+            } finally {
+                console.log("PASS");
+            }
+        }().next().then);
+    }
+    expect_stdout: [
+        "function",
+        "PASS",
+    ]
+    node_version: ">=10"
+}

test/input/invalid/for-of_1.js

@@ -0,0 +1,3 @@
+var a = [ 1 ], b;
+for (b = 2 of a)
+    console.log(b);

test/input/invalid/for-of_2.js

@@ -0,0 +1,3 @@
+var a = [ 1 ];
+for (var b = 2 of a)
+    console.log(b);

test/mocha/cli.js

@@ -56,7 +56,7 @@ describe("bin/uglifyjs", function() {
             "--source-map", [
                 "names=true",
                 "url=inline",
-            ].join(","),
+            ].join(),
         ].join(" "), function(err, stdout) {
             if (err) throw err;
             var expected = [
@@ -84,7 +84,7 @@ describe("bin/uglifyjs", function() {
             "--source-map", [
                 "names=false",
                 "url=inline",
-            ].join(","),
+            ].join(),
         ].join(" "), function(err, stdout) {
             if (err) throw err;
             var expected = [
@@ -171,7 +171,7 @@ describe("bin/uglifyjs", function() {
                 "content=" + mapFile,
                 "includeSources",
                 "url=inline",
-            ].join(","),
+            ].join(),
         ].join(" ");
 
         var child = exec(command, function(err, stdout) {
@@ -333,11 +333,13 @@ describe("bin/uglifyjs", function() {
         var command = uglifyjscmd + " test/input/invalid/simple.js";
         exec(command, function(err, stdout, stderr) {
             assert.ok(err);
-            var lines = stderr.split(/\n/);
-            assert.strictEqual(lines[0], "Parse error at test/input/invalid/simple.js:1,12");
-            assert.strictEqual(lines[1], "function f(a{}");
-            assert.strictEqual(lines[2], "            ^");
-            assert.strictEqual(lines[3], "ERROR: Unexpected token: punc «{», expected: punc «,»");
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/simple.js:1,12",
+                "function f(a{}",
+                "            ^",
+                "ERROR: Unexpected token: punc «{», expected: punc «,»",
+            ].join("\n"));
             done();
         });
     });
@@ -345,11 +347,13 @@ describe("bin/uglifyjs", function() {
         var command = uglifyjscmd + " test/input/invalid/tab.js";
         exec(command, function(err, stdout, stderr) {
             assert.ok(err);
-            var lines = stderr.split(/\n/);
-            assert.strictEqual(lines[0], "Parse error at test/input/invalid/tab.js:1,12");
-            assert.strictEqual(lines[1], "\t\tfoo(\txyz, 0abc);");
-            assert.strictEqual(lines[2], "\t\t    \t     ^");
-            assert.strictEqual(lines[3], "ERROR: Invalid syntax: 0abc");
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/tab.js:1,12",
+                "\t\tfoo(\txyz, 0abc);",
+                "\t\t    \t     ^",
+                "ERROR: Invalid syntax: 0abc",
+            ].join("\n"));
             done();
         });
     });
@@ -357,11 +361,13 @@ describe("bin/uglifyjs", function() {
         var command = uglifyjscmd + " test/input/invalid/eof.js";
         exec(command, function(err, stdout, stderr) {
             assert.ok(err);
-            var lines = stderr.split(/\n/);
-            assert.strictEqual(lines[0], "Parse error at test/input/invalid/eof.js:2,0");
-            assert.strictEqual(lines[1], "foo, bar(");
-            assert.strictEqual(lines[2], "         ^");
-            assert.strictEqual(lines[3], "ERROR: Unexpected token: eof");
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/eof.js:2,0",
+                "foo, bar(",
+                "         ^",
+                "ERROR: Unexpected token: eof",
+            ].join("\n"));
             done();
         });
     });
@@ -369,11 +375,13 @@ describe("bin/uglifyjs", function() {
         var command = uglifyjscmd + " test/input/invalid/loop-no-body.js";
         exec(command, function(err, stdout, stderr) {
             assert.ok(err);
-            var lines = stderr.split(/\n/);
-            assert.strictEqual(lines[0], "Parse error at test/input/invalid/loop-no-body.js:2,0");
-            assert.strictEqual(lines[1], "for (var i = 0; i < 1; i++) ");
-            assert.strictEqual(lines[2], "                            ^");
-            assert.strictEqual(lines[3], "ERROR: Unexpected token: eof");
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/loop-no-body.js:2,0",
+                "for (var i = 0; i < 1; i++) ",
+                "                            ^",
+                "ERROR: Unexpected token: eof",
+            ].join("\n"));
             done();
         });
     });
@@ -386,7 +394,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/assign_1.js:1,18",
                 "console.log(1 || 5--);",
                 "                  ^",
-                "ERROR: Invalid use of -- operator"
+                "ERROR: Invalid use of -- operator",
             ].join("\n"));
             done();
         });
@@ -400,7 +408,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/assign_2.js:1,32",
                 "console.log(2 || (Math.random() /= 2));",
                 "                                ^",
-                "ERROR: Invalid assignment"
+                "ERROR: Invalid assignment",
             ].join("\n"));
             done();
         });
@@ -414,7 +422,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/assign_3.js:1,17",
                 "console.log(3 || ++this);",
                 "                 ^",
-                "ERROR: Invalid use of ++ operator"
+                "ERROR: Invalid use of ++ operator",
             ].join("\n"));
             done();
         });
@@ -428,7 +436,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/assign_4.js:1,0",
                 "++null",
                 "^",
-                "ERROR: Invalid use of ++ operator"
+                "ERROR: Invalid use of ++ operator",
             ].join("\n"));
             done();
         });
@@ -442,7 +450,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/dot_1.js:1,2",
                 "a.=",
                 "  ^",
-                "ERROR: Unexpected token: operator «=», expected: name"
+                "ERROR: Unexpected token: operator «=», expected: name",
             ].join("\n"));
             done();
         });
@@ -456,7 +464,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/dot_2.js:1,0",
                 "%.a;",
                 "^",
-                "ERROR: Unexpected token: operator «%»"
+                "ERROR: Unexpected token: operator «%»",
             ].join("\n"));
             done();
         });
@@ -470,7 +478,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/dot_3.js:1,2",
                 "a./();",
                 "  ^",
-                "ERROR: Unexpected token: operator «/», expected: name"
+                "ERROR: Unexpected token: operator «/», expected: name",
             ].join("\n"));
             done();
         });
@@ -484,7 +492,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/object.js:1,13",
                 "console.log({%: 1});",
                 "             ^",
-                "ERROR: Unexpected token: operator «%»"
+                "ERROR: Unexpected token: operator «%»",
             ].join("\n"));
             done();
         });
@@ -498,7 +506,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/delete.js:13,11",
                 "    delete x;",
                 "           ^",
-                "ERROR: Calling delete on expression not allowed in strict mode"
+                "ERROR: Calling delete on expression not allowed in strict mode",
             ].join("\n"));
             done();
         });
@@ -512,7 +520,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/function_1.js:4,11",
                 "function g(arguments) {",
                 "           ^",
-                "ERROR: Unexpected arguments in strict mode"
+                "ERROR: Unexpected arguments in strict mode",
             ].join("\n"));
             done();
         });
@@ -526,7 +534,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/function_2.js:4,9",
                 "function eval() {",
                 "         ^",
-                "ERROR: Unexpected eval in strict mode"
+                "ERROR: Unexpected eval in strict mode",
             ].join("\n"));
             done();
         });
@@ -540,7 +548,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/function_3.js:4,10",
                 "!function arguments() {",
                 "          ^",
-                "ERROR: Unexpected arguments in strict mode"
+                "ERROR: Unexpected arguments in strict mode",
             ].join("\n"));
             done();
         });
@@ -554,7 +562,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/try.js:7,18",
                 "    try {} catch (eval) {}",
                 "                  ^",
-                "ERROR: Unexpected eval in strict mode"
+                "ERROR: Unexpected eval in strict mode",
             ].join("\n"));
             done();
         });
@@ -568,7 +576,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/var.js:7,8",
                 "    var eval;",
                 "        ^",
-                "ERROR: Unexpected eval in strict mode"
+                "ERROR: Unexpected eval in strict mode",
             ].join("\n"));
             done();
         });
@@ -582,7 +590,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/destructured_var.js:7,10",
                 "    var { eval } = 42;",
                 "          ^",
-                "ERROR: Unexpected eval in strict mode"
+                "ERROR: Unexpected eval in strict mode",
             ].join("\n"));
             done();
         });
@@ -596,7 +604,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/else.js:1,7",
                 "if (0) else 1;",
                 "       ^",
-                "ERROR: Unexpected token: keyword «else»"
+                "ERROR: Unexpected token: keyword «else»",
             ].join("\n"));
             done();
         });
@@ -610,7 +618,7 @@ describe("bin/uglifyjs", function() {
                 "Parse error at test/input/invalid/return.js:1,0",
                 "return 42;",
                 "^",
-                "ERROR: 'return' outside of function"
+                "ERROR: 'return' outside of function",
             ].join("\n"));
             done();
         });
@@ -624,7 +632,7 @@ describe("bin/uglifyjs", function() {
                 "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"
+                "ERROR: Invalid left-hand side in for..in/of loop",
             ].join("\n"));
             done();
         });
@@ -638,7 +646,35 @@ describe("bin/uglifyjs", function() {
                 "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"
+                "ERROR: Only one variable declaration allowed in for..in/of loop",
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (for-of init)", function(done) {
+        var command = uglifyjscmd + " test/input/invalid/for-of_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-of_1.js:2,5",
+                "for (b = 2 of a)",
+                "     ^",
+                "ERROR: Invalid left-hand side in for..in/of loop",
+            ].join("\n"));
+            done();
+        });
+    });
+    it("Should throw syntax error (for-of var)", function(done) {
+        var command = uglifyjscmd + " test/input/invalid/for-of_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-of_2.js:2,13",
+                "for (var b = 2 of a)",
+                "             ^",
+                "ERROR: No initializers allowed in for..of loop",
             ].join("\n"));
             done();
         });
@@ -647,11 +683,13 @@ describe("bin/uglifyjs", function() {
         var command = uglifyjscmd + " test/input/invalid/switch.js";
         exec(command, function(err, stdout, stderr) {
             assert.ok(err);
-            var lines = stderr.split(/\n/);
-            assert.strictEqual(lines[0], "Parse error at test/input/invalid/switch.js:3,2");
-            assert.strictEqual(lines[1], "  default:");
-            assert.strictEqual(lines[2], "  ^");
-            assert.strictEqual(lines[3], "ERROR: More than one default clause in switch statement");
+            assert.strictEqual(stdout, "");
+            assert.strictEqual(stderr.split(/\n/).slice(0, 4).join("\n"), [
+                "Parse error at test/input/invalid/switch.js:3,2",
+                "  default:",
+                "  ^",
+                "ERROR: More than one default clause in switch statement",
+            ].join("\n"));
             done();
         });
     });

