v3.6.0

fixes #3429

LICENSE

@@ -1,6 +1,6 @@
 UglifyJS is released under the BSD license:
 
-Copyright 2012-2018 (c) Mihai Bazon <mihai.bazon@gmail.com>
+Copyright 2012-2019 (c) Mihai Bazon <mihai.bazon@gmail.com>
 
 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions

README.md

@@ -664,8 +664,9 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 
 - `join_vars` (default: `true`) -- join consecutive `var` statements
 
-- `keep_fargs` (default: `true`) -- Prevents the compressor from discarding unused
-  function arguments.  You need this for code which relies on `Function.length`.
+- `keep_fargs` (default: `strict`) -- Discard unused function arguments. Code
+  which relies on `Function.length` will break if this is done indiscriminately,
+  i.e. when passing `true`. Pass `false` to always retain function arguments.
 
 - `keep_fnames` (default: `false`) -- Pass `true` to prevent the
   compressor from discarding function names.  Useful for code relying on

lib/ast.js

@@ -376,7 +376,7 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     }
 }, AST_Scope);
 
-var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments", {
+var AST_Lambda = DEFNODE("Lambda", "name argnames uses_arguments length_read", {
     $documentation: "Base class for functions",
     $propdoc: {
         name: "[AST_SymbolDeclaration?] the name of this function",
@@ -614,6 +614,18 @@ var AST_PropAccess = DEFNODE("PropAccess", "expression property", {
     $propdoc: {
         expression: "[AST_Node] the “container” expression",
         property: "[AST_Node|string] the property to access.  For AST_Dot this is always a plain string, while for AST_Sub it's an arbitrary AST_Node"
+    },
+    getProperty: function() {
+        var p = this.property;
+        if (p instanceof AST_Constant) {
+            return p.getValue();
+        }
+        if (p instanceof AST_UnaryPrefix
+            && p.operator == "void"
+            && p.expression instanceof AST_Constant) {
+            return;
+        }
+        return p;
     }
 });
 

lib/compress.js

@@ -69,7 +69,7 @@ function Compressor(options, false_by_default) {
         if_return       : !false_by_default,
         inline          : !false_by_default,
         join_vars       : !false_by_default,
-        keep_fargs      : true,
+        keep_fargs      : false_by_default || "strict",
         keep_fnames     : false,
         keep_infinity   : false,
         loops           : !false_by_default,
@@ -104,6 +104,17 @@ function Compressor(options, false_by_default) {
         }
     }
     if (this.options["inline"] === true) this.options["inline"] = 3;
+    var keep_fargs = this.options["keep_fargs"];
+    this.drop_fargs = keep_fargs == "strict" ? function(lambda, parent) {
+        if (lambda.length_read) return false;
+        var name = lambda.name;
+        if (!name) return parent && parent.TYPE == "Call" && parent.expression === lambda;
+        if (name.fixed_value() !== lambda) return false;
+        var def = name.definition();
+        if (def.direct_access) return false;
+        var escaped = def.escaped;
+        return escaped && escaped.depth != 1;
+    } : keep_fargs ? return_false : return_true;
     var pure_funcs = this.options["pure_funcs"];
     if (typeof pure_funcs == "function") {
         this.pure_funcs = pure_funcs;
@@ -118,6 +129,8 @@ function Compressor(options, false_by_default) {
     } else {
         this.pure_funcs = return_true;
     }
+    var sequences = this.options["sequences"];
+    this.sequences_limit = sequences == 1 ? 800 : sequences | 0;
     var top_retain = this.options["top_retain"];
     if (top_retain instanceof RegExp) {
         this.top_retain = function(def) {
@@ -141,8 +154,6 @@ function Compressor(options, false_by_default) {
         funcs: toplevel,
         vars: toplevel
     };
-    var sequences = this.options["sequences"];
-    this.sequences_limit = sequences == 1 ? 800 : sequences | 0;
 }
 
 Compressor.prototype = new TreeTransformer;
@@ -272,14 +283,19 @@ merge(Compressor.prototype, {
         self.transform(tt);
     });
 
-    function read_property(obj, key) {
-        key = get_value(key);
+    function read_property(obj, node) {
+        var key = node.getProperty();
         if (key instanceof AST_Node) return;
         var value;
         if (obj instanceof AST_Array) {
             var elements = obj.elements;
             if (key == "length") return make_node_from_constant(elements.length, obj);
             if (typeof key == "number" && key in elements) value = elements[key];
+        } else if (obj instanceof AST_Lambda) {
+            if (key == "length") {
+                obj.length_read = true;
+                return make_node_from_constant(obj.argnames.length, obj);
+            }
         } else if (obj instanceof AST_Object) {
             key = "" + key;
             var props = obj.properties;
@@ -326,11 +342,17 @@ merge(Compressor.prototype, {
             return is_modified(compressor, tw, obj, obj, level + 2);
         }
         if (parent instanceof AST_PropAccess && parent.expression === node) {
-            var prop = read_property(value, parent.property);
+            var prop = read_property(value, parent);
             return !immutable && is_modified(compressor, tw, parent, prop, level + 1);
         }
     }
 
+    function is_arguments(def) {
+        if (def.name != "arguments") return false;
+        var orig = def.orig;
+        return orig.length == 1 && orig[0] instanceof AST_SymbolFunarg;
+    }
+
     (function(def) {
         def(AST_Node, noop);
 
@@ -428,9 +450,9 @@ merge(Compressor.prototype, {
             if (def.single_use == "m") return false;
             if (tw.safe_ids[def.id]) {
                 if (def.fixed == null) {
-                    var orig = def.orig[0];
-                    if (orig instanceof AST_SymbolFunarg || orig.name == "arguments") return false;
-                    def.fixed = make_node(AST_Undefined, orig);
+                    if (is_arguments(def)) return false;
+                    if (def.global && def.name == "arguments") return false;
+                    def.fixed = make_node(AST_Undefined, def.orig);
                 }
                 return true;
             }
@@ -490,23 +512,24 @@ merge(Compressor.prototype, {
                 var obj = tw.parent(level + 1);
                 mark_escaped(tw, d, scope, obj, obj, level + 2, depth);
             } else if (parent instanceof AST_PropAccess && node === parent.expression) {
-                value = read_property(value, parent.property);
+                value = read_property(value, parent);
                 mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1);
                 if (value) return;
             }
             if (level > 0) return;
+            if (parent instanceof AST_Call && node === parent.expression) return;
             if (parent instanceof AST_Sequence && node !== parent.tail_node()) return;
             if (parent instanceof AST_SimpleStatement) return;
+            if (parent instanceof AST_Unary && !unary_side_effects[parent.operator]) return;
             d.direct_access = true;
         }
 
