v3.8.0

- print out Node.js and OS information

README.md

@@ -848,8 +848,14 @@ can pass additional arguments that control the code output:
   statement.
 
 - `comments` (default `false`) -- pass `true` or `"all"` to preserve all
-  comments, `"some"` to preserve some comments, a regular expression string
-  (e.g. `/^!/`) or a function.
+  comments, `"some"` to preserve multi-line comments that contain `@cc_on`,
+  `@license`, or `@preserve` (case-insensitive), a regular expression string
+  (e.g. `/^!/`), or a function which returns `boolean`, e.g.
+  ```js
+  function(node, comment) {
+      return comment.value.indexOf("@type " + node.TYPE) >= 0;
+  }
+  ```
 
 - `indent_level` (default `4`)
 

bin/uglifyjs

@@ -54,6 +54,7 @@ program.option("--toplevel", "Compress and/or mangle variables in toplevel scope
 program.option("--verbose", "Print diagnostic messages.");
 program.option("--warn", "Print warning messages.");
 program.option("--wrap <name>", "Embed everything as a function with “exports” corresponding to “name” globally.");
+program.option("--reduce-test", "Reduce a standalone `console.log` based test case.");
 program.arguments("[files...]").parseArgv(process.argv);
 if (program.configFile) {
     options = JSON.parse(read_file(program.configFile));
@@ -215,7 +216,15 @@ function run() {
     } catch (ex) {
         fatal(ex);
     }
-    var result = UglifyJS.minify(files, options);
+    if (program.reduceTest) {
+        // load on demand - assumes dev tree checked out
+        var reduce_test = require("../test/reduce");
+        var testcase = files[0] || files[Object.keys(files)[0]];
+        var result = reduce_test(testcase, options, {verbose: true});
+    }
+    else {
+        var result = UglifyJS.minify(files, options);
+    }
     if (result.error) {
         var ex = result.error;
         if (ex.name == "SyntaxError") {

lib/ast.js

@@ -169,10 +169,7 @@ var AST_SimpleStatement = DEFNODE("SimpleStatement", "body", {
 }, AST_Statement);
 
 function walk_body(node, visitor) {
-    var body = node.body;
-    if (body instanceof AST_Statement) {
-        body._walk(visitor);
-    } else body.forEach(function(node) {
+    node.body.forEach(function(node) {
         node._walk(visitor);
     });
 }
@@ -351,7 +348,7 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
             filename: "wrap=" + JSON.stringify(name)
         }).transform(new TreeTransformer(function(node) {
             if (node instanceof AST_Directive && node.value == "$ORIG") {
-                return MAP.splice(body);
+                return List.splice(body);
             }
         }));
     },
@@ -370,7 +367,7 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
             filename: "enclose=" + JSON.stringify(args_values)
         }).transform(new TreeTransformer(function(node) {
             if (node instanceof AST_Directive && node.value == "$ORIG") {
-                return MAP.splice(body);
+                return List.splice(body);
             }
         }));
     }

lib/compress.js

@@ -1230,7 +1230,7 @@ merge(Compressor.prototype, {
                         var parent = multi_replacer.parent();
                         if (parent instanceof AST_Sequence && parent.tail_node() !== node) {
                             value_def.replaced++;
-                            return MAP.skip;
+                            return List.skip;
                         }
                         return get_rvalue(candidate);
                       case 1:
@@ -1863,7 +1863,7 @@ merge(Compressor.prototype, {
                         node.value = null;
                         return node;
                     }
-                    return in_list ? MAP.skip : null;
+                    return in_list ? List.skip : null;
                 }, patch_sequence));
             }
 