test/mocha/reduce.js

@@ -294,6 +294,39 @@ describe("test/reduce.js", function() {
             "// }",
         ]).join("\n"));
     });
+    it("Should maintain block-scope for const & let", function() {
+        if (semver.satisfies(process.version, "<4")) return;
+        var code = [
+            '"use strict";',
+            "",
+            "L: for (let a = (1 - .8).toString(); ;) {",
+            "    if (!console.log(a)) {",
+            "        break L;",
+            "    }",
+            "}",
+        ].join("\n");
+        var result = reduce_test(code, {
+            compress: {
+                unsafe_math: true,
+            },
+            mangle: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, [
+            "// (beautified)",
+            code,
+            "// output: 0.19999999999999996",
+            "// ",
+            "// minify: 0.2",
+            "// ",
+            "// options: {",
+            '//   "compress": {',
+            '//     "unsafe_math": true',
+            '//   },',
+            '//   "mangle": false',
+            "// }",
+        ].join("\n"));
+    });
     it("Should handle corner cases when intermediate case differs only in Error.message", function() {
         if (semver.satisfies(process.version, "<=0.10")) return;
         var result = reduce_test(read("test/input/reduce/diff_error.js"), {

test/mocha/string-literal.js

@@ -115,8 +115,8 @@ describe("String literals", function() {
                 UglifyJS.parse(test);
             }, function(e) {
                 return e instanceof UglifyJS.JS_Parse_Error
-                    && e.message === "Invalid hex-character pattern in string";
-            });
+                    && /^Invalid escape sequence: \\u/.test(e.message);
+            }, test);
         });
     });
     it("Should reject invalid code points in Unicode escape sequence", function() {
@@ -130,8 +130,8 @@ describe("String literals", function() {
                 UglifyJS.parse(test);
             }, function(e) {
                 return e instanceof UglifyJS.JS_Parse_Error
-                    && /^Invalid character code: /.test(e.message);
-            });
+                    && /^Invalid escape sequence: \\u{1/.test(e.message);
+            }, test);
         });
     });
 });

test/mocha/templates.js

@@ -0,0 +1,67 @@
+var assert = require("assert");
+var run_code = require("../sandbox").run_code;
+var semver = require("semver");
+var UglifyJS = require("../node");
+
+describe("Template literals", function() {
+    it("Should reject invalid literal", function() {
+        [
+            "`foo\\`",
+            "`foo${bar`",
+            "`foo${bar}",
+        ].forEach(function(input) {
+            assert.throws(function() {
+                UglifyJS.parse(input);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error
+                    && e.message === "Unterminated template literal";
+            }, input);
+        });
+    });
+    it("Should reject invalid expression", function() {
+        [
+            "`foo${bar;}`",
+            "`foo${42bar}`",
+        ].forEach(function(input) {
+            assert.throws(function() {
+                UglifyJS.parse(input);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, input);
+        });
+    });
+    it("Should process line-break characters correctly", function() {
+        [
+            // native line breaks
+            [ "`foo\nbar`", "`foo\nbar`" ],
+            [ "`foo\rbar`", "`foo\rbar`" ],
+            [ "`foo\r\nbar`", "`foo\nbar`" ],
+            [ "`foo\r\n\rbar`", "`foo\n\rbar`" ],
+            // escaped line breaks
+            [ "`foo\\nbar`", "`foo\\nbar`" ],
+            [ "`foo\\rbar`", "`foo\\rbar`" ],
+            [ "`foo\r\\nbar`", "`foo\r\\nbar`" ],
+            [ "`foo\\r\nbar`", "`foo\\r\nbar`" ],
+            [ "`foo\\r\\nbar`", "`foo\\r\\nbar`" ],
+            // continuation
+            [ "`foo\\\nbar`", "`foo\\\nbar`" ],
+            [ "`foo\\\rbar`", "`foo\\\rbar`" ],
+            [ "`foo\\\r\nbar`", "`foo\\\nbar`" ],
+            [ "`foo\\\r\n\rbar`", "`foo\\\n\rbar`" ],
+            [ "`foo\\\\nbar`", "`foo\\\\nbar`" ],
+            [ "`foo\\\\rbar`", "`foo\\\\rbar`" ],
+            [ "`foo\\\\r\nbar`", "`foo\\\\r\nbar`" ],
+        ].forEach(function(test) {
+            var input = "console.log(" + test[0] + ");";
+            var result = UglifyJS.minify(input, {
+                compress: false,
+                mangle: false,
+            });
+            if (result.error) throw result.error;
+            var expected = "console.log(" + test[1] + ");";
+            assert.strictEqual(result.code, expected, test[0]);
+            if (semver.satisfies(process.version, "<4")) return;
+            assert.strictEqual(run_code(result.code), run_code(input), test[0]);
+        });
+    });
+});

test/mocha/yields.js

@@ -0,0 +1,82 @@
+var assert = require("assert");
+var UglifyJS = require("../node");
+
+describe("generator", function() {
+    it("Should reject `yield` as symbol name within generator functions only", function() {
+        [
+            "function yield() {}",
+            "function(yield) {}",
+            "function() { yield:{} }",
+            "function() { var yield; }",
+            "function() { function yield() {} }",
+            "function() { try {} catch (yield) {} }",
+        ].forEach(function(code) {
+            var ast = UglifyJS.parse("(" + code + ")();");
+            assert.strictEqual(ast.TYPE, "Toplevel");
+            assert.strictEqual(ast.body.length, 1);
+            assert.strictEqual(ast.body[0].TYPE, "SimpleStatement");
+            assert.strictEqual(ast.body[0].body.TYPE, "Call");
+            assert.strictEqual(ast.body[0].body.expression.TYPE, "Function");
+            assert.throws(function() {
+                UglifyJS.parse("(" + code.replace(/^function/, "function*") + ")();");
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
+    it("Should reject `yield` expression outside of generator functions", function() {
+        [
+            "yield 42;",
+            "function f() { yield 42; }",
+            "function* f() { function g() { yield 42; } }",
+        ].forEach(function(code) {
+            assert.throws(function() {
+                UglifyJS.parse(code);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
+    it("Should reject `yield` expression directly on computed key of function argument", function() {
+        [
+            "function f({ [yield 42]: a }) {}",
+            "function* f({ [yield 42]: a }) {}",
+        ].forEach(function(code) {
+            assert.throws(function() {
+                UglifyJS.parse(code);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
+    it("Should accept `yield` expression nested within computed key of function argument", function() {
+        [
+            "function f({ [function*() { yield 42; }()]: a }) {}",
+            "function* f({ [function*() { yield 42; }()]: a }) {}",
+        ].forEach(function(code) {
+            var ast = UglifyJS.parse(code);
+            assert.strictEqual(ast.TYPE, "Toplevel");
+            assert.strictEqual(ast.body.length, 1);
+            assert.strictEqual(ast.body[0].argnames.length, 1);
+            assert.strictEqual(ast.body[0].argnames[0].TYPE, "DestructuredObject");
+        });
+    });
+    it("Should reject `yield*` without an expression", function() {
+        [
+            "yield*",
+            "yield*;",
+            "yield*,",
+            "(yield*)",
+            "[ yield* ]",
+            "42[yield*]",
+            "yield* && 42",
+        ].forEach(function(code) {
+            code = "function* f() { " + code + " }";
+            assert.throws(function() {
+                UglifyJS.parse(code);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
+});

test/reduce.js

@@ -70,8 +70,8 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
     } else if (differs.error) {
         differs.warnings = warnings;
         return differs;
-    } else if (is_error(differs.unminified_result)
-        && is_error(differs.minified_result)
+    } else if (sandbox.is_error(differs.unminified_result)
+        && sandbox.is_error(differs.minified_result)
         && differs.unminified_result.name == differs.minified_result.name) {
         return {
             code: [
@@ -131,10 +131,11 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
               case "delete":
                 return;
             }
+            if (parent instanceof U.AST_VarDef && parent.name === node) return;
             // preserve for (var xxx; ...)
             if (parent instanceof U.AST_For && parent.init === node && node instanceof U.AST_Definitions) return node;
-            // preserve for (xxx in ...)
-            if (parent instanceof U.AST_ForIn && parent.init === node) return node;
+            // preserve for (xxx in/of ...)
+            if (parent instanceof U.AST_ForEnumeration && parent.init === node) return node;
 