         function mark_assignment_to_arguments(node) {
             if (!(node instanceof AST_Sub)) return;
             var expr = node.expression;
-            var prop = node.property;
-            if (expr instanceof AST_SymbolRef && expr.name == "arguments" && prop instanceof AST_Number) {
-                expr.definition().reassigned = true;
-            }
+            if (!(expr instanceof AST_SymbolRef)) return;
+            var def = expr.definition();
+            if (is_arguments(def) && node.property instanceof AST_Number) def.reassigned = true;
         }
 
         var suppressor = new TreeWalker(function(node) {
@@ -773,7 +796,7 @@ merge(Compressor.prototype, {
         });
         def(AST_Unary, function(tw, descend) {
             var node = this;
-            if (node.operator != "++" && node.operator != "--") return;
+            if (!unary_arithmetic[node.operator]) return;
             var exp = node.expression;
             if (!(exp instanceof AST_SymbolRef)) {
                 mark_assignment_to_arguments(exp);
@@ -869,9 +892,13 @@ merge(Compressor.prototype, {
         return orig.length == 1 && orig[0] instanceof AST_SymbolLambda;
     });
 
-    function is_lhs_read_only(lhs) {
+    function is_lhs_read_only(lhs, compressor) {
         if (lhs instanceof AST_This) return true;
-        if (lhs instanceof AST_SymbolRef) return lhs.definition().orig[0] instanceof AST_SymbolLambda;
+        if (lhs instanceof AST_SymbolRef) {
+            var def = lhs.definition();
+            return def.orig[0] instanceof AST_SymbolLambda
+                || compressor.exposed(def) && identifier_atom[def.name];
+        }
         if (lhs instanceof AST_PropAccess) {
             lhs = lhs.expression;
             if (lhs instanceof AST_SymbolRef) {
@@ -880,7 +907,7 @@ merge(Compressor.prototype, {
             }
             if (!lhs) return true;
             if (lhs.is_constant()) return true;
-            return is_lhs_read_only(lhs);
+            return is_lhs_read_only(lhs, compressor);
         }
         return false;
     }
@@ -1195,7 +1222,7 @@ merge(Compressor.prototype, {
                     var stop_if_hit = null;
                     var lhs = get_lhs(candidate);
                     var side_effects = lhs && lhs.has_side_effects(compressor);
-                    var scan_lhs = lhs && !side_effects && !is_lhs_read_only(lhs);
+                    var scan_lhs = lhs && !side_effects && !is_lhs_read_only(lhs, compressor);
                     var scan_rhs = foldable(get_rhs(candidate));
                     if (!scan_lhs && !scan_rhs) continue;
                     // Locate symbols which may execute code outside of scanning range
@@ -1419,7 +1446,7 @@ merge(Compressor.prototype, {
                     extract_candidates(expr.expression);
                     expr.body.forEach(extract_candidates);
                 } else if (expr instanceof AST_Unary) {
-                    if (expr.operator == "++" || expr.operator == "--") {
+                    if (unary_arithmetic[expr.operator]) {
                         candidates.push(hit_stack.slice());
                     } else {
                         extract_candidates(expr.expression);
@@ -1489,9 +1516,9 @@ merge(Compressor.prototype, {
             function mangleable_var(var_def) {
                 var value = var_def.value;
                 if (!(value instanceof AST_SymbolRef)) return;
-                if (value.name == "arguments") return;
                 var def = value.definition();
                 if (def.undeclared) return;
+                if (is_arguments(def)) return;
                 return value_def = def;
             }
 
@@ -2217,18 +2244,6 @@ merge(Compressor.prototype, {
         }));
     }
 
-    function get_value(key) {
-        if (key instanceof AST_Constant) {
-            return key.getValue();
-        }
-        if (key instanceof AST_UnaryPrefix
-            && key.operator == "void"
-            && key.expression instanceof AST_Constant) {
-            return;
-        }
-        return key;
-    }
-
     function is_undefined(node, compressor) {
         return node.is_undefined
             || node instanceof AST_Undefined
@@ -2267,8 +2282,7 @@ merge(Compressor.prototype, {
     // returns true if this node may be null, undefined or contain `AST_Accessor`
     (function(def) {
         AST_Node.DEFMETHOD("may_throw_on_access", function(compressor) {
-            return !compressor.option("pure_getters")
-                || this._dot_throw(compressor);
+            return !compressor.option("pure_getters") || this._dot_throw(compressor);
         });
         function is_strict(compressor) {
             return /strict/.test(compressor.option("pure_getters"));
@@ -2276,7 +2290,15 @@ merge(Compressor.prototype, {
         def(AST_Node, is_strict);
         def(AST_Array, return_false);
         def(AST_Assign, function(compressor) {
-            return this.operator == "=" && this.right._dot_throw(compressor);
+            if (this.operator != "=") return false;
+            var rhs = this.right;
+            if (!rhs._dot_throw(compressor)) return false;
+            var sym = this.left;
+            if (!(sym instanceof AST_SymbolRef)) return true;
+            if (rhs instanceof AST_Binary && rhs.operator == "||" && sym.name == rhs.left.name) {
+                return rhs.right._dot_throw(compressor);
+            }
+            return true;
         });
         def(AST_Binary, function(compressor) {
             return lazy_op[this.operator] && (this.left._dot_throw(compressor) || this.right._dot_throw(compressor));
@@ -2307,6 +2329,7 @@ merge(Compressor.prototype, {
             if (!is_strict(compressor)) return false;
             if (is_undeclared_ref(this) && this.is_declared(compressor)) return false;
             if (this.is_immutable()) return false;
+            if (is_arguments(this.definition())) return false;
             var fixed = this.fixed_value();
             if (!fixed) return true;
             this._dot_throw = return_true;
@@ -2334,7 +2357,7 @@ merge(Compressor.prototype, {
               case "&&":
                 return this.left.is_defined(compressor) && this.right.is_defined(compressor);
               case "||":
-                return this.left.is_defined(compressor) || this.right.is_defined(compressor);
+                return this.left.is_truthy() || this.right.is_defined(compressor);
               default:
                 return true;
             }
@@ -2354,7 +2377,7 @@ merge(Compressor.prototype, {
             if (this.is_immutable()) return true;
             var fixed = this.fixed_value();
             if (!fixed) return false;
-            this.is_defined = return_true;
+            this.is_defined = return_false;
             var result = fixed.is_defined(compressor);
             delete this.is_defined;
             return result;
@@ -2549,6 +2572,7 @@ merge(Compressor.prototype, {
     });
 
     var lazy_op = makePredicate("&& ||");
+    var unary_arithmetic = makePredicate("++ --");
     var unary_side_effects = makePredicate("delete ++ --");
 
