v3.12.4

fixes #4485

.github/workflows/ci.yml

@@ -7,13 +7,13 @@ jobs:
   test:
     strategy:
       matrix:
-        node: [ "0.8", "0.10", "0.12", "4", "6", "8", "10", "12", latest ]
+        node: [ '0.8', '0.10', '0.12', '4', '6', '8', '10', '12', latest ]
         os: [ ubuntu-latest, windows-latest ]
         script: [ compress, mocha, release/benchmark, release/jetstream ]
         exclude:
-          - node: "0.8"
+          - node: '0.8'
             script: release/benchmark
-          - node: "0.8"
+          - node: '0.8'
             script: release/jetstream
     name: ${{ matrix.node }} ${{ matrix.os }} ${{ matrix.script }}
     runs-on: ${{ matrix.os }}
@@ -29,7 +29,7 @@ jobs:
       - name: Perform tests
         shell: bash
         run: |
-          git clone --branch v1.5.4 --depth 1 https://github.com/jasongin/nvs.git ~/.nvs
+          git clone --branch v1.6.0 --depth 1 https://github.com/jasongin/nvs.git ~/.nvs
           while ! timeout 60 bash -c '. ~/.nvs/nvs.sh add $NODE && nvs use $NODE'; do
             cd ~/.nvs
             while !(git clean -xdf); do echo "'git clean' failed - retrying..."; done

.github/workflows/ufuzz.yml

@@ -2,7 +2,7 @@ name: Fuzzing
 on:
   pull_request:
   schedule:
-    - cron: "*/5 * * * *"
+    - cron: '*/5 * * * *'
 env:
   BASE_URL: https://api.github.com/repos/${{ github.repository }}
   CAUSE: ${{ github.event_name }}
@@ -13,22 +13,39 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        os: [ ubuntu-latest, windows-latest ]
+        include:
-    name: ${{ matrix.os }}
+          - node: latest
+            os: macos-latest
+          - node: '8'
+            os: ubuntu-latest
+          - node: '8'
+            os: ubuntu-latest
+          - node: '8'
+            os: windows-latest
+          - node: '8'
+            os: windows-latest
+    name: ${{ matrix.node }} ${{ matrix.os }}
     runs-on: ${{ matrix.os }}
+    env:
+      NODE: ${{ matrix.node }}
     steps:
       - uses: actions/checkout@v2
+      - name: Install GNU Core Utilities
+        if: ${{ startsWith(matrix.os, 'macos') }}
+        shell: bash
+        run: |
+          brew install coreutils
       - name: Perform fuzzing
         shell: bash
         run: |
-          git clone --branch v1.5.4 --depth 1 https://github.com/jasongin/nvs.git ~/.nvs
+          git clone --branch v1.6.0 --depth 1 https://github.com/jasongin/nvs.git ~/.nvs
-          while ! timeout 60 bash -c '. ~/.nvs/nvs.sh add 8 && nvs use 8'; do
+          while ! timeout 60 bash -c '. ~/.nvs/nvs.sh add $NODE && nvs use $NODE'; do
             cd ~/.nvs
             while !(git clean -xdf); do echo "'git clean' failed - retrying..."; done
             cd -
           done
           . ~/.nvs/nvs.sh --version
-          nvs use 8
+          nvs use $NODE
           node --version
           npm config set audit false
           npm config set optional false

README.md

@@ -4,10 +4,12 @@ UglifyJS 3
 UglifyJS is a JavaScript parser, minifier, compressor and beautifier toolkit.
 
 #### Note:
-- **`uglify-js@3` has a simplified [API](#api-reference) and [CLI](#command-line-usage) that is not backwards compatible with [`uglify-js@2`](https://github.com/mishoo/UglifyJS/tree/v2.x)**.
+- **`uglify-js@3` has a simplified [API](#api-reference) and [CLI](#command-line-usage)
+  that is not backwards compatible with [`uglify-js@2`](https://github.com/mishoo/UglifyJS/tree/v2.x)**.
 - **Documentation for UglifyJS `2.x` releases can be found [here](https://github.com/mishoo/UglifyJS/tree/v2.x)**.
-- `uglify-js` only supports JavaScript (ECMAScript 5).
+- `uglify-js` supports ECMAScript 5 and some newer language features.
-- To minify ECMAScript 2015 or above, transpile using tools like [Babel](https://babeljs.io/).
+- To minify ECMAScript 2015 or above, you may need to transpile using tools like
+  [Babel](https://babeljs.io/).
 
 Install
 -------
@@ -133,6 +135,10 @@ a double dash to prevent input files being used as option arguments:
                                        `//# sourceMappingURL`.
     --timings                   Display operations run time on STDERR.
     --toplevel                  Compress and/or mangle variables in top level scope.
+    --v8                        Support non-standard Chrome & Node.js
+                                Equivalent to setting `v8: true` in `minify()`
+                                for `mangle` and `output` options.
+                                By default UglifyJS will not try to be v8-proof.
     --verbose                   Print diagnostic messages.
     --warn                      Print warning messages.
     --webkit                    Support non-standard Safari/Webkit.
@@ -520,6 +526,8 @@ if (result.error) throw result.error;
 - `toplevel` (default `false`) -- set to `true` if you wish to enable top level
   variable and function name mangling and to drop unused variables and functions.
 
+- `v8` (default `false`) -- enable workarounds for Chrome & Node.js bugs.
+
 - `warnings` (default `false`) — pass `true` to return compressor warnings
   in `result.warnings`. Use the value `"verbose"` for more detailed warnings.
 
@@ -636,6 +644,8 @@ to be `false` and all symbol names will be omitted.
 
 - `dead_code` (default: `true`) -- remove unreachable code
 
+- `default_values` (default: `true`) -- drop overshadowed default values
+
 - `directives` (default: `true`) -- remove redundant or non-standard directives
 
 - `drop_console` (default: `false`) -- Pass `true` to discard calls to
@@ -681,9 +691,9 @@ to be `false` and all symbol names will be omitted.
 
 - `join_vars` (default: `true`) -- join consecutive `var` statements
 
-- `keep_fargs` (default: `strict`) -- Discard unused function arguments. Code
+- `keep_fargs` (default: `false`) -- discard unused function arguments except
-  which relies on `Function.length` will break if this is done indiscriminately,
+  when unsafe to do so, e.g. code which relies on `Function.prototype.length`.
-  i.e. when passing `true`. Pass `false` to always retain function arguments.
+  Pass `true` to always retain function arguments.
 
 - `keep_fnames` (default: `false`) -- Pass `true` to prevent the
   compressor from discarding function names.  Useful for code relying on
@@ -751,6 +761,8 @@ to be `false` and all symbol names will be omitted.
   annotation `/*@__PURE__*/` or `/*#__PURE__*/` immediately precedes the call. For
   example: `/*@__PURE__*/foo();`
 
+- `spread` (default: `true`) -- flatten spread expressions.
+
 - `strings` (default: `true`) -- compact string concatenations.
 
 - `switches` (default: `true`) -- de-duplicate and remove unreachable `switch` branches
@@ -915,8 +927,6 @@ can pass additional arguments that control the code output:
 
 - `shebang` (default `true`) -- preserve shebang `#!` in preamble (bash scripts)
 
-- `v8` (default `false`) -- enable workarounds for Chrome & Node.js bugs
-
 - `width` (default `80`) -- only takes effect when beautification is on, this
   specifies an (orientative) line width that the beautifier will try to
   obey.  It refers to the width of the line text (excluding indentation).
@@ -1173,6 +1183,18 @@ To allow for better optimizations, the compiler makes various assumptions:
 - Object properties can be added, removed and modified (not prevented with
   `Object.defineProperty()`, `Object.defineProperties()`, `Object.freeze()`,
   `Object.preventExtensions()` or `Object.seal()`).
+- Earlier versions of JavaScript will throw `SyntaxError` with the following:
+  ```js
+  ({
+    p: 42,
+    get p() {},
+  });
+  // SyntaxError: Object literal may not have data and accessor property with
+  //              the same name
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.
+- Iteration order of keys over an object which contains spread syntax in later
+  versions of Chrome and Node.js may be altered.
 - When `toplevel` is enabled, UglifyJS effectively assumes input code is wrapped
   within `function(){ ... }`, thus forbids aliasing of declared global variables:
   ```js
@@ -1193,3 +1215,35 @@ To allow for better optimizations, the compiler makes various assumptions:
   `function({}, arguments) {}` will result in `SyntaxError` in earlier versions
   of Chrome and Node.js - UglifyJS may modify the input which in turn may
   suppress those errors.
+- Earlier versions of Chrome and Node.js will throw `ReferenceError` with the
+  following:
+  ```js
+  var a;
+  try {
+      throw 42;
+  } catch ({
+      [a]: b,
+      // ReferenceError: a is not defined
+  }) {
+      let a;
+  }
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.
+- Later versions of JavaScript will throw `SyntaxError` with the following:
+  ```js
+  a => {
+    let a;
+  };
+  // SyntaxError: Identifier 'a' has already been declared
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.
+- Later versions of JavaScript will throw `SyntaxError` with the following:
+  ```js
+  try {
+    // ...
+  } catch ({ message: a }) {
+    var a;
+  }
+  // SyntaxError: Identifier 'a' has already been declared
+  ```
+  UglifyJS may modify the input which in turn may suppress those errors.

bin/uglifyjs

@@ -3,7 +3,7 @@
 
 "use strict";
 
-require("../tools/exit");
+require("../tools/tty");
 
 var fs = require("fs");
 var info = require("../package.json");

lib/ast.js

@@ -207,11 +207,23 @@ var AST_EmptyStatement = DEFNODE("EmptyStatement", null, {
     $documentation: "The empty statement (empty block or simply a semicolon)"
 }, AST_Statement);
 
-function must_be_expression(node, prop) {
+function validate_expression(value, prop, multiple, allow_spread, allow_hole) {
-    if (!(node[prop] instanceof AST_Node)) throw new Error(prop + " must be AST_Node");
+    multiple = multiple ? "contain" : "be";
-    if (node[prop] instanceof AST_Statement && !(node[prop] instanceof AST_Function)) {
+    if (!(value instanceof AST_Node)) throw new Error(prop + " must " + multiple + " AST_Node");
-        throw new Error(prop + " cannot be AST_Statement");
+    if (value instanceof AST_DefaultValue) throw new Error(prop + " cannot " + multiple + " AST_DefaultValue");
+    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)) {
+        throw new Error(prop + " cannot " + multiple + " AST_Statement");
     }
+    if (value instanceof AST_SymbolDeclaration) {
+        throw new Error(prop + " cannot " + multiple + " AST_SymbolDeclaration");
+    }
+}
+
+function must_be_expression(node, prop) {
+    validate_expression(node[prop], prop);
 }
 
 var AST_SimpleStatement = DEFNODE("SimpleStatement", "body", {
@@ -278,7 +290,7 @@ var AST_Block = DEFNODE("Block", "body", {
     _validate: function() {
         this.body.forEach(function(node) {
             if (!(node instanceof AST_Statement)) throw new Error("body must be AST_Statement[]");
-            if (node instanceof AST_Function) throw new Error("body cannot contain AST_Function");
+            if (is_function(node)) throw new Error("body cannot contain AST_Function");
         });
     },
 }, AST_BlockScope);
@@ -294,7 +306,7 @@ var AST_StatementWithBody = DEFNODE("StatementWithBody", "body", {
     },
     _validate: function() {
         if (!(this.body instanceof AST_Statement)) throw new Error("body must be AST_Statement");
-        if (this.body instanceof AST_Function) throw new Error("body cannot be AST_Function");
+        if (is_function(this.body)) throw new Error("body cannot be AST_Function");
     },
 }, AST_BlockScope);
 
@@ -388,7 +400,7 @@ 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 || this.init instanceof AST_Function)) {
+                && !(this.init instanceof AST_Definitions || is_function(this.init))) {
                 throw new Error("init cannot be AST_Statement");
             }
         }
@@ -500,10 +512,9 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     }
 }, AST_Scope);
 
-var AST_Lambda = DEFNODE("Lambda", "name argnames length_read uses_arguments", {
+var AST_Lambda = DEFNODE("Lambda", "argnames length_read uses_arguments", {
     $documentation: "Base class for functions",
     $propdoc: {
-        name: "[AST_SymbolDeclaration?] the name of this function",
         argnames: "[(AST_Destructured|AST_SymbolFunarg)*] array of function arguments and/or destructured literals",
         uses_arguments: "[boolean/S] tells whether this function accesses the arguments array",
     },
@@ -533,20 +544,59 @@ var AST_Lambda = DEFNODE("Lambda", "name argnames length_read uses_arguments", {
         this.argnames.forEach(function(node) {
             validate_destructured(node, function(node) {
                 if (!(node instanceof AST_SymbolFunarg)) throw new Error("argnames must be AST_SymbolFunarg[]");
-            });
+            }, true);
         });
     },
 }, AST_Scope);
 
 var AST_Accessor = DEFNODE("Accessor", null, {
-    $documentation: "A setter/getter function.  The `name` property is always null.",
+    $documentation: "A getter/setter function",
     _validate: function() {
         if (this.name != null) throw new Error("name must be null");
     },
 }, AST_Lambda);
 
-var AST_Function = DEFNODE("Function", "inlined", {
+function is_function(node) {
-    $documentation: "A function expression",
+    return node instanceof AST_Arrow || node instanceof AST_AsyncFunction || node instanceof AST_Function;
+}
+
+var AST_Arrow = DEFNODE("Arrow", "inlined value", {
+    $documentation: "An arrow function expression",
+    $propdoc: {
+        value: "[AST_Node?] simple return expression, or null if using function body.",
+    },
+    walk: function(visitor) {
+        var node = this;
+        visitor.visit(node, function() {
+            node.argnames.forEach(function(argname) {
+                argname.walk(visitor);
+            });
+            if (node.value) {
+                node.value.walk(visitor);
+            } else {
+                walk_body(node, visitor);
+            }
+        });
+    },
+    _validate: function() {
+        if (this.name != null) throw new Error("name must be null");
+        if (this.uses_arguments) throw new Error("uses_arguments must be false");
+        if (this.value != null) {
+            must_be_expression(this, "value");
+            if (this.body.length) throw new Error("body must be empty if value exists");
+        }
+    },
+}, AST_Lambda);
+
+function is_async(node) {
+    return node instanceof AST_AsyncDefun || node instanceof AST_AsyncFunction;
+}
+
+var AST_AsyncFunction = DEFNODE("AsyncFunction", "inlined name", {
+    $documentation: "An asynchronous 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");
@@ -554,8 +604,37 @@ var AST_Function = DEFNODE("Function", "inlined", {
     },
 }, AST_Lambda);
 
-var AST_Defun = DEFNODE("Defun", "inlined", {
+var AST_Function = DEFNODE("Function", "inlined name", {
+    $documentation: "A 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_Lambda);
+
+function is_defun(node) {
+    return node instanceof AST_AsyncDefun || node instanceof AST_Defun;
+}
+
+var AST_AsyncDefun = DEFNODE("AsyncDefun", "inlined name", {
+    $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);
+
+var AST_Defun = DEFNODE("Defun", "inlined name", {
     $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");
     },
@@ -640,7 +719,7 @@ 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 (this.alternative instanceof AST_Function) throw new error("alternative cannot be AST_Function");
+            if (is_function(this.alternative)) throw new error("alternative cannot be AST_Function");
         }
     },
 }, AST_StatementWithBody);
@@ -721,7 +800,7 @@ var AST_Try = DEFNODE("Try", "bcatch bfinally", {
 var AST_Catch = DEFNODE("Catch", "argname", {
     $documentation: "A `catch` node; only makes sense as part of a `try` statement",
     $propdoc: {
-        argname: "[AST_SymbolCatch?] symbol for the exception, or null if not present",
+        argname: "[(AST_Destructured|AST_SymbolCatch)?] symbol for the exception, or null if not present",
     },
     walk: function(visitor) {
         var node = this;
@@ -731,9 +810,9 @@ var AST_Catch = DEFNODE("Catch", "argname", {
         });
     },
     _validate: function() {
-        if (this.argname != null) {
+        if (this.argname != null) validate_destructured(this.argname, function(node) {
-            if (!(this.argname instanceof AST_SymbolCatch)) throw new Error("argname must be AST_SymbolCatch");
+            if (!(node instanceof AST_SymbolCatch)) throw new Error("argname must be AST_SymbolCatch");
-        }
+        });
     },
 }, AST_Block);
 
@@ -769,7 +848,6 @@ var AST_Const = DEFNODE("Const", null, {
             validate_destructured(node.name, function(node) {
                 if (!(node instanceof AST_SymbolConst)) throw new Error("name must be AST_SymbolConst");
             });
-            if (node.value != null) must_be_expression(node, "value");
         });
     },
 }, AST_Definitions);
@@ -782,7 +860,6 @@ var AST_Let = DEFNODE("Let", null, {
             validate_destructured(node.name, function(node) {
                 if (!(node instanceof AST_SymbolLet)) throw new Error("name must be AST_SymbolLet");
             });
-            if (node.value != null) must_be_expression(node, "value");
         });
     },
 }, AST_Definitions);
@@ -795,7 +872,6 @@ var AST_Var = DEFNODE("Var", null, {
             validate_destructured(node.name, function(node) {
                 if (!(node instanceof AST_SymbolVar)) throw new Error("name must be AST_SymbolVar");
             });
-            if (node.value != null) must_be_expression(node, "value");
         });
     },
 }, AST_Definitions);
@@ -803,8 +879,8 @@ var AST_Var = DEFNODE("Var", null, {
 var AST_VarDef = DEFNODE("VarDef", "name value", {
     $documentation: "A variable declaration; only appears in a AST_Definitions node",
     $propdoc: {
-        name: "[AST_SymbolVar] name of the variable",
+        name: "[AST_Destructured|AST_SymbolVar] name of the variable",
-        value: "[AST_Node?] initializer, or null of there's no initializer"
+        value: "[AST_Node?] initializer, or null of there's no initializer",
     },
     walk: function(visitor) {
         var node = this;
@@ -813,16 +889,34 @@ var AST_VarDef = DEFNODE("VarDef", "name value", {
             if (node.value) node.value.walk(visitor);
         });
     },
+    _validate: function() {
+        if (this.value != null) must_be_expression(this, "value");
+    },
 });
 
 /* -----[ OTHER ]----- */
 
-function must_be_expressions(node, prop) {
+var AST_DefaultValue = DEFNODE("DefaultValue", "name value", {
+    $documentation: "A default value declaration",
+    $propdoc: {
+        name: "[AST_Destructured|AST_SymbolDeclaration] name of the variable",
+        value: "[AST_Node] value to assign if variable is `undefined`",
+    },
+    walk: function(visitor) {
+        var node = this;
+        visitor.visit(node, function() {
+            node.name.walk(visitor);
+            node.value.walk(visitor);
+        });
+    },
+    _validate: function() {
+        must_be_expression(this, "value");
+    },
+});
+
+function must_be_expressions(node, prop, allow_spread, allow_hole) {
     node[prop].forEach(function(node) {
-        if (!(node instanceof AST_Node)) throw new Error(prop + " must be AST_Node[]");
+        validate_expression(node, prop, true, allow_spread, allow_hole);
-        if (node instanceof AST_Statement && !(node instanceof AST_Function)) {
-            throw new Error(prop + " cannot contain AST_Statement");
-        }
     });
 }
 
@@ -843,7 +937,7 @@ var AST_Call = DEFNODE("Call", "expression args pure", {
     },
     _validate: function() {
         must_be_expression(this, "expression");
-        must_be_expressions(this, "args");
+        must_be_expressions(this, "args", true);
     },
 });
 
@@ -920,6 +1014,22 @@ var AST_Sub = DEFNODE("Sub", null, {
     },
 }, AST_PropAccess);
 
+var AST_Spread = DEFNODE("Spread", "expression", {
+    $documentation: "Spread expression in array/object literals or function calls",
+    $propdoc: {
+        expression: "[AST_Node] expression to be expanded",
+    },
+    walk: function(visitor) {
+        var node = this;
+        visitor.visit(node, function() {
+            node.expression.walk(visitor);
+        });
+    },
+    _validate: function() {
+        must_be_expression(this, "expression");
+    },
+});
+
 var AST_Unary = DEFNODE("Unary", "operator expression", {
     $documentation: "Base class for unary expressions",
     $propdoc: {
@@ -961,7 +1071,7 @@ var AST_Binary = DEFNODE("Binary", "operator left right", {
         });
     },
     _validate: function() {
-        must_be_expression(this, "left");
+        if (!(this instanceof AST_Assign)) must_be_expression(this, "left");
         if (typeof this.operator != "string") throw new Error("operator must be string");
         must_be_expression(this, "right");
     },
@@ -1004,6 +1114,22 @@ var AST_Assign = DEFNODE("Assign", null, {
     },
 }, AST_Binary);
 