             // node specific permutations with no parent logic
 
@@ -299,10 +300,10 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 node.start._permute += step;
                 if (expr && (expr !== node.body || !has_loopcontrol(expr, node, parent))) {
                     CHANGED = true;
-                    return to_statement(expr);
+                    return to_statement_init(expr);
                 }
             }
-            else if (node instanceof U.AST_ForIn) {
+            else if (node instanceof U.AST_ForEnumeration) {
                 var expr;
                 switch ((node.start._permute * steps | 0) % 3) {
                   case 0:
@@ -321,7 +322,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 node.start._permute += step;
                 if (expr) {
                     CHANGED = true;
-                    return to_statement(expr);
+                    return to_statement_init(expr);
                 }
             }
             else if (node instanceof U.AST_If) {
@@ -558,8 +559,8 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                         log(code);
                         log(diff.error.stack);
                         log("*** Discarding permutation and continuing.");
-                    } else if (is_error(diff.unminified_result)
-                        && is_error(diff.minified_result)
+                    } else if (sandbox.is_error(diff.unminified_result)
+                        && sandbox.is_error(diff.minified_result)
                         && diff.unminified_result.name == diff.minified_result.name) {
                         // ignore difference in error messages caused by minification
                         diff_error_message = testcase;
@@ -600,10 +601,10 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
         }
         var lines = [ "" ];
         if (isNaN(max_timeout)) {
-            lines.push("// minify error: " + to_comment(strip_color_codes(differs.minified_result.stack)));
+            lines.push("// minify error: " + to_comment(differs.minified_result.stack));
         } else {
-            var unminified_result = strip_color_codes(differs.unminified_result);
-            var minified_result = strip_color_codes(differs.minified_result);
+            var unminified_result = differs.unminified_result;
+            var minified_result = differs.minified_result;
             if (trim_trailing_whitespace(unminified_result) == trim_trailing_whitespace(minified_result)) {
                 lines.push(
                     "// (stringified)",
@@ -624,10 +625,6 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
     }
 };
 
-function strip_color_codes(value) {
-    return ("" + value).replace(/\u001b\[\d+m/g, "");
-}
-
 function to_comment(value) {
     return ("" + value).replace(/\n/g, "\n// ");
 }
@@ -665,20 +662,12 @@ function has_loopcontrol(body, loop, label) {
     return found;
 }
 
-function is_error(result) {
-    return result && typeof result.name == "string" && typeof result.message == "string";
-}
-
 function is_timed_out(result) {
-    return is_error(result) && /timed out/.test(result.message);
+    return sandbox.is_error(result) && /timed out/.test(result.message);
 }
 
 function is_statement(node) {
-    return node instanceof U.AST_Statement
-        && !(node instanceof U.AST_Arrow
-            || node instanceof U.AST_AsyncArrow
-            || node instanceof U.AST_AsyncFunction
-            || node instanceof U.AST_Function);
+    return node instanceof U.AST_Statement && !(node instanceof U.AST_LambdaExpression);
 }
 
 function merge_sequence(array, node) {
@@ -706,6 +695,13 @@ function to_statement(node) {
     });
 }
 
+function to_statement_init(node) {
+    return node instanceof U.AST_Const || node instanceof U.AST_Let ? new U.AST_BlockStatement({
+        body: [ node ],
+        start: {},
+    }) : to_statement(node);;
+}
+
 function wrap_with_console_log(node) {
     // wrap with console.log()
     return new U.AST_Call({

test/sandbox.js

@@ -1,103 +1,39 @@
+var readFileSync = require("fs").readFileSync;
 var semver = require("semver");
+var spawnSync = require("child_process").spawnSync;
 var vm = require("vm");
 