@@ -3071,12 +3071,17 @@ merge(Compressor.prototype, {
         // If the node has been successfully reduced to a constant,
         // then its value is returned; otherwise the element itself
         // is returned.
+        //
         // They can be distinguished as constant value is never a
         // descendant of AST_Node.
-        AST_Node.DEFMETHOD("evaluate", function(compressor) {
+        //
+        // When `ignore_side_effects` is `true`, inspect the constant value
+        // produced without worrying about any side effects caused by said
+        // expression.
+        AST_Node.DEFMETHOD("evaluate", function(compressor, ignore_side_effects) {
             if (!compressor.option("evaluate")) return this;
             var cached = [];
-            var val = this._eval(compressor, cached, 1);
+            var val = this._eval(compressor, ignore_side_effects, cached, 1);
             cached.forEach(function(node) {
                 delete node._eval;
             });
@@ -3104,6 +3109,19 @@ merge(Compressor.prototype, {
         def(AST_Constant, function() {
             return this.value;
         });
+        def(AST_Assign, function(compressor, ignore_side_effects, cached, depth) {
+            if (!ignore_side_effects) return this;
+            if (this.operator != "=") return this;
+            var node = this.right;
+            var value = node._eval(compressor, ignore_side_effects, cached, depth);
+            return value === node ? this : value;
+        });
+        def(AST_Sequence, function(compressor, ignore_side_effects, cached, depth) {
+            if (!ignore_side_effects) return this;
+            var node = this.tail_node();
+            var value = node._eval(compressor, ignore_side_effects, cached, depth);
+            return value === node ? this : value;
+        });
         def(AST_Function, function(compressor) {
             if (compressor.option("unsafe")) {
                 var fn = function() {};
@@ -3115,12 +3133,12 @@ merge(Compressor.prototype, {
             }
             return this;
         });
-        def(AST_Array, function(compressor, cached, depth) {
+        def(AST_Array, function(compressor, ignore_side_effects, cached, depth) {
             if (compressor.option("unsafe")) {
                 var elements = [];
                 for (var i = 0; i < this.elements.length; i++) {
                     var element = this.elements[i];
-                    var value = element._eval(compressor, cached, depth);
+                    var value = element._eval(compressor, ignore_side_effects, cached, depth);
                     if (element === value) return this;
                     elements.push(value);
                 }
@@ -3128,7 +3146,7 @@ merge(Compressor.prototype, {
             }
             return this;
         });
-        def(AST_Object, function(compressor, cached, depth) {
+        def(AST_Object, function(compressor, ignore_side_effects, cached, depth) {
             if (compressor.option("unsafe")) {
                 var val = {};
                 for (var i = 0; i < this.properties.length; i++) {
@@ -3137,14 +3155,14 @@ merge(Compressor.prototype, {
                     if (key instanceof AST_Symbol) {
                         key = key.name;
                     } else if (key instanceof AST_Node) {
-                        key = key._eval(compressor, cached, depth);
+                        key = key._eval(compressor, ignore_side_effects, cached, depth);
                         if (key === prop.key) return this;
                     }
                     if (typeof Object.prototype[key] === 'function') {
                         return this;
                     }
                     if (prop.value instanceof AST_Function) continue;
-                    val[key] = prop.value._eval(compressor, cached, depth);
+                    val[key] = prop.value._eval(compressor, ignore_side_effects, cached, depth);
                     if (val[key] === prop.value) return this;
                 }
                 return val;
@@ -3152,7 +3170,7 @@ merge(Compressor.prototype, {
             return this;
         });
         var non_converting_unary = makePredicate("! typeof void");
-        def(AST_UnaryPrefix, function(compressor, cached, depth) {
+        def(AST_UnaryPrefix, function(compressor, ignore_side_effects, cached, depth) {
             var e = this.expression;
             // Function would be evaluated to an array and so typeof would
             // incorrectly return 'object'. Hence making is a special case.
@@ -3164,7 +3182,7 @@ merge(Compressor.prototype, {
                 return typeof function(){};
             }
             if (!non_converting_unary[this.operator]) depth++;
-            var v = e._eval(compressor, cached, depth);
+            var v = e._eval(compressor, ignore_side_effects, cached, depth);
             if (v === this.expression) return this;
             switch (this.operator) {
               case "!": return !v;
@@ -3187,12 +3205,12 @@ merge(Compressor.prototype, {
             return this;
         });
         var non_converting_binary = makePredicate("&& || === !==");
-        def(AST_Binary, function(compressor, cached, depth) {
+        def(AST_Binary, function(compressor, ignore_side_effects, cached, depth) {
             if (!non_converting_binary[this.operator]) depth++;
-            var left = this.left._eval(compressor, cached, depth);
+            var left = this.left._eval(compressor, ignore_side_effects, cached, depth);
             if (left === this.left) return this;
             if (this.operator == (left ? "||" : "&&")) return left;
-            var right = this.right._eval(compressor, cached, depth);
+            var right = this.right._eval(compressor, ignore_side_effects, cached, depth);
             if (right === this.right) return this;
             var result;
             switch (this.operator) {
@@ -3235,14 +3253,14 @@ merge(Compressor.prototype, {
                 return (match[1] || ".").length - 1 - (match[2] || "").slice(1);
             }
         });
-        def(AST_Conditional, function(compressor, cached, depth) {
-            var condition = this.condition._eval(compressor, cached, depth);
+        def(AST_Conditional, function(compressor, ignore_side_effects, cached, depth) {
+            var condition = this.condition._eval(compressor, ignore_side_effects, cached, depth);
             if (condition === this.condition) return this;
             var node = condition ? this.consequent : this.alternative;
-            var value = node._eval(compressor, cached, depth);
+            var value = node._eval(compressor, ignore_side_effects, cached, depth);
             return value === node ? this : value;
         });
-        def(AST_SymbolRef, function(compressor, cached, depth) {
+        def(AST_SymbolRef, function(compressor, ignore_side_effects, cached, depth) {
             var fixed = this.fixed_value();
             if (!fixed) return this;
             var value;
@@ -3250,7 +3268,7 @@ merge(Compressor.prototype, {
                 value = fixed._eval();
             } else {
                 this._eval = return_this;
-                value = fixed._eval(compressor, cached, depth);
+                value = fixed._eval(compressor, ignore_side_effects, cached, depth);
                 delete this._eval;
                 if (value === fixed) return this;
                 fixed._eval = function() {
@@ -3307,11 +3325,11 @@ merge(Compressor.prototype, {
             ],
         });
         var regexp_props = makePredicate("global ignoreCase multiline source");
-        def(AST_PropAccess, function(compressor, cached, depth) {
+        def(AST_PropAccess, function(compressor, ignore_side_effects, cached, depth) {
             if (compressor.option("unsafe")) {
                 var key = this.property;
                 if (key instanceof AST_Node) {
-                    key = key._eval(compressor, cached, depth);
+                    key = key._eval(compressor, ignore_side_effects, cached, depth);
                     if (key === this.property) return this;
                 }
                 var exp = this.expression;
@@ -3321,7 +3339,7 @@ merge(Compressor.prototype, {
                     if (!static_value || !static_value[key]) return this;
                     val = global_objs[exp.name];
                 } else {
-                    val = exp._eval(compressor, cached, depth + 1);
+                    val = exp._eval(compressor, ignore_side_effects, cached, depth + 1);
                     if (val == null || val === exp) return this;
                     if (val instanceof RegExp) {
                         if (!regexp_props[key]) return this;
@@ -3340,7 +3358,7 @@ merge(Compressor.prototype, {
             }
             return this;
         });
-        def(AST_Call, function(compressor, cached, depth) {
+        def(AST_Call, function(compressor, ignore_side_effects, cached, depth) {
             var exp = this.expression;
             var fn = exp instanceof AST_SymbolRef ? exp.fixed_value() : exp;
             if (fn instanceof AST_Lambda) {
@@ -3361,14 +3379,14 @@ merge(Compressor.prototype, {
                     });
                 });
                 fn.evaluating = true;
-                var val = stat.value._eval(compressor, cached, depth);
+                var val = stat.value._eval(compressor, ignore_side_effects, cached, depth);
                 delete fn.evaluating;
                 if (val === stat.value) return this;
                 return val;
             } else if (compressor.option("unsafe") && exp instanceof AST_PropAccess) {
                 var key = exp.property;
                 if (key instanceof AST_Node) {
-                    key = key._eval(compressor, cached, depth);
+                    key = key._eval(compressor, ignore_side_effects, cached, depth);
                     if (key === exp.property) return this;
                 }
                 var val;
@@ -3378,7 +3396,7 @@ merge(Compressor.prototype, {
                     if (!static_fn || !static_fn[key]) return this;
                     val = global_objs[e.name];
                 } else {
-                    val = e._eval(compressor, cached, depth + 1);
+                    val = e._eval(compressor, ignore_side_effects, cached, depth + 1);
                     if (val == null || val === e) return this;
                     var native_fn = native_fns[val.constructor.name];
                     if (!native_fn || !native_fn[key]) return this;
@@ -3403,7 +3421,7 @@ merge(Compressor.prototype, {
                 var values = [];
                 for (var i = 0; i < args.length; i++) {
                     var arg = args[i];
-                    var value = arg._eval(compressor, cached, depth);
+                    var value = arg._eval(compressor, ignore_side_effects, cached, depth);
                     if (arg === value) return;
                     values.push(value);
                 }
@@ -3988,6 +4006,8 @@ merge(Compressor.prototype, {
         };
         // pass 3: we should drop declarations not in_use
         var unused_fn_names = [];
+        var calls_to_drop_args = [];
+        var fns_with_marked_args = [];
         var tt = new TreeTransformer(function(node, descend, in_list) {
             var parent = tt.parent();
             if (drop_vars) {
@@ -4017,7 +4037,7 @@ merge(Compressor.prototype, {
                         if (value) props.push(value);
                         switch (props.length) {
                           case 0:
-                            return MAP.skip;
+                            return List.skip;
                           case 1:
                             return maintain_this_binding(compressor, parent, node, props[0].transform(tt));
                           default:
@@ -4028,6 +4048,7 @@ merge(Compressor.prototype, {
                     }
                 }
             }
+            if (node instanceof AST_Call) calls_to_drop_args.push(node);
             if (scope !== self) return;
             if (node instanceof AST_Function && node.name && drop_fn_name(node.name.definition())) {
                 unused_fn_names.push(node);
@@ -4046,6 +4067,7 @@ merge(Compressor.prototype, {
                         trim = false;
                     }
                 }
+                fns_with_marked_args.push(node);
             }
             if (drop_funcs && node instanceof AST_Defun && node !== self) {
                 var def = node.name.definition();
@@ -4159,11 +4181,11 @@ merge(Compressor.prototype, {
                 }
                 switch (body.length) {
                   case 0:
-                    return in_list ? MAP.skip : make_node(AST_EmptyStatement, node);
+                    return in_list ? List.skip : make_node(AST_EmptyStatement, node);
                   case 1:
                     return body[0];
                   default:
-                    return in_list ? MAP.splice(body) : make_node(AST_BlockStatement, node, {
+                    return in_list ? List.splice(body) : make_node(AST_BlockStatement, node, {
                         body: body
                     });
                 }
@@ -4177,7 +4199,7 @@ merge(Compressor.prototype, {
                     var block = node.body;
                     node.body = block.body.pop();
                     block.body.push(node);
-                    return in_list ? MAP.splice(block.body) : block;
+                    return in_list ? List.splice(block.body) : block;
                 }
                 return node;
             }
@@ -4214,7 +4236,7 @@ merge(Compressor.prototype, {
                 } else if (is_empty(node.init)) {
                     node.init = null;
                 }
-                return !block ? node : in_list ? MAP.splice(block.body) : block;
+                return !block ? node : in_list ? List.splice(block.body) : block;
             } else if (node instanceof AST_ForIn) {
                 if (!drop_vars || !compressor.option("loops")) return;
                 if (!(node.init instanceof AST_Definitions)) return;
@@ -4229,7 +4251,7 @@ merge(Compressor.prototype, {
                         body: value
                     });
                 }
-                return in_list ? MAP.skip : make_node(AST_EmptyStatement, node);
+                return in_list ? List.skip : make_node(AST_EmptyStatement, node);
             } else if (node instanceof AST_Sequence) {
                 if (node.expressions.length == 1) return node.expressions[0];
             }
@@ -4239,6 +4261,9 @@ merge(Compressor.prototype, {
         unused_fn_names.forEach(function(fn) {
             fn.name = null;
         });
+        calls_to_drop_args.forEach(function(call) {
+            drop_unused_call_args(call, compressor, fns_with_marked_args);
+        });
 
         function log(sym, text, props) {
             AST_Node[sym.unreferenced() ? "warn" : "info"](text, props);
@@ -4478,7 +4503,7 @@ merge(Compressor.prototype, {
             node.in_bool = true;
             var value = node.value;
             if (value) {
-                var ev = value.is_truthy() || value.tail_node().evaluate(compressor);
+                var ev = value.is_truthy() || value.evaluate(compressor, true);
                 if (!ev) {
                     value = value.drop_side_effect_free(compressor);
                     node.value = value ? make_sequence(node.value, [
@@ -4610,7 +4635,7 @@ merge(Compressor.prototype, {
                     }));
                 });
                 defs_by_id[node.name.definition().id] = defs;
-                return MAP.splice(var_defs);
+                return List.splice(var_defs);
             }
 
             function make_sym(sym, key) {
@@ -4746,21 +4771,17 @@ merge(Compressor.prototype, {
                     return exprs && make_sequence(this, exprs);
                 }
                 if (exp instanceof AST_Function && (!exp.name || !exp.name.definition().references.length)) {
-                    var node = this.clone();
                     exp.process_expression(false, function(node) {
                         var value = node.value && node.value.drop_side_effect_free(compressor, true);
                         return value ? make_node(AST_SimpleStatement, node, {
                             body: value
                         }) : make_node(AST_EmptyStatement, node);
                     });
-                    exp.walk(new TreeWalker(function(node) {
-                        if (node instanceof AST_Return && node.value) {
-                            node.value = node.value.drop_side_effect_free(compressor);
-                            return true;
-                        }
-                        if (node instanceof AST_Scope && node !== exp) return true;
-                    }));
-                    return node;
+                    scan_local_returns(exp, function(node) {
+                        if (node.value) node.value = node.value.drop_side_effect_free(compressor);
+                    });
+                    // always shallow clone to ensure stripping of negated IIFEs
+                    return this.clone();
                 }
                 return this;
             }
@@ -4878,7 +4899,7 @@ merge(Compressor.prototype, {
 