+var AST_Await = DEFNODE("Await", "expression", {
+    $documentation: "An await expression",
+    $propdoc: {
+        expression: "[AST_Node] expression with Promise to resolve on",
+    },
+    walk: function(visitor) {
+        var node = this;
+        visitor.visit(node, function() {
+            node.expression.walk(visitor);
+        });
+    },
+    _validate: function() {
+        must_be_expression(this, "expression");
+    },
+});
+
 /* -----[ LITERALS ]----- */
 
 var AST_Array = DEFNODE("Array", "elements", {
@@ -1020,7 +1146,7 @@ var AST_Array = DEFNODE("Array", "elements", {
         });
     },
     _validate: function() {
-        must_be_expressions(this, "elements");
+        must_be_expressions(this, "elements", true, true);
     },
 });
 
@@ -1028,12 +1154,13 @@ var AST_Destructured = DEFNODE("Destructured", null, {
     $documentation: "Base class for destructured literal",
 });
 
-function validate_destructured(node, check) {
+function validate_destructured(node, check, allow_default) {
+    if (node instanceof AST_DefaultValue && allow_default) return validate_destructured(node.name, check);
     if (node instanceof AST_DestructuredArray) return node.elements.forEach(function(node) {
-        if (!(node instanceof AST_Hole)) validate_destructured(node, check);
+        if (!(node instanceof AST_Hole)) validate_destructured(node, check, true);
     });
     if (node instanceof AST_DestructuredObject) return node.properties.forEach(function(prop) {
-        validate_destructured(prop.value, check);
+        validate_destructured(prop.value, check, true);
     });
     check(node);
 }
@@ -1071,7 +1198,7 @@ var AST_DestructuredKeyVal = DEFNODE("DestructuredKeyVal", "key value", {
             if (!(this.key instanceof AST_Node)) throw new Error("key must be string or AST_Node");
             must_be_expression(this, "key");
         }
-        must_be_expression(this, "value");
+        if (!(this.value instanceof AST_Node)) throw new Error("value must be AST_Node");
     },
 });
 
@@ -1098,7 +1225,7 @@ var AST_DestructuredObject = DEFNODE("DestructuredObject", "properties", {
 var AST_Object = DEFNODE("Object", "properties", {
     $documentation: "An object literal",
     $propdoc: {
-        properties: "[AST_ObjectProperty*] array of properties"
+        properties: "[(AST_ObjectProperty|AST_Spread)*] array of properties"
     },
     walk: function(visitor) {
         var node = this;
@@ -1110,7 +1237,9 @@ var AST_Object = DEFNODE("Object", "properties", {
     },
     _validate: function() {
         this.properties.forEach(function(node) {
-            if (!(node instanceof AST_ObjectProperty)) throw new Error("properties must be AST_ObjectProperty[]");
+            if (!(node instanceof AST_ObjectProperty || node instanceof AST_Spread)) {
+                throw new Error("properties must contain AST_ObjectProperty and/or AST_Spread only");
+            }
         });
     },
 });
@@ -1213,7 +1342,7 @@ var AST_Label = DEFNODE("Label", "references", {
     }
 }, AST_Symbol);
 
-var AST_SymbolRef = DEFNODE("SymbolRef", "fixed", {
+var AST_SymbolRef = DEFNODE("SymbolRef", "fixed in_arg", {
     $documentation: "Reference to some symbol (not definition/declaration)",
 }, AST_Symbol);
 
@@ -1389,14 +1518,13 @@ TreeWalker.prototype = {
                 || p.tail_node() === self) {
                 self = p;
             } else if (p instanceof AST_Return) {
-                var fn;
+                for (var call, fn = p; call = this.parent(++i); fn = call) {
-                do {
+                    if (call.TYPE == "Call") {
-                    fn = this.parent(++i);
+                        if (!(fn instanceof AST_Lambda) || fn.name) return false;
-                    if (!fn) return false;
+                    } else if (fn instanceof AST_Lambda) {
-                } while (!(fn instanceof AST_Lambda));
+                        return false;
-                if (fn.name) return false;
+                    }
-                self = this.parent(++i);
+                }
-                if (!self || self.TYPE != "Call" || self.expression !== fn) return false;
             } else {
                 return false;
             }

lib/minify.js

@@ -87,6 +87,7 @@ function minify(files, options) {
             sourceMap: false,
             timings: false,
             toplevel: false,
+            v8: false,
             validate: false,
             warnings: false,
             webkit: false,
@@ -102,6 +103,7 @@ function minify(files, options) {
         set_shorthand("ie8", options, [ "compress", "mangle", "output" ]);
         set_shorthand("keep_fnames", options, [ "compress", "mangle" ]);
         set_shorthand("toplevel", options, [ "compress", "mangle" ]);
+        set_shorthand("v8", options, [ "mangle", "output" ]);
         set_shorthand("webkit", options, [ "mangle", "output" ]);
         var quoted_props;
         if (options.mangle) {
@@ -113,6 +115,7 @@ function minify(files, options) {
                 properties: false,
                 reserved: [],
                 toplevel: false,
+                v8: false,
                 webkit: false,
             }, true);
             if (options.mangle.properties) {

lib/output.js

@@ -661,7 +661,7 @@ function OutputStream(options) {
 
     // a function expression needs parens around it when it's provably
     // the first token to appear in a statement.
-    PARENS(AST_Function, function(output) {
+    function needs_parens_function(output) {
         if (!output.has_parens() && first_in_statement(output)) return true;
         if (output.option("webkit")) {
             var p = output.parent();
@@ -671,12 +671,14 @@ function OutputStream(options) {
             var p = output.parent();
             if (p instanceof AST_Call && p.expression === this) return true;
         }
-    });
+    }
+    PARENS(AST_AsyncFunction, needs_parens_function);
+    PARENS(AST_Function, needs_parens_function);
 
     // same goes for an object literal, because otherwise it would be
     // interpreted as a block of code.
     function needs_parens_obj(output) {
-        return !output.has_parens() && first_in_statement(output);
+        return !output.has_parens() && first_in_statement(output, true);
     }
     PARENS(AST_Object, needs_parens_obj);
 
@@ -689,6 +691,10 @@ function OutputStream(options) {
         var p = output.parent();
             // [ 1, (2, 3), 4 ] ==> [ 1, 3, 4 ]
         return p instanceof AST_Array
+            // () => (foo, bar)
+            || p instanceof AST_Arrow && p.value === this
+            // await (foo, bar)
+            || p instanceof AST_Await
             // 1 + (2, 3) + 4 ==> 8
             || p instanceof AST_Binary
             // new (foo, bar) or foo(1, (2, 3), 4)
@@ -696,12 +702,16 @@ function OutputStream(options) {
             // (false, true) ? (a = 10, b = 20) : (c = 30)
             // ==> 20 (side effect, set a := 10 and b := 20)
             || p instanceof AST_Conditional
+            // [ a = (1, 2) ] = [] ==> a == 2
+            || p instanceof AST_DefaultValue
             // { [(1, 2)]: 3 }[2] ==> 3
             // { foo: (1, 2) }.foo ==> 2
             || p instanceof AST_DestructuredKeyVal
             || p instanceof AST_ObjectProperty
             // (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
@@ -710,6 +720,8 @@ function OutputStream(options) {
 
     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)
         if (p instanceof AST_Binary) {
             var po = p.operator, pp = PRECEDENCE[po];
@@ -777,6 +789,8 @@ function OutputStream(options) {
 
     function needs_parens_assign_cond(self, output) {
         var p = output.parent();
+        // await (a = foo)
+        if (p instanceof AST_Await) return true;
         // 1 + (a = 2) + 3 → 6, side effect setting a = 2
         if (p instanceof AST_Binary) return !(p instanceof AST_Assign);
         // (a = func)() —or— new (a = Object)()
@@ -788,6 +802,9 @@ function OutputStream(options) {
         // !(a = false) → true
         if (p instanceof AST_Unary) return true;
     }
+    PARENS(AST_Arrow, function(output) {
+        return needs_parens_assign_cond(this, output);
+    });
     PARENS(AST_Assign, function(output) {
         if (needs_parens_assign_cond(this, output)) return true;
         //  v8 parser bug   =>     workaround
@@ -800,6 +817,16 @@ function OutputStream(options) {
         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;
+    });
+
     /* -----[ PRINTERS ]----- */
 
     DEFPRINT(AST_Directive, function(output) {
@@ -965,11 +992,26 @@ function OutputStream(options) {
     });
 
     /* -----[ functions ]----- */
-    DEFPRINT(AST_Lambda, function(output, nokeyword) {
+    DEFPRINT(AST_Arrow, function(output) {
         var self = this;
-        if (!nokeyword) {
+        if (self.argnames.length == 1 && self.argnames[0] instanceof AST_SymbolFunarg) {
-            output.print("function");
+            self.argnames[0].print(output);
+        } else output.with_parens(function() {
+            self.argnames.forEach(function(arg, i) {
+                if (i) output.comma();
+                arg.print(output);
+            });
+        });
+        output.space();
+        output.print("=>");
+        output.space();
+        if (self.value) {
+            self.value.print(output);
+        } else {
+            print_braced(self, output, true);
         }
+    });
+    function print_lambda(self, output) {
         if (self.name) {
             output.space();
             self.name.print(output);
@@ -982,7 +1024,19 @@ function OutputStream(options) {
         });
         output.space();
         print_braced(self, output, true);
+    }
+    DEFPRINT(AST_Lambda, function(output) {
+        output.print("function");
+        print_lambda(this, output);
     });
+    function print_async(output) {
+        output.print("async");
+        output.space();
+        output.print("function");
+        print_lambda(this, output);
+    }
+    DEFPRINT(AST_AsyncDefun, print_async);
+    DEFPRINT(AST_AsyncFunction, print_async);
 
     /* -----[ jumps ]----- */
     function print_jump(kind, prop) {
@@ -1146,11 +1200,9 @@ function OutputStream(options) {
         // need to take some precautions here:
         //    https://github.com/mishoo/UglifyJS/issues/60
         if (noin) node.walk(new TreeWalker(function(node) {
-            if (parens || node instanceof AST_Scope) return true;
+            if (parens) return true;
-            if (node instanceof AST_Binary && node.operator == "in") {
+            if (node instanceof AST_Binary && node.operator == "in") return parens = true;
-                parens = true;
+            if (node instanceof AST_Scope && !(node instanceof AST_Arrow && node.value)) return true;
-                return true;
-            }
         }));
         node.print(output, parens);
     }
@@ -1168,6 +1220,15 @@ function OutputStream(options) {
         }
     });
 
+    DEFPRINT(AST_DefaultValue, function(output) {
+        var self = this;
+        self.name.print(output);
+        output.space();
+        output.print("=");
+        output.space();
+        self.value.print(output);
+    });
+
     /* -----[ other expressions ]----- */
     function print_call_args(self, output) {
         if (self.expression instanceof AST_Call || self.expression instanceof AST_Lambda) {
@@ -1231,6 +1292,10 @@ function OutputStream(options) {
         this.property.print(output);
         output.print("]");
     });
+    DEFPRINT(AST_Spread, function(output) {
+        output.print("...");
+        this.expression.print(output);
+    });
     DEFPRINT(AST_UnaryPrefix, function(output) {
         var op = this.operator;
         var exp = this.expression;
@@ -1266,6 +1331,11 @@ function OutputStream(options) {
         output.colon();
         self.alternative.print(output);
     });
+    DEFPRINT(AST_Await, function(output) {
+        output.print("await");
+        output.space();
+        this.expression.print(output);
+    });
 
     /* -----[ literals ]----- */
     DEFPRINT(AST_Array, function(output) {
@@ -1369,7 +1439,7 @@ function OutputStream(options) {
             output.print(type);
             output.space();
             print_property_key(self, output);
-            self.value._codegen(output, true);
+            print_lambda(self.value, output);
         };
     }
     DEFPRINT(AST_ObjectGetter, print_accessor("get"));

lib/parse.js

@@ -47,7 +47,7 @@
 var KEYWORDS = "break case catch const continue debugger default delete do else finally for function if in instanceof let new return switch throw try typeof var void while with";
 var KEYWORDS_ATOM = "false null true";
 var RESERVED_WORDS = [
-    "abstract boolean byte char class double enum export extends final float goto implements import int interface let long native package private protected public short static super synchronized this throws transient volatile yield",
+    "await abstract boolean byte char class double enum export extends final float goto implements import int interface long native package private protected public short static super synchronized this throws transient volatile yield",
     KEYWORDS_ATOM,
     KEYWORDS,
 ].join(" ");
@@ -501,7 +501,16 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
 
     function handle_dot() {
         next();
-        return is_digit(peek().charCodeAt(0)) ? read_num(".") : token("punc", ".");
+        var ch = peek();
+        if (ch == ".") {
+            var op = ".";
+            do {
+                op += ".";
+                next();
+            } while (peek() == ".");
+            return token("operator", op);
+        }
+        return is_digit(ch.charCodeAt(0)) ? read_num(".") : token("punc", ".");
     }
 
     function read_word() {
@@ -560,6 +569,7 @@ function tokenizer($TEXT, filename, html5_comments, shebang) {
             }
             if (is_digit(code)) return read_num();
             if (PUNC_CHARS[ch]) return token("punc", next());
+            if (looking_at("=>")) return token("punc", next() + next());
             if (OPERATOR_CHARS[ch]) return read_operator();
             if (code == 92 || !NON_IDENTIFIER_CHARS[ch]) return read_word();
             break;
@@ -625,7 +635,7 @@ var PRECEDENCE = function(a, ret) {
     ["*", "/", "%"]
 ], {});
 
-var ATOMIC_START_TOKEN = makePredicate("atom num string regexp name");
+var ATOMIC_START_TOKEN = makePredicate("atom num regexp string");
 
 /* -----[ Parser ]----- */
 
@@ -644,13 +654,15 @@ function parse($TEXT, options) {
         input         : typeof $TEXT == "string"
                         ? tokenizer($TEXT, options.filename, options.html5_comments, options.shebang)
                         : $TEXT,
-        token         : null,
+        in_async      : false,
-        prev          : null,
-        peeked        : null,
-        in_function   : 0,
         in_directives : true,
+        in_funarg     : -1,
+        in_function   : 0,
         in_loop       : 0,
-        labels        : []
+        labels        : [],
+        peeked        : null,
+        prev          : null,
+        token         : null,
     };
 
     S.token = next();
@@ -725,12 +737,12 @@ function parse($TEXT, options) {
 
     function semicolon(optional) {
         if (is("punc", ";")) next();
-        else if (!optional && !can_insert_semicolon()) expect_token("punc", ";");
+        else if (!optional && !can_insert_semicolon()) expect(";");
     }
 
     function parenthesised() {
         expect("(");
-        var exp = expression(true);
+        var exp = expression();
         expect(")");
         return exp;
     }
@@ -758,7 +770,7 @@ function parse($TEXT, options) {
         switch (S.token.type) {
           case "string":
             var dir = S.in_directives;
-            var body = expression(true);
+            var body = expression();
             if (dir) {
                 if (body instanceof AST_String) {
                     var value = body.start.raw.slice(1, -1);
@@ -777,9 +789,20 @@ function parse($TEXT, options) {
             return simple_statement();
 
           case "name":
-            return is_token(peek(), "punc", ":")
+            switch (S.token.value) {
-                ? labeled_statement()
+              case "async":
-                : simple_statement();
+                if (is_token(peek(), "keyword", "function")) {
+                    next();
+                    next();
+                    return function_(AST_AsyncDefun);
+                }
+              case "await":
+                if (S.in_async) return simple_statement();
+              default:
+                return is_token(peek(), "punc", ":")
+                    ? labeled_statement()
+                    : simple_statement();
+            }
 
           case "punc":
             switch (S.token.value) {
@@ -865,7 +888,7 @@ function parse($TEXT, options) {
                 if (is("punc", ";")) {
                     next();
                 } else if (!can_insert_semicolon()) {
-                    value = expression(true);
+                    value = expression();
                     semicolon();
                 }
                 return new AST_Return({
@@ -883,7 +906,7 @@ function parse($TEXT, options) {
                 next();
                 if (has_newline_before(S.token))
                     croak("Illegal newline after 'throw'");
-                var value = expression(true);
+                var value = expression();
                 semicolon();
                 return new AST_Throw({
                     value: value
@@ -934,9 +957,7 @@ function parse($TEXT, options) {
             // https://github.com/mishoo/UglifyJS/issues/287
             label.references.forEach(function(ref) {
                 if (ref instanceof AST_Continue) {
-                    ref = ref.label.start;
+                    token_error(ref.label.start, "Continue label `" + label.name + "` must refer to IterationStatement");
-                    croak("Continue label `" + label.name + "` refers to non-IterationStatement.",
-                          ref.line, ref.col, ref.pos);
                 }
             });
         }
@@ -944,7 +965,7 @@ function parse($TEXT, options) {
     }
 
     function simple_statement() {
-        var body = expression(true);
+        var body = expression();
         semicolon();
         return new AST_SimpleStatement({ body: body });
     }
@@ -958,7 +979,7 @@ function parse($TEXT, options) {
             ldef = find_if(function(l) {
                 return l.name == label.name;
             }, S.labels);
-            if (!ldef) croak("Undefined label " + label.name);
+            if (!ldef) token_error(label.start, "Undefined label " + label.name);
             label.thedef = ldef;
         } else if (S.in_loop == 0) croak(type.TYPE + " not inside a loop or switch");
         semicolon();
@@ -977,13 +998,14 @@ function parse($TEXT, options) {
                 ? (next(), let_(true))
                 : is("keyword", "var")
                 ? (next(), var_(true))
-                : expression(true, true);
+                : expression(true);
             if (is("operator", "in")) {
                 if (init instanceof AST_Definitions) {
-                    if (init.definitions.length > 1)
+                    if (init.definitions.length > 1) {
-                        croak("Only one variable declaration allowed in for..in loop", init.start.line, init.start.col, init.start.pos);
+                        token_error(init.start, "Only one variable declaration allowed in for..in loop");
+                    }
                 } else if (!(is_assignable(init) || (init = to_destructured(init)) instanceof AST_Destructured)) {
-                    croak("Invalid left-hand side in for..in loop", init.start.line, init.start.col, init.start.pos);
+                    token_error(init.start, "Invalid left-hand side in for..in loop");
                 }
                 next();
                 return for_in(init);
@@ -994,9 +1016,9 @@ function parse($TEXT, options) {
 
     function regular_for(init) {
         expect(";");
-        var test = is("punc", ";") ? null : expression(true);
+        var test = is("punc", ";") ? null : expression();
         expect(";");
-        var step = is("punc", ")") ? null : expression(true);
+        var step = is("punc", ")") ? null : expression();
         expect(")");
         return new AST_For({
             init      : init,
@@ -1007,7 +1029,7 @@ function parse($TEXT, options) {
     }
 
     function for_in(init) {
-        var obj = expression(true);
+        var obj = expression();
         expect(")");
         return new AST_ForIn({
             init   : init,
@@ -1016,20 +1038,112 @@ function parse($TEXT, options) {
         });
     }
 
