v2.8.4

Avoid variable substitution in the following cases:
- use of variable before declaration
- declaration within conditional code blocks
- declaration within loop body

fixes #1518
fixes #1525

README.md

@@ -621,7 +621,7 @@ function uglify(ast, options, mangle) {
 
   // Compression
   uAST.figure_out_scope();
-  uAST = uAST.transform(UglifyJS.Compressor(options));
+  uAST = UglifyJS.Compressor(options).compress(uAST);
 
   // Mangling (optional)
   if (mangle) {
@@ -865,7 +865,7 @@ toplevel.figure_out_scope()
 Like this:
 ```javascript
 var compressor = UglifyJS.Compressor(options);
-var compressed_ast = toplevel.transform(compressor);
+var compressed_ast = compressor.compress(toplevel);
 ```
 
 The `options` can be missing.  Available options are discussed above in

lib/compress.js

@@ -61,7 +61,7 @@ function Compressor(options, false_by_default) {
         booleans      : !false_by_default,
         loops         : !false_by_default,
         unused        : !false_by_default,
-        toplevel      : !!options["top_retain"],
+        toplevel      : !!(options && options["top_retain"]),
         top_retain    : null,
         hoist_funs    : !false_by_default,
         keep_fargs    : true,
@@ -70,7 +70,7 @@ function Compressor(options, false_by_default) {
         if_return     : !false_by_default,
         join_vars     : !false_by_default,
         collapse_vars : !false_by_default,
-        reduce_vars   : false,
+        reduce_vars   : !false_by_default,
         cascade       : !false_by_default,
         side_effects  : !false_by_default,
         pure_getters  : false,
@@ -179,38 +179,105 @@ merge(Compressor.prototype, {
 
     AST_Node.DEFMETHOD("reset_opt_flags", function(compressor, rescan){
         var reduce_vars = rescan && compressor.option("reduce_vars");
-        var unsafe = compressor.option("unsafe");
+        var safe_ids = [];
+        push();
         var tw = new TreeWalker(function(node){
+            if (!(node instanceof AST_Directive || node instanceof AST_Constant)) {
+                node._squeezed = false;
+                node._optimized = false;
+            }
             if (reduce_vars) {
                 if (node instanceof AST_Toplevel) node.globals.each(reset_def);
                 if (node instanceof AST_Scope) node.variables.each(reset_def);
                 if (node instanceof AST_SymbolRef) {
                     var d = node.definition();
                     d.references.push(node);
-                    if (!d.modified && (d.orig.length > 1 || isModified(node, 0))) {
+                    if (!d.fixed || isModified(node, 0) || !is_safe(d)) {
-                        d.modified = true;
+                        d.fixed = false;
                     }
                 }
-                if (node instanceof AST_Call && node.expression instanceof AST_Function) {
+                if (node instanceof AST_VarDef) {
-                    node.expression.argnames.forEach(function(arg, i) {
+                    var d = node.name.definition();
-                        arg.definition().init = node.args[i] || make_node(AST_Undefined, node);
+                    if (d.fixed === undefined) {
+                        d.fixed = node.value || make_node(AST_Undefined, node);
+                        mark_as_safe(d);
+                    } else {
+                        d.fixed = false;
+                    }
+                }
+                var iife;
+                if (node instanceof AST_Function
+                    && (iife = tw.parent()) instanceof AST_Call
+                    && iife.expression === node) {
+                    node.argnames.forEach(function(arg, i) {
+                        var d = arg.definition();
+                        d.fixed = iife.args[i] || make_node(AST_Undefined, iife);
+                        mark_as_safe(d);
                     });
                 }
+                if (node instanceof AST_If || node instanceof AST_DWLoop) {
+                    node.condition.walk(tw);
+                    push();
+                    node.body.walk(tw);
+                    pop();
+                    if (node.alternative) {
+                        push();
+                        node.alternative.walk(tw);
+                        pop();
+                    }
+                    return true;
+                }
+                if (node instanceof AST_LabeledStatement) {
+                    push();
+                    node.body.walk(tw);
+                    pop();
+                    return true;
+                }
+                if (node instanceof AST_For) {
+                    if (node.init) node.init.walk(tw);
+                    push();
+                    if (node.condition) node.condition.walk(tw);
+                    node.body.walk(tw);
+                    if (node.step) node.step.walk(tw);
+                    pop();
+                    return true;
+                }
+                if (node instanceof AST_ForIn) {
+                    if (node.init instanceof AST_SymbolRef) {
+                        node.init.definition().fixed = false;
+                    }
+                    node.object.walk(tw);
+                    push();
+                    node.body.walk(tw);
+                    pop();
+                    return true;
                 }
-            if (!(node instanceof AST_Directive || node instanceof AST_Constant)) {
-                node._squeezed = false;
-                node._optimized = false;
             }
         });
         this.walk(tw);
 