     OPT(AST_Do, function(self, compressor) {
         if (!compressor.option("loops")) return self;
-        var cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
+        var cond = self.condition.is_truthy() || self.condition.evaluate(compressor, true);
         if (!(cond instanceof AST_Node)) {
             if (cond) return make_node(AST_For, self, {
                 body: make_node(AST_BlockStatement, self.body, {
@@ -5008,16 +5029,14 @@ merge(Compressor.prototype, {
         }
         if (self.condition) {
             var cond = self.condition.evaluate(compressor);
-            if (!(cond instanceof AST_Node)) {
-                if (cond) self.condition = null;
-                else if (!compressor.option("dead_code")) {
-                    var orig = self.condition;
-                    self.condition = make_node_from_constant(cond, self.condition);
-                    self.condition = best_of_expression(self.condition.transform(compressor), orig);
-                }
-            }
             if (cond instanceof AST_Node) {
-                cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
+                cond = self.condition.is_truthy() || self.condition.evaluate(compressor, true);
+            } else if (cond) {
+                self.condition = null;
+            } else if (!compressor.option("dead_code")) {
+                var orig = self.condition;
+                self.condition = make_node_from_constant(cond, self.condition);
+                self.condition = best_of_expression(self.condition.transform(compressor), orig);
             }
             if (!cond) {
                 if (compressor.option("dead_code")) {
@@ -5109,7 +5128,7 @@ merge(Compressor.prototype, {
         }
         if (compressor.option("dead_code")) {
             if (cond instanceof AST_Node) {
-                cond = self.condition.is_truthy() || self.condition.tail_node().evaluate(compressor);
+                cond = self.condition.is_truthy() || self.condition.evaluate(compressor, true);
             }
             if (!cond) {
                 AST_Node.warn("Condition always false [{file}:{line},{col}]", self.condition.start);
@@ -5255,7 +5274,7 @@ merge(Compressor.prototype, {
         }
         if (!compressor.option("dead_code")) return self;
         if (value instanceof AST_Node) {
-            value = self.expression.tail_node().evaluate(compressor);
+            value = self.expression.evaluate(compressor, true);
         }
         var decl = [];
         var body = [];
@@ -5277,7 +5296,7 @@ merge(Compressor.prototype, {
                     eliminate_branch(branch, body[body.length - 1]);
                     continue;
                 }
-                if (exp instanceof AST_Node) exp = branch.expression.tail_node().evaluate(compressor);
+                if (exp instanceof AST_Node) exp = branch.expression.evaluate(compressor, true);
                 if (exp === value) {
                     exact_match = branch;
                     if (default_branch) {
@@ -5437,6 +5456,62 @@ merge(Compressor.prototype, {
         return make_sequence(node, x);
     }
 
+    function drop_unused_call_args(call, compressor, fns_with_marked_args) {
+        var exp = call.expression;
+        var fn = exp instanceof AST_SymbolRef ? exp.fixed_value() : exp;
+        if (!(fn instanceof AST_Lambda)) return;
+        if (fn.uses_arguments) return;
+        if (fn.pinned()) return;
+        if (fns_with_marked_args && fns_with_marked_args.indexOf(fn) < 0) return;
+        var args = call.args;
+        var pos = 0, last = 0;
+        var drop_fargs = fn === exp && !fn.name && compressor.drop_fargs(fn, call);
+        var side_effects = [];
+        for (var i = 0; i < args.length; i++) {
+            var trim = i >= fn.argnames.length;
+            if (trim || fn.argnames[i].__unused) {
+                var node = args[i].drop_side_effect_free(compressor);
+                if (drop_fargs) {
+                    fn.argnames.splice(i, 1);
+                    args.splice(i, 1);
+                    if (node) side_effects.push(node);
+                    i--;
+                    continue;
+                } else if (node) {
+                    side_effects.push(node);
+                    args[pos++] = make_sequence(call, side_effects);
+                    side_effects = [];
+                } else if (!trim) {
+                    if (side_effects.length) {
+                        node = make_sequence(call, side_effects);
+                        side_effects = [];
+                    } else {
+                        node = make_node(AST_Number, args[i], {
+                            value: 0
+                        });
+                    }
+                    args[pos++] = node;
+                    continue;
+                }
+            } else {
+                side_effects.push(args[i]);
+                args[pos++] = make_sequence(call, side_effects);
+                side_effects = [];
+            }
+            last = pos;
+        }
+        if (drop_fargs) for (; i < fn.argnames.length; i++) {
+            if (fn.argnames[i].__unused) fn.argnames.splice(i--, 1);
+        }
+        args.length = last;
+        if (!side_effects.length) return;
+        var arg = make_sequence(call, side_effects);
+        args.push(args.length < fn.argnames.length ? make_node(AST_UnaryPrefix, call, {
+            operator: "void",
+            expression: arg
+        }) : arg);
+    }
+
     OPT(AST_Call, function(self, compressor) {
         var exp = self.expression;
         if (compressor.option("sequences")) {
@@ -5453,63 +5528,7 @@ merge(Compressor.prototype, {
                 if (seq !== self) return seq.optimize(compressor);
             }
         }
-        var fn = exp;
-        if (compressor.option("reduce_vars") && fn instanceof AST_SymbolRef) {
-            fn = fn.fixed_value();
-        }
-        var is_func = fn instanceof AST_Lambda;
-        if (compressor.option("unused")
-            && is_func
-            && !fn.uses_arguments
-            && !fn.pinned()) {
-            var pos = 0, last = 0;
-            var drop_fargs = exp === fn && !fn.name && compressor.drop_fargs(fn, self);
-            var side_effects = [];
-            for (var i = 0; i < self.args.length; i++) {
-                var trim = i >= fn.argnames.length;
-                if (trim || fn.argnames[i].__unused) {
-                    var node = self.args[i].drop_side_effect_free(compressor);
-                    if (drop_fargs) {
-                        fn.argnames.splice(i, 1);
-                        self.args.splice(i, 1);
-                        if (node) side_effects.push(node);
-                        i--;
-                        continue;
-                    } else if (node) {
-                        side_effects.push(node);
-                        self.args[pos++] = make_sequence(self, side_effects);
-                        side_effects = [];
-                    } else if (!trim) {
-                        if (side_effects.length) {
-                            node = make_sequence(self, side_effects);
-                            side_effects = [];
-                        } else {
-                            node = make_node(AST_Number, self.args[i], {
-                                value: 0
-                            });
-                        }
-                        self.args[pos++] = node;
-                        continue;
-                    }
-                } else {
-                    side_effects.push(self.args[i]);
-                    self.args[pos++] = make_sequence(self, side_effects);
-                    side_effects = [];
-                }
-                last = pos;
-            }
-            if (drop_fargs) for (; i < fn.argnames.length; i++) {
-                if (fn.argnames[i].__unused) fn.argnames.splice(i--, 1);
-            }
-            self.args.length = last;
-            if (side_effects.length) {
-                var arg = make_sequence(self, side_effects);
-                self.args.push(self.args.length < fn.argnames.length ? make_node(AST_UnaryPrefix, self, {
-                    operator: "void",
-                    expression: arg
-                }) : arg);
-            }
-        }
+        if (compressor.option("unused")) drop_unused_call_args(self, compressor);
         if (compressor.option("unsafe")) {
             if (is_undeclared_ref(exp)) switch (exp.name) {
               case "Array":
@@ -5775,6 +5794,8 @@ merge(Compressor.prototype, {
                 }
             }
         }
+        var fn = exp instanceof AST_SymbolRef ? exp.fixed_value() : exp;
+        var is_func = fn instanceof AST_Lambda;
         var stat = is_func && fn.first_statement();
         var can_inline = compressor.option("inline") && !self.is_expr_pure(compressor);
         if (exp === fn && can_inline && stat instanceof AST_Return) {
@@ -6162,34 +6183,43 @@ merge(Compressor.prototype, {
     });
 