+    function to_funarg(node) {
+        if (node instanceof AST_Array) return new AST_DestructuredArray({
+            start: node.start,
+            elements: node.elements.map(to_funarg),
+            end: node.end,
+        });
+        if (node instanceof AST_Assign) return new AST_DefaultValue({
+            start: node.start,
+            name: to_funarg(node.left),
+            value: node.right,
+            end: node.end,
+        });
+        if (node instanceof AST_DefaultValue) {
+            node.name = to_funarg(node.name);
+            return node;
+        }
+        if (node instanceof AST_DestructuredArray) {
+            node.elements = node.elements.map(to_funarg);
+            return node;
+        }
+        if (node instanceof AST_DestructuredObject) {
+            node.properties.forEach(function(prop) {
+                prop.value = to_funarg(prop.value);
+            });
+            return node;
+        }
+        if (node instanceof AST_Hole) return node;
+        if (node instanceof AST_Object) return new AST_DestructuredObject({
+            start: node.start,
+            properties: node.properties.map(function(prop) {
+                if (!(prop instanceof AST_ObjectKeyVal)) token_error(prop.start, "Invalid destructuring assignment");
+                return new AST_DestructuredKeyVal({
+                    start: prop.start,
+                    key: prop.key,
+                    value: to_funarg(prop.value),
+                    end: prop.end,
+                });
+            }),
+            end: node.end,
+        });
+        if (node instanceof AST_SymbolRef) return new AST_SymbolFunarg(node);
+        token_error(node.start, "Invalid arrow parameter");
+    }
+
+    function arrow(exprs, start) {
+        var was_async = S.in_async;
+        S.in_async = false;
+        var was_funarg = S.in_funarg;
+        S.in_funarg = S.in_function;
+        var argnames = exprs.map(to_funarg);
+        S.in_funarg = was_funarg;
+        expect("=>");
+        var body, value;
+        var loop = S.in_loop;
+        var labels = S.labels;
+        ++S.in_function;
+        S.in_directives = true;
+        S.input.push_directives_stack();
+        S.in_loop = 0;
+        S.labels = [];
+        if (is("punc", "{")) {
+            body = block_();
+            value = null;
+            if (S.input.has_directive("use strict")) {
+                argnames.forEach(strict_verify_symbol);
+            }
+        } else {
+            body = [];
+            value = maybe_assign();
+        }
+        S.input.pop_directives_stack();
+        --S.in_function;
+        S.in_loop = loop;
+        S.labels = labels;
+        S.in_async = was_async;
+        return new AST_Arrow({
+            start: start,
+            argnames: argnames,
+            body: body,
+            value: value,
+            end: prev(),
+        });
+    }
+
     var function_ = function(ctor) {
-        var in_statement = ctor === AST_Defun;
+        var was_async = S.in_async;
-        var name = is("name") ? as_symbol(in_statement ? AST_SymbolDefun : AST_SymbolLambda) : null;
+        var name;
-        if (in_statement && !name)
+        if (ctor === AST_AsyncDefun) {
-            expect_token("name");
+            name = as_symbol(AST_SymbolDefun);
+            S.in_async = true;
+        } else if (ctor === AST_Defun) {
+            name = as_symbol(AST_SymbolDefun);
+            S.in_async = false;
+        } else {
+            S.in_async = ctor === AST_AsyncFunction;
+            name = as_symbol(AST_SymbolLambda, true);
+        }
         if (name && ctor !== AST_Accessor && !(name instanceof AST_SymbolDeclaration))
             unexpected(prev());
         expect("(");
-        var argnames = [];
+        var was_funarg = S.in_funarg;
-        for (var first = true; !is("punc", ")");) {
+        S.in_funarg = S.in_function;
-            if (first) first = false; else expect(",");
+        var argnames = expr_list(")", !options.strict, false, function() {
-            argnames.push(maybe_destructured(AST_SymbolFunarg));
+            return maybe_default(AST_SymbolFunarg);
-        }
+        });
-        next();
+        S.in_funarg = was_funarg;
         var loop = S.in_loop;
         var labels = S.labels;
         ++S.in_function;
@@ -1046,6 +1160,7 @@ function parse($TEXT, options) {
         --S.in_function;
         S.in_loop = loop;
         S.labels = labels;
+        S.in_async = was_async;
         return new ctor({
             name: name,
             argnames: argnames,
@@ -1070,7 +1185,7 @@ function parse($TEXT, options) {
         expect("{");
         var a = [];
         while (!is("punc", "}")) {
-            if (is("eof")) expect_token("punc", "}");
+            if (is("eof")) expect("}");
             a.push(statement());
         }
         next();
@@ -1081,13 +1196,13 @@ function parse($TEXT, options) {
         expect("{");
         var a = [], branch, cur, default_branch, tmp;
         while (!is("punc", "}")) {
-            if (is("eof")) expect_token("punc", "}");
+            if (is("eof")) expect("}");
             if (is("keyword", "case")) {
                 if (branch) branch.end = prev();
                 cur = [];
                 branch = new AST_Case({
                     start      : (tmp = S.token, next(), tmp),
-                    expression : expression(true),
+                    expression : expression(),
                     body       : cur
                 });
                 a.push(branch);
@@ -1120,7 +1235,7 @@ function parse($TEXT, options) {
             var name = null;
             if (is("punc", "(")) {
                 next();
-                name = as_symbol(AST_SymbolCatch);
+                name = maybe_destructured(AST_SymbolCatch);
                 expect(")");
             }
             bcatch = new AST_Catch({
@@ -1156,7 +1271,7 @@ function parse($TEXT, options) {
             var value = null;
             if (is("operator", "=")) {
                 next();
-                value = expression(false, no_in);
+                value = maybe_assign(no_in);
             } else if (!no_in && (type === AST_SymbolConst || name instanceof AST_Destructured)) {
                 croak("Missing initializer in declaration");
             }
@@ -1203,7 +1318,7 @@ function parse($TEXT, options) {
         var newexp = expr_atom(false), args;
         if (is("punc", "(")) {
             next();
-            args = expr_list(")");
+            args = expr_list(")", !options.strict);
         } else {
             args = [];
         }
@@ -1220,9 +1335,6 @@ function parse($TEXT, options) {
     function as_atom_node() {
         var tok = S.token, ret;
         switch (tok.type) {
-          case "name":
-            ret = _make_symbol(AST_SymbolRef, tok);
-            break;
           case "num":
             ret = new AST_Number({ start: tok, end: tok, value: tok.value });
             break;
@@ -1264,7 +1376,11 @@ function parse($TEXT, options) {
             switch (start.value) {
               case "(":
                 next();
-                var ex = expression(true);
+                if (is("punc", ")")) {
+                    next();
+                    return arrow([], start);
+                }
+                var ex = expression(false, true);
                 var len = start.comments_before.length;
                 [].unshift.apply(ex.start.comments_before, start.comments_before);
                 start.comments_before.length = 0;
@@ -1287,6 +1403,7 @@ function parse($TEXT, options) {
                 end.comments_after = ex.end.comments_after;
                 ex.end = end;
                 if (ex instanceof AST_Call) mark_pure(ex);
+                if (is("punc", "=>")) return arrow(ex instanceof AST_Sequence ? ex.expressions : [ ex ], start);
                 return subscripts(ex, allow_calls);
               case "[":
                 return subscripts(array_(), allow_calls);
@@ -1295,13 +1412,25 @@ function parse($TEXT, options) {
             }
             unexpected();
         }
-        if (is("keyword", "function")) {
+        var ctor;
+        if (is("name", "async") && is_token(peek(), "keyword", "function")) {
             next();
-            var func = function_(AST_Function);
+            ctor = AST_AsyncFunction;
+        } else if (is("keyword", "function")) {
+            ctor = AST_Function;
+        }
+        if (ctor) {
+            next();
+            var func = function_(ctor);
             func.start = start;
             func.end = prev();
             return subscripts(func, allow_calls);
         }
+        if (is("name")) {
+            var sym = _make_symbol(AST_SymbolRef, start);
+            next();
+            return is("punc", "=>") ? arrow([ sym ], start) : subscripts(sym, allow_calls);
+        }
         if (ATOMIC_START_TOKEN[S.token.type]) {
             return subscripts(as_atom_node(), allow_calls);
         }
@@ -1309,13 +1438,19 @@ function parse($TEXT, options) {
     };
 
     function expr_list(closing, allow_trailing_comma, allow_empty, parser) {
-        if (!parser) parser = expression;
+        if (!parser) parser = maybe_assign;
         var first = true, a = [];
         while (!is("punc", closing)) {
             if (first) first = false; else expect(",");
             if (allow_trailing_comma && is("punc", closing)) break;
-            if (is("punc", ",") && allow_empty) {
+            if (allow_empty && is("punc", ",")) {
                 a.push(new AST_Hole({ start: S.token, end: S.token }));
+            } else if (parser === maybe_assign && is("operator", "...")) {
+                a.push(new AST_Spread({
+                    start: S.token,
+                    expression: (next(), parser()),
+                    end: prev(),
+                }));
             } else {
                 a.push(parser());
             }
@@ -1343,6 +1478,41 @@ function parse($TEXT, options) {
             // allow trailing comma
             if (!options.strict && is("punc", "}")) break;
             var start = S.token;
+            if (is("operator", "...")) {
+                next();
+                a.push(new AST_Spread({
+                    start: start,
+                    expression: maybe_assign(),
+                    end: prev(),
+                }));
+                continue;
+            }
+            if (is_token(peek(), "operator", "=")) {
+                var name = as_symbol(AST_SymbolRef);
+                next();
+                a.push(new AST_ObjectKeyVal({
+                    start: start,
+                    key: start.value,
+                    value: new AST_Assign({
+                        start: start,
+                        left: name,
+                        operator: "=",
+                        right: maybe_assign(),
+                        end: prev(),
+                    }),
+                    end: prev(),
+                }));
+                continue;
+            }
+            if (is_token(peek(), "punc", ",") || is_token(peek(), "punc", "}")) {
+                a.push(new AST_ObjectKeyVal({
+                    start: start,
+                    key: start.value,
+                    value: as_symbol(AST_SymbolRef),
+                    end: prev(),
+                }));
+                continue;
+            }
             var key = as_property_key();
             if (is("punc", "(")) {
                 var func_start = S.token;
@@ -1357,7 +1527,30 @@ function parse($TEXT, options) {
                 }));
                 continue;
             }
-            if (!is("punc", ":") && start.type == "name") switch (key) {
+            if (is("punc", ":")) {
+                next();
+                a.push(new AST_ObjectKeyVal({
+                    start: start,
+                    key: key,
+                    value: maybe_assign(),
+                    end: prev(),
+                }));
+                continue;
+            }
+            if (start.type == "name") switch (key) {
+              case "async":
+                key = as_property_key();
+                var func_start = S.token;
+                var func = function_(AST_AsyncFunction);
+                func.start = func_start;
+                func.end = prev();
+                a.push(new AST_ObjectKeyVal({
+                    start: start,
+                    key: key,
+                    value: func,
+                    end: prev(),
+                }));
+                continue;
               case "get":
                 a.push(new AST_ObjectGetter({
                     start: start,
@@ -1374,22 +1567,8 @@ function parse($TEXT, options) {
                     end: prev(),
                 }));
                 continue;
-              default:
-                a.push(new AST_ObjectKeyVal({
-                    start: start,
-                    key: key,
-                    value: _make_symbol(AST_SymbolRef, start),
-                    end: prev(),
-                }));
-                continue;
             }
-            expect(":");
+            unexpected();
-            a.push(new AST_ObjectKeyVal({
-                start: start,
-                key: key,
-                value: expression(false),
-                end: prev(),
-            }));
         }
         next();
         return new AST_Object({ properties: a });
@@ -1408,9 +1587,8 @@ function parse($TEXT, options) {
             next();
             return "" + tmp.value;
           case "punc":
-            if (tmp.value != "[") unexpected();
+            expect("[");
-            next();
+            var key = maybe_assign();
-            var key = expression(false);
             expect("]");
             return key;
           default:
@@ -1419,14 +1597,14 @@ function parse($TEXT, options) {
     }
 
     function as_name() {
-        if (!is("name")) expect_token("name");
         var name = S.token.value;
-        next();
+        expect_token("name");
         return name;
     }
 
     function _make_symbol(type, token) {
         var name = token.value;
+        if (name === "await" && S.in_async) unexpected(token);
         return new (name === "this" ? AST_This : type)({
             name: "" + name,
             start: token,
@@ -1436,7 +1614,7 @@ function parse($TEXT, options) {
 
     function strict_verify_symbol(sym) {
         if (sym.name == "arguments" || sym.name == "eval")
-            croak("Unexpected " + sym.name + " in strict mode", sym.start.line, sym.start.col, sym.start.pos);
+            token_error(sym.start, "Unexpected " + sym.name + " in strict mode");
     }
 
     function as_symbol(type, noerror) {
@@ -1459,7 +1637,7 @@ function parse($TEXT, options) {
             return new AST_DestructuredArray({
                 start: start,
                 elements: expr_list("]", !options.strict, true, function() {
-                    return maybe_destructured(type);
+                    return maybe_default(type);
                 }),
                 end: prev(),
             });
@@ -1472,21 +1650,31 @@ function parse($TEXT, options) {
                 // allow trailing comma
                 if (!options.strict && is("punc", "}")) break;
                 var key_start = S.token;
-                var key = as_property_key();
+                if (is("punc", "[") || is_token(peek(), "punc", ":")) {
-                if (!is("punc", ":") && key_start.type == "name") {
+                    var key = as_property_key();
+                    expect(":");
                     a.push(new AST_DestructuredKeyVal({
                         start: key_start,
                         key: key,
-                        value: _make_symbol(type, key_start),
+                        value: maybe_default(type),
                         end: prev(),
                     }));
                     continue;
                 }
-                expect(":");
+                var name = as_symbol(type);
+                if (is("operator", "=")) {
+                    next();
+                    name = new AST_DefaultValue({
+                        start: name.start,
+                        name: name,
+                        value: maybe_assign(),
+                        end: prev(),
+                    });
+                }
                 a.push(new AST_DestructuredKeyVal({
                     start: key_start,
-                    key: key,
+                    key: key_start.value,
-                    value: maybe_destructured(type),
+                    value: name,
                     end: prev(),
                 }));
             }
@@ -1500,6 +1688,19 @@ function parse($TEXT, options) {
         return as_symbol(type);
     }
 
+    function maybe_default(type) {
+        var start = S.token;
+        var name = maybe_destructured(type);
+        if (!is("operator", "=")) return name;
+        next();
+        return new AST_DefaultValue({
+            start: start,
+            name: name,
+            value: maybe_assign(),
+            end: prev(),
+        });
+    }
+
     function mark_pure(call) {
         var start = call.start;
         var comments = start.comments_before;
@@ -1526,7 +1727,7 @@ function parse($TEXT, options) {
         }
         if (is("punc", "[")) {
             next();
-            var prop = expression(true);
+            var prop = expression();
             expect("]");
             return subscripts(new AST_Sub({
                 start      : start,
@@ -1540,7 +1741,7 @@ function parse($TEXT, options) {
             var call = new AST_Call({
                 start      : start,
                 expression : expr,
-                args       : expr_list(")"),
+                args       : expr_list(")", !options.strict),
                 end        : prev()
             });
             mark_pure(call);
@@ -1549,17 +1750,17 @@ function parse($TEXT, options) {
         return expr;
     };
 
-    var maybe_unary = function(allow_calls) {
+    function maybe_unary() {
         var start = S.token;
         if (is("operator") && UNARY_PREFIX[start.value]) {
             next();
             handle_regexp();
-            var ex = make_unary(AST_UnaryPrefix, start, maybe_unary(allow_calls));
+            var ex = make_unary(AST_UnaryPrefix, start, maybe_await());
             ex.start = start;
             ex.end = prev();
             return ex;
         }
-        var val = expr_atom(allow_calls);
+        var val = expr_atom(true);
         while (is("operator") && UNARY_POSTFIX[S.token.value] && !has_newline_before(S.token)) {
             val = make_unary(AST_UnaryPostfix, S.token, val);
             val.start = start;
@@ -1567,7 +1768,7 @@ function parse($TEXT, options) {
             next();
         }
         return val;
-    };
+    }
 
     function make_unary(ctor, token, expr) {
         var op = token.value;
@@ -1575,23 +1776,36 @@ function parse($TEXT, options) {
           case "++":
           case "--":
             if (!is_assignable(expr))
-                croak("Invalid use of " + op + " operator", token.line, token.col, token.pos);
+                token_error(token, "Invalid use of " + op + " operator");
             break;
           case "delete":
             if (expr instanceof AST_SymbolRef && S.input.has_directive("use strict"))
-                croak("Calling delete on expression not allowed in strict mode", expr.start.line, expr.start.col, expr.start.pos);
+                token_error(expr.start, "Calling delete on expression not allowed in strict mode");
             break;
         }
         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_unary(true), prec, no_in);
+            var right = expr_op(maybe_await(), prec, no_in);
             return expr_op(new AST_Binary({
                 start    : left.start,
                 left     : left,
@@ -1604,7 +1818,7 @@ function parse($TEXT, options) {
     };
 
     function expr_ops(no_in) {
-        return expr_op(maybe_unary(true), 0, no_in);
+        return expr_op(maybe_await(), 0, no_in);
     }
 
     var maybe_conditional = function(no_in) {
@@ -1612,13 +1826,13 @@ function parse($TEXT, options) {
         var expr = expr_ops(no_in);
         if (is("operator", "?")) {
             next();
-            var yes = expression(false);
+            var yes = maybe_assign();
             expect(":");
             return new AST_Conditional({
                 start       : start,
                 condition   : expr,
                 consequent  : yes,
-                alternative : expression(false, no_in),
+                alternative : maybe_assign(no_in),
                 end         : prev()
             });
         }
@@ -1633,20 +1847,34 @@ function parse($TEXT, options) {
         if (node instanceof AST_Array) {
             var elements = node.elements.map(to_destructured);
             return all(elements, function(node) {
-                return node instanceof AST_Destructured || node instanceof AST_Hole || is_assignable(node);
+                return node instanceof AST_DefaultValue
+                    || node instanceof AST_Destructured
+                    || node instanceof AST_Hole
+                    || is_assignable(node);
             }) ? new AST_DestructuredArray({
                 start: node.start,
                 elements: elements,
                 end: node.end,
             }) : node;
         }
+        if (node instanceof AST_Assign) {
+            var name = to_destructured(node.left);
+            return name instanceof AST_Destructured || is_assignable(name) ? new AST_DefaultValue({
+                start: node.start,
+                name: name,
+                value: node.right,
+                end: node.end,
+            }) : node;
+        }
         if (!(node instanceof AST_Object)) return node;
         var props = [];
         for (var i = 0; i < node.properties.length; i++) {
             var prop = node.properties[i];
             if (!(prop instanceof AST_ObjectKeyVal)) return node;
             var value = to_destructured(prop.value);
-            if (!(value instanceof AST_Destructured || is_assignable(value))) return node;
+            if (!(value instanceof AST_DefaultValue || value instanceof AST_Destructured || is_assignable(value))) {
+                return node;
+            }
             props.push(new AST_DestructuredKeyVal({
                 start: prop.start,
                 key: prop.key,
@@ -1661,7 +1889,7 @@ function parse($TEXT, options) {
         });
     }
 
-    var maybe_assign = function(no_in) {
+    function maybe_assign(no_in) {
         var start = S.token;
         var left = maybe_conditional(no_in), val = S.token.value;
         if (is("operator") && ASSIGNMENT[val]) {
@@ -1678,23 +1906,23 @@ function parse($TEXT, options) {
             croak("Invalid assignment");
         }
         return left;
-    };
+    }
 
-    var expression = function(commas, no_in) {
+    function expression(no_in, maybe_arrow) {
         var start = S.token;
         var exprs = [];
         while (true) {
             exprs.push(maybe_assign(no_in));
-            if (!commas || !is("punc", ",")) break;
+            if (!is("punc", ",")) break;
             next();
-            commas = true;
+            if (maybe_arrow && is("punc", ")") && is_token(peek(), "punc", "=>")) break;
         }
         return exprs.length == 1 ? exprs[0] : new AST_Sequence({
             start       : start,
             expressions : exprs,
-            end         : peek()
+            end         : prev()
         });
-    };
+    }
 
     function in_loop(cont) {
         ++S.in_loop;
@@ -1705,7 +1933,9 @@ function parse($TEXT, options) {
 
     if (options.expression) {
         handle_regexp();
-        return expression(true);
+        var exp = expression();
+        expect_token("eof");
+        return exp;
     }
 
     return function() {

lib/scope.js

@@ -100,6 +100,8 @@ SymbolDef.prototype = {
     },
 };
 
