diff --git a/README.md b/README.md
index 9efa0c94..6dab6ff4 100644
--- a/README.md
+++ b/README.md
@@ -624,7 +624,7 @@ 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) {
@@ -868,7 +868,7 @@ 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
diff --git a/lib/compress.js b/lib/compress.js
index b107367d..c27b2b96 100644
--- a/lib/compress.js
+++ b/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,
@@ -180,38 +180,105 @@ 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))) {
-                        d.modified = true;
+                    if (!d.fixed || isModified(node, 0) || !is_safe(d)) {
+                        d.fixed = false;
                     }
                 }
-                if (node instanceof AST_Call && node.expression instanceof AST_Function) {
-                    node.expression.argnames.forEach(function(arg, i) {
-                        arg.definition().init = node.args[i] || make_node(AST_Undefined, node);
+                if (node instanceof AST_VarDef) {
+                    var d = node.name.definition();
+                    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_Directive || node instanceof AST_Constant)) {
-                node._squeezed = false;
-                node._optimized = false;
+                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;
+                }
             }
         });
         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) {
@@ -988,12 +1055,6 @@ merge(Compressor.prototype, {
         def(AST_Conditional, function(compressor){
             return this.consequent.is_string(compressor) && this.alternative.is_string(compressor);
         });
-        def(AST_Call, function(compressor){
-            return compressor.option("unsafe")
-                && this.expression instanceof AST_SymbolRef
-                && this.expression.name == "String"
-                && this.expression.undeclared();
-        });
     })(function(node, func){
         node.DEFMETHOD("is_string", func);
     });
@@ -1149,11 +1210,14 @@ 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) {
@@ -1181,7 +1245,9 @@ 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') {
@@ -1259,14 +1325,14 @@ 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) {
-                            d.init._evaluated = ev(d.init, compressor);
+                        if (!HOP(d.fixed, "_evaluated")) {
+                            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;
@@ -2190,7 +2256,7 @@ 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)) {
@@ -2416,6 +2482,20 @@ merge(Compressor.prototype, {
     });
 
     OPT(AST_Call, function(self, compressor){
+        if (compressor.option("unused")
+            && self.expression instanceof AST_Function
+            && !self.expression.uses_arguments
+            && !self.expression.uses_eval
+            && self.args.length > self.expression.argnames.length) {
+            var end = self.expression.argnames.length;
+            for (var i = end, len = self.args.length; i < len; i++) {
+                var node = self.args[i].drop_side_effect_free(compressor);
+                if (node) {
+                    self.args[end++] = node;
+                }
+            }
+            self.args.length = end;
+        }
         if (compressor.option("unsafe")) {
             var exp = self.expression;
             if (exp instanceof AST_SymbolRef && exp.undeclared()) {
@@ -2455,7 +2535,7 @@ 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: "!"
                         }),
@@ -2627,6 +2707,12 @@ merge(Compressor.prototype, {
                 }
             }
         }
+        if (self.args.length == 0
+            && self.expression instanceof AST_Function
+            && self.expression.body[0] instanceof AST_Return
+            && self.expression.body[0].value.is_constant()) {
+            return self.expression.body[0].value;
+        }
         if (compressor.option("negate_iife")
             && compressor.parent() instanceof AST_SimpleStatement
             && is_iife_call(self)) {
@@ -2890,7 +2976,7 @@ 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]) {
@@ -2953,10 +3039,25 @@ merge(Compressor.prototype, {
                 }
             }
         }
-        if (self.operator == "+" && self.right instanceof AST_String
-            && self.right.getValue() === "" && self.left instanceof AST_Binary
-            && self.left.operator == "+" && self.left.is_string(compressor)) {
-            return self.left;
+        if (self.operator == "+") {
+            if (self.right instanceof AST_String
+                && self.right.getValue() == ""
+                && self.left.is_string(compressor)) {
+                return self.left;
+            }
+            if (self.left instanceof AST_String
+                && self.left.getValue() == ""
+                && self.right.is_string(compressor)) {
+                return self.right;
+            }
+            if (self.left instanceof AST_Binary
+                && self.left.operator == "+"
+                && self.left.left instanceof AST_String
+                && self.left.left.getValue() == ""
+                && self.right.is_string(compressor)) {
+                self.left = self.left.right;
+                return self.transform(compressor);
+            }
         }
         if (compressor.option("evaluate")) {
             switch (self.operator) {
@@ -3081,9 +3182,9 @@ 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;
diff --git a/lib/utils.js b/lib/utils.js
index 46adfd4c..da663546 100644
--- a/lib/utils.js
+++ b/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];
     });
 };
 