     AST_Binary.DEFMETHOD("lift_sequences", function(compressor) {
-        if (compressor.option("sequences")) {
-            if (this.left instanceof AST_Sequence) {
-                var x = this.left.expressions.slice();
-                var e = this.clone();
-                e.left = x.pop();
-                x.push(e);
-                return make_sequence(this, x).optimize(compressor);
+        if (this.left instanceof AST_PropAccess) {
+            if (!(this.left.expression instanceof AST_Sequence)) return this;
+            var x = this.left.expression.expressions.slice();
+            var e = this.clone();
+            e.left = e.left.clone();
+            e.left.expression = x.pop();
+            x.push(e);
+            return make_sequence(this, x);
+        }
+        if (this.left instanceof AST_Sequence) {
+            var x = this.left.expressions.slice();
+            var e = this.clone();
+            e.left = x.pop();
+            x.push(e);
+            return make_sequence(this, x);
+        }
+        if (this.right instanceof AST_Sequence) {
+            if (this.left.has_side_effects(compressor)) return this;
+            var assign = this.operator == "=" && this.left instanceof AST_SymbolRef;
+            var x = this.right.expressions;
+            var last = x.length - 1;
+            for (var i = 0; i < last; i++) {
+                if (!assign && x[i].has_side_effects(compressor)) break;
             }
-            if (this.right instanceof AST_Sequence && !this.left.has_side_effects(compressor)) {
-                var assign = this.operator == "=" && this.left instanceof AST_SymbolRef;
-                var x = this.right.expressions;
-                var last = x.length - 1;
-                for (var i = 0; i < last; i++) {
-                    if (!assign && x[i].has_side_effects(compressor)) break;
-                }
-                if (i == last) {
-                    x = x.slice();
-                    var e = this.clone();
-                    e.right = x.pop();
-                    x.push(e);
-                    return make_sequence(this, x).optimize(compressor);
-                } else if (i > 0) {
-                    var e = this.clone();
-                    e.right = make_sequence(this.right, x.slice(i));
-                    x = x.slice(0, i);
-                    x.push(e);
-                    return make_sequence(this, x).optimize(compressor);
-                }
+            if (i == last) {
+                x = x.slice();
+                var e = this.clone();
+                e.right = x.pop();
+                x.push(e);
+                return make_sequence(this, x);
+            }
+            if (i > 0) {
+                var e = this.clone();
+                e.right = make_sequence(this.right, x.slice(i));
+                x = x.slice(0, i);
+                x.push(e);
+                return make_sequence(this, x);
             }
         }
         return this;
@@ -6240,8 +6270,10 @@ merge(Compressor.prototype, {
             // result.  hence, force switch.
             reverse();
         }
-        var seq = self.lift_sequences(compressor);
-        if (seq !== self) return seq;
+        if (compressor.option("sequences")) {
+            var seq = self.lift_sequences(compressor);
+            if (seq !== self) return seq.optimize(compressor);
+        }
         if (compressor.option("assignments") && lazy_op[self.operator]) {
             var assign = self.right;
             // a || (a = x) => a = a || x
@@ -6450,7 +6482,7 @@ merge(Compressor.prototype, {
                 }
                 // (x || false) && y => x ? y : false
                 if (self.left.operator == "||") {
-                    var lr = self.left.right.tail_node().evaluate(compressor);
+                    var lr = self.left.right.evaluate(compressor, true);
                     if (!lr) return make_node(AST_Conditional, self, {
                         condition: self.left.left,
                         consequent: self.right,
@@ -6484,7 +6516,7 @@ merge(Compressor.prototype, {
                 }
                 // x && true || y => x ? true : y
                 if (self.left.operator == "&&") {
-                    var lr = self.left.right.is_truthy() || self.left.right.tail_node().evaluate(compressor);
+                    var lr = self.left.right.is_truthy() || self.left.right.evaluate(compressor, true);
                     if (lr && !(lr instanceof AST_Node)) return make_node(AST_Conditional, self, {
                         condition: self.left.left,
                         consequent: self.left.right,
@@ -6953,9 +6985,9 @@ merge(Compressor.prototype, {
                             var fn = node.fixed_value();
                             if (!(fn instanceof AST_Lambda)) return;
                             if (!fn.name) return;
-                            var fn_def = fn.name.definition();
-                            if (fn_def.scope !== fn.name.scope) return;
-                            if (fixed.variables.get(fn.name.name) !== fn_def) return;
+                            if (fn.name.definition() !== def) return;
+                            if (def.scope !== fn.name.scope) return;
+                            if (fixed.variables.get(fn.name.name) !== def) return;
                             fn.name = fn.name.clone();
                             var value_def = value.variables.get(fn.name.name) || value.def_function(fn.name);
                             node.thedef = value_def;
@@ -7158,8 +7190,10 @@ merge(Compressor.prototype, {
                     || parent instanceof AST_UnaryPrefix);
             }
         }
-        var seq = self.lift_sequences(compressor);
-        if (seq !== self) return seq;
+        if (compressor.option("sequences")) {
+            var seq = self.lift_sequences(compressor);
+            if (seq !== self) return seq.optimize(compressor);
+        }
         if (!compressor.option("assignments")) return self;
         if (self.operator == "=" && self.left instanceof AST_SymbolRef && self.right instanceof AST_Binary) {
             // x = expr1 OP expr2
@@ -7581,16 +7615,14 @@ merge(Compressor.prototype, {
             value = value.fixed_value();
         }
         if (!value) return false;
-        return !(value instanceof AST_Lambda)
-            || compressor.parent() instanceof AST_New
-            || !value.contains_this();
+        if (!(value instanceof AST_Lambda)) return true;
+        var parent = compressor.parent();
+        if (parent.TYPE != "Call") return true;
+        if (parent.expression !== compressor.self()) return true;
+        return !value.contains_this();
     }
 
     OPT(AST_Sub, function(self, compressor) {
-        if (compressor.option("sequences") && compressor.parent().TYPE != "Call") {
-            var seq = lift_sequence_in_expression(self, compressor);
-            if (seq !== self) return seq.optimize(compressor);
-        }
         var expr = self.expression;
         var prop = self.property;
         if (compressor.option("properties")) {
@@ -7661,6 +7693,10 @@ merge(Compressor.prototype, {
             }
         }
         if (is_lhs(compressor.self(), parent)) return self;
+        if (compressor.option("sequences") && compressor.parent().TYPE != "Call") {
+            var seq = lift_sequence_in_expression(self, compressor);
+            if (seq !== self) return seq.optimize(compressor);
+        }
         if (key !== prop) {
             var sub = self.flatten_object(property, compressor);
             if (sub) {
@@ -7755,10 +7791,6 @@ merge(Compressor.prototype, {
     });
 
     OPT(AST_Dot, function(self, compressor) {
-        if (compressor.option("sequences") && compressor.parent().TYPE != "Call") {
-            var seq = lift_sequence_in_expression(self, compressor);
-            if (seq !== self) return seq.optimize(compressor);
-        }
         if (self.property == "arguments" || self.property == "caller") {
             AST_Node.warn("Function.prototype.{prop} not supported [{file}:{line},{col}]", {
                 prop: self.property,
@@ -7768,6 +7800,10 @@ merge(Compressor.prototype, {
             });
         }
         if (is_lhs(compressor.self(), compressor.parent())) return self;
+        if (compressor.option("sequences") && compressor.parent().TYPE != "Call") {
+            var seq = lift_sequence_in_expression(self, compressor);
+            if (seq !== self) return seq.optimize(compressor);
+        }
         if (compressor.option("unsafe_proto")
             && self.expression instanceof AST_Dot
             && self.expression.property == "prototype") {

lib/output.js

@@ -783,6 +783,8 @@ function OutputStream(options) {
         var p = output.parent();
         if (p instanceof AST_PropAccess && p.expression === this) {
             var value = this.value;
+            // https://github.com/mishoo/UglifyJS2/issues/115
+            // https://github.com/mishoo/UglifyJS2/pull/1009
             if (value < 0 || /^0/.test(make_num(value))) {
                 return true;
             }
@@ -1352,11 +1354,18 @@ function OutputStream(options) {
     DEFPRINT(AST_RegExp, function(self, output) {
         var regexp = self.value;
         var str = regexp.toString();
+        var end = str.lastIndexOf("/");
         if (regexp.raw_source) {
-            str = "/" + regexp.raw_source + str.slice(str.lastIndexOf("/"));
+            str = "/" + regexp.raw_source + str.slice(end);
+        } else if (end == 1) {
+            str = "/(?:)" + str.slice(end);
+        } else if (str.indexOf("/", 1) < end) {
+            str = "/" + str.slice(1, end).replace(/\\\\|[^/]?\//g, function(match) {
+                return match[0] == "\\" ? match : match.slice(0, -1) + "\\/";
+            }) + str.slice(end);
         }
-        output.print(output.to_utf8(str).replace(/\\(?:\0(?![0-9])|[^\0])/g, function(seq) {
-            switch (seq[1]) {
+        output.print(output.to_utf8(str).replace(/\\(?:\0(?![0-9])|[^\0])/g, function(match) {
+            switch (match[1]) {
               case "\n": return "\\n";
               case "\r": return "\\r";
               case "\t": return "\t";
@@ -1366,7 +1375,7 @@ function OutputStream(options) {
               case "\x0B": return "\v";
               case "\u2028": return "\\u2028";
               case "\u2029": return "\\u2029";
-              default: return seq;
+              default: return match;
             }
         }).replace(/[\n\r\u2028\u2029]/g, function(c) {
             switch (c) {

lib/transform.js

@@ -52,7 +52,7 @@ TreeTransformer.prototype = new TreeWalker;
 
 (function(DEF) {
     function do_list(list, tw) {
-        return MAP(list, function(node) {
+        return List(list, function(node) {
             return node.transform(tw, true);
         });
     }

lib/utils.js

@@ -113,8 +113,8 @@ function return_true() { return true; }
 function return_this() { return this; }
 function return_null() { return null; }
 
-var MAP = (function() {
-    function MAP(a, f, backwards) {
+var List = (function() {
+    function List(a, f, backwards) {
         var ret = [], top = [], i;
         function doit() {
             var val = f(a[i], i);
@@ -149,14 +149,14 @@ var MAP = (function() {
         }
         return top.concat(ret);
     }
-    MAP.at_top = function(val) { return new AtTop(val) };
-    MAP.splice = function(val) { return new Splice(val) };
-    MAP.last = function(val) { return new Last(val) };
-    var skip = MAP.skip = {};
-    function AtTop(val) { this.v = val }
-    function Splice(val) { this.v = val }
-    function Last(val) { this.v = val }
-    return MAP;
+    List.at_top = function(val) { return new AtTop(val); };
+    List.splice = function(val) { return new Splice(val); };
+    List.last = function(val) { return new Last(val); };
+    var skip = List.skip = {};
+    function AtTop(val) { this.v = val; }
+    function Splice(val) { this.v = val; }
+    function Last(val) { this.v = val; }
+    return List;
 })();
 
 function push_uniq(array, el) {

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": "3.7.7",
+  "version": "3.8.0",
   "engines": {
     "node": ">=0.8.0"
   },

test/compress/drop-unused.js

@@ -1191,10 +1191,10 @@ issue_2105_1: {
     input: {
         !function(factory) {
             factory();
-        }( function() {
+        }(function() {
             return function(fn) {
                 fn()().prop();
-            }( function() {
+            }(function() {
                 function bar() {
                     var quux = function() {
                         console.log("PASS");
@@ -1205,7 +1205,7 @@ issue_2105_1: {
                     return { prop: foo };
                 }
                 return bar;
-            } );
+            });
         });
     }
     expect: {
@@ -1235,10 +1235,10 @@ issue_2105_2: {
     input: {
         !function(factory) {
             factory();
-        }( function() {
+        }(function() {
             return function(fn) {
                 fn()().prop();
-            }( function() {
+            }(function() {
                 function bar() {
                     var quux = function() {
                         console.log("PASS");
@@ -1249,7 +1249,7 @@ issue_2105_2: {
                     return { prop: foo };
                 }
                 return bar;
-            } );
+            });
         });
     }
     expect: {
@@ -1258,6 +1258,44 @@ issue_2105_2: {
     expect_stdout: "PASS"
 }
 