     function is_lhs(node, parent) {
@@ -3601,7 +3625,7 @@ merge(Compressor.prototype, {
                     var value = null;
                     if (node instanceof AST_Assign) {
                         if (!in_use || node.left === sym && def.id in fixed_ids && fixed_ids[def.id] !== node) {
-                            value = node.right;
+                            value = get_rhs(node);
                         }
                     } else if (!in_use) {
                         value = make_node(AST_Number, node, {
@@ -3621,7 +3645,7 @@ merge(Compressor.prototype, {
                 node.name = null;
             }
             if (node instanceof AST_Lambda && !(node instanceof AST_Accessor)) {
-                var trim = !compressor.option("keep_fargs");
+                var trim = compressor.drop_fargs(node, parent);
                 for (var a = node.argnames, i = a.length; --i >= 0;) {
                     var sym = a[i];
                     if (!(sym.definition().id in in_use_ids)) {
@@ -3812,6 +3836,7 @@ merge(Compressor.prototype, {
                 };
             }
         });
+        tt.push(compressor.parent());
         self.transform(tt);
 
         function verify_safe_usage(def, read, modified) {
@@ -3825,6 +3850,15 @@ merge(Compressor.prototype, {
             }
         }
 
+        function get_rhs(assign) {
+            var rhs = assign.right;
+            if (!assign.write_only) return rhs;
+            if (!(rhs instanceof AST_Binary && lazy_op[rhs.operator])) return rhs;
+            var sym = assign.left;
+            if (!(sym instanceof AST_SymbolRef) || sym.name != rhs.left.name) return rhs;
+            return rhs.right.has_side_effects(compressor) ? rhs : rhs.right;
+        }
+
         function scan_ref_scoped(node, descend) {
             var node_def, props = [], sym = assign_as_unused(node, props);
             if (sym && self.variables.get(sym.name) === (node_def = sym.definition())) {
@@ -3832,9 +3866,10 @@ merge(Compressor.prototype, {
                     prop.walk(tw);
                 });
                 if (node instanceof AST_Assign) {
-                    node.right.walk(tw);
+                    var right = get_rhs(node);
+                    right.walk(tw);
                     if (node.left === sym) {
-                        if (!node_def.chained && sym.fixed_value(true) === node.right) {
+                        if (!node_def.chained && sym.fixed_value(true) === right) {
                             fixed_ids[node_def.id] = node;
                         }
                         if (!node.write_only) {
@@ -4052,6 +4087,16 @@ merge(Compressor.prototype, {
                 }));
                 return make_sequence(node, assignments);
             }
+            if (node instanceof AST_Unary
+                && !unary_side_effects[node.operator]
+                && node.expression instanceof AST_SymbolRef
+                && node.expression.definition().id in defs_by_id) {
+                node = node.clone();
+                node.expression = make_node(AST_Object, node, {
+                    properties: []
+                });
+                return node;
+            }
             if (node instanceof AST_VarDef && can_hoist(node.name, node.value, 0)) {
                 descend(node, this);
                 var defs = new Dictionary();
@@ -4068,7 +4113,7 @@ merge(Compressor.prototype, {
             if (node instanceof AST_PropAccess && node.expression instanceof AST_SymbolRef) {
                 var defs = defs_by_id[node.expression.definition().id];
                 if (defs) {
-                    var def = defs.get(get_value(node.property));
+                    var def = defs.get(node.getProperty());
                     var sym = make_node(AST_SymbolRef, node, {
                         name: def.name,
                         scope: node.expression.scope,
@@ -4135,12 +4180,14 @@ merge(Compressor.prototype, {
         });
         def(AST_Assign, function(compressor) {
             var left = this.left;
-            if (left.has_side_effects(compressor)
-                || compressor.has_directive("use strict")
-                    && left instanceof AST_PropAccess
-                    && left.expression.is_constant()) {
-                return this;
+            if (left instanceof AST_PropAccess) {
+                var expr = left.expression;
+                if (expr instanceof AST_Assign && !expr.may_throw_on_access(compressor)) {
+                    expr.write_only = true;
+                }
+                if (compressor.has_directive("use strict") && expr.is_constant()) return this;
             }
+            if (left.has_side_effects(compressor)) return this;
             this.write_only = true;
             if (root_expr(left).is_constant_expression(compressor.find_parent(AST_Scope))) {
                 return this.right.drop_side_effect_free(compressor);
@@ -4215,8 +4262,9 @@ merge(Compressor.prototype, {
         });
         def(AST_Constant, return_null);
         def(AST_Dot, function(compressor, first_in_statement) {
-            if (this.expression.may_throw_on_access(compressor)) return this;
-            return this.expression.drop_side_effect_free(compressor, first_in_statement);
+            var expr = this.expression;
+            if (expr.may_throw_on_access(compressor)) return this;
+            return expr.drop_side_effect_free(compressor, first_in_statement);
         });
         def(AST_Function, function(compressor) {
             return this.name && compressor.option("ie8") ? this : null;
@@ -4406,8 +4454,9 @@ merge(Compressor.prototype, {
 
     OPT(AST_For, function(self, compressor) {
         if (!compressor.option("loops")) return self;
-        if (compressor.option("side_effects") && self.init) {
-            self.init = self.init.drop_side_effect_free(compressor);
+        if (compressor.option("side_effects")) {
+            if (self.init) self.init = self.init.drop_side_effect_free(compressor);
+            if (self.step) self.step = self.step.drop_side_effect_free(compressor);
         }
         if (self.condition) {
             var cond = self.condition.evaluate(compressor);
@@ -5527,20 +5576,29 @@ merge(Compressor.prototype, {
                 self.right = tmp;
             }
         }
-        if (commutativeOperators[self.operator]) {
-            if (self.right.is_constant()
-                && !self.left.is_constant()) {
-                // if right is a constant, whatever side effects the
-                // left side might have could not influence the
-                // result.  hence, force switch.
-
-                if (!(self.left instanceof AST_Binary
-                      && PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
-                    reverse();
-                }
+        if (commutativeOperators[self.operator] && self.right.is_constant() && !self.left.is_constant()) {
+            // if right is a constant, whatever side effects the
+            // left side might have could not influence the
+            // result.  hence, force switch.
+            if (!(self.left instanceof AST_Binary
+                    && PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
+                reverse();
             }
         }
         self = self.lift_sequences(compressor);
+        if (compressor.option("assignments") && lazy_op[self.operator]) {
+            var assign = self.right;
+            // a || (a = x) => a = a || x
+            // a && (a = x) => a = a && x
+            if (self.left instanceof AST_SymbolRef
+                && assign instanceof AST_Assign
+                && assign.operator == "="
+                && self.left.equivalent_to(assign.left)) {
+                self.right = assign.right;
+                assign.right = self;
+                return assign;
+            }
+        }
         if (compressor.option("comparisons")) switch (self.operator) {
           case "===":
           case "!==":
@@ -5938,11 +5996,10 @@ merge(Compressor.prototype, {
                 }
             }
         }
-        if (compressor.option("unsafe")
-            && self.right instanceof AST_Call
-            && self.right.expression instanceof AST_Dot
-            && indexFns[self.right.expression.property]) {
+        if (compressor.option("unsafe")) {
+            var indexRight = is_indexFn(self.right);
             if (compressor.option("booleans")
+                && indexRight
                 && (self.operator == "==" || self.operator == "!=")
                 && self.left instanceof AST_Number
                 && self.left.getValue() == 0
@@ -5952,18 +6009,26 @@ merge(Compressor.prototype, {
                     expression: self.right
                 }) : self.right).optimize(compressor);
             }
+            var indexLeft = is_indexFn(self.left);
             if (compressor.option("comparisons") && is_indexOf_match_pattern()) {
                 var node = make_node(AST_UnaryPrefix, self, {
                     operator: "!",
                     expression: make_node(AST_UnaryPrefix, self, {
                         operator: "~",
-                        expression: self.right
+                        expression: indexLeft ? self.left : self.right
                     })
                 });
-                if (self.operator == "!=" || self.operator == "<=") node = make_node(AST_UnaryPrefix, self, {
-                    operator: "!",
-                    expression: node
-                });
+                switch (self.operator) {
+                  case "<":
+                    if (indexLeft) break;
+                  case "<=":
+                  case "!=":
+                    node = make_node(AST_UnaryPrefix, self, {
+                        operator: "!",
+                        expression: node
+                    });
+                    break;
+                }
                 return node.optimize(compressor);
             }
         }
@@ -6001,17 +6066,26 @@ merge(Compressor.prototype, {
             return node.evaluate(compressor);
         }
 