+        function mark_as_safe(def) {
+            safe_ids[safe_ids.length - 1][def.id] = true;
+        }
+
+        function is_safe(def) {
+            for (var i = safe_ids.length, id = def.id; --i >= 0;) {
+                if (safe_ids[i][id]) return true;
+            }
+        }
+
+        function push() {
+            safe_ids.push(Object.create(null));
+        }
+
+        function pop() {
+            safe_ids.pop();
+        }
+
         function reset_def(def) {
-            def.modified = false;
+            def.fixed = undefined;
             def.references = [];
             def.should_replace = undefined;
-            if (unsafe && def.init) {
-                def.init._evaluated = undefined;
-            }
         }
 
         function isModified(node, level) {
@@ -1148,11 +1215,14 @@ merge(Compressor.prototype, {
         def(AST_Statement, function(){
             throw new Error(string_template("Cannot evaluate a statement [{file}:{line},{col}]", this.start));
         });
+        // XXX: AST_Accessor and AST_Function both inherit from AST_Scope,
+        // which itself inherits from AST_Statement; however, they aren't
+        // really statements.  This could bite in other places too. :-(
+        // Wish JS had multiple inheritance.
+        def(AST_Accessor, function(){
+            throw def;
+        });
         def(AST_Function, function(){
-            // XXX: AST_Function inherits from AST_Scope, which itself
-            // inherits from AST_Statement; however, an AST_Function
-            // isn't really a statement.  This could byte in other
-            // places too. :-( Wish JS had multiple inheritance.
             throw def;
         });
         function ev(node, compressor) {
@@ -1180,7 +1250,9 @@ merge(Compressor.prototype, {
                 for (var i = 0, len = this.properties.length; i < len; i++) {
                     var prop = this.properties[i];
                     var key = prop.key;
-                    if (key instanceof AST_Node) {
+                    if (key instanceof AST_Symbol) {
+                        key = key.name;
+                    } else if (key instanceof AST_Node) {
                         key = ev(key, compressor);
                     }
                     if (typeof Object.prototype[key] === 'function') {
@@ -1258,14 +1330,14 @@ merge(Compressor.prototype, {
             this._evaluating = true;
             try {
                 var d = this.definition();
-                if (compressor.option("reduce_vars") && !d.modified && d.init) {
+                if (compressor.option("reduce_vars") && d.fixed) {
                     if (compressor.option("unsafe")) {
-                        if (d.init._evaluated === undefined) {
+                        if (!HOP(d.fixed, "_evaluated")) {
-                            d.init._evaluated = ev(d.init, compressor);
+                            d.fixed._evaluated = ev(d.fixed, compressor);
                         }
-                        return d.init._evaluated;
+                        return d.fixed._evaluated;
                     }
-                    return ev(d.init, compressor);
+                    return ev(d.fixed, compressor);
                 }
             } finally {
                 this._evaluating = false;
@@ -2189,7 +2261,7 @@ merge(Compressor.prototype, {
             // here because they are only used in an equality comparison later on.
             self.condition = negated;
             var tmp = self.body;
-            self.body = self.alternative || make_node(AST_EmptyStatement);
+            self.body = self.alternative || make_node(AST_EmptyStatement, self);
             self.alternative = tmp;
         }
         if (is_empty(self.body) && is_empty(self.alternative)) {
@@ -2454,7 +2526,7 @@ merge(Compressor.prototype, {
                   case "Boolean":
                     if (self.args.length == 0) return make_node(AST_False, self);
                     if (self.args.length == 1) return make_node(AST_UnaryPrefix, self, {
-                        expression: make_node(AST_UnaryPrefix, null, {
+                        expression: make_node(AST_UnaryPrefix, self, {
                             expression: self.args[0],
                             operator: "!"
                         }),
@@ -2850,7 +2922,7 @@ merge(Compressor.prototype, {
                 compressor.warn("Boolean && always false [{file}:{line},{col}]", self.start);
                 return make_node(AST_Seq, self, {
                     car: self.left,
-                    cdr: make_node(AST_False)
+                    cdr: make_node(AST_False, self)
                 }).optimize(compressor);
             }
             if (ll.length > 1 && ll[1]) {
@@ -3041,9 +3113,9 @@ merge(Compressor.prototype, {
         }
         if (compressor.option("evaluate") && compressor.option("reduce_vars")) {
             var d = self.definition();
-            if (!d.modified && d.init) {
+            if (d.fixed) {
                 if (d.should_replace === undefined) {
-                    var init = d.init.evaluate(compressor);
+                    var init = d.fixed.evaluate(compressor);
                     if (init.length > 1) {
                         var value = init[0].print_to_string().length;
                         var name = d.name.length;