+issue_2105_3: {
+    options = {
+        inline: true,
+        passes: 2,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        !function(factory) {
+            factory();
+        }(function() {
+            return function(fn) {
+                fn()().prop();
+            }(function() {
+                function bar() {
+                    var quux = function() {
+                        console.log("PASS");
+                    }, foo = function() {
+                        console.log;
+                        quux();
+                    };
+                    return { prop: foo };
+                }
+                return bar;
+            });
+        });
+    }
+    expect: {
+        !void void {
+            prop: function() {
+                console.log;
+                void console.log("PASS");
+            }
+        }.prop();
+    }
+    expect_stdout: "PASS"
+}
+
 issue_2226_1: {
     options = {
         side_effects: true,
@@ -2330,7 +2368,7 @@ function_parameter_ie8: {
         (function() {
             (function f() {
                 console.log("PASS");
-            })(0);
+            })();
         })();
     }
     expect_stdout: "PASS"

test/compress/functions.js

@@ -1276,7 +1276,7 @@ issue_2630_3: {
         (function() {
             (function f1(a) {
                 f2();
-                --x >= 0 && f1({});
+                --x >= 0 && f1();
             })(a++);
             function f2() {
                 a++;

test/compress/ie8.js

@@ -2361,3 +2361,40 @@ issue_3542: {
     }
     expect_stdout: "1"
 }
+
+issue_3703: {
+    options = {
+        ie8: true,
+        reduce_vars: true,
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = "PASS";
+        function f() {
+            var b;
+            function g() {
+                a = "FAIL";
+            }
+            var c = g;
+            function h() {
+                f;
+            }
+            a ? b |= c : b.p;
+        }
+        f();
+        console.log(a);
+    }
+    expect: {
+        var a = "PASS";
+        (function() {
+            var b;
+            var c = function g() {
+                a = "FAIL";
+            };
+            a ? b |= c : b.p;
+        })();
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}

test/compress/keep_fargs.js

@@ -728,7 +728,7 @@ issue_2630_3: {
         (function() {
             (function f1() {
                 f2();
-                --x >= 0 && f1({});
+                --x >= 0 && f1();
             })(a++);
             function f2() {
                 a++;
@@ -1369,7 +1369,7 @@ recursive_iife_1: {
     }
     expect: {
         console.log(function f(a, b) {
-            return b || f("FAIL", "PASS");
+            return b || f(0, "PASS");
         }());
     }
     expect_stdout: "PASS"
@@ -1388,7 +1388,7 @@ recursive_iife_2: {
     }
     expect: {
         console.log(function f(a, b) {
-            return b || f("FAIL", "PASS");
+            return b || f(0, "PASS");
         }(0, 0));
     }
     expect_stdout: "PASS"
@@ -1416,7 +1416,7 @@ recursive_iife_3: {
         var a = 1, c = "PASS";
         (function() {
             (function f(b, d, e) {
-                a-- && f(null, 42, 0);
+                a-- && f(0, 42, 0);
                 e && (c = "FAIL");
                 d && d.p;
             })();

test/compress/properties.js

@@ -817,6 +817,29 @@ issue_2208_5: {
     expect_stdout: "42"
 }
 
+issue_2208_6: {
+    options = {
+        inline: true,
+        properties: true,
+        side_effects: true,
+    }
+    input: {
+        a = 42;
+        console.log(("FAIL", {
+            p: function() {
+                return this.a;
+            }
+        }.p)());
+    }
+    expect: {
+        a = 42;
+        console.log(function() {
+            return this.a;
+        }());
+    }
+    expect_stdout: "42"
+}
+
 issue_2256: {
     options = {
         side_effects: true,

test/compress/reduce_vars.js

@@ -2071,13 +2071,8 @@ issue_1670_6: {
     }
     expect: {
         (function(a) {
-            switch (1) {
-              case a = 1:
-                console.log(a);
-                break;
-              default:
-                console.log(2);
-            }
+            a = 1;
+            console.log(a);
         })(1);
     }
     expect_stdout: "1"

test/compress/regexp.js

@@ -186,3 +186,72 @@ issue_3434_3: {
         /\nfo\n[\n]o\bbb/;
     }
 }
+
+issue_3434_4: {
+    options = {
+        evaluate: true,
+        unsafe: true,
+    }
+    input: {
+        [
+            [ "", RegExp("") ],
+            [ "/", RegExp("/") ],
+            [ "//", RegExp("//") ],
+            [ "\/", RegExp("\\/") ],
+            [ "///", RegExp("///") ],
+            [ "/\/", RegExp("/\\/") ],
+            [ "\//", RegExp("\\//") ],
+            [ "\\/", RegExp("\\\\/") ],
+            [ "////", RegExp("////") ],
+            [ "//\/", RegExp("//\\/") ],
+            [ "/\//", RegExp("/\\//") ],
+            [ "/\\/", RegExp("/\\\\/") ],
+            [ "\///", RegExp("\\///") ],
+            [ "\/\/", RegExp("\\/\\/") ],
+            [ "\\//", RegExp("\\\\//") ],
+            [ "\\\/", RegExp("\\\\\\/") ],
+        ].forEach(function(test) {
+            console.log(test[1].test("\\"), test[1].test(test[0]));
+        });
+    }
+    expect: {
+        [
+            [ "", /(?:)/ ],
+            [ "/", /\// ],
+            [ "//", /\/\// ],
+            [ "/", /\// ],
+            [ "///", /\/\/\// ],
+            [ "//", /\/\// ],
+            [ "//", /\/\// ],
+            [ "\\/", /\\\// ],
+            [ "////", /\/\/\/\// ],
+            [ "///", /\/\/\// ],
+            [ "///", /\/\/\// ],
+            [ "/\\/", /\/\\\// ],
+            [ "///", /\/\/\// ],
+            [ "//", /\/\// ],
+            [ "\\//", /\\\/\// ],
+            [ "\\/", /\\\// ],
+        ].forEach(function(test) {
+            console.log(test[1].test("\\"), test[1].test(test[0]));
+        });
+    }
+    expect_stdout: [
+        "true true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+        "false true",
+    ]
+}

test/compress/sequences.js

@@ -1093,3 +1093,22 @@ issue_3490_2: {
     }
     expect_stdout: "PASS 42"
 }
+
+issue_3703: {
+    options = {
+        evaluate: true,
+        sequences: true,
+        unsafe: true,
+    }
+    input: {
+        var a = "FAIL";
+        while ((a = "PASS", 0).foo = 0);
+        console.log(a);
+    }
+    expect: {
+        var a = "FAIL";
+        while (a = "PASS", (0).foo = 0);
+        console.log(a);
+    }
+    expect_stdout: "PASS"
+}

test/exports.js

@@ -1,6 +1,7 @@
 exports["Compressor"] = Compressor;
 exports["defaults"] = defaults;
 exports["JS_Parse_Error"] = JS_Parse_Error;
+exports["List"] = List;
 exports["mangle_properties"] = mangle_properties;
 exports["minify"] = minify;
 exports["OutputStream"] = OutputStream;

test/input/reduce/label.js

@@ -0,0 +1,9 @@
+var o = this;
+
+for (var k in o) L17060: {
+    a++;
+}
+
+var a;
+
+console.log(k);

test/input/reduce/label.reduced.js

@@ -0,0 +1,16 @@
+var o = this;
+
+for (var k in o) {
+    0;
+}
+
+var a;
+
+console.log(k);
+// output: a
+// 
+// minify: k
+// 
+// options: {
+//   "mangle": false
+// }

test/input/reduce/unsafe_math.js

@@ -0,0 +1,18 @@
+var _calls_ = 10, a = 100, b = 10, c = 0;
+
+function f0(b_1, a, undefined_2) {
+    a++ + ++b;
+    {
+        var expr2 = (b + 1 - .1 - .1 - .1 || a || 3).toString();
+        L20778: for (var key2 in expr2) {
+            (c = c + 1) + [ --b + b_1, typeof f0 == "function" && --_calls_ >= 0 && f0(--b + typeof (undefined_2 = 1 === 1 ? a : b), --b + {
+                c: (c = c + 1) + null
+            }, a++ + (typeof f0 == "function" && --_calls_ >= 0 && f0(typeof (c = 1 + c, 3 / "a" * ("c" >>> 23..toString()) >= (b_1 && (b_1[(c = c + 1) + a--] = (- -0,
+            true + {})))), 3, 25))), 1 === 1 ? a : b ];
+        }
+    }
+}
+
+var a_1 = f0([ , 0 ].length === 2);
+
+console.log(null, a, b, c, Infinity, NaN, undefined);