+var unary_side_effects = makePredicate("delete ++ --");
+
 AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
     options = defaults(options, {
         cache: null,
@@ -112,7 +114,7 @@ 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 (node instanceof AST_Defun) {
+        if (is_defun(node)) {
             node.name.walk(tw);
             walk_scope(function() {
                 node.argnames.forEach(function(argname) {
@@ -190,7 +192,7 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
         function entangle(defun, scope) {
             if (defun === scope) return;
             node.mark_enclosed(options);
-            var def = scope.find_variable(node);
+            var def = scope.find_variable(node.name);
             if (node.thedef === def) return;
             node.thedef = def;
             def.orig.push(node);
@@ -206,19 +208,46 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
     self.globals = new Dictionary();
     var in_arg = [];
     var tw = new TreeWalker(function(node) {
+        if (node instanceof AST_Catch) {
+            if (!(node.argname instanceof AST_Destructured)) return;
+            in_arg.push(node);
+            node.argname.walk(tw);
+            in_arg.pop();
+            walk_body(node, tw);
+            return true;
+        }
         if (node instanceof AST_Lambda) {
             in_arg.push(node);
             node.argnames.forEach(function(argname) {
                 argname.walk(tw);
             });
             in_arg.pop();
-            walk_body(node, tw);
+            if (node instanceof AST_Arrow && node.value) {
+                node.value.walk(tw);
+            } else {
+                walk_body(node, tw);
+            }
             return true;
         }
         if (node instanceof AST_LoopControl) {
             if (node.label) node.label.thedef.references.push(node);
             return true;
         }
+        // ensure mangling works if `catch` reuses a scope variable
+        if (node instanceof AST_SymbolCatch) {
+            var def = node.definition().redefined();
+            if (def) for (var s = node.scope; s; s = s.parent_scope) {
+                push_uniq(s.enclosed, def);
+                if (s === def.scope) break;
+            }
+            return true;
+        }
+        // ensure compression works if `const` reuses a scope variable
+        if (node instanceof AST_SymbolConst) {
+            var redef = node.definition().redefined();
+            if (redef) redef.const_redefs = true;
+            return true;
+        }
         if (node instanceof AST_SymbolRef) {
             var name = node.name;
             var sym = node.scope.find_variable(name);
@@ -226,7 +255,9 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
                 i = in_arg.lastIndexOf(sym.scope, i - 1);
                 if (i < 0) break;
                 var decl = sym.orig[0];
-                if (decl instanceof AST_SymbolFunarg || decl instanceof AST_SymbolLambda) {
+                if (decl instanceof AST_SymbolCatch
+                    || decl instanceof AST_SymbolFunarg
+                    || decl instanceof AST_SymbolLambda) {
                     node.in_arg = true;
                     break;
                 }
@@ -234,9 +265,14 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             }
             if (!sym) {
                 sym = self.def_global(node);
-            } else if (name == "arguments" && sym.scope instanceof AST_Lambda) {
+            } else if (name == "arguments" && is_arguments(sym)) {
-                if (!(tw.parent() instanceof AST_PropAccess)) {
+                var parent = tw.parent();
-                    sym.scope.uses_arguments = "d";
+                if (parent instanceof AST_Assign && parent.left === node
+                    || parent instanceof AST_Unary && unary_side_effects[parent.operator]) {
+                    sym.scope.uses_arguments = 3;
+                } else if (sym.scope.uses_arguments < 2
+                    && !(parent instanceof AST_PropAccess && parent.expression === node)) {
+                    sym.scope.uses_arguments = 2;
                 } else if (!sym.scope.uses_arguments) {
                     sym.scope.uses_arguments = true;
                 }
@@ -258,20 +294,12 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
             node.reference(options);
             return true;
         }
-        // ensure mangling works if `catch` reuses a scope variable
+        if (node instanceof AST_VarDef) {
-        if (node instanceof AST_SymbolCatch) {
+            if (node.value && node.name.name == "arguments") {
-            var def = node.definition().redefined();
+                var sym = node.name.scope.resolve().find_variable("arguments");
-            if (def) for (var s = node.scope; s; s = s.parent_scope) {
+                if (sym && is_arguments(sym)) sym.scope.uses_arguments = 3;
-                push_uniq(s.enclosed, def);
-                if (s === def.scope) break;
             }
-            return true;
+            return;
-        }
-        // ensure compression works if `const` reuses a scope variable
-        if (node instanceof AST_SymbolConst) {
-            var redef = node.definition().redefined();
-            if (redef) redef.const_redefs = true;
-            return true;
         }
     });
     self.walk(tw);
@@ -298,6 +326,12 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(options) {
         }
     }));
 
+    function is_arguments(sym) {
+        return sym.orig[0] instanceof AST_SymbolFunarg
+            && !(sym.orig[1] instanceof AST_SymbolFunarg || sym.orig[2] instanceof AST_SymbolFunarg)
+            && !(sym.scope instanceof AST_Arrow);
+    }
+
     function redefine(node, scope) {
         var name = node.name;
         var old_def = node.thedef;
@@ -360,6 +394,9 @@ AST_BlockScope.DEFMETHOD("init_vars", function(parent_scope) {
 AST_Scope.DEFMETHOD("init_vars", function(parent_scope) {
     init_scope_vars(this, parent_scope);
 });
+AST_Arrow.DEFMETHOD("init_vars", function(parent_scope) {
+    init_scope_vars(this, parent_scope);
+});
 AST_Lambda.DEFMETHOD("init_vars", function(parent_scope) {
     init_scope_vars(this, parent_scope);
     this.uses_arguments = false;
@@ -390,14 +427,13 @@ AST_Symbol.DEFMETHOD("reference", function(options) {
 });
 
 AST_BlockScope.DEFMETHOD("find_variable", function(name) {
-    if (name instanceof AST_Symbol) name = name.name;
     return this.variables.get(name)
-        || (this.parent_scope && this.parent_scope.find_variable(name));
+        || this.parent_scope && this.parent_scope.find_variable(name);
 });
 
 AST_BlockScope.DEFMETHOD("def_function", function(symbol, init) {
     var def = this.def_variable(symbol, init);
-    if (!def.init || def.init instanceof AST_Defun) def.init = init;
+    if (!def.init || is_defun(def.init)) def.init = init;
     this.functions.set(symbol.name, def);
     return def;
 });
@@ -406,7 +442,7 @@ AST_BlockScope.DEFMETHOD("def_variable", function(symbol, init) {
     var def = this.variables.get(symbol.name);
     if (def) {
         def.orig.push(symbol);
-        if (def.init instanceof AST_Function) def.init = init;
+        if (is_function(def.init)) def.init = init;
     } else {
         def = this.make_def(symbol, init);
         this.variables.set(symbol.name, def);
@@ -486,6 +522,7 @@ function _default_mangler_options(options) {
         keep_fnames : false,
         reserved    : [],
         toplevel    : false,
+        v8          : false,
         webkit      : false,
     });
     if (!Array.isArray(options.reserved)) options.reserved = [];
@@ -517,7 +554,7 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
             // lname is incremented when we get to the AST_Label
             var save_nesting = lname;
             descend();
-            lname = save_nesting;
+            if (!options.v8 || !in_label(tw)) lname = save_nesting;
             return true;
         }
         if (node instanceof AST_BlockScope) {
@@ -590,6 +627,14 @@ AST_Toplevel.DEFMETHOD("mangle_names", function(options) {
             sym.thedef = def;
         }
     }
+
+    function in_label(tw) {
+        var level = 0, parent;
+        while (parent = tw.parent(level++)) {
+            if (parent instanceof AST_Block) return parent instanceof AST_Toplevel && !options.toplevel;
+            if (parent instanceof AST_LabeledStatement) return true;
+        }
+    }
 });
 
 AST_Toplevel.DEFMETHOD("find_colliding_names", function(options) {

lib/transform.js

@@ -126,11 +126,23 @@ TreeTransformer.prototype = new TreeWalker;
         self.name = self.name.transform(tw);
         if (self.value) self.value = self.value.transform(tw);
     });
+    DEF(AST_DefaultValue, function(self, tw) {
+        self.name = self.name.transform(tw);
+        self.value = self.value.transform(tw);
+    });
     DEF(AST_Lambda, function(self, tw) {
         if (self.name) self.name = self.name.transform(tw);
         self.argnames = do_list(self.argnames, tw);
         self.body = do_list(self.body, tw);
     });
+    DEF(AST_Arrow, function(self, tw) {
+        self.argnames = do_list(self.argnames, tw);
+        if (self.value) {
+            self.value = self.value.transform(tw);
+        } else {
+            self.body = do_list(self.body, tw);
+        }
+    });
     DEF(AST_Call, function(self, tw) {
         self.expression = self.expression.transform(tw);
         self.args = do_list(self.args, tw);
@@ -138,6 +150,9 @@ TreeTransformer.prototype = new TreeWalker;
     DEF(AST_Sequence, function(self, tw) {
         self.expressions = do_list(self.expressions, tw);
     });
+    DEF(AST_Await, function(self, tw) {
+        self.expression = self.expression.transform(tw);
+    });
     DEF(AST_Dot, function(self, tw) {
         self.expression = self.expression.transform(tw);
     });
@@ -145,6 +160,9 @@ TreeTransformer.prototype = new TreeWalker;
         self.expression = self.expression.transform(tw);
         self.property = self.property.transform(tw);
     });
+    DEF(AST_Spread, function(self, tw) {
+        self.expression = self.expression.transform(tw);
+    });
     DEF(AST_Unary, function(self, tw) {
         self.expression = self.expression.transform(tw);
     });

lib/utils.js

@@ -238,13 +238,15 @@ function HOP(obj, prop) {
 // return true if the node at the top of the stack (that means the
 // innermost node in the current output) is lexically the first in
 // a statement.
-function first_in_statement(stack) {
+function first_in_statement(stack, arrow) {
     var node = stack.parent(-1);
     for (var i = 0, p; p = stack.parent(i++); node = p) {
-        if (p.TYPE == "Call") {
+        if (p instanceof AST_Arrow) {
-            if (p.expression === node) continue;
+            return arrow && p.value === node;
         } else if (p instanceof AST_Binary) {
             if (p.left === node) continue;
+        } else if (p.TYPE == "Call") {
+            if (p.expression === node) continue;
         } else if (p instanceof AST_Conditional) {
             if (p.condition === node) continue;
         } else if (p instanceof AST_PropAccess) {

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": "3.12.1",
+  "version": "3.12.4",
   "engines": {
     "node": ">=0.8.0"
   },

test/compress.js

@@ -1,6 +1,6 @@
 "use strict";
 
-require("../tools/exit");
+require("../tools/tty");
 
 var assert = require("assert");
 var child_process = require("child_process");

test/compress/arguments.js

@@ -78,7 +78,7 @@ replace_index_strict: {
     ]
 }
 
-replace_index_keep_fargs: {
+replace_index_drop_fargs_1: {
     options = {
         arguments: true,
         evaluate: true,
@@ -101,6 +101,13 @@ replace_index_keep_fargs: {
             var arguments;
             console.log(arguments[1], arguments["1"], arguments["foo"]);
         })("bar", 42);
+        (function() {
+            var arguments = {
+                1: "foo",
+                foo: "bar",
+            };
+            console.log(arguments[1], arguments["1"], arguments["foo"]);
+        })("bar", 42);
     }
     expect: {
         var arguments = [];
@@ -114,8 +121,15 @@ replace_index_keep_fargs: {
         (function(arguments) {
             console.log(arguments[1], arguments[1], arguments.foo);
         })("bar", 42);
-        (function() {
+        (function(argument_0, argument_1) {
             var arguments;
+            console.log(argument_1, argument_1, arguments.foo);
+        })("bar", 42);
+        (function() {
+            var arguments = {
+                1: "foo",
+                foo: "bar",
+            };
             console.log(arguments[1], arguments[1], arguments.foo);
         })("bar", 42);
     }
@@ -125,10 +139,11 @@ replace_index_keep_fargs: {
         "42 42 undefined",
         "a a undefined",
         "42 42 undefined",
+        "foo foo bar",
     ]
 }
 
-replace_index_keep_fargs_strict: {
+replace_index_drop_fargs_2: {
     options = {
         arguments: true,
         evaluate: true,
@@ -412,7 +427,7 @@ issue_3273_global_strict_reduce_vars: {
     ]
 }
 
-issue_3273_keep_fargs_false: {
+issue_3273_drop_fargs_1: {
     options = {
         arguments: true,
         keep_fargs: false,
@@ -435,10 +450,10 @@ issue_3273_keep_fargs_false: {
     expect_stdout: "1"
 }
 
-issue_3273_keep_fargs_strict: {
+issue_3273_drop_fargs_2: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
     }
     input: {
@@ -633,7 +648,7 @@ issue_3282_2_passes: {
 issue_3420_1: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         console.log(function() {
@@ -655,7 +670,7 @@ issue_3420_1: {
 issue_3420_2: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         var foo = function() {
@@ -675,7 +690,7 @@ issue_3420_2: {
 issue_3420_3: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         "use strict";
@@ -697,7 +712,7 @@ issue_3420_3: {
 issue_3420_4: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         !function() {
@@ -722,7 +737,7 @@ issue_3420_4: {
 issue_3420_5: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         "use strict";
@@ -749,7 +764,7 @@ issue_3420_5: {
 issue_3420_6: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         console.log(function() {
@@ -767,7 +782,7 @@ issue_3420_6: {
 issue_3420_7: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         "use strict";
@@ -811,7 +826,7 @@ issue_4200: {
 issue_4291_1: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         console.log(function() {
@@ -831,7 +846,7 @@ issue_4291_1: {
 issue_4291_2: {
     options = {
         arguments: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         var a = function() {
@@ -851,3 +866,114 @@ issue_4291_2: {
     }
     expect_stdout: "PASS 42 1"
 }
+
+issue_4397: {
+    options = {
+        arguments: true,
+        keep_fargs: false,
+    }
+    input: {
+        console.log(typeof function() {
+            arguments += 0;
+            return arguments[0];
+        }());
+    }
+    expect: {
+        console.log(typeof function() {
+            arguments += 0;
+            return arguments[0];
+        }());
+    }
+    expect_stdout: "string"
+}
+
+issue_4410_1: {
+    options = {
+        arguments: true,
+        conditionals: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        (function(a) {
+            console.log(arguments[0] === (a = 0) ? "FAIL" : "PASS");
+        })(1);
+    }
+    expect: {
+        (function(a) {
+            console.log(a === (a = 0) ? "FAIL" : "PASS");
+        })(1);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4410_2: {
+    options = {
+        arguments: true,
+        conditionals: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        (function f(a) {
+            console.log(arguments[0] === (a = 0) ? "FAIL" : "PASS");
+        })(1);
+    }
+    expect: {
+        (function f(a) {
+            console.log(arguments[0] === (a = 0) ? "FAIL" : "PASS");
+        })(1);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4410_3: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        var a = 1;
+        (function f(b) {
+            a-- && f();
+            for (var c = 2; c--;)
+                switch (arguments[0]) {
+                  case b = 42:
+                  case 42:
+                    console.log("PASS");
+                }
+        })(null);
+    }
+    expect: {
+        var a = 1;
+        (function f(b) {
+            a-- && f();
+            for (var c = 2; c--;)
+                switch (arguments[0]) {
+                  case b = 42:
+                  case 42:
+                    console.log("PASS");
+                }
+        })(null);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4432: {
+    options = {
+        arguments: true,
+        reduce_vars: true,
+    }
+    input: {
+        console.log(function(a) {
+            for (a in { FAIL: 42 });
+            return arguments[0];
+        }() || "PASS");
+    }
+    expect: {
+        console.log(function(a) {
+            for (a in { FAIL: 42 });
+            return arguments[0];
+        }() || "PASS");
+    }
+    expect_stdout: "PASS"
+}

test/compress/arrows.js

@@ -0,0 +1,640 @@
+no_funarg: {
+    input: {
+        (() => console.log(42))();
+    }
+    expect_exact: "(()=>console.log(42))();"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+single_funarg: {
+    input: {
+        (a => console.log(a))(42);
+    }
+    expect_exact: "(a=>console.log(a))(42);"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+multiple_funargs: {
+    input: {
+        ((a, b) => console.log(a, b))("foo", "bar");
+    }
+    expect_exact: '((a,b)=>console.log(a,b))("foo","bar");'
+    expect_stdout: "foo bar"
+    node_version: ">=4"
+}
+
+destructured_funarg: {
+    input: {
+        (([ a, b, c ]) => console.log(a, b, c))("foo");
+    }
+    expect_exact: '(([a,b,c])=>console.log(a,b,c))("foo");'
+    expect_stdout: "f o o"
+    node_version: ">=6"
+}
+
+await_parenthesis: {
+    input: {
+        async function f() {
+            await (a => a);
+        }
+    }
+    expect_exact: "async function f(){await(a=>a)}"
+}
+
+for_parenthesis_init: {
+    input: {
+        for (a => (a in a); console.log(42););
+    }
+    expect_exact: "for((a=>a in a);console.log(42););"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+for_parenthesis_condition: {
+    input: {
+        for (console.log(42); a => (a in a);)
+            break;
+    }
+    expect_exact: "for(console.log(42);a=>a in a;)break;"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+for_parenthesis_step: {
+    input: {
+        for (; console.log(42); a => (a in a));
+    }
+    expect_exact: "for(;console.log(42);a=>a in a);"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+for_assign_parenthesis_init: {
+    input: {
+        for (f = a => (a in a); console.log(42););
+    }
+    expect_exact: "for((f=a=>a in a);console.log(42););"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+for_assign_parenthesis_condition: {
+    input: {
+        for (console.log(42); f = a => (a in a);)
+            break;
+    }
+    expect_exact: "for(console.log(42);f=a=>a in a;)break;"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+for_assign_parenthesis_step: {
+    input: {
+        for (; console.log(42); f = a => (a in a));
+    }
+    expect_exact: "for(;console.log(42);f=a=>a in a);"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+for_declaration_parenthesis_init: {
+    input: {
+        for (var f = a => (a in a); console.log(42););
+    }
+    expect_exact: "for(var f=(a=>a in a);console.log(42););"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+for_statement_parenthesis_init: {
+    input: {
+        for (a => {
+            a in a;
+        }; console.log(42););
+    }
+    expect_exact: "for(a=>{a in a};console.log(42););"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+body_call: {
+    input: {
+        (() => {
+            console.log("foo");
+            console.log("bar");
+        })();
+    }
+    expect_exact: '(()=>{console.log("foo");console.log("bar")})();'
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=4"
+}
+
+body_conditional: {
+    input: {
+        console.log((a => {}) ? "PASS" : "FAIL");
+    }
+    expect_exact: 'console.log((a=>{})?"PASS":"FAIL");'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+destructured_object_value: {
+    input: {
+        console.log((a => ({} = a))(42));
+    }
+    expect_exact: "console.log((a=>({}=a))(42));"
+    expect_stdout: "42"
+    node_version: ">=6"
+}
+
+function_value: {
+    input: {
+        console.log((a => function() {
+            return a;
+        })(42)());
+    }
+    expect_exact: "console.log((a=>function(){return a})(42)());"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+in_value: {
+    input: {
+        console.log((a => a in {
+            foo: 42,
+        })("foo"));
+    }
+    expect_exact: 'console.log((a=>a in{foo:42})("foo"));'
+    expect_stdout: "true"
+    node_version: ">=4"
+}
+
+object_value: {
+    input: {
+        console.log((() => ({
+            4: 2,
+        }))()[4]);
+    }
+    expect_exact: "console.log((()=>({4:2}))()[4]);"
+    expect_stdout: "2"
+    node_version: ">=4"
+}
+
+object_first_in_value: {
+    input: {
+        console.log((a => ({
+            p: a,
+        }.p ? "FAIL" : "PASS"))());
+    }
+    expect_exact: 'console.log((a=>({p:a}).p?"FAIL":"PASS")());'
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+sequence_value: {
+    input: {
+        console.log((a => (console.log("foo"), a))("bar"));
+    }
+    expect_exact: 'console.log((a=>(console.log("foo"),a))("bar"));'
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=4"
+}
+
+side_effects_value: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        console.log((a => function() {
+            return a;
+        })(42)());
+    }
+    expect: {
+        console.log((a => function() {
+            return a;
+        })(42)());
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+arrow_property: {
+    input: {
+        console.log((a => 42).prototype);
+    }
+    expect_exact: "console.log((a=>42).prototype);"
+    expect_stdout: "undefined"
+    node_version: ">=4"
+}
+
+assign_arrow: {
+    input: {
+        var f = a => a;
+        console.log(f(42));
+    }
+    expect_exact: "var f=a=>a;console.log(f(42));"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+binary_arrow: {
+    input: {
+        console.log(4 || (() => 2));
+    }
+    expect_exact: "console.log(4||(()=>2));"
+    expect_stdout: "4"
+    node_version: ">=4"
+}
+
+unary_arrow: {
+    input: {
+        console.log(+(() => 42));
+    }
+    expect_exact: "console.log(+(()=>42));"
+    expect_stdout: "NaN"
+    node_version: ">=4"
+}
+
+trailing_comma: {
+    input: {
+        ((a,) => console.log(a))(42);
+    }
+    expect_exact: "(a=>console.log(a))(42);"
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+drop_arguments: {
+    options = {
+        arguments: true,
+        keep_fargs: false,
+    }
+    input: {
+        console.log(function() {
+            return () => arguments[0];
+        }("PASS")("FAIL"));
+    }
+    expect: {
+        console.log(function(argument_0) {
+            return () => argument_0;
+        }("PASS")("FAIL"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+funarg_arguments: {
+    options = {
+        inline: true,
+    }
+    input: {
+        console.log((arguments => arguments)(42));
+    }
+    expect: {
+        console.log(42);
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+inline_arguments: {
+    options = {
+        inline: true,
+    }
+    input: {
+        console.log(function() {
+            return () => arguments[0];
+        }("PASS")("FAIL"));
+    }
+    expect: {
+        console.log(function() {
+            return () => arguments[0];
+        }("PASS")("FAIL"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+var_arguments: {
+    options = {
+        inline: true,
+        properties: true,
+        reduce_vars: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            return () => {
+                var arguments = [ "PASS" ];
+                return arguments;
+            };
+        }("FAIL 1")("FAIL 2")[0]);
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+negate: {
+    options = {
+        conditionals: true,
+    }
+    input: {
+        if (!console ? 0 : () => 1)
+            console.log("PASS");
+    }
+    expect: {
+        (console ? () => 1 : 0) && console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+inline_this: {
+    options = {
+        inline: true,
+    }
+    input: {
+        var o = {
+            p: function() {
+                return function() {
+                    return () => this.q;
+                }();
+            },
+            q: "FAIL",
+        };
+        q = "PASS";
+        console.log(o.p()());
+    }
+    expect: {
+        var o = {
+            p: function() {
+                return function() {
+                    return () => this.q;
+                }();
+            },
+            q: "FAIL",
+        };
+        q = "PASS";
+        console.log(o.p()());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+trim_body: {
+    options = {
+        arrows: true,
+        if_return: true,
+        side_effects: true,
+    }
+    input: {
+        var f = a => {
+            return a;
+        };
+        var g = b => void b;
+        console.log(f("PASS"), g("FAIL"));
+    }
+    expect: {
+        var f = a => a;
+        var g = b => {};
+        console.log(f("PASS"), g("FAIL"));
+    }
+    expect_stdout: "PASS undefined"
+    node_version: ">=4"
+}
+
+collapse_value: {
+    options = {
+        arrows: true,
+        collapse_vars: true,
+        keep_fargs: false,
+        unused: true,
+    }
+    input: {
+        var a = 42;
+        console.log((b => Math.floor(b))(a));
+    }
+    expect: {
+        var a = 42;
+        console.log((() => Math.floor(a))());
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+reduce_iife_1: {
+    options = {
+        evaluate: true,
+        keep_fargs: false,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (a => console.log(a + a))(21);
+    }
+    expect: {
+        (() => console.log(42))();
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+reduce_iife_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 21;
+        (() => console.log(a + a))();
+    }
+    expect: {
+        (() => console.log(42))();
+    }
+    expect_stdout: "42"
+    node_version: ">=4"
+}
+
+reduce_iife_3: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "foo";
+        (() => {
+            console.log(a);
+            console.log(a);
+        })();
+        a = "bar";
+    }
+    expect: {
+        (() => {
+            console.log("foo");
+            console.log("foo");
+        })();
+    }
+    expect_stdout: [
+        "foo",
+        "foo",
+    ]
+    node_version: ">=4"
+}
+
+single_use_recursive: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            return (() => f)();
+        }
+        console.log(typeof f());
+    }
+    expect: {
+        console.log(typeof function f() {
+            return (() => f)();
+        }());
+    }
+    expect_stdout: "function"
+    node_version: ">=4"
+}
+
+issue_4388: {
+    options = {
+        inline: true,
+        toplevel: true,
+    }
+    input: {
+        (arguments => console.log(arguments && arguments))();
+    }
+    expect: {
+        (arguments => console.log(arguments && arguments))();
+    }
+    expect_stdout: "undefined"
+    node_version: ">=4"
+}
+
+issue_4390: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        function log() {
+            console.log.apply(console, arguments);
+        }
+        var a = 42, b = "FAIL";
+        b = "PASS";
+        (c => log(b, c))(a);
+        log(b);
+    }
+    expect: {
+        function log() {
+            console.log.apply(console, arguments);
+        }
+        var a = 42, b = "FAIL";
+        b = "PASS";
+        (c => log(b, c))(a);
+        log(b);
+    }
+    expect_stdout: [
+        "PASS 42",
+        "PASS",
+    ]
+    node_version: ">=4"
+}
+
+issue_4401: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        (function() {
+            var a = (b => b(a))(console.log || a);
+            var c = console.log;
+            c && c(typeof b);
+        })();
+    }
+    expect: {
+        (function() {
+            var a = (b => b(a))(console.log || a);
+            var c = console.log;
+            c && c(typeof b);
+        })();
+    }
+    expect_stdout: [
+        "undefined",
+        "undefined",
+    ]
+    node_version: ">=4"
+}
+
+issue_4448: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        var A;
+        try {
+            (arguments => {
+                arguments[0];
+            })(A);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        var A;
+        try {
+            (arguments => {
+                arguments[0];
+            })(A);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4476: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        (function(a, b) {
+            (a => {
+                console.log(arguments[0], a);
+            })(b);
+        })("foo", "bar");
+    }
+    expect: {
+        (function(a, b) {
+            (a => {
+                console.log(arguments[0], a);
+            })(b);
+        })("foo", "bar");
+    }
+    expect_stdout: "foo bar"
+    node_version: ">=4"
+}