diff --git a/package.json b/package.json
index 8bd00fa3..33bfc236 100644
--- a/package.json
+++ b/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"
   },
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index d7432f3f..5f63488f 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -1141,7 +1141,7 @@ collapse_vars_constants: {
         function f3(x) {
             var b = x.prop;
             sideeffect1();
-            return b + (function() { return -9; })();
+            return b + -9;
         }
     }
 }
diff --git a/test/compress/concat-strings.js b/test/compress/concat-strings.js
index d2503c6d..2f99375c 100644
--- a/test/compress/concat-strings.js
+++ b/test/compress/concat-strings.js
@@ -164,3 +164,53 @@ concat_6: {
         );
     }
 }
+
+concat_7: {
+    input: {
+        console.log(
+            "" + 1,
+            "" + "1",
+            "" + 1 + 2,
+            "" + 1 + "2",
+            "" + "1" + 2,
+            "" + "1" + "2",
+            "" + (x += "foo")
+        );
+    }
+    expect: {
+        console.log(
+            "" + 1,
+            "1",
+            "" + 1 + 2,
+            1 + "2",
+            "1" + 2,
+            "1" + "2",
+            x += "foo"
+        );
+    }
+}
+
+concat_8: {
+    input: {
+        console.log(
+            1 + "",
+            "1" + "",
+            1 + 2 + "",
+            1 + "2" + "",
+            "1" + 2 + "",
+            "1" + "2" + "",
+            (x += "foo") + ""
+        );
+    }
+    expect: {
+        console.log(
+            1 + "",
+            "1",
+            1 + 2 + "",
+            1 + "2",
+            "1" + 2,
+            "1" + "2",
+            x += "foo"
+        );
+    }
+}
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index 6bed73fb..26b6e489 100644
--- a/test/compress/evaluate.js
+++ b/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,
@@ -620,6 +646,29 @@ call_args: {
     }
 }
 
+call_args_drop_param: {
+    options = {
+        evaluate: true,
+        keep_fargs: false,
+        reduce_vars: true,
+        unused: true,
+    }
+    input: {
+        const a = 1;
+        console.log(a);
+        +function(a) {
+            return a;
+        }(a, b);
+    }
+    expect: {
+        const a = 1;
+        console.log(1);
+        +function() {
+            return 1;
+        }(b);
+    }
+}
+
 in_boolean_context: {
     options = {
         booleans: true,
diff --git a/test/compress/functions.js b/test/compress/functions.js
index 3a8701b7..d3d99b57 100644
--- a/test/compress/functions.js
+++ b/test/compress/functions.js
@@ -6,3 +6,71 @@ non_ascii_function_identifier_name: {
     }
     expect_exact: "function fooλ(δλ){}function λ(δλ){}(function λ(δλ){})();"
 }
+
+iifes_returning_constants_keep_fargs_true: {
+    options = {
+        keep_fargs    : true,
+        side_effects  : true,
+        evaluate      : true,
+        unused        : true,
+        dead_code     : true,
+        conditionals  : true,
+        comparisons   : true,
+        booleans      : true,
+        if_return     : true,
+        join_vars     : true,
+        reduce_vars   : true,
+        cascade       : true,
+    }
+    input: {
+        (function(){ return -1.23; }());
+        console.log( function foo(){ return "okay"; }() );
+        console.log( function foo(x, y, z){ return 123; }() );
+        console.log( function(x, y, z){ return z; }() );
+        console.log( function(x, y, z){ if (x) return y; return z; }(1, 2, 3) );
+        console.log( function(x, y){ return x * y; }(2, 3) );
+        console.log( function(x, y){ return x * y; }(2, 3, a(), b()) );
+    }
+    expect: {
+        console.log("okay");
+        console.log(123);
+        console.log(void 0);
+        console.log(function(x,y,z){return 2}(1,2,3));
+        console.log(function(x,y){return 6}(2,3));
+        console.log(function(x, y){return 6}(2,3,a(),b()));
+    }
+}
+
+iifes_returning_constants_keep_fargs_false: {
+    options = {
+        keep_fargs    : false,
+        side_effects  : true,
+        evaluate      : true,
+        unused        : true,
+        dead_code     : true,
+        conditionals  : true,
+        comparisons   : true,
+        booleans      : true,
+        if_return     : true,
+        join_vars     : true,
+        reduce_vars   : true,
+        cascade       : true,
+    }
+    input: {
+        (function(){ return -1.23; }());
+        console.log( function foo(){ return "okay"; }() );
+        console.log( function foo(x, y, z){ return 123; }() );
+        console.log( function(x, y, z){ return z; }() );
+        console.log( function(x, y, z){ if (x) return y; return z; }(1, 2, 3) );
+        console.log( function(x, y){ return x * y; }(2, 3) );
+        console.log( function(x, y){ return x * y; }(2, 3, a(), b()) );
+    }
+    expect: {
+        console.log("okay");
+        console.log(123);
+        console.log(void 0);
+        console.log(2);
+        console.log(6);
+        console.log(function(){return 6}(a(),b()));
+    }
+}
diff --git a/test/compress/negate-iife.js b/test/compress/negate-iife.js
index 001795c5..f17ae206 100644
--- a/test/compress/negate-iife.js
+++ b/test/compress/negate-iife.js
@@ -38,10 +38,10 @@ negate_iife_3: {
         conditionals: true
     };
     input: {
-        (function(){ return true })() ? console.log(true) : console.log(false);
+        (function(){ return t })() ? console.log(true) : console.log(false);
     }
     expect: {
-        !function(){ return true }() ? console.log(false) : console.log(true);
+        !function(){ return t }() ? console.log(false) : console.log(true);
     }
 }
 