test/input/reduce/unsafe_math.reduced.js

@@ -0,0 +1,19 @@
+var b = 0;
+
+var expr2 = (0 - 1 - .1 - .1).toString();
+
+for (var key2 in expr2) {
+    --b;
+}
+
+console.log(b);
+// output: -19
+// 
+// minify: -4
+// 
+// options: {
+//   "compress": {
+//     "unsafe_math": true
+//   },
+//   "mangle": false
+// }

test/mocha/reduce.js

@@ -0,0 +1,167 @@
+var assert = require("assert");
+var exec = require("child_process").exec;
+var fs = require("fs");
+var reduce_test = require("../reduce");
+var semver = require("semver");
+
+function read(path) {
+    return fs.readFileSync(path, "utf8");
+}
+
+describe("test/reduce.js", function() {
+    this.timeout(60000);
+    it("Should reduce test case", function() {
+        var result = reduce_test(read("test/input/reduce/unsafe_math.js"), {
+            compress: {
+                unsafe_math: true,
+            },
+            mangle: false,
+        }, {
+            verbose: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, read("test/input/reduce/unsafe_math.reduced.js"));
+    });
+    it("Should eliminate unreferenced labels", function() {
+        var result = reduce_test(read("test/input/reduce/label.js"), {
+            mangle: false,
+        }, {
+            verbose: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, read("test/input/reduce/label.reduced.js"));
+    });
+    it("Should handle test cases with --toplevel", function() {
+        var result = reduce_test([
+            "var Infinity = 42;",
+            "console.log(Infinity);",
+        ].join("\n"), {
+            toplevel: true,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, [
+            "// Can't reproduce test failure with minify options provided:",
+            "// {",
+            '//   "toplevel": true',
+            "// }",
+        ].join("\n"));
+    });
+    it("Should handle test result of NaN", function() {
+        var result = reduce_test("throw 0 / 0;");
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, [
+            "// Can't reproduce test failure with minify options provided:",
+            "// {",
+            '//   "compress": {},',
+            '//   "mangle": false',
+            "// }",
+        ].join("\n"));
+    });
+    it("Should print correct output for irreducible test case", function() {
+        var result = reduce_test([
+            "console.log(function f(a) {",
+            "    return f.length;",
+            "}());",
+        ].join("\n"), {
+            compress: {
+                keep_fargs: false,
+            },
+            mangle: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, [
+            "console.log(function f(a) {",
+            "    return f.length;",
+            "}());",
+            "// output: 1",
+            "// ",
+            "// minify: 0",
+            "// ",
+            "// options: {",
+            '//   "compress": {',
+            '//     "keep_fargs": false',
+            "//   },",
+            '//   "mangle": false',
+            "// }",
+        ].join("\n"));
+    });
+    it("Should fail when invalid option is supplied", function() {
+        var result = reduce_test("", {
+            compress: {
+                unsafe_regex: true,
+            },
+        });
+        var err = result.error;
+        assert.ok(err instanceof Error);
+        assert.strictEqual(err.stack.split(/\n/)[0], "DefaultsError: `unsafe_regex` is not a supported option");
+    });
+    it("Should report on test case with invalid syntax", function() {
+        var result = reduce_test("var 0 = 1;");
+        var err = result.error;
+        assert.ok(err instanceof Error);
+        assert.strictEqual(err.stack.split(/\n/)[0], "SyntaxError: Name expected");
+    });
+    it("Should format multi-line output correctly", function() {
+        var code = [
+            "var a = 0;",
+            "",
+            "for (var b in [ 1, 2, 3 ]) {",
+            "    a = +a + 1 - .2;",
+            "    console.log(a);",
+            "}",
+        ].join("\n");
+        var result = reduce_test(code, {
+            compress: {
+                unsafe_math: true,
+            },
+            mangle: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code, [
+            code,
+            "// output: 0.8",
+            "// 1.6",
+            "// 2.4",
+            "// ",
+            "// minify: 0.8",
+            "// 1.6",
+            "// 2.4000000000000004",
+            "// ",
+            "// options: {",
+            '//   "compress": {',
+            '//     "unsafe_math": true',
+            "//   },",
+            '//   "mangle": false',
+            "// }",
+        ].join("\n"));
+    });
+    it("Should reduce infinite loops with reasonable performance", function() {
+        if (semver.satisfies(process.version, "0.10")) return;
+        this.timeout(120000);
+        var code = [
+            "var a = 9007199254740992, b = 1;",
+            "",
+            "while (a++ + (1 - b) < a) {",
+            "    0;",
+            "}",
+        ].join("\n");
+        var result = reduce_test(code, {
+            compress: {
+                unsafe_math: true,
+            },
+            mangle: false,
+        });
+        if (result.error) throw result.error;
+        assert.strictEqual(result.code.replace(/ timed out after [0-9]+ms/, " timed out."), [
+            code,
+            "// output: ",
+            "// minify: Error: Script execution timed out.",
+            "// options: {",
+            '//   "compress": {',
+            '//     "unsafe_math": true',
+            "//   },",
+            '//   "mangle": false',
+            "// }",
+        ].join("\n"));
+    });
+});