test/compress/async.js

@@ -0,0 +1,746 @@
+await_await: {
+    input: {
+        (async function() {
+            console.log("PASS");
+            await await 42;
+        })();
+    }
+    expect: {
+        (async function() {
+            console.log("PASS");
+            await await 42;
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+defun_name: {
+    input: {
+        async function await() {
+            console.log("PASS");
+        }
+        await();
+    }
+    expect: {
+        async function await() {
+            console.log("PASS");
+        }
+        await();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+drop_fname: {
+    rename = true
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    mangle = {
+        toplevel: true,
+    }
+    input: {
+        async function await() {
+            console.log("PASS");
+        }
+        await();
+    }
+    expect: {
+        (async function() {
+            console.log("PASS");
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+keep_fname: {
+    options = {
+        keep_fnames: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        async function await() {
+            console.log("PASS");
+        }
+        await();
+    }
+    expect: {
+        async function await() {
+            console.log("PASS");
+        }
+        await();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+nested_await: {
+    input: {
+        (async function() {
+            console.log(function(await) {
+                return await;
+            }("PASS"));
+        })();
+    }
+    expect: {
+        (async function() {
+            console.log(function(await) {
+                return await;
+            }("PASS"));
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+reduce_single_use_defun: {
+    options = {
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        async function f(a) {
+            console.log(a);
+        }
+        f("PASS");
+    }
+    expect: {
+        (async function(a) {
+            console.log(a);
+        })("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+dont_inline: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function() {
+            A;
+        })().catch(function() {});
+        console.log("PASS");
+    }
+    expect: {
+        (async function() {
+            A;
+        })().catch(function() {});
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+evaluate: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = async function() {}();
+        console.log(typeof a);
+    }
+    expect: {
+        var a = async function() {}();
+        console.log(typeof a);
+    }
+    expect_stdout: "object"
+    node_version: ">=8"
+}
+
+negate: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        console && async function() {} && console.log("PASS");
+    }
+    expect: {
+        console && async function() {} && console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+negate_iife: {
+    options = {
+        negate_iife: true,
+    }
+    input: {
+        (async function() {
+            console.log("PASS");
+        })();
+    }
+    expect: {
+        !async function() {
+            console.log("PASS");
+        }();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+object_function: {
+    options = {
+        properties: true,
+        side_effects: true,
+    }
+    input: {
+        ({
+            async f() {
+                console.log("PASS");
+            },
+        }).f();
+    }
+    expect: {
+        (async function() {
+            console.log("PASS");
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+collapse_vars_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        (async function() {
+            a = "PASS";
+            await 42;
+            return "PASS";
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (async function() {
+            a = "PASS";
+            await 42;
+            return "PASS";
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+collapse_vars_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        (async function() {
+            await (a = "PASS");
+            return "PASS";
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (async function() {
+            await (a = "PASS");
+            return "PASS";
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+collapse_vars_3: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        (async function() {
+            await (a = "PASS", 42);
+            return "PASS";
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        (async function() {
+            await (a = "PASS", 42);
+            return "PASS";
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4335_1: {
+    options = {
+        inline: true,
+    }
+    input: {
+        var await = "PASS";
+        (async function() {
+            console.log(function() {
+                return await;
+            }());
+        })();
+    }
+    expect: {
+        var await = "PASS";
+        (async function() {
+            console.log(function() {
+                return await;
+            }());
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4335_2: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function() {
+            console.log(function() {
+                function await() {}
+                return "PASS";
+            }());
+        })();
+    }
+    expect: {
+        (async function() {
+            console.log(function() {
+                function await() {}
+                return "PASS";
+            }());
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4337: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function(a) {
+            a();
+        })(async function() {
+            console.log("PASS");
+        });
+    }
+    expect: {
+        (function(a) {
+            (async function() {
+                console.log("PASS");
+            })();
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4340: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        (async function a(a) {
+            console.log(a || "PASS");
+        })();
+    }
+    expect: {
+        (async function a(a) {
+            console.log(a || "PASS");
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+call_expression: {
+    input: {
+        console.log(typeof async function(log) {
+            (await log)("FAIL");
+        }(console.log).then);
+    }
+    expect_exact: 'console.log(typeof async function(log){(await log)("FAIL")}(console.log).then);'
+    expect_stdout: "function"
+    node_version: ">=8"
+}
+
+property_access_expression: {
+    input: {
+        console.log(typeof async function(con) {
+            (await con).log("FAIL");
+        }(console).then);
+    }
+    expect_exact: 'console.log(typeof async function(con){(await con).log("FAIL")}(console).then);'
+    expect_stdout: "function"
+    node_version: ">=8"
+}
+
+reduce_iife_1: {
+    options = {
+        evaluate: true,
+        keep_fargs: false,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (async function(a) {
+            console.log(a + a);
+        })(21);
+    }
+    expect: {
+        (async function() {
+            console.log(42);
+        })();
+    }
+    expect_stdout: "42"
+    node_version: ">=8"
+}
+
+reduce_iife_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 21;
+        (async function() {
+            console.log(a + a);
+        })();
+    }
+    expect: {
+        (async function() {
+            console.log(42);
+        })();
+    }
+    expect_stdout: "42"
+    node_version: ">=8"
+}
+
+reduce_iife_3: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "foo";
+        (async function() {
+            console.log(a);
+            console.log(await a);
+        })();
+        a = "bar";
+    }
+    expect: {
+        var a = "foo";
+        (async function() {
+            console.log(a);
+            console.log(await a);
+        })();
+        a = "bar";
+    }
+    expect_stdout: "foo"
+    node_version: ">=8"
+}
+
+issue_4347_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "foo";
+        f();
+        a = "bar";
+        f();
+        async function f() {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = "foo";
+        f();
+        a = "bar";
+        f();
+        async function f() {
+            console.log(a);
+        }
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=8"
+}
+
+issue_4347_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (async function() {
+            throw 42;
+            a = "FAIL";
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (async function() {
+            throw 42;
+            a = "FAIL";
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4349_1: {
+    input: {
+        console.log(typeof async function() {
+            await /abc/;
+        }().then);
+    }
+    expect_exact: "console.log(typeof async function(){await/abc/}().then);"
+    expect_stdout: "function"
+    node_version: ">=8"
+}
+
+issue_4349_2: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof async function() {
+            (function(a) {
+                this[a];
+            }(await 0));
+        }().then);
+    }
+    expect: {
+        console.log(typeof async function() {
+            (function(a) {
+                this[a];
+            }(await 0));
+        }().then);
+    }
+    expect_stdout: "function"
+    node_version: ">=8"
+}
+
+issue_4349_3: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(typeof function(await) {
+            return async function(a) {
+                this[a];
+            }(await);
+        }(this).then);
+    }
+    expect: {
+        console.log(typeof function(await) {
+            return async function(a) {
+                this[a];
+            }(await);
+        }(this).then);
+    }
+    expect_stdout: "function"
+    node_version: ">=8"
+}
+
+issue_4359: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        try {
+            (async function(a) {
+                return a;
+            })(A);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            (async function(a) {
+                return a;
+            })(A);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4377: {
+    options = {
+        dead_code: true,
+        inline: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(typeof function() {
+            return function() {
+                f;
+                async function f() {}
+                return f();
+            }();
+        }().then);
+    }
+    expect: {
+        console.log(typeof function() {
+            return f();
+            async function f() {}
+        }().then);
+    }
+    expect_stdout: "function"
+    node_version: ">=8"
+}
+
+issue_4406: {
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        A = "PASS";
+        B = "FAIL";
+        (function() {
+            var a, b;
+            a = A;
+            (async function({
+                [console.log(a)]: {},
+            }) {})((b = B) && { undefined: b });
+        })();
+    }
+    expect: {
+        A = "PASS";
+        B = "FAIL";
+        (function() {
+            var a, b;
+            a = A;
+            (async function({
+                [console.log(a)]: {},
+            }) {})((b = B) && { undefined: b });
+        })();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4417: {
+    options = {
+        inline: true,
+    }
+    input: {
+        (async function() {
+            console.log(function() {
+                return await => 0;
+            }().prototype);
+        })();
+    }
+    expect: {
+        (async function() {
+            console.log(function() {
+                return await => 0;
+            }().prototype);
+        })();
+    }
+    expect_stdout: "undefined"
+    node_version: ">=8"
+}
+
+issue_4454_1: {
+    rename = false
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        function f(a) {
+            (async function(b = console.log(a)) {})();
+            var await = 42..toString();
+            console.log(await);
+        }
+        f("PASS");
+    }
+    expect: {
+        function f(a) {
+            (async function(b = console.log(a)) {})();
+            var await = 42..toString();
+            console.log(await);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=8"
+}
+
+issue_4454_2: {
+    rename = true
+    options = {
+        merge_vars: true,
+    }
+    input: {
+        function f(a) {
+            (async function(b = console.log(a)) {})();
+            var await = 42..toString();
+            console.log(await);
+        }
+        f("PASS");
+    }
+    expect: {
+        function f(b) {
+            (async function(c = console.log(b)) {})();
+            var b = 42..toString();
+            console.log(b);
+        }
+        f("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "42",
+    ]
+    node_version: ">=8"
+}

test/compress/booleans.js

@@ -153,3 +153,31 @@ issue_3690: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4374: {
+    options = {
+        booleans: true,
+        conditionals: true,
+        if_return: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            console.log(f());
+            function f(a) {
+                if (null) return 0;
+                if (a) return 1;
+                return 0;
+            }
+        })();
+    }
+    expect: {
+        (function() {
+            console.log(function(a) {
+                return !null && a ? 1 : 0;
+            }());
+        })();
+    }
+    expect_stdout: "0"
+}

test/compress/collapse_vars.js

@@ -4273,8 +4273,8 @@ issue_2436_14: {
         var b = {};
         (function() {
             a && function(c, d) {
-                console.log(c, d);
+                console.log(b, d);
-            }(b, a);
+            }(0, a);
         })();
     }
     expect_stdout: true
@@ -8602,3 +8602,63 @@ issue_4248: {
     }
     expect_stdout: "1"
 }
+
+issue_4430_1: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+    }
+    input: {
+        function f(a) {
+            switch (a = 1, arguments[0]) {
+              case 1:
+                return "PASS";
+              case 2:
+                return "FAIL";
+            }
+        }
+        console.log(f(2));
+    }
+    expect: {
+        function f(a) {
+            switch (a = 1, arguments[0]) {
+              case 1:
+                return "PASS";
+              case 2:
+                return "FAIL";
+            }
+        }
+        console.log(f(2));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4430_2: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+    }
+    input: {
+        function f(a) {
+            switch (a = 0, arguments[0]) {
+              case 0:
+                return "PASS";
+              case 1:
+                return "FAIL";
+            }
+        }
+        console.log(f(1));
+    }
+    expect: {
+        function f(a) {
+            switch (arguments[a = 0]) {
+              case 0:
+                return "PASS";
+              case 1:
+                return "FAIL";
+            }
+        }
+        console.log(f(1));
+    }
+    expect_stdout: "PASS"
+}

test/compress/const.js

@@ -658,6 +658,30 @@ legacy_scope: {
     expect_stdout: true
 }
 
+hoist_vars: {
+    options = {
+        hoist_vars: true,
+    }
+    input: {
+        {
+            const a = "FAIL";
+            var b = 42;
+        }
+        var a = "PASS";
+        console.log(a, b);
+    }
+    expect: {
+        var b;
+        {
+            const a = "FAIL";
+            b = 42;
+        }
+        var a = "PASS";
+        console.log(a, b);
+    }
+    expect_stdout: true
+}
+
 issue_4191: {
     options = {
         functions: true,
@@ -1347,3 +1371,31 @@ issue_4305_2: {
     }
     expect_stdout: true
 }
+
+issue_4365_1: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        const arguments = 42;
+    }
+    expect: {
+        const arguments = 42;
+    }
+    expect_stdout: true
+}
+
+issue_4365_2: {
+    options = {
+        toplevel: true,
+        varify: true,
+    }
+    input: {
+        const arguments = 42;
+    }
+    expect: {
+        const arguments = 42;
+    }
+    expect_stdout: true
+}

test/compress/dead-code.js

@@ -1375,3 +1375,27 @@ issue_4051: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4366: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        function f() {
+            return "PASS";
+            ({
+                p: 42,
+                get p() {},
+            });
+        }
+        console.log(f());
+    }
+    expect: {
+        function f() {
+            return "PASS";
+        }
+        console.log(f());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/destructured.js

@@ -40,7 +40,7 @@ redefine_arguments_2: {
 
 redefine_arguments_3: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -259,7 +259,7 @@ funarg_side_effects_3: {
 
 funarg_unused_1: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -318,7 +318,7 @@ funarg_unused_3: {
 
 funarg_unused_4: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         pure_getters: "strict",
         unused: true,
     }
@@ -384,7 +384,7 @@ funarg_unused_6_inline: {
 
 funarg_unused_6_keep_fargs: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -426,7 +426,7 @@ funarg_collapse_vars_1: {
 funarg_collapse_vars_2: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -505,7 +505,7 @@ funarg_reduce_vars_1: {
 funarg_reduce_vars_2: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         pure_getters: "strict",
         reduce_vars: true,
         unsafe: true,
@@ -691,6 +691,28 @@ funarg_inline: {
     node_version: ">=6"
 }
 
+process_boolean_returns: {
+    options = {
+        booleans: true,
+    }
+    input: {
+        console.log(function({ length }) {
+            return length ? "FAIL" : "PASS";
+        }(function() {
+            return 42;
+        }));
+    }
+    expect: {
+        console.log(function({ length }) {
+            return length ? "FAIL" : "PASS";
+        }(function() {
+            return 42;
+        }));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 simple_const: {
     options = {
         evaluate: true,
@@ -750,6 +772,46 @@ simple_var: {
     node_version: ">=6"
 }
 
+drop_catch: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        try {} catch ({
+            [console.log("FAIL")]: e,
+        }) {} finally {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+drop_catch_var: {
+    options = {
+        unused: true,
+    }
+    input: {
+        try {
+            throw new Error("PASS");
+        } catch ({ name, message }) {
+            console.log(message);
+        }
+    }
+    expect: {
+        try {
+            throw new Error("PASS");
+        } catch ({ message }) {
+            console.log(message);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
 collapse_vars_1: {
     options = {
         collapse_vars: true,
@@ -1061,7 +1123,7 @@ join_vars: {
 
 keep_fargs: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -1296,6 +1358,24 @@ fn_name_unused: {
     node_version: ">=6"
 }
 