-var setupContext = new vm.Script([
-    "[ Array, Boolean, Error, Function, Number, Object, RegExp, String ].forEach(function(f) {",
-    "    f.toString = Function.prototype.toString;",
-    "});",
-    "Function.prototype.toString = function() {",
-    "    var id = 100000;",
-    "    return function() {",
-    "        var n = this.name;",
-    "        if (!/^F[0-9]{6}N$/.test(n)) {",
-    '            n = "F" + ++id + "N";',
-].concat(Object.getOwnPropertyDescriptor(Function.prototype, "name").configurable ? [
-    '            Object.defineProperty(this, "name", {',
-    "                get: function() {",
-    "                    return n;",
-    "                }",
-    "            });",
-] : [], [
-    "        }",
-    '        return "function(){}";',
-    "    };",
-    "}();",
-    "this;",
-]).join("\n"));
-
-function createContext() {
-    var ctx = vm.createContext(Object.defineProperties({}, {
-        console: { value: { log: log } },
-        global: { get: self },
-        self: { get: self },
-        window: { get: self },
-    }));
-    var global = setupContext.runInContext(ctx);
-    return ctx;
-
-    function self() {
-        return this;
-    }
-
-    function safe_log(arg, level) {
-        if (arg) switch (typeof arg) {
-          case "function":
-            return arg.toString();
-          case "object":
-            if (arg === global) return "[object global]";
-            if (/Error$/.test(arg.name)) return arg.toString();
-            if (typeof arg.then == "function") return "[object Promise]";
-            arg.constructor.toString();
-            if (level--) for (var key in arg) {
-                var desc = Object.getOwnPropertyDescriptor(arg, key);
-                if (!desc || !desc.get && !desc.set) arg[key] = safe_log(arg[key], level);
-            }
-        }
-        return arg;
-    }
-
-    function log(msg) {
-        if (arguments.length == 1 && typeof msg == "string") return console.log("%s", msg);
-        return console.log.apply(console, [].map.call(arguments, function(arg) {
-            return safe_log(arg, 3);
-        }));
-    }
-}
-
-function run_code(code, toplevel, timeout) {
-    timeout = timeout || 5000;
-    var stdout = "";
-    var original_write = process.stdout.write;
-    process.stdout.write = function(chunk) {
-        stdout += chunk;
-    };
-    try {
-        vm.runInContext(toplevel ? "(function(){" + code + "})()" : code, createContext(), { timeout: timeout });
-        return stdout;
-    } catch (ex) {
-        return ex;
-    } finally {
-        process.stdout.write = original_write;
-    }
-}
-
+setup_log();
+var setup_code = "(" + setup + ")(" + [
+    "this",
+    find_builtins(),
+    setup_log,
+    "function(process) {" + readFileSync(require.resolve("../tools/tty", "utf8")) + "}",
+].join(",\n") + ");\n";
+exports.has_toplevel = function(options) {
+    return options.toplevel
+        || options.mangle && options.mangle.toplevel
+        || options.compress && options.compress.toplevel;
+};
+exports.is_error = is_error;
 exports.run_code = semver.satisfies(process.version, "0.8") ? function(code, toplevel, timeout) {
-    var stdout = run_code(code, toplevel, timeout);
+    var stdout = run_code_vm(code, toplevel, timeout);
     if (typeof stdout != "string" || !/arguments/.test(code)) return stdout;
     do {
         var prev = stdout;
-        stdout = run_code(code, toplevel, timeout);
+        stdout = run_code_vm(code, toplevel, timeout);
     } while (prev !== stdout);
     return stdout;
-} : run_code;
-
-function strip_func_ids(text) {
-    return ("" + text).replace(/F[0-9]{6}N/g, "<F<>N>");
-}
-
+} : semver.satisfies(process.version, "<0.12") ? run_code_vm : function(code, toplevel, timeout) {
+    if (/\basync([ \t]+[^\s()[\]{},.&|!~=*%/+-]+|[ \t]*\([\s\S]*?\))[ \t]*=>|\b(async[ \t]+function|setInterval|setTimeout)\b/.test(code)) {
+        return run_code_exec(code, toplevel, timeout);
+    } else {
+        return run_code_vm(code, toplevel, timeout);
+    }
+};
 exports.same_stdout = semver.satisfies(process.version, "0.12") ? function(expected, actual) {
     if (typeof expected != typeof actual) return false;
-    if (typeof expected == "object" && typeof expected.name == "string" && typeof expected.message == "string") {
+    if (is_error(expected)) {
         if (expected.name !== actual.name) return false;
         if (typeof actual.message != "string") return false;
         expected = expected.message.slice(expected.message.lastIndexOf("\n") + 1);
@@ -107,8 +43,228 @@ exports.same_stdout = semver.satisfies(process.version, "0.12") ? function(expec
 } : function(expected, actual) {
     return typeof expected == typeof actual && strip_func_ids(expected) == strip_func_ids(actual);
 };
-exports.has_toplevel = function(options) {
-    return options.toplevel
-        || options.mangle && options.mangle.toplevel
-        || options.compress && options.compress.toplevel;
-};
+
+function is_error(result) {
+    return result && typeof result.name == "string" && typeof result.message == "string";
+}
+
+function strip_color_codes(value) {
+    return value.replace(/\u001b\[\d+m/g, "");
+}
+
+function strip_func_ids(text) {
+    return ("" + text).replace(/F[0-9]{6}N/g, "<F<>N>");
+}
+
+function setup_log() {
+    var inspect = require("util").inspect;
+    if (inspect.defaultOptions) {
+        var log_options = {
+            breakLength: Infinity,
+            colors: false,
+            compact: true,
+            customInspect: false,
+            depth: Infinity,
+            maxArrayLength: Infinity,
+            maxStringLength: Infinity,
+            showHidden: false,
+        };
+        for (var name in log_options) {
+            if (name in inspect.defaultOptions) inspect.defaultOptions[name] = log_options[name];
+        }
+    }
+    return inspect;
+}
+
+function find_builtins() {
+    setup_code = "console.log(Object.keys(this));";
+    var builtins = run_code_vm("");
+    if (semver.satisfies(process.version, ">=0.12")) builtins += ".concat(" + run_code_exec("") + ")";
+    return builtins;
+}
+
+function setup(global, builtins, setup_log, setup_tty) {
+    [ Array, Boolean, Error, Function, Number, Object, RegExp, String ].forEach(function(f) {
+        f.toString = Function.prototype.toString;
+    });
+    Function.prototype.toString = function() {
+        var configurable = Object.getOwnPropertyDescriptor(Function.prototype, "name").configurable;
+        var id = 100000;
+        return function() {
+            var n = this.name;
+            if (!/^F[0-9]{6}N$/.test(n)) {
+                n = "F" + ++id + "N";
+                if (configurable) Object.defineProperty(this, "name", {
+                    get: function() {
+                        return n;
+                    }
+                });
+            }
+            return "function(){}";
+        };
+    }();
+    var process = global.process;
+    if (process) {
+        setup_tty(process);
+        var inspect = setup_log();
+        process.on("uncaughtException", function(ex) {
+            var value = ex;
+            if (value instanceof Error) {
+                value = {};
+                for (var name in ex) {
+                    value[name] = ex[name];
+                    delete ex[name];
+                }
+            }
+            process.stderr.write(inspect(value) + "\n\n-----===== UNCAUGHT EXCEPTION =====-----\n\n");
+            throw ex;
+        }).on("unhandledRejection", function() {});
+    }
+    var log = console.log;
+    var safe_console = {
+        log: function(msg) {
+            if (arguments.length == 1 && typeof msg == "string") return log("%s", msg);
+            return log.apply(null, [].map.call(arguments, function(arg) {
+                return safe_log(arg, {
+                    level: 5,
+                    original: [],
+                    replaced: [],
+                });
+            }));
+        },
+    };
+    var props = {
+        // for Node.js v8
+        console: {
+            get: function() {
+                return safe_console;
+            },
+        },
+        global: { get: self },
+        self: { get: self },
+        window: { get: self },
+    };
+    [
+        // for Node.js v0.12
+        "Buffer",
+        "clearInterval",
+        "clearTimeout",
+        // for Node.js v0.12
+        "DTRACE_NET_STREAM_END",
+        // for Node.js v8
+        "process",
+        "setInterval",
+        "setTimeout",
+    ].forEach(function(name) {
+        var value = global[name];
+        props[name] = {
+            get: function() {
+                return value;
+            },
+        };
+    });
+    builtins.forEach(function(name) {
+        try {
+            delete global[name];
+        } catch (e) {}
+    });
+    Object.defineProperties(global, props);
+    // for Node.js v8+
+    global.toString = function() {
+        return "[object global]";
+    };
+
+    function self() {
+        return this;
+    }
+
+    function safe_log(arg, cache) {
+        if (arg) switch (typeof arg) {
+          case "function":
+            return arg.toString();
+          case "object":
+            if (arg === global) return "[object global]";
+            if (/Error$/.test(arg.name)) return arg.toString();
+            if (typeof arg.then == "function") return "[object Promise]";
+            arg.constructor.toString();
+            var index = cache.original.indexOf(arg);
+            if (index >= 0) return cache.replaced[index];
+            if (--cache.level < 0) return "[object Object]";
+            var value = {};
+            cache.original.push(arg);
+            cache.replaced.push(value);
+            for (var key in arg) {
+                var desc = Object.getOwnPropertyDescriptor(arg, key);
+                if (desc && (desc.get || desc.set)) {
+                    Object.defineProperty(value, key, desc);
+                } else {
+                    value[key] = safe_log(arg[key], cache);
+                }
+            }
+            return value;
+        }
+        return arg;
+    }
+}
+
+function run_code_vm(code, toplevel, timeout) {
+    timeout = timeout || 5000;
+    var stdout = "";
+    var original_write = process.stdout.write;
+    process.stdout.write = function(chunk) {
+        stdout += chunk;
+    };
+    try {
+        var ctx = vm.createContext({ console: console });
+        // for Node.js v6
+        vm.runInContext(setup_code, ctx);
+        vm.runInContext(toplevel ? "(function(){" + code + "})();" : code, ctx, { timeout: timeout });
+        return strip_color_codes(stdout);
+    } catch (ex) {
+        return ex;
+    } finally {
+        process.stdout.write = original_write;
+    }
+}
+
+function run_code_exec(code, toplevel, timeout) {
+    if (toplevel) {
+        code = setup_code + "(function(){" + code + "})();";
+    } else {
+        code = code.replace(/^((["'])[^"']*\2(;|$))?/, function(directive) {
+            return directive + setup_code;
+        });
+    }
+    var result = spawnSync(process.argv[0], [ '--max-old-space-size=2048' ], {
+        encoding: "utf8",
+        input: code,
+        stdio: "pipe",
+        timeout: timeout || 5000,
+    });
+    if (result.status === 0) return result.stdout;
+    if (result.error && result.error.code == "ETIMEDOUT" || /FATAL ERROR:/.test(msg)) {
+        return new Error("Script execution timed out.");
+    }
+    if (result.error) return result.error;
+    var msg = result.stderr.replace(/\r\n/g, "\n");
+    var end = msg.indexOf("\n\n-----===== UNCAUGHT EXCEPTION =====-----\n\n");
+    var details;
+    if (end >= 0) {
+        details = msg.slice(0, end).replace(/<([1-9][0-9]*) empty items?>/g, function(match, count) {
+            return new Array(+count).join();
+        });
+        try {
+            details = vm.runInNewContext("(" + details + ")");
+        } catch (e) {}
+    }
+    var match = /\n([^:\s]*Error)(?:: ([\s\S]+?))?\n(    at [\s\S]+)\n$/.exec(msg);
+    if (!match) return details;
+    var ex = new global[match[1]](match[2]);
+    ex.stack = ex.stack.slice(0, ex.stack.indexOf("    at ")) + match[3];
+    if (typeof details == "object") {
+        for (var name in details) ex[name] = details[name];
+    } else if (end >= 0) {
+        ex.details = details;
+    }
+    return ex;
+}

test/ufuzz/actions.js

@@ -10,16 +10,17 @@ exports.init = function(url, auth, num) {
 exports.should_stop = function(callback) {
     read(base + "/actions/runs?per_page=100", function(reply) {
         if (!reply || !Array.isArray(reply.workflow_runs)) return;
-        var runs = reply.workflow_runs.filter(function(workflow) {
-            return workflow.status != "completed";
-        }).sort(function(a, b) {
+        var runs = reply.workflow_runs.sort(function(a, b) {
             return b.run_number - a.run_number;
         });
         var found = false, remaining = 20;
         (function next() {
-            if (!runs.length) return;
-            var workflow = runs.pop();
-            if (workflow.event == "schedule" && workflow.run_number == run_number) found = true;
+            var workflow;
+            do {
+                workflow = runs.pop();
+                if (!workflow) return;
+                if (workflow.event == "schedule" && workflow.run_number == run_number) found = true;
+            } while (!found && workflow.status == "completed");
             read(workflow.jobs_url, function(reply) {
                 if (!reply || !Array.isArray(reply.jobs)) return;
                 if (!reply.jobs.every(function(job) {

test/ufuzz/index.js

@@ -27,7 +27,7 @@ var STMT_IF_ELSE = STMT_("ifelse");
 var STMT_DO_WHILE = STMT_("dowhile");
 var STMT_WHILE = STMT_("while");
 var STMT_FOR_LOOP = STMT_("forloop");
-var STMT_FOR_IN = STMT_("forin");
+var STMT_FOR_ENUM = STMT_("forenum");
 var STMT_SEMI = STMT_("semi");
 var STMT_EXPR = STMT_("expr");
 var STMT_SWITCH = STMT_("switch");
@@ -134,16 +134,23 @@ var SUPPORT = function(matrix) {
 }({
     arrow: "a => 0;",
     async: "async function f(){}",
+    async_generator: "async function* f(){}",
+    bigint: "42n",
     catch_omit_var: "try {} catch {}",
     computed_key: "({[0]: 0});",
     const_block: "var a; { const a = 0; }",
     default_value: "[ a = 0 ] = [];",
     destructuring: "[] = [];",
+    exponentiation: "0 ** 0",
+    for_await_of: "async function f(a) { for await (a of []); }",
+    for_of: "for (var a of []);",
+    generator: "function* f(){}",
     let: "let a;",
     rest: "var [...a] = [];",
     rest_object: "var {...a} = {};",
     spread: "[...[]];",
     spread_object: "({...0});",
+    template: "``",
     trailing_comma: "function f(a,) {}",
 });
 