+        function is_indexFn(node) {
+            return node instanceof AST_Call
+                && node.expression instanceof AST_Dot
+                && indexFns[node.expression.property];
+        }
+
         function is_indexOf_match_pattern() {
             switch (self.operator) {
-              case ">":
               case "<=":
-                // 0 > array.indexOf(string) => !~array.indexOf(string)
                 // 0 <= array.indexOf(string) => !!~array.indexOf(string)
-                return self.left instanceof AST_Number && self.left.getValue() == 0;
+                return indexRight && self.left instanceof AST_Number && self.left.getValue() == 0;
+              case "<":
+                // array.indexOf(string) < 0 => !~array.indexOf(string)
+                if (indexLeft && self.right instanceof AST_Number && self.right.getValue() == 0) return true;
+                // -1 < array.indexOf(string) => !!~array.indexOf(string)
               case "==":
               case "!=":
                 // -1 == array.indexOf(string) => !~array.indexOf(string)
                 // -1 != array.indexOf(string) => !!~array.indexOf(string)
+                if (!indexRight) return false;
                 return self.left instanceof AST_Number && self.left.getValue() == -1
                     || self.left instanceof AST_UnaryPrefix && self.left.operator == "-"
                         && self.left.expression instanceof AST_Number && self.left.expression.getValue() == 1;
@@ -6635,24 +6709,30 @@ merge(Compressor.prototype, {
                 }
             }
         }
-        var fn;
+        var parent = compressor.parent();
+        var def, fn, fn_parent;
         if (compressor.option("arguments")
             && expr instanceof AST_SymbolRef
-            && expr.name == "arguments"
-            && expr.definition().orig.length == 1
+            && is_arguments(def = expr.definition())
             && prop instanceof AST_Number
-            && (fn = expr.scope) === compressor.find_parent(AST_Lambda)) {
+            && (fn = expr.scope) === find_lambda()) {
             var index = prop.getValue();
+            if (parent instanceof AST_UnaryPrefix && parent.operator == "delete") {
+                if (!def.deleted) def.deleted = [];
+                def.deleted[index] = true;
+            }
             var argname = fn.argnames[index];
-            if (argname && compressor.has_directive("use strict")) {
-                var def = argname.definition();
+            if (def.deleted && def.deleted[index]) {
+                argname = null;
+            } else if (argname && compressor.has_directive("use strict")) {
+                var arg_def = argname.definition();
                 if (!compressor.option("reduce_vars")
-                    || expr.definition().reassigned
-                    || def.assignments
-                    || def.orig.length > 1) {
+                    || def.reassigned
+                    || arg_def.assignments
+                    || arg_def.orig.length > 1) {
                     argname = null;
                 }
-            } else if (!argname && !compressor.option("keep_fargs") && index < fn.argnames.length + 5) {
+            } else if (!argname && index < fn.argnames.length + 5 && compressor.drop_fargs(fn, fn_parent)) {
                 while (index >= fn.argnames.length) {
                     argname = make_node(AST_SymbolFunarg, fn, {
                         name: fn.make_var_name("argument_" + fn.argnames.length),
@@ -6665,13 +6745,14 @@ merge(Compressor.prototype, {
             if (argname && find_if(function(node) {
                 return node.name === argname.name;
             }, fn.argnames) === argname) {
+                def.reassigned = false;
                 var sym = make_node(AST_SymbolRef, self, argname);
                 sym.reference({});
                 delete argname.__unused;
                 return sym;
             }
         }
-        if (is_lhs(compressor.self(), compressor.parent())) return self;
+        if (is_lhs(compressor.self(), parent)) return self;
         if (key !== prop) {
             var sub = self.flatten_object(property, compressor);
             if (sub) {
@@ -6720,6 +6801,16 @@ merge(Compressor.prototype, {
             return best_of(compressor, ev, self);
         }
         return self;
+
+        function find_lambda() {
+            var i = 0, p;
+            while (p = compressor.parent(i++)) {
+                if (p instanceof AST_Lambda) {
+                    fn_parent = compressor.parent(i);
+                    return p;
+                }
+            }
+        }
     });
 
     AST_Scope.DEFMETHOD("contains_this", function() {

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": "3.5.12",
+  "version": "3.6.0",
   "engines": {
     "node": ">=0.8.0"
   },

test/compress.js

@@ -1,35 +1,47 @@
-#! /usr/bin/env node
-
 var assert = require("assert");
+var child_process = require("child_process");
 var fs = require("fs");
 var path = require("path");
 var sandbox = require("./sandbox");
 var semver = require("semver");
 var U = require("./node");
 