lib/utils.js

@@ -185,7 +185,7 @@ function push_uniq(array, el) {
 
 function string_template(text, props) {
     return text.replace(/\{(.+?)\}/g, function(str, p){
-        return props[p];
+        return props && props[p];
     });
 };
 

package.json

@@ -4,7 +4,7 @@
   "homepage": "http://lisperator.net/uglifyjs",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "2.8.1",
+  "version": "2.8.4",
   "engines": {
     "node": ">=0.8.0"
   },

test/compress/evaluate.js

@@ -337,6 +337,32 @@ unsafe_object_repeated: {
     }
 }
 
+unsafe_object_accessor: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        unsafe: true,
+    }
+    input: {
+        function f() {
+            var a = {
+                get b() {},
+                set b() {}
+            };
+            return {a:a};
+        }
+    }
+    expect: {
+        function f() {
+            var a = {
+                get b() {},
+                set b() {}
+            };
+            return {a:a};
+        }
+    }
+}
+
 unsafe_function: {
     options = {
         evaluate  : true,

test/compress/reduce_vars.js

@@ -470,3 +470,122 @@ multi_def_2: {
         var repeatLength = this.getBits(bitsLength) + bitsOffset;
     }
 }
+
+use_before_var: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        console.log(t);
+        var t = 1;
+    }
+    expect: {
+        console.log(t);
+        var t = 1;
+    }
+}
+
+inner_var_if: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        function f(){
+            return 0;
+        }
+        if (f())
+            var t = 1;
+        if (!t)
+            console.log(t);
+    }
+    expect: {
+        function f(){
+            return 0;
+        }
+        if (f())
+            var t = 1;
+        if (!t)
+            console.log(t);
+    }
+}
+
+inner_var_label: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        function f(){
+            return 1;
+        }
+        l: {
+            if (f()) break l;
+            var t = 1;
+        }
+        console.log(t);
+    }
+    expect: {
+        function f(){
+            return 1;
+        }
+        l: {
+            if (f()) break l;
+            var t = 1;
+        }
+        console.log(t);
+    }
+}
+
+inner_var_for: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        var a = 1;
+        x(a, b, d);
+        for (var b = 2, c = 3; x(a, b, c, d); x(a, b, c, d)) {
+            var d = 4, e = 5;
+            x(a, b, c, d, e);
+        }
+        x(a, b, c, d, e)
+    }
+    expect: {
+        var a = 1;
+        x(1, b, d);
+        for (var b = 2, c = 3; x(1, b, 3, d); x(1, b, 3, d)) {
+            var d = 4, e = 5;
+            x(1, b, 3, d, e);
+        }
+        x(1, b, 3, d, e);
+    }
+}
+
+inner_var_for_in: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+    }
+    input: {
+        var a = 1, b = 2;
+        for (b in (function() {
+            return x(a, b, c);
+        })()) {
+            var c = 3, d = 4;
+            x(a, b, c, d);
+        }
+        x(a, b, c, d);
+    }
+    expect: {
+        var a = 1, b = 2;
+        for (b in (function() {
+            return x(1, b, c);
+        })()) {
+            var c = 3, d = 4;
+            x(1, b, c, d);
+        }
+        x(1, b, c, d);
+    }
+}

test/mocha/minify.js

@@ -182,4 +182,13 @@ describe("minify", function() {
         });
     });
 
+    describe("Compressor", function() {
+        it("should be backward compatible with ast.transform(compressor)", function() {
+            var ast = Uglify.parse("function f(a){for(var i=0;i<a;i++)console.log(i)}");
+            ast.figure_out_scope();
+            ast = ast.transform(Uglify.Compressor());
+            assert.strictEqual(ast.print_to_string(), "function f(a){for(var i=0;i<a;i++)console.log(i)}");
+        });
+    })
+
 });