@@ -167,7 +174,7 @@ var VALUES = [
     "4",
     "5",
     "22",
-    "-0", // 0/-0 !== 0
+    "(-0)", // 0/-0 !== 0
     "23..toString()",
     "24 .toString()",
     "25. ",
@@ -188,6 +195,12 @@ var VALUES = [
     '"function"',
     "this",
 ];
+if (SUPPORT.bigint) VALUES = VALUES.concat([
+    "(!0o644n)",
+    "([3n][0] > 2)",
+    "(-42n).toString()",
+    "Number(0XDEADn << 16n | 0xbeefn)",
+]);
 
 var BINARY_OPS = [
     " + ", // spaces needed to disambiguate with ++ cases (could otherwise cause syntax errors)
@@ -217,6 +230,7 @@ var BINARY_OPS = [
 BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
 BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
 BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
+if (SUPPORT.exponentiation) BINARY_OPS.push("**");
 BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
 BINARY_OPS = BINARY_OPS.concat(BINARY_OPS);
 BINARY_OPS.push(" in ");
@@ -317,10 +331,9 @@ var VAR_NAMES = [
     "NaN",
     "Infinity",
     "arguments",
-    "Math",
-    "parseInt",
     "async",
     "await",
+    "yield",
 ];
 var INITIAL_NAMES_LEN = VAR_NAMES.length;
 
@@ -341,6 +354,7 @@ var avoid_vars = [];
 var block_vars = [];
 var unique_vars = [];
 var async = false;
+var generator = false;
 var loops = 0;
 var funcs = 0;
 var called = Object.create(null);
@@ -360,6 +374,7 @@ function createTopLevelCode() {
     block_vars.length = 0;
     unique_vars.length = 0;
     async = false;
+    generator = false;
     loops = 0;
     funcs = 0;
     called = Object.create(null);
@@ -387,9 +402,11 @@ function addTrailingComma(list) {
     return SUPPORT.trailing_comma && list && rng(20) == 0 ? list + "," : list;
 }
 
-function createParams(was_async, noDuplicate) {
+function createParams(was_async, was_generator, noDuplicate) {
     var save_async = async;
     if (was_async) async = true;
+    var save_generator = generator;
+    if (was_generator) generator = true;
     var len = unique_vars.length;
     var params = [];
     for (var n = rng(4); --n >= 0;) {
@@ -398,12 +415,14 @@ function createParams(was_async, noDuplicate) {
         params.push(name);
     }
     unique_vars.length = len;
+    generator = save_generator;
     async = save_async;
     return addTrailingComma(params.join(", "));
 }
 
-function createArgs(recurmax, stmtDepth, canThrow) {
+function createArgs(recurmax, stmtDepth, canThrow, noTemplate) {
     recurmax--;
+    if (SUPPORT.template && !noTemplate && rng(20) == 0) return createTemplateLiteral(recurmax, stmtDepth, canThrow);
     var args = [];
     for (var n = rng(4); --n >= 0;) switch (SUPPORT.spread ? rng(50) : 3) {
       case 0:
@@ -422,10 +441,10 @@ function createArgs(recurmax, stmtDepth, canThrow) {
         args.push(rng(2) ? createValue() : createExpression(recurmax, NO_COMMA, stmtDepth, canThrow));
         break;
     }
-    return addTrailingComma(args.join(", "));
+    return "(" + addTrailingComma(args.join(", ")) + ")";
 }
 
-function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was_async) {
+function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was_async, was_generator) {
     var avoid = [];
     var len = unique_vars.length;
     var pairs = createPairs(recurmax, !nameLenBefore);
@@ -433,6 +452,22 @@ function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was
     unique_vars.length = len;
     return pairs;
 
+    function mapShuffled(values, fn) {
+        var declare_only = [];
+        var side_effects = [];
+        values.forEach(function(value, index) {
+            value = fn(value, index);
+            if (/]:|=/.test(value) ? canThrow && rng(10) == 0 : rng(5)) {
+                declare_only.splice(rng(declare_only.length + 1), 0, value);
+            } else if (canThrow && rng(5) == 0) {
+                side_effects.splice(rng(side_effects.length + 1), 0, value);
+            } else {
+                side_effects.push(value);
+            }
+        });
+        return declare_only.concat(side_effects);
+    }
+
     function convertToRest(names) {
         var last = names.length - 1;
         if (last >= 0 && SUPPORT.rest && rng(20) == 0) {
@@ -451,9 +486,18 @@ function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was
             async = false;
             if (save_async || was_async) addAvoidVar("await");
         }
+        var save_generator = generator;
+        if (was_generator != null) {
+            generator = false;
+            if (save_generator || was_generator) addAvoidVar("yield");
+        }
         avoid.forEach(addAvoidVar);
         var save_vars = nameLenBefore && VAR_NAMES.splice(nameLenBefore);
         if (nameFn) nameFn();
+        if (was_generator != null) {
+            generator = was_generator;
+            if (save_generator || was_generator) removeAvoidVar("yield");
+        }
         if (was_async != null) {
             async = was_async;
             if (save_async || was_async) removeAvoidVar("await");
@@ -461,6 +505,7 @@ function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was
         if (valueFn) valueFn();
         if (save_vars) [].push.apply(VAR_NAMES, save_vars);
         avoid.forEach(removeAvoidVar);
+        generator = save_generator;
         async = save_async;
     }
 
@@ -484,7 +529,10 @@ function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was
         unique_vars.push("a", "b", "c", "undefined", "NaN", "Infinity");
         var save_async = async;
         if (was_async) async = true;
+        var save_generator = generator;
+        if (was_generator) generator = true;
         var name = createVarName(MANDATORY);
+        generator = save_generator;
         async = save_async;
         unique_vars.length -= 6;
         avoid.push(name);
@@ -563,19 +611,24 @@ function createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, was
                     }
                 });
                 fill(function() {
-                    var last = pairs.names.length - 1, has_rest = false;
-                    var s = pairs.names.map(function(name, index) {
+                    var last = pairs.names.length - 1, rest;
+                    if (last >= 0 && !(last in keys) && SUPPORT.rest_object && rng(20) == 0) {
+                        rest = pairs.names.pop();
+                        if (!/=/.test(rest)) rest = "..." + rest;
+                    }
+                    var s = mapShuffled(pairs.names, function(name, index) {
                         if (index in keys) return keys[index] + ": " + name;
-                        if (index == last && SUPPORT.rest_object && rng(20) == 0 && name.indexOf("=") < 0) {
-                            has_rest = true;
-                            return "..." + name;
-                        }
                         return rng(10) == 0 ? name : createKey(recurmax, keys) + ": " + name;
-                    }).join(", ");
-                    if (!has_rest) s = addTrailingComma(s);
+                    });
+                    if (rest) {
+                        s.push(rest);
+                        s = s.join(", ");
+                    } else {
+                        s = addTrailingComma(s.join(", "));
+                    }
                     names.unshift("{ " + s + " }" + createDefaultValue(recurmax, noDefault));
                 }, function() {
-                    values.unshift("{ " + addTrailingComma(pairs.values.map(function(value, index) {
+                    values.unshift("{ " + addTrailingComma(mapShuffled(pairs.values, function(value, index) {
                         var key = index in keys ? keys[index] : createKey(recurmax, keys);
                         return key + ": " + value;
                     }).join(", ")) + " }");
@@ -677,7 +730,25 @@ function mayCreateBlockVariables(recurmax, stmtDepth, canThrow, fn) {
 }
 
 function makeFunction(name) {
-    return (async ? "async function " : "function ") + name;
+    if (generator) {
+        name = "function* " + name;
+    } else {
+        name = "function " + name;
+    }
+    if (async) name = "async " + name;
+    return name;
+}
+
+function invokeGenerator(was_generator) {
+    if (generator && !was_generator) switch (rng(4)) {
+      case 0:
+        return ".next()";
+      case 1:
+        return ".next().done";
+      case 2:
+        return ".next().value";
+    }
+    return "";
 }
 
 function createFunction(recurmax, allowDefun, canThrow, stmtDepth) {
@@ -688,6 +759,15 @@ function createFunction(recurmax, allowDefun, canThrow, stmtDepth) {
     var nameLenBefore = VAR_NAMES.length;
     var save_async = async;
     async = SUPPORT.async && rng(50) == 0;
+    var save_generator = generator;
+    generator = SUPPORT.generator && rng(50) == 0;
+    if (async && generator && !SUPPORT.async_generator) {
+        if (rng(2)) {
+            async = false;
+        } else {
+            generator = false;
+        }
+    }
     createBlockVariables(recurmax, stmtDepth, canThrow, function(defns) {
         if (allowDefun || rng(5) > 0) {
             name = "f" + funcs++;
@@ -699,12 +779,12 @@ function createFunction(recurmax, allowDefun, canThrow, stmtDepth) {
         var params;
         if (SUPPORT.destructuring && (!allowDefun || !(name in called)) && rng(2)) {
             called[name] = false;
-            var pairs = createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, save_async);
+            var pairs = createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, save_async, save_generator);
             params = pairs.names.join(", ");
             if (!pairs.has_rest) params = addTrailingComma(params);
-            args = addTrailingComma(pairs.values.join(", "));
+            args = "(" + addTrailingComma(pairs.values.join(", ")) + ")";
         } else {
-            params = createParams(save_async);
+            params = createParams(save_async, save_generator);
         }
         s.push(makeFunction(name) + "(" + params + "){", strictMode());
         s.push(defns());
@@ -718,16 +798,20 @@ function createFunction(recurmax, allowDefun, canThrow, stmtDepth) {
         s.push("}", "");
         s = filterDirective(s).join("\n");
     });
+    var call_next = invokeGenerator(save_generator);
+    generator = save_generator;
     async = save_async;
     VAR_NAMES.length = nameLenBefore;
 