-var failures = 0;
-var failed_files = Object.create(null);
-var minify_options = require("./ufuzz.json").map(JSON.stringify);
+var file = process.argv[2];
 var dir = path.resolve(path.dirname(module.filename), "compress");
-fs.readdirSync(dir).filter(function(name) {
-    return /\.js$/i.test(name);
-}).forEach(function(file) {
+if (file) {
+    var minify_options = require("./ufuzz.json").map(JSON.stringify);
     log("--- {file}", { file: file });
     var tests = parse_test(path.resolve(dir, file));
-    for (var i in tests) if (!test_case(tests[i])) {
-        failures++;
-        failed_files[file] = 1;
-    }
-});
-if (failures) {
-    console.error();
-    console.error("!!! Failed " + failures + " test case(s).");
-    console.error("!!! " + Object.keys(failed_files).join(", "));
-    process.exit(1);
+    process.exit(Object.keys(tests).filter(function(name) {
+        return !test_case(tests[name]);
+    }).length);
+} else {
+    var files = fs.readdirSync(dir).filter(function(name) {
+        return /\.js$/i.test(name);
+    });
+    var failures = 0;
+    var failed_files = Object.create(null);
+    (function next() {
+        var file = files.shift();
+        if (file) {
+            child_process.spawn(process.argv[0], [ process.argv[1], file ], {
+                stdio: [ "ignore", 1, 2 ]
+            }).on("exit", function(code) {
+                if (code) {
+                    failures += code;
+                    failed_files[file] = code;
+                }
+                next();
+            });
+        } else if (failures) {
+            console.error();
+            console.error("!!! Failed " + failures + " test case(s).");
+            console.error("!!! " + Object.keys(failed_files).join(", "));
+            process.exit(1);
+        }
+    })();
 }
 
-/* -----[ utils ]----- */
-
 function evaluate(code) {
     if (code instanceof U.AST_Node) code = make_code(code, { beautify: true });
     return new Function("return(" + code + ")")();
@@ -160,7 +172,7 @@ function parse_test(file) {
 
 // Try to reminify original input with standard options
 // to see if it matches expect_stdout.
-function reminify(orig_options, input_code, input_formatted, expect_stdout) {
+function reminify(orig_options, input_code, input_formatted, stdout) {
     for (var i = 0; i < minify_options.length; i++) {
         var options = JSON.parse(minify_options[i]);
         if (options.compress) [
@@ -191,11 +203,12 @@ function reminify(orig_options, input_code, input_formatted, expect_stdout) {
             });
             return false;
         } else {
-            var stdout = run_code(result.code);
-            if (typeof expect_stdout != "string" && typeof stdout != "string" && expect_stdout.name == stdout.name) {
-                stdout = expect_stdout;
+            var expected = stdout[options.toplevel ? 1 : 0];
+            var actual = run_code(result.code, options.toplevel);
+            if (typeof expected != "string" && typeof actual != "string" && expected.name == actual.name) {
+                actual = expected;
             }
-            if (!sandbox.same_stdout(expect_stdout, stdout)) {
+            if (!sandbox.same_stdout(expected, actual)) {
                 log([
                     "!!! failed running reminified input",
                     "---INPUT---",
@@ -214,10 +227,10 @@ function reminify(orig_options, input_code, input_formatted, expect_stdout) {
                     input: input_formatted,
                     options: options_formatted,
                     output: result.code,
-                    expected_type: typeof expect_stdout == "string" ? "STDOUT" : "ERROR",
-                    expected: expect_stdout,
-                    actual_type: typeof stdout == "string" ? "STDOUT" : "ERROR",
-                    actual: stdout,
+                    expected_type: typeof expected == "string" ? "STDOUT" : "ERROR",
+                    expected: expected,
+                    actual_type: typeof actual == "string" ? "STDOUT" : "ERROR",
+                    actual: actual,
                 });
                 return false;
             }
@@ -226,8 +239,8 @@ function reminify(orig_options, input_code, input_formatted, expect_stdout) {
     return true;
 }
 
-function run_code(code) {
-    var result = sandbox.run_code(code, true);
+function run_code(code, toplevel) {
+    var result = sandbox.run_code(code, toplevel);
     return typeof result == "string" ? result.replace(/\u001b\[\d+m/g, "") : result;
 }
 
@@ -359,13 +372,14 @@ function test_case(test) {
             return false;
         }
     }
-    if (test.expect_stdout
-        && (!test.node_version || semver.satisfies(process.version, test.node_version))) {
-        var stdout = run_code(input_code);
+    if (test.expect_stdout && (!test.node_version || semver.satisfies(process.version, test.node_version))) {
+        var stdout = [ run_code(input_code), run_code(input_code, true) ];
+        var toplevel = test.options.toplevel;
+        var actual = stdout[toplevel ? 1 : 0];
         if (test.expect_stdout === true) {
-            test.expect_stdout = stdout;
+            test.expect_stdout = actual;
         }
-        if (!sandbox.same_stdout(test.expect_stdout, stdout)) {
+        if (!sandbox.same_stdout(test.expect_stdout, actual)) {
             log([
                 "!!! Invalid input or expected stdout",
                 "---INPUT---",
@@ -380,13 +394,13 @@ function test_case(test) {
                 input: input_formatted,
                 expected_type: typeof test.expect_stdout == "string" ? "STDOUT" : "ERROR",
                 expected: test.expect_stdout,
-                actual_type: typeof stdout == "string" ? "STDOUT" : "ERROR",
-                actual: stdout,
+                actual_type: typeof actual == "string" ? "STDOUT" : "ERROR",
+                actual: actual,
             });
             return false;
         }
-        stdout = run_code(output);
-        if (!sandbox.same_stdout(test.expect_stdout, stdout)) {
+        actual = run_code(output, toplevel);
+        if (!sandbox.same_stdout(test.expect_stdout, actual)) {
             log([
                 "!!! failed",
                 "---INPUT---",
@@ -401,12 +415,12 @@ function test_case(test) {
                 input: input_formatted,
                 expected_type: typeof test.expect_stdout == "string" ? "STDOUT" : "ERROR",
                 expected: test.expect_stdout,
-                actual_type: typeof stdout == "string" ? "STDOUT" : "ERROR",
-                actual: stdout,
+                actual_type: typeof actual == "string" ? "STDOUT" : "ERROR",
+                actual: actual,
             });
             return false;
         }
-        if (!reminify(test.options, input_code, input_formatted, test.expect_stdout)) {
+        if (!reminify(test.options, input_code, input_formatted, stdout)) {
             return false;
         }
     }