+hoist_vars: {
+    options = {
+        hoist_vars: true,
+    }
+    input: {
+        var a = "PASS";
+        var [ b ] = [ 42 ];
+        console.log(a, b);
+    }
+    expect: {
+        var a = "PASS";
+        var [ b ] = [ 42 ];
+        console.log(a, b);
+    }
+    expect_stdout: "PASS 42"
+    node_version: ">=6"
+}
+
 issue_4280: {
     options = {
         evaluate: true,
@@ -1714,7 +1794,7 @@ issue_4319: {
 issue_4321: {
     options = {
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         try {
@@ -1777,3 +1857,448 @@ issue_4323: {
     expect_stdout: "function"
     node_version: ">=6"
 }
+
+issue_4355: {
+    options = {
+        loops: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        (function({
+            [function() {
+                for (a in "foo");
+            }()]: b,
+        }) {
+            var a;
+        })(0);
+        console.log(a);
+    }
+    expect: {
+        var a;
+        (function({
+            [function() {
+                for (a in "foo");
+            }()]: b,
+        }) {})(0);
+        console.log(a);
+    }
+    expect_stdout: "2"
+    node_version: ">=6"
+}
+
+issue_4372_1: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        var a = "FAIL";
+        a += {
+            [console.log(a)]: a,
+        } = a = "PASS";
+    }
+    expect: {
+        var a = "FAIL";
+        a += {
+            [console.log(a)]: a,
+        } = a = "PASS";
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4372_2: {
+    options = {
+        dead_code: true,
+    }
+    input: {
+        var a;
+        [ a ] = a = [ "PASS", "FAIL" ];
+        console.log(a);
+    }
+    expect: {
+        var a;
+        [ a ] = [ "PASS", "FAIL" ];
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4383: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        unsafe: true,
+    }
+    input: {
+        console.log(function(a) {
+            [ a[0] ] = [];
+            return a.length;
+        }([]));
+    }
+    expect: {
+        console.log(function(a) {
+            [ a[0] ] = [];
+            return a.length;
+        }([]));
+    }
+    expect_stdout: "1"
+    node_version: ">=6"
+}
+
+issue_4386: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        function f({}) {
+            return arguments[0];
+        }
+        console.log(f("PASS"));
+    }
+    expect: {
+        function f({}) {
+            return arguments[0];
+        }
+        console.log(f("PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4395: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        console.log(function(a, {}) {
+            a = "FAIL";
+            return arguments[0];
+        }("PASS", 42));
+    }
+    expect: {
+        console.log(function(a, {}) {
+            a = "FAIL";
+            return arguments[0];
+        }("PASS", 42));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4399: {
+    options = {
+        arguments: true,
+    }
+    input: {
+        console.log(function({
+            [arguments[1]]: a,
+        }, b) {
+            return a;
+        }([ "PASS" ], 0));
+    }
+    expect: {
+        console.log(function({
+            [arguments[1]]: a,
+        }, b) {
+            return a;
+        }([ "PASS" ], 0));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4420: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            var a = 1;
+            try {
+                throw [ "FAIL", "PASS" ];
+            } catch ({
+                [a]: b,
+            }) {
+                let a = 0;
+                return b;
+            }
+        }());
+    }
+    expect: {
+        console.log(function() {
+            var a = 1;
+            try {
+                throw [ "FAIL", "PASS" ];
+            } catch ({
+                [a]: b,
+            }) {
+                return b;
+            }
+        }());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4425: {
+    rename = true
+    input: {
+        var a;
+        console.log(function() {
+            try {
+                try {
+                    throw 42;
+                } catch ({
+                    [a]: a,
+                }) {}
+                return "FAIL";
+            } catch (e) {
+                return "PASS";
+            }
+        }());
+    }
+    expect: {
+        var a;
+        console.log(function() {
+            try {
+                try {
+                    throw 42;
+                } catch ({
+                    [b]: b,
+                }) {}
+                return "FAIL";
+            } catch (c) {
+                return "PASS";
+            }
+        }());
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4436_Infinity: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function({
+            [delete Infinity]: a,
+        }) {
+            var Infinity;
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect: {
+        console.log(function({
+            [delete Infinity]: a,
+        }) {
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}
+
+issue_4436_NaN: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function({
+            [delete NaN]: a,
+        }) {
+            var NaN;
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect: {
+        console.log(function({
+            [delete NaN]: a,
+        }) {
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}
+
+issue_4436_undefined: {
+    options = {
+        unused: true,
+    }
+    input: {
+        console.log(function({
+            [delete undefined]: a,
+        }) {
+            var undefined;
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect: {
+        console.log(function({
+            [delete undefined]: a,
+        }) {
+            return a;
+        }({
+            true: "FAIL",
+            false: "PASS",
+        }));
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}
+
+issue_4446: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        a = "PASS";
+        var a = [ a[0] ] = [ a ];
+        console.log(a[0]);
+    }
+    expect: {
+        a = "PASS";
+        var a = [ a[0] ] = [ a ];
+        console.log(a[0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4456: {
+    options = {
+        pure_getters: true,
+        unused: true,
+    }
+    input: {
+        var o = {
+            set p(v) {
+                console.log(v);
+            },
+        };
+        [ function() {
+            try {
+                return o;
+            } catch ({}) {}
+        }().p ] = [ "PASS" ];
+    }
+    expect: {
+        var o = {
+            set p(v) {
+                console.log(v);
+            },
+        };
+        [ function() {
+            try {
+                return o;
+            } catch ({}) {}
+        }().p ] = [ "PASS" ];
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4485_1: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        (function([]) {
+            var arguments;
+            try {
+                arguments.length;
+            } catch (e) {
+                console.log("PASS");
+            }
+        })([]);
+    }
+    expect: {
+        (function([]) {
+            var arguments;
+            try {
+                arguments.length;
+            } catch (e) {
+                console.log("PASS");
+            }
+        })([]);
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}
+
+issue_4485_2: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        (function([]) {
+            var arguments = null;
+            try {
+                arguments.length;
+            } catch (e) {
+                console.log("PASS");
+            }
+        })([]);
+    }
+    expect: {
+        (function([]) {
+            var arguments = null;
+            try {
+                arguments.length;
+            } catch (e) {
+                console.log("PASS");
+            }
+        })([]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4485_3: {
+    options = {
+        keep_fargs: false,
+        unused: true,
+    }
+    input: {
+        (function([]) {
+            var arguments;
+            try {
+                arguments.length;
+            } catch (e) {
+                console.log("PASS");
+            }
+        })([]);
+    }
+    expect: {
+        (function([]) {
+            var arguments;
+            try {
+                arguments.length;
+            } catch (e) {
+                console.log("PASS");
+            }
+        })([]);
+    }
+    expect_stdout: true
+    node_version: ">=6"
+}

test/compress/drop-unused.js

@@ -4,15 +4,16 @@ unused_funarg_1: {
         unused: true,
     }
     input: {
-        function f(a, b, c, d, e) {
+        console.log(function f(a, b, c, d, e) {
             return a + b;
-        }
+        }(14, 28));
     }
     expect: {
-        function f(a, b) {
+        console.log(function(a, b) {
             return a + b;
-        }
+        }(14, 28));
     }
+    expect_stdout: "42"
 }
 
 unused_funarg_2: {
@@ -21,15 +22,16 @@ unused_funarg_2: {
         unused: true,
     }
     input: {
-        function f(a, b, c, d, e) {
+        console.log(function f(a, b, c, d, e) {
             return a + c;
-        }
+        }(14, 21, 28));
     }
     expect: {
-        function f(a, b, c) {
+        console.log(function(a, c) {
             return a + c;
-        }
+        }(14, 28));
     }
+    expect_stdout: "42"
 }
 
 unused_nested_function: {
@@ -357,37 +359,6 @@ drop_toplevel_vars: {
     }
 }
 
-drop_toplevel_vars_fargs: {
-    options = {
-        keep_fargs: false,
-        toplevel: "vars",
-        unused: true,
-    }
-    input: {
-        var a, b = 1, c = g;
-        function f(d) {
-            return function() {
-                c = 2;
-            };
-        }
-        a = 2;
-        function g() {}
-        function h() {}
-        console.log(b = 3);
-    }
-    expect: {
-        function f() {
-            return function() {
-                2;
-            };
-        }
-        2;
-        function g() {}
-        function h() {}
-        console.log(3);
-    }
-}
-
 drop_toplevel_all: {
     options = {
         toplevel: true,
@@ -625,13 +596,14 @@ drop_fargs: {
         unused: true,
     }
     input: {
-        function f(a) {
+        console.log(function f(a) {
             var b = a;
-        }
+        }());
     }
     expect: {
-        function f() {}
+        console.log(function() {}());
     }
+    expect_stdout: "undefined"
 }
 
 drop_fnames: {
@@ -2027,7 +1999,7 @@ issue_3192_1: {
 
 issue_3192_2: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -2435,7 +2407,7 @@ issue_3673: {
 
 issue_3746: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         side_effects: true,
         unused: true,
     }
@@ -2713,7 +2685,7 @@ issue_3956: {
 issue_3962_1: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -2745,7 +2717,7 @@ issue_3962_1: {
 
 issue_3962_2: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         side_effects: true,
         toplevel: true,
@@ -2948,7 +2920,7 @@ issue_4133: {
 
 issue_4144: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         unused: true,
     }
@@ -3112,3 +3084,115 @@ issue_4235: {
     }
     expect_stdout: "undefined"
 }
+
+issue_4404: {
+    options = {
+        pure_getters: "strict",
+        unused: true,
+    }
+    input: {
+        function f(a) {
+            arguments[0] = "PASS";
+            console.log(a);
+        }
+        f("FAIL");
+    }
+    expect: {
+        function f(a) {
+            arguments[0] = "PASS";
+            console.log(a);
+        }
+        f("FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4413: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f(arguments) {
+            var arguments = function() {};
+            return arguments.length;
+        }());
+    }
+    expect: {
+        console.log(function(arguments) {
+            return function() {}.length;
+        }());
+    }
+    expect_stdout: "0"
+}
+
+issue_4464_1: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function f(a) {
+            var a = function() {};
+            return [ arguments, a ];
+        }
+        console.log(typeof f()[1]);
+    }
+    expect: {
+        function f(a) {
+            a = function() {};
+            return [ arguments, a ];
+        }
+        console.log(typeof f()[1]);
+    }
+    expect_stdout: "function"
+}
+
+issue_4464_2: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        function f(a) {
+            var a = function() {};
+            return [ arguments, a ];
+        }
+        console.log(typeof f(42)[0][0]);
+    }
+    expect: {
+        function f(a) {
+            a = function() {};
+            return [ arguments, a ];
+        }
+        console.log(typeof f(42)[0][0]);
+    }
+    expect_stdout: "function"
+}
+
+issue_4464_3: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function a(a) {
+            var a = function() {};
+            return [ arguments[0], a ];
+        })(42).forEach(function(b) {
+            console.log(typeof b);
+        });
+    }
+    expect: {
+        (function(a) {
+            a = function() {};
+            return [ arguments[0], a ];
+        })(42).forEach(function(b) {
+            console.log(typeof b);
+        });
+    }
+    expect_stdout: [
+        "function",
+        "function",
+    ]
+}

test/compress/evaluate.js

@@ -3074,3 +3074,71 @@ issue_4271: {
         "PASS",
     ]
 }
+
+issue_4393: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        (function f(a) {
+            a = "PASS";
+            console.log(arguments[0]);
+        })("FAIL");
+    }
+    expect: {
+        (function f(a) {
+            a = "PASS";
+            console.log(arguments[0]);
+        })("FAIL");
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4422: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f(a) {
+            a = "FAIL 1";
+            arguments[0] = "PASS";
+            return a;
+        }("FAIL 2"));
+    }
+    expect: {
+        console.log(function(a) {
+            a = "FAIL 1";
+            arguments[0] = "PASS";
+            return a;
+        }("FAIL 2"));
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4480: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        var a = function f(b) {
+            b = "FAIL";
+            arguments[0] = "PASS";
+            var arguments = 0;
+            console.log(b);
+        }(a);
+    }
+    expect: {
+        var a = function(b) {
+            b = "FAIL";
+            arguments[0] = "PASS";
+            var arguments = 0;
+            console.log(b);
+        }(a);
+    }
+    expect_stdout: "PASS"
+}

test/compress/functions.js

@@ -229,7 +229,7 @@ issue_203: {
     }
     expect: {
         var m = {};
-        var fn = Function("n,o", "o.exports=42");
+        var fn = Function("n,o,t", "o.exports=42");
         fn(null, m, m.exports);
         console.log(m.exports);
     }
@@ -4230,7 +4230,7 @@ substitute: {
 substitute_add_farg: {
     options = {
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
     }
     input: {
         function f(g) {
@@ -4411,7 +4411,9 @@ substitute_drop_farg: {
                 return f;
             },
             function() {
-                return f;
+                return function(d, e) {
+                    return f(d, e);
+                };
             },
         ].forEach(function(g) {
             console.log(g()(o), g().call(o, o));
@@ -4594,7 +4596,7 @@ substitute_use_strict: {
 issue_3833: {
     options = {
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -4751,7 +4753,7 @@ issue_4006: {
         dead_code: true,
         evaluate: true,
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         sequences: true,
         side_effects: true,
@@ -5132,8 +5134,8 @@ issue_4259: {
         console.log(typeof a);
     }
     expect: {
-        function a() {
+        var a = function b() {
-            for (a in a);
+            for (b in b);
         }
         a();
         console.log(typeof a);
@@ -5213,3 +5215,71 @@ issue_4265: {
     }
     expect_stdout: "undefined"
 }
+
+trailing_comma: {
+    input: {
+        new function(a, b,) {
+            console.log(b, a,);
+        }(42, "PASS",);
+    }
+    expect_exact: 'new function(a,b){console.log(b,a)}(42,"PASS");'
+    expect_stdout: "PASS 42"
+}
+
+issue_4451: {
+    options = {
+        functions: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = function f() {
+            for (f in "foo")
+                return f;
+        };
+        while (console.log(typeof a()));
+    }
+    expect: {
+        var a = function f() {
+            for (f in "foo")
+                return f;
+        };
+        while (console.log(typeof a()));
+    }
+    expect_stdout: "function"
+}
+
+issue_4471: {
+    options = {
+        inline: true,
+        reduce_funcs: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        f(f());
+        function f() {
+            return g();
+        }
+        function g() {
+            {
+                console.log("PASS");
+            }
+        }
+    }
+    expect: {
+        f(g());
+        function f() {
+            return g();
+        }
+        function g() {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+    ]
+}

test/compress/hoist_vars.js

@@ -89,6 +89,31 @@ sequences_funs: {
     }
 }
 
+catch_var: {
+    options = {
+        dead_code: true,
+        hoist_vars: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        try {
+            a;
+        } catch (a) {
+            var a = 0;
+            a;
+        }
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
 issue_2295: {
     options = {
         collapse_vars: true,

test/compress/ie8.js

@@ -588,7 +588,6 @@ issue_3197_1: {
         ie8: false,
     }
     input: {
-        var window = {};
         !function() {
             function Foo() {
                 console.log(this instanceof Foo);
@@ -598,7 +597,6 @@ issue_3197_1: {
         new window.Foo();
     }
     expect: {
-        var window = {};
         window.Foo = function o() {
             console.log(this instanceof o);
         };
@@ -619,7 +617,6 @@ issue_3197_1_ie8: {
         ie8: true,
     }
     input: {
-        var window = {};
         !function() {
             function Foo() {
                 console.log(this instanceof Foo);
@@ -629,7 +626,6 @@ issue_3197_1_ie8: {
         new window.Foo();
     }
     expect: {
-        var window = {};
         window.Foo = function Foo() {
             console.log(this instanceof Foo);
         };

test/compress/issue-976.js

@@ -63,42 +63,81 @@ eval_unused: {
         unused: true,
     }
     input: {
-        function f1(a, eval, c, d, e) {
+        function o(k) {
-            return a('c') + eval;
+            return { c: 14 }[k];
-        }
-        function f2(a, b, c, d, e) {
-            return a + eval('c');
-        }
-        function f3(a, eval, c, d, e) {
-            return a + eval('c');
         }
+        console.log(function f1(a, eval, c, d, e) {
+            return a("c") + eval;
+        }(o, 28, true));
+        console.log(function f2(a, b, c, d, e) {
+            return a + eval("c");
+        }(14, true, 28));
+        console.log(function f3(a, eval, c, d, e) {
+            return a + eval("c");
+        }(28, o, true));
     }
     expect: {
-        function f1(a, eval) {
+        function o(k) {
-            return a('c') + eval;
+            return { c: 14 }[k];
-        }
-        function f2(a, b, c, d, e) {
-            return a + eval('c');
-        }
-        function f3(a, eval, c, d, e) {
-            return a + eval('c');
         }
+        console.log(function(a, eval) {
+            return a("c") + eval;
+        }(o, 28));
+        console.log(function f2(a, b, c, d, e) {
+            return a + eval("c");
+        }(14, true, 28));
+        console.log(function f3(a, eval, c, d, e) {
+            return a + eval("c");
+        }(28, o, true));
     }
+    expect_stdout: [
+        "42",
+        "42",
+        "42",
+    ]
 }
 
 eval_mangle: {
-    mangle = {
+    mangle = {}
-    };
+    beautify = {
-    input: {
+        beautify: true,
-        function f1(a, eval, c, d, e) {
-            return a('c') + eval;
-        }
-        function f2(a, b, c, d, e) {
-            return a + eval('c');
-        }
-        function f3(a, eval, c, d, e) {
-            return a + eval('c');
-        }
     }
-    expect_exact: 'function f1(n,c,e,a,f){return n("c")+c}function f2(a,b,c,d,e){return a+eval("c")}function f3(a,eval,c,d,e){return a+eval("c")}'
+    input: {
+        function o(k) {
+            return { cc: 14 }[k + "c"];
+        }
+        console.log(function f1(a, eval, c, d, e) {
+            return a("c") + eval;
+        }(o, 28, true));
+        console.log(function f2(a, b, c, d, e) {
+            return a + eval("c");
+        }(14, true, 28));
+        console.log(function f3(a, eval, c, d, e) {
+            return a + eval("c");
+        }(28, o, true));
+    }
+    expect_exact: [
+        "function o(o) {",
+        "    return {",
+        "        cc: 14",
+        '    }[o + "c"];',
+        "}",
+        "",
+        "console.log(function o(c, e, n, r, t) {",
+        '    return c("c") + e;',
+        "}(o, 28, true));",
+        "",
+        "console.log(function f2(a, b, c, d, e) {",
+        '    return a + eval("c");',
+        "}(14, true, 28));",
+        "",
+        "console.log(function f3(a, eval, c, d, e) {",
+        '    return a + eval("c");',
+        "}(28, o, true));",
+    ]
+    expect_stdout: [
+        "42",
+        "42",
+        "42",
+    ]
 }

test/compress/join_vars.js

@@ -790,7 +790,7 @@ issue_3795: {
         dead_code: true,
         evaluate: true,
         join_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         loops: true,
         passes: 2,
         reduce_vars: true,

test/compress/keep_fargs.js

@@ -18,43 +18,6 @@ keep_fargs_false: {
         function j(e) {}
         console.log(h(), i().length, j.length);
     }
-    expect: {
-        console.log(function f() {
-            return f.length;
-        }(), function g() {
-            return g;
-        }().length);
-        function h() {
-            return h.length;
-        }
-        function i() {
-            return i;
-        }
-        function j() {}
-        console.log(h(), i().length, j.length);
-    }
-}
-
-keep_fargs_strict: {
-    options = {
-        keep_fargs: "strict",
-        unused: true,
-    }
-    input: {
-        console.log(function f(a) {
-            return f.length;
-        }(), function g(b) {
-            return g;
-        }().length);
-        function h(c) {
-            return h.length;
-        }
-        function i(d) {
-            return i;
-        }
-        function j(e) {}
-        console.log(h(), i().length, j.length);
-    }
     expect: {
         console.log(function f(a) {
             return f.length;
@@ -117,61 +80,11 @@ keep_fargs_true: {
     ]
 }
 