     if (!allowDefun) {
         // avoid "function statements" (decl inside statements)
         s = "var " + createVarName(MANDATORY) + " = " + s;
-        s += "(" + (args || createArgs(recurmax, stmtDepth, canThrow)) + ")";
+        s += args || createArgs(recurmax, stmtDepth, canThrow);
+        s += call_next;
     } else if (!(name in called) || args || rng(3)) {
         s += "var " + createVarName(MANDATORY) + " = " + name;
-        s += "(" + (args || createArgs(recurmax, stmtDepth, canThrow)) + ")";
+        s += args || createArgs(recurmax, stmtDepth, canThrow);
+        s += call_next;
     }
 
     return s + ";";
@@ -820,21 +904,58 @@ function createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn
         canBreak = label.break || enableLoopControl(canBreak, CAN_BREAK);
         canContinue = label.continue || enableLoopControl(canContinue, CAN_CONTINUE);
         return label.target + "for (var brake" + loop + " = 5; " + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + " && brake" + loop + " > 0; --brake" + loop + ")" + createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn, stmtDepth);
-      case STMT_FOR_IN:
+      case STMT_FOR_ENUM:
         var label = createLabel(canBreak, canContinue);
         canBreak = label.break || enableLoopControl(canBreak, CAN_BREAK);
         canContinue = label.continue || enableLoopControl(canContinue, CAN_CONTINUE);
         var key = rng(10) ? "key" + loop : getVarName(NO_CONST);
-        return [
-            "{var expr" + loop + " = " + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + "; ",
-            label.target + " for (",
-            !/^key/.test(key) ? rng(10) ? "" : "var " : !SUPPORT.let || rng(10) ? "var " : rng(2) ? "let " : "const ",
-            !SUPPORT.destructuring || rng(10) ? key : rng(5) ? "[ " + key + " ]" : "{ length: " + key + " }",
-            " in expr" + loop + ") {",
-            rng(5) > 1 ? "c = 1 + c; var " + createVarName(MANDATORY) + " = expr" + loop + "[" + key + "]; " : "",
-            createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn, stmtDepth),
-            "}}",
-        ].join("");
+        var of = SUPPORT.for_of && rng(20) == 0;
+        var init = "";
+        if (!/^key/.test(key)) {
+            if (!(of && bug_for_of_var) && rng(10) == 0) init = "var ";
+        } else if (!SUPPORT.let || !(of && bug_for_of_var) && rng(10)) {
+            init = "var ";
+        } else if (rng(2)) {
+            init = "let ";
+        } else {
+            init = "const ";
+        }
+        if (!SUPPORT.destructuring || of && !(canThrow && rng(10) == 0) || rng(10)) {
+            init += key;
+        } else if (rng(5)) {
+            init += "[ " + key + " ]";
+        } else {
+            init += "{ length: " + key + " }";
+        }
+        var s = "var expr" + loop + " = ";
+        if (of) {
+            var await = SUPPORT.for_await_of && async && rng(20) == 0;
+            if (SUPPORT.generator && rng(20) == 0) {
+                var gen = getVarName();
+                if (canThrow && rng(10) == 0) {
+                    s += gen + "; ";
+                } else {
+                    s += gen + " && typeof " + gen + "[Symbol.";
+                    s += await ? "asyncIterator" : "iterator";
+                    s += '] == "function" ? ' + gen + " : " + createArrayLiteral(recurmax, stmtDepth, canThrow) + "; ";
+                }
+            } else if (rng(5)) {
+                s += createArrayLiteral(recurmax, stmtDepth, canThrow) + "; ";
+            } else if (canThrow && rng(10) == 0) {
+                s += createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + "; ";
+            } else {
+                s += '"" + (' + createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + "); ";
+            }
+            s += label.target + " for ";
+            if (await) s += "await ";
+            s += "(" + init + " of expr" + loop + ") {";
+        } else {
+            s += createExpression(recurmax, COMMA_OK, stmtDepth, canThrow) + "; ";
+            s += label.target + " for (" + init + " in expr" + loop + ") {";
+        }
+        if (rng(3)) s += "c = 1 + c; var " + createVarName(MANDATORY) + " = expr" + loop + "[" + key + "]; ";
+        s += createStatement(recurmax, canThrow, canBreak, canContinue, cannotReturn, stmtDepth) + "}";
+        return "{" + s + "}";
       case STMT_SEMI:
         return use_strict && rng(20) === 0 ? '"use strict";' : ";";
       case STMT_EXPR:
@@ -989,7 +1110,9 @@ function createExpression(recurmax, noComma, stmtDepth, canThrow) {
         return "((c = c + 1) + (" + _createExpression(recurmax, noComma, stmtDepth, canThrow) + "))"; // c only gets incremented
       default:
         var expr = "(" + _createExpression(recurmax, noComma, stmtDepth, canThrow) + ")";
-        return async && rng(50) == 0 ? "(await" + expr + ")" : expr;
+        if (async && rng(50) == 0) return "(await" + expr + ")";
+        if (generator && rng(50) == 0) return "(yield" + (canThrow && rng(20) == 0 ? "*" : "") + expr + ")";
+        return expr;
     }
 }
 
@@ -997,6 +1120,7 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
     var p = 0;
     switch (rng(_createExpression.N)) {
       case p++:
+        if (generator && rng(50) == 0) return "yield";
       case p++:
         return createUnaryPrefix() + (rng(2) ? "a" : "b");
       case p++:
@@ -1010,6 +1134,11 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
       case p++:
         return rng(2) + " === 1 ? a : b";
       case p++:
+        if (SUPPORT.template && rng(20) == 0) {
+            var tmpl = createTemplateLiteral(recurmax, stmtDepth, canThrow);
+            if (rng(10) == 0) tmpl = "String.raw" + tmpl;
+            return tmpl;
+        }
       case p++:
         return createValue();
       case p++:
@@ -1020,9 +1149,9 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
           case 0:
             return [
                 "[ ",
-                new Array(rng(3)).join(","),
+                new Array(rng(3)).join(),
                 getVarName(NO_CONST),
-                new Array(rng(3)).join(","),
+                new Array(rng(3)).join(),
                 " ] = ",
                 createArrayLiteral(recurmax, stmtDepth, canThrow),
             ].join("");
@@ -1047,25 +1176,34 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
         var nameLenBefore = VAR_NAMES.length;
         var save_async = async;
         async = SUPPORT.async && rng(50) == 0;
+        var save_generator = generator;
+        generator = SUPPORT.generator && rng(50) == 0;
+        if (async && generator && !SUPPORT.async_generator) {
+            if (rng(2)) {
+                async = false;
+            } else {
+                generator = false;
+            }
+        }
         unique_vars.push("c");
         var name = createVarName(MAYBE); // note: this name is only accessible from _within_ the function. and immutable at that.
         unique_vars.pop();
         var s = [];
         switch (rng(5)) {
           case 0:
-            if (SUPPORT.arrow && !name && rng(2)) {
+            if (SUPPORT.arrow && !name && !generator && rng(2)) {
                 var args, suffix;
                 (rng(2) ? createBlockVariables : function() {
                     arguments[3]();
                 })(recurmax, stmtDepth, canThrow, function(defns) {
                     var params;
                     if (SUPPORT.destructuring && rng(2)) {
-                        var pairs = createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, save_async);
+                        var pairs = createAssignmentPairs(recurmax, stmtDepth, canThrow, nameLenBefore, save_async, save_generator);
                         params = pairs.names.join(", ");
                         if (!pairs.has_rest) params = addTrailingComma(params);
-                        args = addTrailingComma(pairs.values.join(", "));
+                        args = "(" + addTrailingComma(pairs.values.join(", ")) + ")";
                     } else {
-                        params = createParams(save_async, NO_DUPLICATE);
+                        params = createParams(save_async, save_generator, NO_DUPLICATE);
                     }
                     params = (async ? "async (" : "(") + params + ") => ";
                     if (defns) {
@@ -1092,17 +1230,18 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
                         suffix = ")";
                     }
                 });
+                generator = save_generator;
                 async = save_async;
                 VAR_NAMES.length = nameLenBefore;
                 if (!args && rng(2)) args = createArgs(recurmax, stmtDepth, canThrow);
-                if (args) suffix += "(" + args + ")";
+                if (args) suffix += args;
                 s.push(suffix);
             } else {
                 s.push(
                     "(" + makeFunction(name) + "(){",
                     strictMode(),
                     createStatements(rng(5) + 1, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth),
-                    rng(2) ? "})" : "})()"
+                    rng(2) ? "})" : "})()" + invokeGenerator(save_generator)
                 );
             }
             break;
@@ -1111,7 +1250,7 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
                 "+" + makeFunction(name) + "(){",
                 strictMode(),
                 createStatements(rng(5) + 1, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth),
-                "}()"
+                "}()" + invokeGenerator(save_generator)
             );
             break;
           case 2:
@@ -1119,7 +1258,7 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
                 "!" + makeFunction(name) + "(){",
                 strictMode(),
                 createStatements(rng(5) + 1, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth),
-                "}()"
+                "}()" + invokeGenerator(save_generator)
             );
             break;
           case 3:
@@ -1127,15 +1266,16 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
                 "void " + makeFunction(name) + "(){",
                 strictMode(),
                 createStatements(rng(5) + 1, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth),
-                "}()"
+                "}()" + invokeGenerator(save_generator)
             );
             break;
           default:
             async = false;
+            generator = false;
+            var instantiate = rng(4) ? "new " : "";
             createBlockVariables(recurmax, stmtDepth, canThrow, function(defns) {
-                var instantiate = rng(4) ? "new " : "";
                 s.push(
-                    instantiate + "function " + name + "(" + createParams(save_async) + "){",
+                    instantiate + "function " + name + "(" + createParams(save_async, save_generator) + "){",
                     strictMode(),
                     defns()
                 );
@@ -1145,11 +1285,13 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
                 }
                 s.push(_createStatements(rng(5) + 1, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth));
             });
+            generator = save_generator;
             async = save_async;
             VAR_NAMES.length = nameLenBefore;
-            s.push(rng(2) ? "}" : "}(" + createArgs(recurmax, stmtDepth, canThrow) + ")");
+            s.push(rng(2) ? "}" : "}" + createArgs(recurmax, stmtDepth, canThrow, instantiate));
             break;
         }
+        generator = save_generator;
         async = save_async;
         VAR_NAMES.length = nameLenBefore;
         return filterDirective(s).join("\n");
@@ -1225,7 +1367,7 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
       case p++:
         var name = getVarName();
         var s = name + "." + getDotKey();
-        s = "typeof " + s + ' == "function" && --_calls_ >= 0 && ' + s + "(" + createArgs(recurmax, stmtDepth, canThrow) + ")";
+        s = "typeof " + s + ' == "function" && --_calls_ >= 0 && ' + s + createArgs(recurmax, stmtDepth, canThrow);
         return canThrow && rng(8) == 0 ? s : name + " && " + s;
       case p++:
       case p++:
@@ -1236,7 +1378,7 @@ function _createExpression(recurmax, noComma, stmtDepth, canThrow) {
             name = rng(3) == 0 ? getVarName() : "f" + rng(funcs + 2);
         } while (name in called && !called[name]);
         called[name] = true;
-        return "typeof " + name + ' == "function" && --_calls_ >= 0 && ' + name + "(" + createArgs(recurmax, stmtDepth, canThrow) + ")";
+        return "typeof " + name + ' == "function" && --_calls_ >= 0 && ' + name + createArgs(recurmax, stmtDepth, canThrow);
     }
     _createExpression.N = p;
     return _createExpression(recurmax, noComma, stmtDepth, canThrow);
@@ -1270,9 +1412,29 @@ function createArrayLiteral(recurmax, stmtDepth, canThrow) {
     return "[" + arr.join(", ") + "]";
 }
 