test/compress/arguments.js

@@ -405,6 +405,52 @@ issue_3273_global_strict_reduce_vars: {
     ]
 }
 
+issue_3273_keep_fargs_false: {
+    options = {
+        arguments: true,
+        keep_fargs: false,
+        reduce_vars: true,
+    }
+    input: {
+        (function() {
+            "use strict";
+            arguments[0]++;
+            console.log(arguments[0]);
+        })(0);
+    }
+    expect: {
+        (function(argument_0) {
+            "use strict";
+            argument_0++;
+            console.log(argument_0);
+        })(0);
+    }
+    expect_stdout: "1"
+}
+
+issue_3273_keep_fargs_strict: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+        reduce_vars: true,
+    }
+    input: {
+        (function() {
+            "use strict";
+            arguments[0]++;
+            console.log(arguments[0]);
+        })(0);
+    }
+    expect: {
+        (function(argument_0) {
+            "use strict";
+            argument_0++;
+            console.log(argument_0);
+        })(0);
+    }
+    expect_stdout: "1"
+}
+
 issue_3282_1: {
     options = {
         arguments: true,
@@ -576,3 +622,157 @@ issue_3282_2_passes: {
     }
     expect_stdout: true
 }
+
+issue_3420_1: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+    }
+    input: {
+        console.log(function() {
+            return function() {
+                return arguments[0];
+            };
+        }().length);
+    }
+    expect: {
+        console.log(function() {
+            return function() {
+                return arguments[0];
+            };
+        }().length);
+    }
+    expect_stdout: "0"
+}
+
+issue_3420_2: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+    }
+    input: {
+        var foo = function() {
+            delete arguments[0];
+        };
+        foo();
+    }
+    expect: {
+        var foo = function() {
+            delete arguments[0];
+        };
+        foo();
+    }
+    expect_stdout: true
+}
+
+issue_3420_3: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+    }
+    input: {
+        "use strict";
+        var foo = function() {
+            delete arguments[0];
+        };
+        foo();
+    }
+    expect: {
+        "use strict";
+        var foo = function() {
+            delete arguments[0];
+        };
+        foo();
+    }
+    expect_stdout: true
+}
+
+issue_3420_4: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+    }
+    input: {
+        !function() {
+            console.log(arguments[0]);
+            delete arguments[0];
+            console.log(arguments[0]);
+        }(42);
+    }
+    expect: {
+        !function(argument_0) {
+            console.log(argument_0);
+            delete arguments[0];
+            console.log(arguments[0]);
+        }(42);
+    }
+    expect_stdout: [
+        "42",
+        "undefined",
+    ]
+}
+
+issue_3420_5: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+    }
+    input: {
+        "use strict";
+        !function() {
+            console.log(arguments[0]);
+            delete arguments[0];
+            console.log(arguments[0]);
+        }(42);
+    }
+    expect: {
+        "use strict";
+        !function(argument_0) {
+            console.log(argument_0);
+            delete arguments[0];
+            console.log(arguments[0]);
+        }(42);
+    }
+    expect_stdout: [
+        "42",
+        "undefined",
+    ]
+}
+
+issue_3420_6: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+    }
+    input: {
+        console.log(function() {
+            return delete arguments[0];
+        }());
+    }
+    expect: {
+        console.log(function() {
+            return delete arguments[0];
+        }());
+    }
+    expect_stdout: "true"
+}
+
+issue_3420_7: {
+    options = {
+        arguments: true,
+        keep_fargs: "strict",
+    }
+    input: {
+        "use strict";
+        console.log(function() {
+            return delete arguments[0];
+        }());
+    }
+    expect: {
+        "use strict";
+        console.log(function() {
+            return delete arguments[0];
+        }());
+    }
+    expect_stdout: "true"
+}

test/compress/assignment.js

@@ -311,3 +311,65 @@ issue_3375: {
     }
     expect_stdout: "string"
 }
+
+issue_3427: {
+    options = {
+        assignments: true,
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            var a;
+            a || (a = {});
+        })();
+    }
+    expect: {}
+}
+
+issue_3429_1: {
+    options = {
+        assignments: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        (function(b) {
+            b && (b = a = "FAIL");
+        })();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (function(b) {
+            b = b && (a = "FAIL");
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}
+
+issue_3429_2: {
+    options = {
+        assignments: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        (function(b) {
+            b || (b = a = "FAIL");
+        })(42);
+        console.log(a);
+    }
+    expect: {
+        var a;
+        (function(b) {
+            b = b || (a = "FAIL");
+        })(42);
+        console.log(a);
+    }
+    expect_stdout: "undefined"
+}

test/compress/collapse_vars.js

@@ -6178,3 +6178,22 @@ assign_undeclared: {
         "object",
     ]
 }
+
+Infinity_assignment: {
+    options = {
+        collapse_vars: true,
+        pure_getters: "strict",
+        unsafe: true,
+    }
+    input: {
+        var Infinity;
+        Infinity = 42;
+        console.log(Infinity);
+    }
+    expect: {
+        var Infinity;
+        Infinity = 42;
+        console.log(Infinity);
+    }
+    expect_stdout: true
+}

test/compress/comparisons.js

@@ -373,10 +373,70 @@ unsafe_indexOf: {
         unsafe: true,
     }
     input: {
-        if (Object.keys({ foo: 42 }).indexOf("foo") >= 0) console.log("PASS");
+        var a = Object.keys({ foo: 42 });
+        if (a.indexOf("bar") < 0) console.log("PASS");
+        if (0 > a.indexOf("bar")) console.log("PASS");
+        if (a.indexOf("foo") >= 0) console.log("PASS");
+        if (0 <= a.indexOf("foo")) console.log("PASS");
+        if (a.indexOf("foo") > -1) console.log("PASS");
+        if (-1 < a.indexOf("foo")) console.log("PASS");
+        if (a.indexOf("bar") == -1) console.log("PASS");
+        if (-1 == a.indexOf("bar")) console.log("PASS");
+        if (a.indexOf("bar") === -1) console.log("PASS");
+        if (-1 === a.indexOf("bar")) console.log("PASS");
+        if (a.indexOf("foo") != -1) console.log("PASS");
+        if (-1 != a.indexOf("foo")) console.log("PASS");
+        if (a.indexOf("foo") !== -1) console.log("PASS");
+        if (-1 !== a.indexOf("foo")) console.log("PASS");
     }
     expect: {
-        if (~Object.keys({ foo: 42 }).indexOf("foo")) console.log("PASS");
+        var a = Object.keys({ foo: 42 });
+        if (!~a.indexOf("bar")) console.log("PASS");
+        if (!~a.indexOf("bar")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+        if (!~a.indexOf("bar")) console.log("PASS");
+        if (!~a.indexOf("bar")) console.log("PASS");
+        if (!~a.indexOf("bar")) console.log("PASS");
+        if (!~a.indexOf("bar")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+        if (~a.indexOf("foo")) console.log("PASS");
+    }
+    expect_stdout: [
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+        "PASS",
+    ]
+}
+
+issue_3413: {
+    options = {
+        comparisons: true,
+        evaluate: true,
+        side_effects: true,
+    }
+    input: {
+        var b;
+        void 0 !== ("" < b || void 0) || console.log("PASS");
+    }
+    expect: {
+        var b;
+        void 0 !== ("" < b || void 0) || console.log("PASS");
     }
     expect_stdout: "PASS"
 }