-replace_index: {
-    options = {
-        arguments: true,
-        evaluate: true,
-        keep_fargs: "strict",
-        properties: true,
-    }
-    input: {
-        var arguments = [];
-        console.log(arguments[0]);
-        (function() {
-            console.log(arguments[1], arguments["1"], arguments["foo"]);
-        })("bar", 42);
-        (function(a, b) {
-            console.log(arguments[1], arguments["1"], arguments["foo"]);
-        })("bar", 42);
-        (function(arguments) {
-            console.log(arguments[1], arguments["1"], arguments["foo"]);
-        })("bar", 42);
-        (function() {
-            var arguments;
-            console.log(arguments[1], arguments["1"], arguments["foo"]);
-        })("bar", 42);
-    }
-    expect: {
-        var arguments = [];
-        console.log(arguments[0]);
-        (function(argument_0, argument_1) {
-            console.log(argument_1, argument_1, arguments.foo);
-        })("bar", 42);
-        (function(a, b) {
-            console.log(b, b, arguments.foo);
-        })("bar", 42);
-        (function(arguments) {
-            console.log(arguments[1], arguments[1], arguments.foo);
-        })("bar", 42);
-        (function() {
-            var arguments;
-            console.log(arguments[1], arguments[1], arguments.foo);
-        })("bar", 42);
-    }
-    expect_stdout: [
-        "undefined",
-        "42 42 undefined",
-        "42 42 undefined",
-        "a a undefined",
-        "42 42 undefined",
-    ]
-}
-
 replace_index_strict: {
     options = {
         arguments: true,
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         properties: true,
         reduce_vars: true,
     }
@@ -202,7 +115,7 @@ replace_index_strict: {
 issue_1858: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         pure_getters: true,
         unused: true,
     }
@@ -224,7 +137,7 @@ issue_1858: {
 issue_2187_2: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -245,7 +158,7 @@ issue_2187_2: {
 issue_2203_2: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -280,7 +193,7 @@ issue_2203_2: {
 issue_2298: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_funcs: true,
         reduce_vars: true,
@@ -323,7 +236,7 @@ issue_2298: {
 issue_2319_1: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -346,7 +259,7 @@ issue_2319_1: {
 issue_2319_2: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -371,7 +284,7 @@ issue_2319_2: {
 issue_2319_3: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -396,7 +309,7 @@ issue_2319_3: {
 issue_2425_1: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -419,7 +332,7 @@ issue_2425_1: {
 issue_2425_2: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -442,7 +355,7 @@ issue_2425_2: {
 issue_2425_3: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -465,7 +378,7 @@ issue_2425_3: {
 issue_2436_13: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_vars: true,
         unused: true,
@@ -499,7 +412,7 @@ issue_2436_13: {
 issue_2506: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_vars: true,
         unused: true,
@@ -538,7 +451,7 @@ issue_2506: {
 
 issue_2226_1: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         side_effects: true,
         unused: true,
     }
@@ -585,7 +498,7 @@ issue_2226_1: {
 issue_2226_2: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         sequences: true,
         side_effects: true,
         unused: true,
@@ -607,7 +520,7 @@ issue_2226_2: {
 issue_2226_3: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         side_effects: true,
         unused: true,
     }
@@ -627,7 +540,7 @@ issue_2226_3: {
 
 issue_3192: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -657,7 +570,7 @@ issue_3192: {
 if_increment: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         unused: true,
     }
@@ -679,7 +592,7 @@ if_increment: {
 try_increment: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         unused: true,
     }
@@ -703,7 +616,7 @@ try_increment: {
 issue_2630_3: {
     options = {
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         unused: true,
     }
@@ -740,7 +653,7 @@ issue_2630_3: {
 issue_3364: {
     options = {
         functions: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         toplevel: true,
         unused: true,
@@ -805,7 +718,7 @@ issue_3364: {
 
 defun_label: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_funcs: true,
         reduce_vars: true,
@@ -837,7 +750,7 @@ defun_label: {
 
 iife_func_side_effects: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_funcs: true,
         reduce_vars: true,
         unused: true,
@@ -889,7 +802,7 @@ iife_func_side_effects: {
 issue_1595_1: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_funcs: true,
         reduce_vars: true,
         unused: true,
@@ -909,7 +822,7 @@ issue_1595_1: {
 issue_1595_2: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_funcs: true,
         reduce_vars: true,
         unused: true,
@@ -929,7 +842,7 @@ issue_1595_2: {
 issue_1595_3: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_funcs: true,
         reduce_vars: true,
@@ -950,7 +863,7 @@ issue_1595_3: {
 issue_1595_4: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_funcs: true,
         reduce_vars: true,
         unused: true,
@@ -972,7 +885,7 @@ issue_1595_4: {
 
 duplicate_lambda_defun_name_1: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
     }
     input: {
@@ -992,7 +905,7 @@ duplicate_lambda_defun_name_1: {
 
 duplicate_lambda_defun_name_2: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_vars: true,
         unused: true,
@@ -1013,7 +926,7 @@ duplicate_lambda_defun_name_2: {
 
 function_name_mangle: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         keep_fnames: true,
         reduce_vars: true,
         unused: true,
@@ -1031,7 +944,7 @@ function_name_mangle: {
 
 function_name_mangle_ie8: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         keep_fnames: true,
         reduce_vars: true,
         unused: true,
@@ -1052,7 +965,7 @@ function_name_mangle_ie8: {
 
 issue_3420_1: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -1075,7 +988,7 @@ issue_3420_1: {
 issue_3420_2: {
     options = {
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -1096,7 +1009,7 @@ issue_3420_2: {
 issue_3420_3: {
     options = {
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         unused: true,
     }
@@ -1118,7 +1031,7 @@ issue_3420_3: {
 
 issue_3423_1: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -1138,7 +1051,7 @@ issue_3423_1: {
 
 issue_3423_2: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -1165,7 +1078,7 @@ collapse_vars_repeated: {
         hoist_funs: true,
         if_return: true,
         join_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         loops: true,
         properties: true,
         reduce_funcs: true,
@@ -1212,7 +1125,7 @@ collapse_vars_repeated: {
 chained_3: {
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -1236,7 +1149,7 @@ replace_all_var_scope: {
     rename = true
     options = {
         collapse_vars: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     mangle = {}
@@ -1265,7 +1178,7 @@ replace_all_var_scope: {
 
 issue_1583: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_funcs: true,
         reduce_vars: true,
@@ -1302,7 +1215,7 @@ issues_3267_1: {
         dead_code: true,
         evaluate: true,
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         sequences: true,
         side_effects: true,
@@ -1331,7 +1244,7 @@ issues_3267_1: {
 
 trailing_argument_side_effects: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -1355,7 +1268,7 @@ trailing_argument_side_effects: {
 
 recursive_iife_1: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         unused: true,
     }
@@ -1374,7 +1287,7 @@ recursive_iife_1: {
 
 recursive_iife_2: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         unused: true,
     }
@@ -1452,3 +1365,37 @@ issue_3619: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4353_1: {
+    options = {
+        keep_fargs: false,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function f(a) {}.length);
+    }
+    expect: {
+        console.log(function(a) {}.length);
+    }
+    expect_stdout: "1"
+}
+
+issue_4353_2: {
+    options = {
+        keep_fargs: false,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            while (console.log("PASS"));
+        })();
+    }
+    expect: {
+        (function() {
+            while (console.log("PASS"));
+        })();
+    }
+    expect_stdout: "PASS"
+}

test/compress/labels.js

@@ -207,3 +207,123 @@ labels_10: {
         }
     }
 }
+
+issue_4466_1: {
+    mangle = {
+        v8: false,
+    }
+    input: {
+        A: if (console.log("PASS"))
+            B:;
+        else
+            C:;
+    }
+    expect: {
+        e: if (console.log("PASS"))
+            l:;
+        else
+            l:;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_4466_1_v8: {
+    mangle = {
+        v8: true,
+    }
+    input: {
+        A: if (console.log("PASS"))
+            B:;
+        else
+            C:;
+    }
+    expect: {
+        e: if (console.log("PASS"))
+            l:;
+        else
+            o:;
+    }
+    expect_stdout: "PASS"
+    node_version: ">=12"
+}
+
+issue_4466_2: {
+    mangle = {
+        toplevel: false,
+        v8: false,
+    }
+    input: {
+        if (console.log("PASS"))
+            A:;
+        else
+            B:;
+    }
+    expect: {
+        if (console.log("PASS"))
+            e:;
+        else
+            e:;
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4466_2_v8: {
+    mangle = {
+        toplevel: false,
+        v8: true,
+    }
+    input: {
+        if (console.log("PASS"))
+            A:;
+        else
+            B:;
+    }
+    expect: {
+        if (console.log("PASS"))
+            e:;
+        else
+            l:;
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4466_2_toplevel: {
+    mangle = {
+        toplevel: true,
+        v8: false,
+    }
+    input: {
+        if (console.log("PASS"))
+            A:;
+        else
+            B:;
+    }
+    expect: {
+        if (console.log("PASS"))
+            e:;
+        else
+            e:;
+    }
+    expect_stdout: "PASS"
+}
+
+issue_4466_2_toplevel_v8: {
+    mangle = {
+        toplevel: true,
+        v8: true,
+    }
+    input: {
+        if (console.log("PASS"))
+            A:;
+        else
+            B:;
+    }
+    expect: {
+        if (console.log("PASS"))
+            e:;
+        else
+            e:;
+    }
+    expect_stdout: "PASS"
+}

test/compress/let.js

@@ -359,6 +359,28 @@ reduce_block_2_toplevel: {
     node_version: ">=4"
 }
 
+reduce_vars: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        "use strict";
+        let a = "PASS";
+        console.log(a);
+        a = "FAIL";
+    }
+    expect: {
+        "use strict";
+        console.log("PASS");
+        "FAIL";
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
 hoist_props: {
     options = {
         hoist_props: true,
@@ -1228,3 +1250,35 @@ issue_1753_toplevel: {
     expect_stdout: "0"
     node_version: ">=4"
 }
+
+issue_4438: {
+    options = {
+        if_return: true,
+    }
+    input: {
+        "use strict";
+        function f() {
+            if (console) {
+                {
+                    let a = console.log;
+                    return void a("PASS");
+                }
+            }
+        }
+        f();
+    }
+    expect: {
+        "use strict";
+        function f() {
+            if (!console)
+                ;
+            else {
+                let a = console.log;
+                a("PASS");
+            }
+        }
+        f();
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/loops.js

@@ -1026,7 +1026,7 @@ issue_4075: {
 
 issue_4082: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         loops: true,
         unused: true,
     }
@@ -1050,7 +1050,7 @@ issue_4082: {
 
 issue_4084: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         loops: true,
         passes: 2,
         reduce_vars: true,
@@ -1255,3 +1255,28 @@ issue_4240: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4355: {
+    options = {
+        dead_code: true,
+        evaluate: true,
+        loops: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        while (function() {
+            var a;
+            for (a in console.log("PASS"))
+                var b = 0;
+        }())
+            var c;
+    }
+    expect: {
+        (function() {
+            console.log("PASS");
+        })();
+        var c;
+    }
+    expect_stdout: "PASS"
+}

test/compress/merge_vars.js

@@ -327,7 +327,7 @@ issue_4103: {
 
 issue_4107: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         merge_vars: true,
         reduce_vars: true,
         unused: true,

test/compress/objects.js

@@ -45,8 +45,8 @@ duplicate_key_strict: {
         "use strict";
         var o = {
             a: 1,
-            b: 2,
             a: 3,
+            b: 2,
         };
         for (var k in o)
             console.log(k, o[k]);
@@ -257,6 +257,29 @@ keep_computed_key: {
     node_version: ">=4"
 }
 
+shorthand_keywords: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unsafe: true,
+        unused: true,
+    }
+    input: {
+        var async = 1, get = 2, set = 3, o = {
+            async,
+            get,
+            set,
+        };
+        console.log(o.async, o.get, o.set);
+    }
+    expect: {
+        console.log(1, 2, 3);
+    }
+    expect_stdout: "1 2 3"
+    node_version: ">=6"
+}
+
 issue_4269_1: {
     options = {
         evaluate: true,
@@ -323,8 +346,8 @@ issue_4269_3: {
     }
     expect: {
         console.log({
-            ["foo"]: "bar",
+            foo: "bar",
-            get 42() {
+            get [42]() {
                 return "FAIL";
             },
             42: "PASS",
@@ -353,10 +376,82 @@ issue_4269_4: {
             get 42() {
                 return "FAIL";
             },
-            ["foo"]: "bar",
+            foo: "bar",
+            [42]: "PASS",
+        }[42]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4269_5: {
+    options = {
+        evaluate: true,
+        objects: true,
+    }
+    input: {
+        console.log({
+            get 42() {
+                return "FAIL";
+            },
+            [console]: "bar",
+            42: "PASS",
+        }[42]);
+    }
+    expect: {
+        console.log({
+            get 42() {
+                return "FAIL";
+            },
+            [console]: "bar",
             42: "PASS",
         }[42]);
     }
     expect_stdout: "PASS"
     node_version: ">=4"
 }
+
+issue_4380: {
+    options = {
+        evaluate: true,
+        objects: true,
+    }
+    input: {
+        console.log({
+            get 0() {
+                return "FAIL 1";
+            },
+            0: "FAIL 2",
+            [0]: "PASS",
+        }[0]);
+    }
+    expect: {
+        console.log({
+            get 0() {
+                return "FAIL 1";
+            },
+            [0]: ("FAIL 2", "PASS"),
+        }[0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4415: {
+    options = {
+        evaluate: true,
+        objects: true,
+    }
+    input: {
+        console.log({
+            ["00"]: "FAIL",
+        }[0] || "PASS");
+    }
+    expect: {
+        console.log({
+            "00": "FAIL",
+        }[0] || "PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/pure_funcs.js

@@ -685,7 +685,7 @@ issue_3858: {
     options = {
         collapse_vars: true,
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         unused: true,
     }
     input: {
@@ -711,7 +711,7 @@ inline_pure_call_1: {
     options = {
         collapse_vars: true,
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         sequences: true,
         side_effects: true,
@@ -733,7 +733,7 @@ inline_pure_call_2: {
     options = {
         collapse_vars: true,
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         sequences: true,
         side_effects: true,
@@ -756,7 +756,7 @@ inline_pure_call_3: {
         collapse_vars: true,
         evaluate: true,
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         reduce_vars: true,
         toplevel: true,

test/compress/pure_getters.js

@@ -1208,3 +1208,32 @@ issue_3427: {
     expect: {}
     expect_stdout: true
 }
+
+issue_4440: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        try {
+            (function() {
+                arguments = null;
+                console.log(arguments.p = "FAIL");
+            })();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            (function() {
+                arguments = null;
+                console.log(arguments.p = "FAIL");
+            })();
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+}

test/compress/reduce_vars.js

@@ -2373,7 +2373,7 @@ redefine_farg_1: {
         function f(a) {
             return typeof a;
         }
-        function g() {
+        function g(a) {
             return "number";
         }
         function h(a, b) {
@@ -6928,7 +6928,7 @@ issue_3622: {
     options = {
         evaluate: true,
         inline: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         reduce_vars: true,
         sequences: true,
         toplevel: true,
@@ -7196,7 +7196,7 @@ issue_3894: {
 issue_3922: {
     options = {
         evaluate: true,
-        keep_fargs: "strict",
+        keep_fargs: false,
         pure_getters: "strict",
         reduce_vars: true,
         side_effects: true,

test/compress/side_effects.js

@@ -436,7 +436,7 @@ trim_new: {
 
 issue_4325: {
     options = {
-        keep_fargs: "strict",
+        keep_fargs: false,
         passes: 2,
         pure_getters: "strict",
         reduce_vars: true,
@@ -470,3 +470,39 @@ issue_4325: {
     }
     expect_stdout: "PASS"
 }
+
+issue_4366_1: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        ({
+            p: 42,
+            get p() {},
+            q: console.log("PASS"),
+        });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}
+
+issue_4366_2: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        ({
+            set p(v) {},
+            q: console.log("PASS"),
+            p: 42,
+        });
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=4"
+}

test/compress/spread.js

@@ -0,0 +1,806 @@
+collapse_vars_1: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a;
+        [ ...a = "PASS", "PASS"].slice();
+        console.log(a);
+    }
+    expect: {
+        var a;
+        [ ...a = "PASS", "PASS"].slice();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+collapse_vars_2: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        try {
+            a = "PASS";
+            [ ...42, "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = "FAIL";
+        try {
+            a = "PASS";
+            [ ...42, "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+collapse_vars_3: {
+    options = {
+        collapse_vars: true,
+    }
+    input: {
+        var a = "FAIL";
+        try {
+            [ ...(a = "PASS", 42), "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect: {
+        var a = "FAIL";
+        try {
+            [ ...(a = "PASS", 42), "PASS"].slice();
+        } catch (e) {
+            console.log(a);
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+collapse_vars_4: {
+    options = {
+        collapse_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+dont_inline: {
+    options = {
+        inline: true,
+    }
+    input: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+do_inline: {
+    options = {
+        inline: true,
+        spread: true,
+    }
+    input: {
+        console.log(function(a) {
+            return a;
+        }(...[ "PASS", "FAIL" ]));
+    }
+    expect: {
+        console.log(("FAIL", "PASS"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+drop_empty_call_1: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        try {
+            (function() {})(...null);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            [ ...null ];
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+drop_empty_call_2: {
+    options = {
+        side_effects: true,
+        spread: true,
+    }
+    input: {
+        (function() {})(...[ console.log("PASS") ]);
+    }
+    expect: {
+        console.log("PASS");
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+convert_hole: {
+    options = {
+        spread: true,
+    }
+    input: {
+        console.log(...[ "PASS", , 42 ]);
+    }
+    expect: {
+        console.log("PASS", void 0, 42);
+    }
+    expect_stdout: "PASS undefined 42"
+    node_version: ">=6"
+}
+
+keep_property_access: {
+    options = {
+        properties: true,
+        side_effects: true,
+    }
+    input: {
+        console.log(function() {
+            return [ ..."foo" ][0];
+        }());
+    }
+    expect: {
+        console.log(function() {
+            return [ ..."foo" ][0];
+        }());
+    }
+    expect_stdout: "f"
+    node_version: ">=6"
+}
+
+keep_fargs: {
+    options = {
+        keep_fargs: false,
+        unused: true,
+    }
+    input: {
+        var a = [ "PASS" ];
+        (function(b, c) {
+            console.log(c);
+        })(console, ...a);
+    }
+    expect: {
+        var a = [ "PASS" ];
+        (function(b, c) {
+            console.log(c);
+        })(console, ...a);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+reduce_vars_1: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+reduce_vars_2: {
+    options = {
+        conditionals: true,
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect: {
+        console.log(function(b, c) {
+            return c ? "PASS" : "FAIL";
+        }(..."foo"));
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+convert_setter: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            ...{
+                set PASS(v) {},
+            },
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            PASS: void 0,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: "PASS undefined"
+    node_version: ">=8"
+}
+
+keep_getter_1: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        ({
+            ...{
+                get p() {
+                    console.log("PASS");
+                },
+            },
+            get q() {
+                console.log("FAIL");
+            },
+        });
+    }
+    expect: {
+        ({
+            ...{
+                get p() {
+                    console.log("PASS");
+                },
+            },
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+keep_getter_2: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        ({
+            ...(console.log("foo"), {
+                get p() {
+                    console.log("bar");
+                },
+            }),
+        });
+    }
+    expect: {
+        ({
+            ...(console.log("foo"), {
+                get p() {
+                    console.log("bar");
+                },
+            }),
+        });
+    }
+    expect_stdout: [
+        "foo",
+        "bar",
+    ]
+    node_version: ">=8"
+}
+
+keep_getter_3: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        ({
+            ...function() {
+                return {
+                    get p() {
+                        console.log("PASS");
+                    },
+                };
+            }(),
+        });
+    }
+    expect: {
+        ({
+            ...function() {
+                return {
+                    get p() {
+                        console.log("PASS");
+                    },
+                };
+            }(),
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+keep_getter_4: {
+    options = {
+        reduce_vars: true,
+        side_effects: true,
+        toplevel: true,
+    }
+    input: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            },
+        };
+        ({
+            q: o,
+            ...o,
+        });
+    }
+    expect: {
+        var o = {
+            get p() {
+                console.log("PASS");
+            },
+        };
+        ({
+            ...o,
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+keep_accessor: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            ...{
+                get p() {
+                    console.log("GET");
+                    return this.r;
+                },
+                set q(v) {
+                    console.log("SET", v);
+                },
+                r: 42,
+            },
+            r: null,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            ...{
+                get p() {
+                    console.log("GET");
+                    return this.r;
+                },
+                set q(v) {
+                    console.log("SET", v);
+                },
+                r: 42,
+            },
+            r: null,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "GET",
+        "p 42",
+        "q undefined",
+        "r null",
+    ]
+    node_version: ">=8"
+}
+
+object_key_order_1: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            ...{},
+            a: 1,
+            b: 2,
+            a: 3,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            a: (1, 3),
+            b: 2,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "a 3",
+        "b 2",
+    ]
+    node_version: ">=8 <=10"
+}
+
+object_key_order_2: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            a: 1,
+            ...{},
+            b: 2,
+            a: 3,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            a: (1, 3),
+            b: 2,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "a 3",
+        "b 2",
+    ]
+    node_version: ">=8"
+}
+
+object_key_order_3: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            a: 1,
+            b: 2,
+            ...{},
+            a: 3,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            a: (1, 3),
+            b: 2,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "a 3",
+        "b 2",
+    ]
+    node_version: ">=8"
+}
+
+object_key_order_4: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            a: 1,
+            b: 2,
+            a: 3,
+            ...{},
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            a: (1, 3),
+            b: 2,
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "a 3",
+        "b 2",
+    ]
+    node_version: ">=8"
+}
+
+object_spread_array: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            ...[ "foo", "bar" ],
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            ...[ "foo", "bar" ],
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "0 foo",
+        "1 bar",
+    ]
+    node_version: ">=8"
+}
+
+object_spread_string: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        var o = {
+            ..."foo",
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect: {
+        var o = {
+            ..."foo",
+        };
+        for (var k in o)
+            console.log(k, o[k]);
+    }
+    expect_stdout: [
+        "0 f",
+        "1 o",
+        "2 o",
+    ]
+    node_version: ">=8"
+}
+
+unused_var_side_effects: {
+    options = {
+        unused: true,
+    }
+    input: {
+        (function f(a) {
+            var b = {
+                ...a,
+            };
+        })({
+            get p() {
+                console.log("PASS");
+            },
+        });
+    }
+    expect: {
+        (function(a) {
+            ({
+                ...a,
+            });
+        })({
+            get p() {
+                console.log("PASS");
+            },
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4329: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        console.log({
+            ...{
+                get 0() {
+                    return "FAIL";
+                },
+                ...{
+                    0: "PASS",
+                },
+            },
+        }[0]);
+    }
+    expect: {
+        console.log({
+            ...{
+                get 0() {
+                    return "FAIL";
+                },
+                [0]: "PASS",
+            },
+        }[0]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4331: {
+    options = {
+        collapse_vars: true,
+        toplevel: true,
+    }
+    input: {
+        var a = "PASS", b;
+        console,
+        b = a;
+        (function() {
+            a++;
+        })(...a);
+        console.log(b);
+    }
+    expect: {
+        var a = "PASS", b;
+        console;
+        (function() {
+            a++;
+        })(...b = a);
+        console.log(b);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4342: {
+    options = {
+        side_effects: true,
+    }
+    input: {
+        try {
+            new function() {}(...42);
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect: {
+        try {
+            [ ...42 ];
+        } catch (e) {
+            console.log("PASS");
+        }
+    }
+    expect_stdout: "PASS"
+    node_version: ">=6"
+}
+
+issue_4345: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        console.log({
+            ...{
+                get 42() {
+                    return "FAIL";
+                },
+                ...{},
+                42: "PASS",
+            },
+        }[42]);
+    }
+    expect: {
+        console.log({
+            ...{
+                get 42() {
+                    return "FAIL";
+                },
+                [42]: "PASS",
+            },
+        }[42]);
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}
+
+issue_4361: {
+    options = {
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        console.log(function() {
+            var a = console.log("foo");
+            console;
+            var b = {
+                ...a,
+            };
+        }());
+    }
+    expect: {
+        console.log(function() {
+            var a = console.log("foo");
+            console;
+            ({
+                ...a,
+            });
+        }());
+    }
+    expect_stdout: [
+        "foo",
+        "undefined",
+    ]
+    node_version: ">=8"
+}
+
+issue_4363: {
+    options = {
+        objects: true,
+        spread: true,
+    }
+    input: {
+        ({
+            ...{
+                set [console.log("PASS")](v) {},
+            },
+        });
+    }
+    expect: {
+        ({
+            [console.log("PASS")]: void 0,
+        });
+    }
+    expect_stdout: "PASS"
+    node_version: ">=8"
+}