test/reduce.js

@@ -0,0 +1,564 @@
+var crypto = require("crypto");
+var U = require("./node");
+var List = U.List;
+var os = require("os");
+var sandbox = require("./sandbox");
+
+// Reduce a ufuzz-style `console.log` based test case by iteratively replacing
+// AST nodes with various permutations. Each AST_Statement in the tree is also
+// speculatively dropped to determine whether it is needed.  If the altered
+// tree and the last known good tree produce the same non-nil error-free output
+// after being run, then the permutation survives to the next generation and
+// is the basis for subsequent iterations.  The test case is reduced as a
+// consequence of complex expressions being replaced with simpler ones.
+// This function assumes that the testcase will not result in a parse or
+// runtime Error.  Note that a reduced test case will have different runtime
+// output - it is not functionally equivalent to the original. The only criteria
+// is that once the generated reduced test case is run without minification, it
+// will produce different output from the code minified with `minify_options`.
+// Returns a `minify` result object with an additonal boolean property `reduced`.
+
+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 || { compress: {}, mangle: false };
+    reduce_options = reduce_options || {};
+    var max_iterations = reduce_options.max_iterations || 1000;
+    var max_timeout = reduce_options.max_timeout || 10000;
+    var verbose = reduce_options.verbose;
+    var minify_options_json = JSON.stringify(minify_options, null, 2);
+    var result_cache = Object.create(null);
+    // the initial timeout to assess the viability of the test case must be large
+    var differs = producesDifferentResultWhenMinified(result_cache, testcase, minify_options, max_timeout);
+
+    if (verbose) {
+        console.error("// Node.js " + process.version + " on " + os.platform() + " " + os.arch());
+    }
+    if (!differs) {
+        // same stdout result produced when minified
+        return {
+            code: "// Can't reproduce test failure with minify options provided:"
+                + "\n// " + to_comment(minify_options_json)
+        };
+    } else if (differs.timed_out) {
+        return {
+            code: "// Can't reproduce test failure within " + max_timeout + "ms:"
+                + "\n// " + to_comment(minify_options_json)
+        };
+    } else if (differs.error) {
+        return differs;
+    } else {
+        max_timeout = Math.min(100 * differs.elapsed, max_timeout);
+        // Replace expressions with constants that will be parsed into
+        // AST_Nodes as required.  Each AST_Node has its own permutation count,
+        // so these replacements can't be shared.
+        // Although simpler replacements are generally faster and better,
+        // feel free to experiment with a different replacement set.
+        var REPLACEMENTS = [
+            // "null", "''", "false", "'foo'", "undefined", "9",
+            "1", "0",
+        ];
+
+        // There's a relationship between each node's _permute counter and
+        // REPLACEMENTS.length which is why fractional _permutes were needed.
+        // One could scale all _permute operations by a factor of `steps`
+        // to only deal with integer operations, but this works well enough.
+        var steps = 4;        // must be a power of 2
+        var step = 1 / steps; // 0.25 is exactly representable in floating point
+
+        var tt = new U.TreeTransformer(function(node, descend, in_list) {
+            if (CHANGED) return;
+
+            // quick ignores
+            if (node instanceof U.AST_Accessor) return;
+            if (node instanceof U.AST_Directive) return;
+            if (node instanceof U.AST_Label) return;
+            if (node instanceof U.AST_LabelRef) return;
+            if (!in_list && node instanceof U.AST_SymbolDeclaration) return;
+            if (node instanceof U.AST_Toplevel) return;
+
+            var parent = tt.parent();
+
+            // ensure that the _permute prop is a number.
+            // can not use `node.start._permute |= 0;` as it will erase fractional part.
+            if (typeof node.start._permute === "undefined") node.start._permute = 0;
+
+            // if node reached permutation limit - skip over it.
+            // no structural AST changes before this point.
+            if (node.start._permute >= REPLACEMENTS.length) return;
+
+            if (parent instanceof U.AST_Assign
+                    && parent.left === node
+                || parent instanceof U.AST_Unary
+                    && parent.expression === node
+                    && ["++", "--", "delete"].indexOf(parent.operator) >= 0) {
+                // ignore lvalues
+                return;
+            }
+            if ((parent instanceof U.AST_For || parent instanceof U.AST_ForIn)
+                && parent.init === node && node instanceof U.AST_Var) {
+                // preserve for (var ...)
+                return node;
+            }
+
+            // node specific permutations with no parent logic
+
+            if (node instanceof U.AST_Array) {
+                var expr = node.elements[0];
+                if (expr && !(expr instanceof U.AST_Hole)) {
+                    node.start._permute++;
+                    CHANGED = true;
+                    return expr;
+                }
+            }
+            else if (node instanceof U.AST_Binary) {
+                CHANGED = true;
+                return [
+                    node.left,
+                    node.right,
+                ][ ((node.start._permute += step) * steps | 0) % 2 ];
+            }
+            else if (node instanceof U.AST_Catch || node instanceof U.AST_Finally) {
+                // drop catch or finally block
+                node.start._permute++;
+                CHANGED = true;
+                return null;
+            }
+            else if (node instanceof U.AST_Conditional) {
+                CHANGED = true;
+                return [
+                    node.condition,
+                    node.consequent,
+                    node.alternative,
+                ][ ((node.start._permute += step) * steps | 0) % 3 ];
+            }
+            else if (node instanceof U.AST_BlockStatement) {
+                if (in_list) {
+                    node.start._permute++;
+                    CHANGED = true;
+                    return List.splice(node.body);
+                }
+            }
+            else if (node instanceof U.AST_Call) {
+                var expr = [
+                    node.expression,
+                    node.args[0],
+                    null,  // intentional
+                ][ ((node.start._permute += step) * steps | 0) % 3 ];
+                if (expr) {
+                    CHANGED = true;
+                    return expr;
+                }
+                if (node.expression instanceof U.AST_Function) {
+                    // hoist and return expressions from the IIFE function expression
+                    var body = node.expression.body;
+                    node.expression.body = [];
+                    var seq = [];
+                    body.forEach(function(node) {
+                        var expr = expr instanceof U.AST_Exit ? node.value : node.body;
+                        if (expr instanceof U.AST_Node && !is_statement(expr)) {
+                            // collect expressions from each statements' body
+                            seq.push(expr);
+                        }
+                    });
+                    CHANGED = true;
+                    return to_sequence(seq);
+                }
+            }
+            else if (node instanceof U.AST_Defun) {
+                switch (((node.start._permute += step) * steps | 0) % 2) {
+                  case 0:
+                    CHANGED = true;
+                    return List.skip;
+                  case 1:
+                    if (!has_exit(node)) {
+                        // hoist function declaration body
+                        var body = node.body;
+                        node.body = [];
+                        body.push(node); // retain function with empty body to be dropped later
+                        CHANGED = true;
+                        return List.splice(body);
+                    }
+                }
+            }
+            else if (node instanceof U.AST_DWLoop) {
+                var expr = [
+                    node.condition,
+                    node.body,
+                    null,  // intentional
+                ][ (node.start._permute * steps | 0) % 3 ];
+                node.start._permute += step;
+                if (!expr) {
+                    if (node.body[0] instanceof U.AST_Break) {
+                        if (node instanceof U.AST_Do) {
+                            CHANGED = true;
+                            return List.skip;
+                        }
+                        expr = node.condition; // AST_While - fall through
+                    }
+                }
+                if (expr && (expr !== node.body || !has_loopcontrol(expr, node, parent))) {
+                    CHANGED = true;
+                    return to_statement(expr);
+                }
+            }
+            else if (node instanceof U.AST_PropAccess) {
+                var expr = [
+                    node.expression,
+                    node.property instanceof U.AST_Node && node.property,
+                ][ node.start._permute++ % 2 ];
+                if (expr) {
+                    CHANGED = true;
+                    return expr;
+                }
+            }
+            else if (node instanceof U.AST_For) {
+                var expr = [
+                    node.init,
+                    node.condition,
+                    node.step,
+                    node.body,
+                ][ (node.start._permute * steps | 0) % 4 ];
+                node.start._permute += step;
+                if (expr && (expr !== node.body || !has_loopcontrol(expr, node, parent))) {
+                    CHANGED = true;
+                    return to_statement(expr);
+                }
+            }
+            else if (node instanceof U.AST_ForIn) {
+                var expr = [
+                    node.init,
+                    node.object,
+                    node.body,
+                ][ (node.start._permute * steps | 0) % 3 ];
+                node.start._permute += step;
+                if (expr && (expr !== node.body || !has_loopcontrol(expr, node, parent))) {
+                    CHANGED = true;
+                    return to_statement(expr);
+                }
+            }
+            else if (node instanceof U.AST_If) {
+                var expr = [
+                    node.condition,
+                    node.body,
+                    node.alternative,
+                ][ (node.start._permute * steps | 0) % 3 ];
+                node.start._permute += step;
+                if (expr) {
+                    // replace if statement with its condition, then block or else block
+                    CHANGED = true;
+                    return to_statement(expr);
+                }
+            }
+            else if (node instanceof U.AST_Object) {
+                // first property's value
+                var expr = node.properties[0] instanceof U.AST_ObjectKeyVal && node.properties[0].value;
+                if (expr) {
+                    node.start._permute++;
+                    CHANGED = true;
+                    return expr;
+                }
+            }
+            else if (node instanceof U.AST_SimpleStatement) {
+                if (node.body instanceof U.AST_Call && node.body.expression instanceof U.AST_Function) {
+                    // hoist simple statement IIFE function expression body
+                    node.start._permute++;
+                    if (!has_exit(node.body.expression)) {
+                        var body = node.body.expression.body;
+                        node.body.expression.body = [];
+                        CHANGED = true;
+                        return List.splice(body);
+                    }
+                }
+            }
+            else if (node instanceof U.AST_Switch) {
+                var expr = [
+                    node.expression,                         // switch expression
+                    node.body[0] && node.body[0].expression, // first case expression or undefined
+                    node.body[0] && node.body[0],            // first case body or undefined
+                ][ (node.start._permute * steps | 0) % 4 ];
+                node.start._permute += step;
+                if (expr && (!(expr instanceof U.AST_Statement) || !has_loopcontrol(expr, node, parent))) {
+                    CHANGED = true;
+                    return expr instanceof U.AST_SwitchBranch ? new U.AST_BlockStatement({
+                        body: expr.body.slice(),
+                        start: {},
+                    }) : to_statement(expr);
+                }
+            }
+            else if (node instanceof U.AST_Try) {
+                var body = [
+                    node.body,
+                    node.bcatch && node.bcatch.body,
+                    node.bfinally && node.bfinally.body,
+                    null,  // intentional
+                ][ (node.start._permute * steps | 0) % 4 ];
+                node.start._permute += step;
+                if (body) {
+                    // replace try statement with try block, catch block, or finally block
+                    CHANGED = true;
+                    return new U.AST_BlockStatement({
+                        body: body,
+                        start: {},
+                    });
+                } else {
+                    // replace try with a break or return if first in try statement
+                    if (node.body[0] instanceof U.AST_Break
+                        || node.body[0] instanceof U.AST_Return) {
+                        CHANGED = true;
+                        return node.body[0];
+                    }
+                }
+            }
+            else if (node instanceof U.AST_Unary) {
+                node.start._permute++;
+                CHANGED = true;
+                return node.expression;
+            }
+            else if (node instanceof U.AST_Var) {
+                if (node.definitions.length == 1 && node.definitions[0].value) {
+                    // first declaration value
+                    node.start._permute++;
+                    CHANGED = true;
+                    return to_statement(node.definitions[0].value);
+                }
+            }
+            else if (node instanceof U.AST_LabeledStatement) {
+                if (node.body instanceof U.AST_Statement
+                    && !has_loopcontrol(node.body, node.body, node)) {
+                    // replace labelled statement with its non-labelled body
+                    node.start._permute = REPLACEMENTS.length;
+                    CHANGED = true;
+                    return node.body;
+                }
+            }
+
+            if (in_list) {
+                // special case to drop object properties and switch branches
+                if (parent instanceof U.AST_Object
+                    || parent instanceof U.AST_Switch && parent.expression != node) {
+                    node.start._permute++;
+                    CHANGED = true;
+                    return List.skip;
+                }
+
+                // replace or skip statement
+                if (node instanceof U.AST_Statement) {
+                    node.start._permute++;
+                    CHANGED = true;
+                    return List.skip;
+                }
+
+                // remove this node unless its the sole element of a (transient) sequence
+                if (!(parent instanceof U.AST_Sequence) || parent.expressions.length > 1) {
+                    node.start._permute++;
+                    CHANGED = true;
+                    return List.skip;
+                }
+            }
+
+            // replace this node
+            var newNode = U.parse(REPLACEMENTS[node.start._permute % REPLACEMENTS.length | 0], {
+                expression: true,
+            });
+            if (is_statement(node)) {
+                newNode = new U.AST_SimpleStatement({
+                    body: newNode,
+                    start: {},
+                });
+            }
+            newNode.start._permute = ++node.start._permute;
+            CHANGED = true;
+            return newNode;
+        }, function(node, in_list) {
+            if (node instanceof U.AST_Sequence) {
+                // expand single-element sequence
+                if (node.expressions.length == 1) return node.expressions[0];
+            }
+            else if (node instanceof U.AST_Try) {
+                // expand orphaned try block
+                if (!node.bcatch && !node.bfinally) return new U.AST_BlockStatement({
+                    body: node.body,
+                    start: {},
+                });
+            }
+            else if (node instanceof U.AST_Var) {
+                // remove empty var statement
+                if (node.definitions.length == 0) return in_list ? List.skip : new U.AST_EmptyStatement({
+                    start: {},
+                });
+            }
+        });
+
+        for (var pass = 1; pass <= 3; ++pass) {
+            var testcase_ast = U.parse(testcase);
+            testcase_ast.walk(new U.TreeWalker(function(node) {
+                // unshare start props to retain visit data between iterations
+                node.start = JSON.parse(JSON.stringify(node.start));
+                node.start._permute = 0;
+            }));
+            for (var c = 0; c < max_iterations; ++c) {
+                if (verbose) {
+                    if (pass == 1 && c % 25 == 0) {
+                        console.error("// reduce test pass "
+                            + pass + ", iteration " + c + ": " + testcase.length + " bytes");
+                    }
+                }
+                var CHANGED = false;
+                var code_ast = testcase_ast.clone(true).transform(tt);
+                if (!CHANGED) break;
+                try {
+                    var code = code_ast.print_to_string();
+                } catch (ex) {
+                    // AST is not well formed.
+                    // no harm done - just log the error, ignore latest change and continue iterating.
+                    console.error("*** Error generating code from AST.");
+                    console.error(ex);
+                    console.error("*** Discarding permutation and continuing.");
+                    continue;
+                }
+                var diff = producesDifferentResultWhenMinified(result_cache, code, minify_options, max_timeout);
+                if (diff) {
+                    if (diff.timed_out) {
+                        // can't trust the validity of `code_ast` and `code` when timed out.
+                        // no harm done - just ignore latest change and continue iterating.
+                    } else if (diff.error) {
+                        // something went wrong during minify() - could be malformed AST or genuine bug.
+                        // no harm done - just log code & error, ignore latest change and continue iterating.
+                        console.error("*** Error during minification.");
+                        console.error(code);
+                        console.error(diff.error);
+                        console.error("*** Discarding permutation and continuing.");
+                    } else if (is_error(diff.unminified_result)
+                        && is_error(diff.minified_result)
+                        && diff.unminified_result.name == diff.minified_result.name) {
+                        // ignore difference in error messages caused by minification
+                    } else {
+                        // latest permutation is valid, so use it as the basis of new changes
+                        testcase_ast = code_ast;
+                        testcase = code;
+                        differs = diff;
+                    }
+                }
+            }
+            if (c == 0) break;
+            if (verbose) {
+                console.error("// reduce test pass " + pass + ": " + testcase.length + " bytes");
+            }
+        }
+        testcase = U.minify(testcase, {
+            compress: false,
+            mangle: false,
+            output: {
+                beautify: true,
+                braces: true,
+                comments: true,
+            },
+        });
+        testcase.code += [
+            "",
+            "// output: " + to_comment(differs.unminified_result),
+            "// minify: " + to_comment(differs.minified_result),
+            "// options: " + to_comment(minify_options_json),
+        ].join("\n").replace(/\u001b\[\d+m/g, "");
+        return testcase;
+    }
+};
+
+function to_comment(value) {
+    return ("" + value).replace(/\n/g, "\n// ");
+}
+
+function has_exit(fn) {
+    var found = false;
+    var tw = new U.TreeWalker(function(node) {
+        if (found) return found;
+        if (node instanceof U.AST_Exit) {
+            return found = true;
+        }
+        if (node instanceof U.AST_Scope && node !== fn) {
+            return true; // don't descend into nested functions
+        }
+    });
+    fn.walk(tw);
+    return found;
+}
+
+function has_loopcontrol(body, loop, label) {
+    var found = false;
+    var tw = new U.TreeWalker(function(node) {
+        if (found) return true;
+        if (node instanceof U.AST_LoopControl && this.loopcontrol_target(node) === loop) {
+            return found = true;
+        }
+    });
+    if (label instanceof U.AST_LabeledStatement) tw.push(label);
+    tw.push(loop);
+    body.walk(tw);
+    return found;
+}
+
+function is_error(result) {
+    return typeof result == "object" && typeof result.name == "string" && typeof result.message == "string";
+}
+
+function is_timed_out(result) {
+    return is_error(result) && /timed out/.test(result);
+}
+
+function is_statement(node) {
+    return node instanceof U.AST_Statement && !(node instanceof U.AST_Function);
+}
+
+function merge_sequence(array, node) {
+    if (node instanceof U.AST_Sequence) {
+        array.push.apply(array, node.expressions);
+    } else {
+        array.push(node);
+    }
+    return array;
+}
+
+function to_sequence(expressions) {
+    if (expressions.length == 0) return new U.AST_Number({value: 0, start: {}});
+    if (expressions.length == 1) return expressions[0];
+    return new U.AST_Sequence({
+        expressions: expressions.reduce(merge_sequence, []),
+        start: {},
+    });
+}
+
+function to_statement(node) {
+    return is_statement(node) ? node : new U.AST_SimpleStatement({
+        body: node,
+        start: {},
+    });
+}
+
+function run_code(result_cache, code, toplevel, timeout) {
+    var key = crypto.createHash("sha1").update(code).digest("base64");
+    return result_cache[key] || (result_cache[key] = sandbox.run_code(code, toplevel, timeout));
+}
+
+function producesDifferentResultWhenMinified(result_cache, code, minify_options, max_timeout) {
+    var minified = U.minify(code, minify_options);
+    if (minified.error) return minified;
+
+    var toplevel = minify_options.toplevel;
+    var elapsed = Date.now();
+    var unminified_result = run_code(result_cache, code, toplevel, max_timeout);
+    elapsed = Date.now() - elapsed;
+    var timeout = Math.min(100 * elapsed, max_timeout);
+    var minified_result = run_code(result_cache, minified.code, toplevel, timeout);
+
+    if (sandbox.same_stdout(unminified_result, minified_result)) {
+        return is_timed_out(unminified_result) && is_timed_out(minified_result) && {
+            timed_out: true,
+        };
+    }
+    return {
+        unminified_result: unminified_result,
+        minified_result: minified_result,
+        elapsed: elapsed,
+    };
+}
+Error.stackTraceLimit = Infinity;