test/compress/drop-unused.js

@@ -2028,3 +2028,37 @@ issue_3375: {
     }
     expect_stdout: "0 0"
 }
+
+issue_3427_1: {
+    options = {
+        sequences: true,
+        side_effects: true,
+        unused: true,
+    }
+    input: {
+        (function() {
+            var a;
+            a = a || {};
+        })();
+    }
+    expect: {}
+}
+
+issue_3427_2: {
+    options = {
+        unused: true,
+    }
+    input: {
+        (function() {
+            var s = "PASS";
+            console.log(s = s || "FAIL");
+        })();
+    }
+    expect: {
+        (function() {
+            var s = "PASS";
+            console.log(s = s || "FAIL");
+        })();
+    }
+    expect_stdout: "PASS"
+}

test/compress/hoist_props.js

@@ -862,3 +862,27 @@ issue_3071_3: {
     }
     expect_stdout: "2"
 }
+
+issue_3411: {
+    options = {
+        hoist_props: true,
+        reduce_vars: true,
+    }
+    input: {
+        var c = 1;
+        !function f() {
+            var o = {
+                p: --c && f()
+            };
+            +o || console.log("PASS");
+        }();
+    }
+    expect: {
+        var c = 1;
+        !function f() {
+            var o_p = --c && f();
+            +{} || console.log("PASS");
+        }();
+    }
+    expect_stdout: "PASS"
+}

test/compress/issue-1704.js

@@ -366,7 +366,7 @@ mangle_catch_redef_3: {
         console.log(o);
     }
     expect_exact: 'var o="PASS";try{throw 0}catch(o){(function(){function c(){o="FAIL"}c(),c()})()}console.log(o);'
-    expect_stdout: "PASS"
+    expect_stdout: true
 }
 
 mangle_catch_redef_3_toplevel: {
@@ -389,10 +389,10 @@ mangle_catch_redef_3_toplevel: {
         console.log(o);
     }
     expect_exact: 'var c="PASS";try{throw 0}catch(c){(function(){function o(){c="FAIL"}o(),o()})()}console.log(c);'
-    expect_stdout: "PASS"
+    expect_stdout: true
 }
 
-mangle_catch_redef_ie8_3: {
+mangle_catch_redef_3_ie8: {
     mangle = {
         ie8: true,
         toplevel: false,
@@ -412,7 +412,7 @@ mangle_catch_redef_ie8_3: {
         console.log(o);
     }
     expect_exact: 'var o="PASS";try{throw 0}catch(o){(function(){function c(){o="FAIL"}c(),c()})()}console.log(o);'
-    expect_stdout: "PASS"
+    expect_stdout: true
 }
 
 mangle_catch_redef_3_ie8_toplevel: {
@@ -435,5 +435,5 @@ mangle_catch_redef_3_ie8_toplevel: {
         console.log(o);
     }
     expect_exact: 'var c="PASS";try{throw 0}catch(c){(function(){function o(){c="FAIL"}o(),o()})()}console.log(c);'
-    expect_stdout: "PASS"
+    expect_stdout: true
 }

test/compress/loops.js

@@ -673,3 +673,19 @@ issue_3371: {
     }
     expect_stdout: "PASS"
 }
+
+step: {
+    options = {
+        loops: true,
+        side_effects: true,
+    }
+    input: {
+        for (var i = 0; i < 42; "foo", i++, "bar");
+        console.log(i);
+    }
+    expect: {
+        for (var i = 0; i < 42; i++);
+        console.log(i);
+    }
+    expect_stdout: "42"
+}

test/compress/pure_getters.js

@@ -1161,3 +1161,49 @@ collapse_rhs_lhs: {
     }
     expect_stdout: "1 3"
 }
+
+drop_arguments: {
+    options = {
+        pure_getters: "strict",
+        side_effects: true,
+    }
+    input: {
+        (function() {
+            arguments.slice = function() {
+                console.log("PASS");
+            };
+            arguments[42];
+            arguments.length;
+            arguments.slice();
+        })();
+    }
+    expect: {
+        (function() {
+            arguments.slice = function() {
+                console.log("PASS");
+            };
+            arguments.slice();
+        })();
+    }
+    expect_stdout: "PASS"
+}
+
+issue_3427: {
+    options = {
+        assignments: true,
+        collapse_vars: true,
+        inline: true,
+        pure_getters: "strict",
+        sequences: true,
+        side_effects: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a;
+        (function(b) {
+            b.p = 42;
+        })(a || (a = {}));
+    }
+    expect: {}
+}

test/compress/sandbox.js

@@ -12,3 +12,71 @@ console_log: {
         "% %s",
     ]
 }
+
+typeof_arguments: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var arguments;
+        console.log((typeof arguments).length);
+    }
+    expect: {
+        var arguments;
+        console.log((typeof arguments).length);
+    }
+    expect_stdout: "6"
+}
+
+typeof_arguments_assigned: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var arguments = void 0;
+        console.log((typeof arguments).length);
+    }
+    expect: {
+        console.log("undefined".length);
+    }
+    expect_stdout: "9"
+}
+
+toplevel_Infinity_NaN_undefined: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var Infinity = "foo";
+        var NaN = 42;
+        var undefined = null;
+        console.log(Infinity, NaN, undefined);
+    }
+    expect: {
+        console.log("foo", 42, null);
+    }
+    expect_stdout: "foo 42 null"
+}
+
+log_global: {
+    input: {
+        console.log(function() {
+            return this;
+        }());
+    }
+    expect: {
+        console.log(function() {
+            return this;
+        }());
+    }
+    expect_stdout: "[object global]"
+}

test/sandbox.js

@@ -1,29 +1,7 @@
 var semver = require("semver");
 var vm = require("vm");
 
-function safe_log(arg, level) {
-    if (arg) switch (typeof arg) {
-      case "function":
-        return arg.toString();
-      case "object":
-        if (/Error$/.test(arg.name)) return arg.toString();
-        arg.constructor.toString();
-        if (level--) for (var key in arg) {
-            var desc = Object.getOwnPropertyDescriptor(arg, key);
-            if (!desc || !desc.get) arg[key] = safe_log(arg[key], level);
-        }
-    }
-    return arg;
-}
-
-function log(msg) {
-    if (arguments.length == 1 && typeof msg == "string") return console.log("%s", msg);
-    return console.log.apply(console, [].map.call(arguments, function(arg) {
-        return safe_log(arg, 3);
-    }));
-}
-
-var func_toString = new vm.Script([
+var setupContext = new vm.Script([
     "[ Array, Boolean, Error, Function, Number, Object, RegExp, String ].forEach(function(f) {",
     "    f.toString = Function.prototype.toString;",
     "});",
@@ -44,40 +22,51 @@ var func_toString = new vm.Script([
     '        return "function(){}";',
     "    };",
     "}();",
+    "this;",
 ]).join("\n"));
 
 function createContext() {
     var ctx = vm.createContext(Object.defineProperty({}, "console", { value: { log: log } }));
-    func_toString.runInContext(ctx);
+    var global = setupContext.runInContext(ctx);
     return ctx;
+
+    function safe_log(arg, level) {
+        if (arg) switch (typeof arg) {
+        case "function":
+            return arg.toString();
+        case "object":
+            if (arg === global) return "[object global]";
+            if (/Error$/.test(arg.name)) return arg.toString();
+            arg.constructor.toString();
+            if (level--) for (var key in arg) {
+                var desc = Object.getOwnPropertyDescriptor(arg, key);
+                if (!desc || !desc.get) arg[key] = safe_log(arg[key], level);
+            }
+        }
+        return arg;
+    }
+
+    function log(msg) {
+        if (arguments.length == 1 && typeof msg == "string") return console.log("%s", msg);
+        return console.log.apply(console, [].map.call(arguments, function(arg) {
+            return safe_log(arg, 3);
+        }));
+    }
 }
 