+function createTemplateLiteral(recurmax, stmtDepth, canThrow) {
+    recurmax--;
+    var s = [];
+    addText();
+    for (var i = rng(6); --i >= 0;) {
+        s.push("${", createExpression(recurmax, COMMA_OK, stmtDepth, canThrow), "}");
+        addText();
+    }
+    return "`" + s.join(rng(5) ? "" : "\n") + "`";
+
+    function addText() {
+        while (rng(5) == 0) s.push([
+            " ",
+            "$",
+            "}",
+            "\\`",
+            "\\\\",
+            "tmpl",
+        ][rng(6)]);
+    }
+}
+
 var SAFE_KEYS = [
-    "length",
-    "foo",
     "a",
     "b",
     "c",
@@ -1280,7 +1442,13 @@ var SAFE_KEYS = [
     "null",
     "NaN",
     "Infinity",
+    "done",
+    "foo",
     "in",
+    "length",
+    "next",
+    "then",
+    "value",
     "var",
 ];
 var KEYS = [
@@ -1310,12 +1478,15 @@ function createObjectKey(recurmax, stmtDepth, canThrow) {
 function createObjectFunction(recurmax, stmtDepth, canThrow) {
     var nameLenBefore = VAR_NAMES.length;
     var save_async = async;
+    var save_generator = generator;
     var s;
     var name = createObjectKey(recurmax, stmtDepth, canThrow);
-    createBlockVariables(recurmax, stmtDepth, canThrow, function(defns) {
-        switch (rng(SUPPORT.computed_key ? 3 : 2)) {
-          case 0:
-            async = false;
+    var fn;
+    switch (rng(SUPPORT.computed_key ? 3 : 2)) {
+      case 0:
+        async = false;
+        generator = false;
+        fn = function(defns) {
             s = [
                 "get " + name + "(){",
                 strictMode(),
@@ -1324,13 +1495,16 @@ function createObjectFunction(recurmax, stmtDepth, canThrow) {
                 createStatement(recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth, STMT_RETURN_ETC),
                 "},",
             ];
-            break;
-          case 1:
-            var prop;
-            do {
-                prop = getDotKey();
-            } while (name == prop);
-            async = false;
+        };
+        break;
+      case 1:
+        var prop;
+        do {
+            prop = getDotKey();
+        } while (name == prop);
+        async = false;
+        generator = false;
+        fn = function(defns) {
             s = [
                 "set " + name + "(" + createVarName(MANDATORY) + "){",
                 strictMode(),
@@ -1339,19 +1513,33 @@ function createObjectFunction(recurmax, stmtDepth, canThrow) {
                 "this." + prop + createAssignment() + _createBinaryExpr(recurmax, COMMA_OK, stmtDepth, canThrow) + ";",
                 "},",
             ];
-            break;
-          default:
-            async = SUPPORT.async && rng(50) == 0;
+        };
+        break;
+      default:
+        async = SUPPORT.async && rng(50) == 0;
+        generator = SUPPORT.generator && rng(50) == 0;
+        if (async && generator && !SUPPORT.async_generator) {
+            if (rng(2)) {
+                async = false;
+            } else {
+                generator = false;
+            }
+        }
+        fn = function(defns) {
+            if (generator) name = "*" + name;
+            if (async) name = "async "+ name;
             s = [
-                (async ? "async " : "") + name + "(" + createParams(save_async, NO_DUPLICATE) + "){",
+                name + "(" + createParams(save_async, save_generator, NO_DUPLICATE) + "){",
                 strictMode(),
                 defns(),
                 _createStatements(3, recurmax, canThrow, CANNOT_BREAK, CANNOT_CONTINUE, CAN_RETURN, stmtDepth),
                 "},",
             ]
-            break;
-        }
-    });
+        };
+        break;
+    }
+    createBlockVariables(recurmax, stmtDepth, canThrow, fn);
+    generator = save_generator;
     async = save_async;
     VAR_NAMES.length = nameLenBefore;
     return filterDirective(s).join("\n");
@@ -1500,8 +1688,11 @@ function createTypeofExpr(recurmax, stmtDepth, canThrow) {
 
     function createVar() {
         var save_async = async;
+        var save_generator = generator;
         if (!async && avoid_vars.indexOf("await") >= 0) async = true;
+        if (!generator && avoid_vars.indexOf("yield") >= 0) generator = true;
         var name = createVarName(MANDATORY, DONT_STORE);
+        generator = save_generator;
         async = save_async;
         return name;
     }
@@ -1550,18 +1741,26 @@ function getVarName(noConst) {
     do {
         if (--tries < 0) return "a";
         name = VAR_NAMES[INITIAL_NAMES_LEN + rng(VAR_NAMES.length - INITIAL_NAMES_LEN)];
-    } while (!name || avoid_vars.indexOf(name) >= 0 || noConst && block_vars.indexOf(name) >= 0 || async && name == "await");
+    } while (!name
+        || avoid_vars.indexOf(name) >= 0
+        || noConst && block_vars.indexOf(name) >= 0
+        || async && name == "await"
+        || generator && name == "yield");
     return name;
 }
 
 function createVarName(maybe, dontStore) {
     if (!maybe || rng(2)) {
         var suffix = rng(3);
-        var name;
+        var name, tries = 10;
         do {
             name = VAR_NAMES[rng(VAR_NAMES.length)];
+            if (--tries < 0) suffix++;
             if (suffix) name += "_" + suffix;
-        } while (unique_vars.indexOf(name) >= 0 || block_vars.indexOf(name) >= 0 || async && name == "await");
+        } while (unique_vars.indexOf(name) >= 0
+            || block_vars.indexOf(name) >= 0
+            || async && name == "await"
+            || generator && name == "yield");
         if (!dontStore) VAR_NAMES.push(name);
         return name;
     }
@@ -1743,24 +1942,52 @@ function log(options) {
 }
 
 function sort_globals(code) {
-    var globals = sandbox.run_code("throw Object.keys(this).sort();" + code);
+    var globals = sandbox.run_code("throw Object.keys(this).sort(" + function(global) {
+        return function(m, n) {
+            return (n == "toString") - (m == "toString")
+                || (typeof global[n] == "function") - (typeof global[m] == "function")
+                || (m < n ? -1 : m > n ? 1 : 0);
+        };
+    } + "(this));" + code);
+    if (!Array.isArray(globals)) {
+        errorln();
+        errorln();
+        errorln("//-------------------------------------------------------------");
+        errorln("// !!! sort_globals() failed !!!");
+        errorln("// expected Array, got:");
+        if (!sandbox.is_error(globals)) try {
+            globals = JSON.stringify(globals);
+        } catch (e) {}
+        errorln(globals);
+        errorln("//");
+        errorln(code);
+        errorln();
+        return code;
+    }
     return globals.length ? "var " + globals.map(function(name) {
         return name + "=" + name;
-    }).join(",") + ";" + code : code;
+    }).join() + ";" + code : code;
 }
 