test/input/invalid/destructured_var.js

@@ -0,0 +1,8 @@
+function f() {
+    var { eval } = null;
+}
+
+function g() {
+    "use strict";
+    var { eval } = 42;
+}

test/input/reduce/destructured_catch.js

@@ -0,0 +1,7 @@
+try {
+    "foo" in 42;
+} catch ({
+    message,
+}) {
+    console.log(message);
+}

test/input/reduce/destructured_catch.reduced.js

@@ -0,0 +1,15 @@
+// (beautified)
+try {
+    1 in 0;
+} catch ({
+    message: message
+}) {
+    console.log(message);
+}
+// output: Cannot use 'in' operator to search for '1' in 0
+// 
+// minify: Cannot use 'in' operator to search for '0' in 0
+// 
+// options: {
+//   "mangle": false
+// }

test/input/reduce/diff_error.js

@@ -1,5 +1,5 @@
-(function f(a) {
+console.log(function(undefined) {
-    do {
+    return undefined[function() {
-        console.log(f.length);
+        {}
-    } while (console.log(f += 0));
+    }] || 1 + .1 + .1;
-})();
+}(42));

test/input/reduce/diff_error.reduced.js

@@ -1,19 +1,14 @@
 // (beautified)
-(function f(a) {
+console.log(function() {
-    do {
+    return 1 + .1 + .1;
-        console.log(f.length);
+}());
-    } while (console.log(f += 0));
+// output: 1.2000000000000002
-})();
-// output: 1
-// function(){}0
 // 
-// minify: 0
+// minify: 1.2
-// function(){}0
 // 
 // options: {
 //   "compress": {
-//     "keep_fargs": false,
+//     "unsafe_math": true
-//     "unsafe": true
 //   },
 //   "mangle": false
 // }

test/input/reduce/setter.js

@@ -1,8 +1,5 @@
-console.log(function f(a) {
+({
-    ({
+    set p(v) {
-        set p(v) {
+        console.log(+v + .1 + .1);
-            f++;
+    }
-        }
+}).p = 1;
-    });
-    return f.length;
-}());

test/input/reduce/setter.reduced.js

@@ -1,20 +1,16 @@
 // (beautified)
-console.log(function f(a) {
+({
-    ({
+    set p(v) {
-        set p(v) {
+        console.log(1 + .1 + .1);
-            f++;
+    }
-        }
+}).p = 0;
-    });
+// output: 1.2000000000000002
-    return f.length;
-}());
-// output: 1
 // 
-// minify: 0
+// minify: 1.2
 // 
 // options: {
 //   "compress": {
-//     "keep_fargs": false,
+//     "unsafe_math": true
-//     "unsafe": true
 //   },
 //   "mangle": false
 // }

test/jetstream.js

@@ -5,7 +5,7 @@
 
 var site = "https://browserbench.org/JetStream1.1";
 if (typeof phantom == "undefined") {
-    require("../tools/exit");
+    require("../tools/tty");
     var args = process.argv.slice(2);
     var debug = args.indexOf("--debug");
     if (debug < 0) {

test/mocha/async.js

@@ -0,0 +1,65 @@
+var assert = require("assert");
+var UglifyJS = require("../node");
+
+describe("async", function() {
+    it("Should reject `await` as symbol name within async functions only", function() {
+        [
+            "function await() {}",
+            "function(await) {}",
+            "function() { await; }",
+            "function() { await:{} }",
+            "function() { var await; }",
+            "function() { function await() {} }",
+            "function() { try {} catch (await) {} }",
+        ].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("(async " + code + ")();");
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
+    it("Should reject `await` expression outside of async functions", function() {
+        [
+            "await 42;",
+            "function f() { await 42; }",
+            "async function f() { function g() { await 42; } }",
+        ].forEach(function(code) {
+            assert.throws(function() {
+                UglifyJS.parse(code);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
+    it("Should reject `await` expression directly on computed key of function argument", function() {
+        [
+            "function f({ [await 42]: a }) {}",
+            "async function f({ [await 42]: a }) {}",
+        ].forEach(function(code) {
+            assert.throws(function() {
+                UglifyJS.parse(code);
+            }, function(e) {
+                return e instanceof UglifyJS.JS_Parse_Error;
+            }, code);
+        });
+    });
+    it("Should accept `await` expression nested within computed key of function argument", function() {
+        [
+            "function f({ [async function() { await 42; }()]: a }) {}",
+            "async function f({ [async function() { await 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");
+        });
+    });
+});

test/mocha/cli.js

@@ -573,6 +573,20 @@ describe("bin/uglifyjs", function() {
             done();
         });
     });
+    it("Should throw syntax error (var { eval })", function(done) {
+        var command = uglifyjscmd + " test/input/invalid/destructured_var.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/destructured_var.js:7,10",
+                "    var { eval } = 42;",
+                "          ^",
+                "ERROR: Unexpected eval in strict mode"
+            ].join("\n"));
+            done();
+        });
+    });
     it("Should throw syntax error (else)", function(done) {
         var command = uglifyjscmd + " test/input/invalid/else.js";
         exec(command, function(err, stdout, stderr) {

test/mocha/getter-setter.js

@@ -3,7 +3,7 @@ var UglifyJS = require("../node");
 
 describe("Getters and setters", function() {
     it("Should not accept operator symbols as getter/setter name", function() {
-        var illegalOperators = [
+        [
             "++",
             "--",
             "+",
@@ -42,43 +42,26 @@ describe("Getters and setters", function() {
             "&=",
             "&&",
             "||"
-        ];
+        ].reduce(function(tests, illegalOperator) {
-        var generator = function() {
+            tests.push({
-            var results = [];
+                code: "var obj = { get " + illegalOperator + "() { return test; }};",
-
+                operator: illegalOperator,
-            for (var i in illegalOperators) {
+            });
-                results.push({
+            tests.push({
-                    code: "var obj = { get " + illegalOperators[i] + "() { return test; }};",
+                code: "var obj = { set " + illegalOperator + "(value) { test = value; }};",
-                    operator: illegalOperators[i],
+                operator: illegalOperator,
-                    method: "get"
+            });
-                });
+            return tests;
-                results.push({
+        }, []).forEach(function(test) {
-                    code: "var obj = { set " + illegalOperators[i] + "(value) { test = value}};",
+            assert.throws(function() {
-                    operator: illegalOperators[i],
+                UglifyJS.parse(test.code);
-                    method: "set"
+            }, test.operator == "=" ? function(e) {
-                });
-            }
-
-            return results;
-        };
-        var testCase = function(data) {
-            return function() {
-                UglifyJS.parse(data.code);
-            };
-        };
-        var fail = function(data) {
-            return function(e) {
                 return e instanceof UglifyJS.JS_Parse_Error
-                    && e.message === "Unexpected token: operator «" + data.operator + "»";
+                    && /^Unexpected token: punc «{», expected: punc «.*?»$/.test(e.message);
-            };
+            } : function(e) {
-        };
+                return e instanceof UglifyJS.JS_Parse_Error
-        var errorMessage = function(data) {
+                    && e.message === "Unexpected token: operator «" + test.operator + "»";
-            return "Expected but didn't get a syntax error while parsing following line:\n" + data.code;
+            }, "Expected but didn't get a syntax error while parsing following line:\n" + test.code);
-        };
+        });
-        var tests = generator();
-        for (var i = 0; i < tests.length; i++) {
-            var test = tests[i];
-            assert.throws(testCase(test), fail(test), errorMessage(test));
-        }
     });
 });

test/mocha/number-literal.js

@@ -89,4 +89,13 @@ describe("Number literals", function() {
             }, code);
         });
     });
+    it("Should reject invalid syntax under expression=true", function() {
+        assert.throws(function() {
+            UglifyJS.parse("42.g", {
+                expression: true,
+            });
+        }, function(e) {
+            return e instanceof UglifyJS.JS_Parse_Error;
+        });
+    });
 });

test/mocha/reduce.js

@@ -37,8 +37,7 @@ describe("test/reduce.js", function() {
     it("Should retain setter arguments", function() {
         var result = reduce_test(read("test/input/reduce/setter.js"), {
             compress: {
-                keep_fargs: false,
+                unsafe_math: true,
-                unsafe: true,
             },
             mangle: false,
         }, {
@@ -110,28 +109,24 @@ describe("test/reduce.js", function() {
     });
     it("Should print correct output for irreducible test case", function() {
         var result = reduce_test([
-            "console.log(function f(a) {",
+            "console.log(1 + .1 + .1);",
-            "    return f.length;",
-            "}());",
         ].join("\n"), {
             compress: {
-                keep_fargs: false,
+                unsafe_math: true,
             },
             mangle: false,
         });
         if (result.error) throw result.error;
         assert.strictEqual(result.code, [
             "// (beautified)",
-            "console.log(function f(a) {",
+            "console.log(1 + .1 + .1);",
-            "    return f.length;",
+            "// output: 1.2000000000000002",
-            "}());",
-            "// output: 1",
             "// ",
-            "// minify: 0",
+            "// minify: 1.2",
             "// ",
             "// options: {",
             '//   "compress": {',
-            '//     "keep_fargs": false',
+            '//     "unsafe_math": true',
             "//   },",
             '//   "mangle": false',
             "// }",
@@ -303,8 +298,7 @@ describe("test/reduce.js", function() {
         if (semver.satisfies(process.version, "<=0.10")) return;
         var result = reduce_test(read("test/input/reduce/diff_error.js"), {
             compress: {
-                keep_fargs: false,
+                unsafe_math: true,
-                unsafe: true,
             },
             mangle: false,
         }, {
@@ -313,4 +307,12 @@ describe("test/reduce.js", function() {
         if (result.error) throw result.error;
         assert.strictEqual(result.code, read("test/input/reduce/diff_error.reduced.js"));
     });
+    it("Should handle destructured catch expressions", function() {
+        if (semver.satisfies(process.version, "<6")) return;
+        var result = reduce_test(read("test/input/reduce/destructured_catch.js"), {
+            mangle: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, read("test/input/reduce/destructured_catch.reduced.js"));
+    });
 });

test/reduce.js

@@ -18,9 +18,18 @@ var sandbox = require("./sandbox");
 
 Error.stackTraceLimit = Infinity;
 module.exports = function reduce_test(testcase, minify_options, reduce_options) {
-    if (testcase instanceof U.AST_Node) testcase = testcase.print_to_string();
     minify_options = minify_options || {};
     reduce_options = reduce_options || {};
+    var print_options = {};
+    [
+        "ie8",
+        "v8",
+        "webkit",
+    ].forEach(function(name) {
+        var value = minify_options[name] || minify_options.output && minify_options.output[name];
+        if (value) print_options[name] = value;
+    });
+    if (testcase instanceof U.AST_Node) testcase = testcase.print_to_string(print_options);
     var max_iterations = reduce_options.max_iterations || 1000;
     var max_timeout = reduce_options.max_timeout || 10000;
     var warnings = [];
@@ -115,7 +124,6 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
 
             // ignore lvalues
             if (parent instanceof U.AST_Assign && parent.left === node) return;
-            if (parent instanceof U.AST_DestructuredArray) return;
             if (parent instanceof U.AST_DestructuredKeyVal && parent.value === node) return;
             if (parent instanceof U.AST_Unary && parent.expression === node) switch (parent.operator) {
               case "++":
@@ -135,7 +143,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 if (expr && !(expr instanceof U.AST_Hole)) {
                     node.start._permute++;
                     CHANGED = true;
-                    return expr;
+                    return expr instanceof U.AST_Spread ? expr.expression : expr;
                 }
             }
             else if (node instanceof U.AST_Binary) {
@@ -144,6 +152,20 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                     node.left,
                     node.right,
                 ][ permute & 1 ];
+                if (expr instanceof U.AST_Destructured) expr = expr.transform(new U.TreeTransformer(function(node, descend) {
+                    if (node instanceof U.AST_DefaultValue) return new U.AST_Assign({
+                        operator: "=",
+                        left: node.name.transform(this),
+                        right: node.value,
+                        start: {},
+                    });
+                    if (node instanceof U.AST_DestructuredKeyVal) return new U.AST_ObjectKeyVal(node);
+                    if (node instanceof U.AST_Destructured) {
+                        node = new (node instanceof U.AST_DestructuredArray ? U.AST_Array : U.AST_Object)(node);
+                        descend(node, this);
+                    }
+                    return node;
+                }));
                 CHANGED = true;
                 return permute < 2 ? expr : wrap_with_console_log(expr);
             }
@@ -164,7 +186,13 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 ][ ((node.start._permute += step) * steps | 0) % 3 ];
                 if (expr) {
                     CHANGED = true;
-                    return expr;
+                    return expr instanceof U.AST_Spread ? expr.expression : expr;
+                }
+                if (node.expression instanceof U.AST_Arrow && node.expression.value) {
+                    var seq = node.args.slice();
+                    seq.push(node.expression.value);
+                    CHANGED = true;
+                    return to_sequence(seq);
                 }
                 if (node.expression instanceof U.AST_Function) {
                     // hoist and return expressions from the IIFE function expression
@@ -196,6 +224,11 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                     node.alternative,
                 ][ ((node.start._permute += step) * steps | 0) % 3 ];
             }
+            else if (node instanceof U.AST_DefaultValue) {
+                node.start._permute++;
+                CHANGED = true;
+                return node.name;
+            }
             else if (node instanceof U.AST_Defun) {
                 switch (((node.start._permute += step) * steps | 0) % 2) {
                   case 0:
@@ -318,6 +351,11 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                     }
                 }
             }
+            else if (node instanceof U.AST_Spread) {
+                node.start._permute++;
+                CHANGED = true;
+                return node.expression;
+            }
             else if (node instanceof U.AST_Switch) {
                 var expr = [
                     node.expression,                         // switch expression
@@ -381,9 +419,8 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
             }
 
             if (in_list) {
-                // special case to drop object properties and switch branches
+                // drop switch branches
-                if (parent instanceof U.AST_Object
+                if (parent instanceof U.AST_Switch && parent.expression != node) {
-                    || parent instanceof U.AST_Switch && parent.expression != node) {
                     node.start._permute++;
                     CHANGED = true;
                     return List.skip;
@@ -404,7 +441,9 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 }
 
                 // skip element/property from (destructured) array/object
-                if (parent instanceof U.AST_Array || parent instanceof U.AST_Destructured || parent instanceof AST_Object) {
+                if (parent instanceof U.AST_Array
+                    || parent instanceof U.AST_Destructured
+                    || parent instanceof U.AST_Object) {
                     node.start._permute++;
                     CHANGED = true;
                     return List.skip;
@@ -449,7 +488,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                     if (node.TYPE == "Call" && node.expression.print_to_string() == "console.log") {
                         return to_sequence(node.args);
                     }
-                    if (node instanceof U.AST_Catch && node.argname) {
+                    if (node instanceof U.AST_Catch && node.argname instanceof U.AST_SymbolCatch) {
                         descend(node, this);
                         node.body.unshift(new U.AST_SimpleStatement({
                             body: wrap_with_console_log(new U.AST_SymbolRef(node.argname)),
@@ -458,7 +497,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                         return node;
                     }
                 }));
-                var code = testcase_ast.print_to_string();
+                var code = testcase_ast.print_to_string(print_options);
                 var diff = test_for_diff(code, minify_options, result_cache, max_timeout);
                 if (diff && !diff.timed_out && !diff.error) {
                     testcase = code;
@@ -482,7 +521,7 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
                 var code_ast = testcase_ast.clone(true).transform(tt);
                 if (!CHANGED) break;
                 try {
-                    var code = code_ast.print_to_string();
+                    var code = code_ast.print_to_string(print_options);
                 } catch (ex) {
                     // AST is not well formed.
                     // no harm done - just log the error, ignore latest change and continue iterating.
@@ -524,11 +563,13 @@ module.exports = function reduce_test(testcase, minify_options, reduce_options)
         var beautified = U.minify(testcase, {
             compress: false,
             mangle: false,
-            output: {
+            output: function() {
-                beautify: true,
+                var options = JSON.parse(JSON.stringify(print_options));
-                braces: true,
+                options.beautify = true;
-                comments: true,
+                options.braces = true;
-            },
+                options.comments = true;
+                return options;
+            }(),
         });
         testcase = {
             code: testcase,
@@ -617,7 +658,8 @@ function is_timed_out(result) {
 }
 
 function is_statement(node) {
-    return node instanceof U.AST_Statement && !(node instanceof U.AST_Function);
+    return node instanceof U.AST_Statement
+        && !(node instanceof U.AST_Arrow || node instanceof U.AST_AsyncFunction || node instanceof U.AST_Function);
 }
 
 function merge_sequence(array, node) {

test/sandbox.js

@@ -26,17 +26,27 @@ var setupContext = new vm.Script([
 ]).join("\n"));
 
 function createContext() {
-    var ctx = vm.createContext(Object.defineProperty({}, "console", { value: { log: log } }));
+    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":
+          case "function":
             return arg.toString();
-        case "object":
+          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);
@@ -54,7 +64,7 @@ function createContext() {
     }
 }
 
-exports.run_code = function(code, toplevel, timeout) {
+function run_code(code, toplevel, timeout) {
     timeout = timeout || 5000;
     var stdout = "";
     var original_write = process.stdout.write;
@@ -69,7 +79,17 @@ exports.run_code = function(code, toplevel, timeout) {
     } finally {
         process.stdout.write = original_write;
     }
-};
+}
+
+exports.run_code = semver.satisfies(process.version, "0.8") ? function(code, toplevel, timeout) {
+    var stdout = run_code(code, toplevel, timeout);
+    if (typeof stdout != "string" || !/arguments/.test(code)) return stdout;
+    do {
+        var prev = stdout;
+        stdout = run_code(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>");

test/ufuzz/job.js

@@ -70,7 +70,7 @@ function run() {
 
     function trap(data) {
         stderr += data;
-        if (~stderr.indexOf("\nminify(options):\n")) {
+        if (~stderr.indexOf("!!!!!! Failed... round ")) {
             process.exitCode = 1;
             child.stderr.removeListener("data", trap);
         }

test/ufuzz/options.json

@@ -21,14 +21,16 @@
     },
     {
         "compress": {
+            "hoist_vars": true,
+            "keep_infinity": true,
             "passes": 1e6,
             "unsafe": true
         },
+        "keep_fnames": true,
         "toplevel": true
     },
     {
         "compress": {
-            "keep_fargs": false,
             "passes": 1e6,
             "sequences": 1e6,
             "unsafe": true,

tools/exit.js

@@ -1,15 +0,0 @@
-// workaround for tty output truncation upon process.exit()
-var exit = process.exit;
-process.exit = function() {
-    var args = [].slice.call(arguments);
-    process.once("uncaughtException", function() {
-        (function callback() {
-            if (process.stdout.bufferSize || process.stderr.bufferSize) {
-                setTimeout(callback, 1);
-            } else {
-                exit.apply(process, args);
-            }
-        })();
-    });
-    throw exit;
-};

tools/tty.js

@@ -0,0 +1,22 @@
+// workaround for tty output truncation on Node.js
+try {
+    // prevent buffer overflow and other asynchronous bugs
+    process.stdout._handle.setBlocking(true);
+    process.stderr._handle.setBlocking(true);
+} catch (e) {
+    // ensure output buffers are flushed before process termination
+    var exit = process.exit;
+    process.exit = function() {
+        var args = [].slice.call(arguments);
+        process.once("uncaughtException", function() {
+            (function callback() {
+                if (process.stdout.bufferSize || process.stderr.bufferSize) {
+                    setTimeout(callback, 1);
+                } else {
+                    exit.apply(process, args);
+                }
+            })();
+        });
+        throw exit;
+    };
+}