-var context;
-exports.run_code = function(code, reuse) {
+exports.run_code = function(code, toplevel) {
     var stdout = "";
     var original_write = process.stdout.write;
     process.stdout.write = function(chunk) {
         stdout += chunk;
     };
     try {
-        if (!reuse || !context) context = createContext();
-        vm.runInContext([
-            "!function() {",
-            code,
-            "}();",
-        ].join("\n"), context, { timeout: 5000 });
+        vm.runInContext(toplevel ? "(function(){" + code + "})()" : code, createContext(), { timeout: 5000 });
         return stdout;
     } catch (ex) {
         return ex;
     } finally {
         process.stdout.write = original_write;
-        if (!reuse || code.indexOf(".prototype") >= 0) {
-            context = null;
-        } else {
-            vm.runInContext(Object.keys(context).map(function(name) {
-                return "delete " + name;
-            }).join("\n"), context);
-        }
     }
 };
 

test/ufuzz.js

@@ -969,7 +969,7 @@ function errorln(msg) {
     process.stderr.write("\n");
 }
 
-function try_beautify(code, result, printfn) {
+function try_beautify(code, toplevel, result, printfn) {
     var beautified = UglifyJS.minify(code, {
         compress: false,
         mangle: false,
@@ -981,7 +981,7 @@ function try_beautify(code, result, printfn) {
     if (beautified.error) {
         printfn("// !!! beautify failed !!!");
         printfn(beautified.error.stack);
-    } else if (sandbox.same_stdout(sandbox.run_code(beautified.code), result)) {
+    } else if (sandbox.same_stdout(sandbox.run_code(beautified.code, toplevel), result)) {
         printfn("// (beautified)");
         printfn(beautified.code);
         return;
@@ -1009,7 +1009,7 @@ function log_suspects(minify_options, component) {
                 errorln("Error testing options." + component + "." + name);
                 errorln(result.error.stack);
             } else {
-                var r = sandbox.run_code(result.code);
+                var r = sandbox.run_code(result.code, m.toplevel);
                 return sandbox.same_stdout(original_result, r);
             }
         }
@@ -1031,7 +1031,7 @@ function log_rename(options) {
         errorln("Error testing options.rename");
         errorln(result.error.stack);
     } else {
-        var r = sandbox.run_code(result.code);
+        var r = sandbox.run_code(result.code, m.toplevel);
         if (sandbox.same_stdout(original_result, r)) {
             errorln("Suspicious options:");
             errorln("  rename");
@@ -1045,23 +1045,24 @@ function log(options) {
     errorln("//=============================================================");
     if (!ok) errorln("// !!!!!! Failed... round " + round);
     errorln("// original code");
-    try_beautify(original_code, original_result, errorln);
+    try_beautify(original_code, false, original_result, errorln);
     errorln();
     errorln();
     errorln("//-------------------------------------------------------------");
+    options = JSON.parse(options);
     if (typeof uglify_code == "string") {
         errorln("// uglified code");
-        try_beautify(uglify_code, uglify_result, errorln);
+        try_beautify(uglify_code, options.toplevel, uglify_result, errorln);
         errorln();
         errorln();
         errorln("original result:");
-        errorln(typeof original_result == "string" ? original_result : original_result.stack);
+        errorln(errored ? original_result.stack : original_result);
         errorln("uglified result:");
         errorln(typeof uglify_result == "string" ? uglify_result : uglify_result.stack);
     } else {
         errorln("// !!! uglify failed !!!");
         errorln(uglify_code.stack);
-        if (typeof original_result != "string") {
+        if (errored) {
             errorln();
             errorln();
             errorln("original stacktrace:");
@@ -1069,7 +1070,6 @@ function log(options) {
         }
     }
     errorln("minify(options):");
-    options = JSON.parse(options);
     errorln(JSON.stringify(options, null, 2));
     errorln();
     if (!ok && typeof uglify_code == "string") {
@@ -1084,30 +1084,34 @@ var fallback_options = [ JSON.stringify({
     mangle: false
 }) ];
 var minify_options = require("./ufuzz.json").map(JSON.stringify);
-var original_code, original_result;
+var original_code, original_result, errored;
 var uglify_code, uglify_result, ok;
 for (var round = 1; round <= num_iterations; round++) {
     process.stdout.write(round + " of " + num_iterations + "\r");
 
     original_code = createTopLevelCode();
-    original_result = sandbox.run_code(original_code);
-    (typeof original_result != "string" ? fallback_options : minify_options).forEach(function(options) {
-        uglify_code = UglifyJS.minify(original_code, JSON.parse(options));
+    var orig_result = [ sandbox.run_code(original_code) ];
+    errored = typeof orig_result[0] != "string";
+    if (!errored) orig_result.push(sandbox.run_code(original_code, true));
+    (errored ? fallback_options : minify_options).forEach(function(options) {
+        var o = JSON.parse(options);
+        uglify_code = UglifyJS.minify(original_code, o);
+        original_result = orig_result[o.toplevel ? 1 : 0];
         if (!uglify_code.error) {
             uglify_code = uglify_code.code;
-            uglify_result = sandbox.run_code(uglify_code);
+            uglify_result = sandbox.run_code(uglify_code, o.toplevel);
             ok = sandbox.same_stdout(original_result, uglify_result);
         } else {
             uglify_code = uglify_code.error;
-            if (typeof original_result != "string") {
+            if (errored) {
                 ok = uglify_code.name == original_result.name;
             }
         }
         if (verbose || (verbose_interval && !(round % INTERVAL_COUNT)) || !ok) log(options);
-        else if (typeof original_result != "string") {
+        else if (errored) {
             println("//=============================================================");
             println("// original code");
-            try_beautify(original_code, original_result, println);
+            try_beautify(original_code, o.toplevel, original_result, println);
             println();
             println();
             println("original result:");