 function fuzzy_match(original, uglified) {
-    uglified = uglified.split(" ");
-    var i = uglified.length;
-    original = original.split(" ", i);
-    while (--i >= 0) {
-        if (original[i] === uglified[i]) continue;
-        var a = +original[i];
-        var b = +uglified[i];
-        if (Math.abs((b - a) / a) < 1e-10) continue;
-        return false;
+    var m = [], n = [];
+    if (collect(original, m) !== collect(uglified, n)) return false;
+    for (var i = 0; i < m.length; i++) {
+        var a = m[i];
+        var b = n[i];
+        if (Math.abs((b - a) / a) > 1e-10) return false;
     }
     return true;
+
+    function collect(input, nums) {
+        return input.replace(/-?([1-9][0-9]*(\.[0-9]+)?|0\.[0-9]+)(e-?[1-9][0-9]*)?/ig, function(num) {
+            return "<|" + nums.push(+num) + "|>";
+        });
+    }
+}
+
+function is_error_timeout(ex) {
+    return /timed out/.test(ex.message);
 }
 
 function is_error_in(ex) {
@@ -1768,13 +1995,17 @@ function is_error_in(ex) {
 }
 
 function is_error_spread(ex) {
-    return ex.name == "TypeError" && /Found non-callable @@iterator|is not iterable|undefined is not a function/.test(ex.message);
+    return ex.name == "TypeError" && /Found non-callable @@iterator| is not iterable| is not a function/.test(ex.message);
 }
 
 function is_error_recursion(ex) {
     return ex.name == "RangeError" && /Invalid string length|Maximum call stack size exceeded/.test(ex.message);
 }
 
+function is_error_destructuring(ex) {
+    return ex.name == "TypeError" && /^Cannot destructure /.test(ex.message);
+}
+
 function patch_try_catch(orig, toplevel) {
     var stack = [ {
         code: orig,
@@ -1782,6 +2013,7 @@ function patch_try_catch(orig, toplevel) {
         offset: 0,
         tries: [],
     } ];
+    var tail_throw = '\nif (typeof UFUZZ_ERROR == "object") throw UFUZZ_ERROR;\n';
     var re = /(?:(?:^|[\s{}):;])try|}\s*catch\s*\(([^)[{]+)\)|}\s*finally)\s*(?={)/g;
     while (stack.length) {
         var code = stack[0].code;
@@ -1798,7 +2030,7 @@ function patch_try_catch(orig, toplevel) {
             var insert;
             if (/}\s*finally\s*$/.test(match[0])) {
                 tries.shift();
-                insert = 'if (typeof UFUZZ_ERROR == "object") throw UFUZZ_ERROR;';
+                insert = tail_throw;
             } else {
                 while (tries.length && tries[0].catch) tries.shift();
                 tries[0].catch = index - offset;
@@ -1812,9 +2044,9 @@ function patch_try_catch(orig, toplevel) {
                     "throw " + match[1] + ";",
                 ].join("\n");
             }
-            var new_code = code.slice(0, index) + insert + code.slice(index);
+            var new_code = code.slice(0, index) + insert + code.slice(index) + tail_throw;
             var result = sandbox.run_code(new_code, toplevel);
-            if (typeof result != "object" || typeof result.name != "string" || typeof result.message != "string") {
+            if (!sandbox.is_error(result)) {
                 if (!stack.filled && match[1]) stack.push({
                     code: code,
                     index: index && index - 1,
@@ -1832,6 +2064,9 @@ function patch_try_catch(orig, toplevel) {
             } else if (is_error_recursion(result)) {
                 index = result.ufuzz_try;
                 return orig.slice(0, index) + 'throw new Error("skipping infinite recursion");' + orig.slice(index);
+            } else if (is_error_destructuring(result)) {
+                index = result.ufuzz_catch;
+                return orig.slice(0, index) + result.ufuzz_var + ' = new Error("cannot destructure");' + orig.slice(index);
             }
         }
         stack.filled = true;
@@ -1853,12 +2088,13 @@ if (typeof sandbox.run_code("A:if (0) B:; else B:;") != "string") {
         if (o.mangle) o.mangle.v8 = true;
     });
 }
-var is_bug_async_arrow_rest = function() {};
+var bug_async_arrow_rest = function() {};
 if (SUPPORT.arrow && SUPPORT.async && SUPPORT.rest && typeof sandbox.run_code("async (a = f(...[], b)) => 0;") != "string") {
-    is_bug_async_arrow_rest = function(ex) {
+    bug_async_arrow_rest = function(ex) {
         return ex.name == "SyntaxError" && ex.message == "Rest parameter must be last formal parameter";
     };
 }
+var bug_for_of_var = SUPPORT.for_of && SUPPORT.let && typeof sandbox.run_code("try {} catch (e) { for (var e of []); }") != "string";
 if (SUPPORT.destructuring && typeof sandbox.run_code("console.log([ 1 ], {} = 2);") != "string") {
     beautify_options.output.v8 = true;
     minify_options.forEach(function(o) {
@@ -1875,37 +2111,56 @@ for (var round = 1; round <= num_iterations; round++) {
 
     original_code = createTopLevelCode();
     var orig_result = [ sandbox.run_code(original_code), sandbox.run_code(original_code, true) ];
-    errored = typeof orig_result[0] != "string";
-    if (errored) {
+    if (orig_result.some(function(result, toplevel) {
+        if (typeof result == "string") return;
         println();
         println();
         println("//=============================================================");
-        println("// original code");
-        try_beautify(original_code, false, orig_result[0], println);
+        println("// original code" + (toplevel ? " (toplevel)" : ""));
+        try_beautify(original_code, toplevel, result, println);
         println();
         println();
         println("original result:");
-        println(orig_result[0]);
+        println(result);
         println();
-        if (is_bug_async_arrow_rest(orig_result[0])) continue;
-    }
+        // ignore v8 parser bug
+        return bug_async_arrow_rest(result);
+    })) continue;
     minify_options.forEach(function(options) {
         var o = JSON.parse(options);
         var toplevel = sandbox.has_toplevel(o);
         o.validate = true;
         uglify_code = UglifyJS.minify(original_code, o);
         original_result = orig_result[toplevel ? 1 : 0];
+        errored = typeof original_result != "string";
         if (!uglify_code.error) {
             uglify_code = uglify_code.code;
             uglify_result = sandbox.run_code(uglify_code, toplevel);
             ok = sandbox.same_stdout(original_result, uglify_result);
+            // ignore v8 parser bug
+            if (!ok && bug_async_arrow_rest(uglify_result)) ok = true;
+            // handle difference caused by time-outs
+            if (!ok && errored && is_error_timeout(original_result)) {
+                if (is_error_timeout(uglify_result)) {
+                    // ignore difference in error message
+                    ok = true;
+                } else {
+                    // ignore spurious time-outs
+                    if (!orig_result[toplevel ? 3 : 2]) orig_result[toplevel ? 3 : 2] = sandbox.run_code(original_code, toplevel, 10000);
+                    ok = sandbox.same_stdout(orig_result[toplevel ? 3 : 2], uglify_result);
+                }
+            }
             // ignore declaration order of global variables
             if (!ok && !toplevel) {
                 ok = sandbox.same_stdout(sandbox.run_code(sort_globals(original_code)), sandbox.run_code(sort_globals(uglify_code)));
             }
             // ignore numerical imprecision caused by `unsafe_math`
-            if (!ok && o.compress && o.compress.unsafe_math && typeof original_result == "string" && typeof uglify_result == "string") {
-                ok = fuzzy_match(original_result, uglify_result);
+            if (!ok && o.compress && o.compress.unsafe_math && typeof original_result == typeof uglify_result) {
+                if (typeof original_result == "string") {
+                    ok = fuzzy_match(original_result, uglify_result);
+                } else if (sandbox.is_error(original_result)) {
+                    ok = original_result.name == uglify_result.name && fuzzy_match(original_result.message, uglify_result.message);
+                }
                 if (!ok) {
                     var fuzzy_result = sandbox.run_code(original_code.replace(/( - 0\.1){3}/g, " - 0.3"), toplevel);
                     ok = sandbox.same_stdout(fuzzy_result, uglify_result);
@@ -1913,11 +2168,6 @@ for (var round = 1; round <= num_iterations; round++) {
             }
             // ignore difference in error message caused by Temporal Dead Zone
             if (!ok && errored && uglify_result.name == "ReferenceError" && original_result.name == "ReferenceError") ok = true;
-            // ignore spurious time-outs
-            if (!ok && errored && /timed out/.test(original_result.message) && !/timed out/.test(uglify_result.message)) {
-                if (!orig_result[toplevel ? 3 : 2]) orig_result[toplevel ? 3 : 2] = sandbox.run_code(original_code, toplevel, 10000);
-                ok = sandbox.same_stdout(orig_result[toplevel ? 3 : 2], uglify_result);
-            }
             // ignore difference in error message caused by `in`
             if (!ok && errored && is_error_in(uglify_result) && is_error_in(original_result)) ok = true;
             // ignore difference in error message caused by spread syntax
@@ -1926,6 +2176,10 @@ for (var round = 1; round <= num_iterations; round++) {
             if (!ok && errored && is_error_recursion(original_result)) {
                 if (is_error_recursion(uglify_result) || typeof uglify_result == "string") ok = true;
             }
+            // ignore difference in error message caused by destructuring
+            if (!ok && errored && is_error_destructuring(uglify_result) && is_error_destructuring(original_result)) {
+                ok = true;
+            }
             // ignore errors above when caught by try-catch
             if (!ok) {
                 var orig_skipped = patch_try_catch(original_code, toplevel);