test/sandbox.js

@@ -54,14 +54,15 @@ function createContext() {
     }
 }
 
-exports.run_code = function(code, toplevel) {
+exports.run_code = function(code, toplevel, timeout) {
+    timeout = timeout || 5000;
     var stdout = "";
     var original_write = process.stdout.write;
     process.stdout.write = function(chunk) {
         stdout += chunk;
     };
     try {
-        vm.runInContext(toplevel ? "(function(){" + code + "})()" : code, createContext(), { timeout: 5000 });
+        vm.runInContext(toplevel ? "(function(){" + code + "})()" : code, createContext(), { timeout: timeout });
         return stdout;
     } catch (ex) {
         return ex;
@@ -76,8 +77,9 @@ function strip_func_ids(text) {
 
 exports.same_stdout = semver.satisfies(process.version, "0.12") ? function(expected, actual) {
     if (typeof expected != typeof actual) return false;
-    if (typeof expected != "string") {
-        if (expected.name != actual.name) return false;
+    if (typeof expected == "object" && typeof expected.name == "string" && typeof expected.message == "string") {
+        if (expected.name !== actual.name) return false;
+        if (typeof actual.message != "string") return false;
         expected = expected.message.slice(expected.message.lastIndexOf("\n") + 1);
         actual = actual.message.slice(actual.message.lastIndexOf("\n") + 1);
     }

test/ufuzz/index.js

@@ -10,6 +10,7 @@ require("../../tools/exit");
 var UglifyJS = require("../..");
 var randomBytes = require("crypto").randomBytes;
 var sandbox = require("../sandbox");
+var reduce_test = require("../reduce");
 
 var MAX_GENERATED_TOPLEVELS_PER_RUN = 1;
 var MAX_GENERATION_RECURSION_DEPTH = 12;
@@ -1051,6 +1052,7 @@ function log_rename(options) {
 }
 
 function log(options) {
+    var options_copy = JSON.parse(options);
     options = JSON.parse(options);
     if (!ok) errorln("\n\n\n\n\n\n!!!!!!!!!!\n\n\n");
     errorln("//=============================================================");
@@ -1069,6 +1071,18 @@ function log(options) {
         errorln(original_result);
         errorln("uglified result:");
         errorln(uglify_result);
+        errorln("//-------------------------------------------------------------");
+        var reduced = reduce_test(original_code, options_copy, {
+            verbose: false,
+        }).code;
+        if (reduced) {
+            errorln();
+            errorln("// reduced test case (output will differ)");
+            errorln();
+            errorln(reduced);
+            errorln();
+            errorln("//-------------------------------------------------------------");
+        }
     } else {
         errorln("// !!! uglify failed !!!");
         errorln(uglify_code);

tools/exports.js

@@ -1,4 +1,5 @@
 exports["Dictionary"] = Dictionary;
+exports["List"] = List;
 exports["minify"] = minify;
 exports["parse"] = parse;
 exports["push_uniq"] = push_uniq;