@@ -51,10 +51,10 @@ negate_iife_3_off: {
         conditionals: true,
     };
     input: {
-        (function(){ return true })() ? console.log(true) : console.log(false);
+        (function(){ return t })() ? console.log(true) : console.log(false);
     }
     expect: {
-        !function(){ return true }() ? console.log(false) : console.log(true);
+        !function(){ return t }() ? console.log(false) : console.log(true);
     }
 }
 
@@ -65,13 +65,13 @@ negate_iife_4: {
         sequences: true
     };
     input: {
-        (function(){ return true })() ? console.log(true) : console.log(false);
+        (function(){ return t })() ? console.log(true) : console.log(false);
         (function(){
             console.log("something");
         })();
     }
     expect: {
-        !function(){ return true }() ? console.log(false) : console.log(true), function(){
+        !function(){ return t }() ? console.log(false) : console.log(true), function(){
             console.log("something");
         }();
     }
@@ -86,7 +86,7 @@ sequence_off: {
     };
     input: {
         function f() {
-            (function(){ return true })() ? console.log(true) : console.log(false);
+            (function(){ return t })() ? console.log(true) : console.log(false);
             (function(){
                 console.log("something");
             })();
@@ -95,19 +95,19 @@ sequence_off: {
             (function(){
                 console.log("something");
             })();
-            (function(){ return true })() ? console.log(true) : console.log(false);
+            (function(){ return t })() ? console.log(true) : console.log(false);
         }
     }
     expect: {
         function f() {
-            !function(){ return true }() ? console.log(false) : console.log(true), function(){
+            !function(){ return t }() ? console.log(false) : console.log(true), function(){
                 console.log("something");
             }();
         }
         function g() {
             (function(){
                 console.log("something");
-            })(), function(){ return true }() ? console.log(true) : console.log(false);
+            })(), function(){ return t }() ? console.log(true) : console.log(false);
         }
     }
 }
@@ -119,7 +119,7 @@ negate_iife_5: {
         conditionals: true,
     };
     input: {
-        if ((function(){ return true })()) {
+        if ((function(){ return t })()) {
             foo(true);
         } else {
             bar(false);
@@ -129,7 +129,7 @@ negate_iife_5: {
         })();
     }
     expect: {
-        !function(){ return true }() ? bar(false) : foo(true), function(){
+        !function(){ return t }() ? bar(false) : foo(true), function(){
             console.log("something");
         }();
     }
@@ -142,7 +142,7 @@ negate_iife_5_off: {
         conditionals: true,
     };
     input: {
-        if ((function(){ return true })()) {
+        if ((function(){ return t })()) {
             foo(true);
         } else {
             bar(false);
@@ -152,7 +152,7 @@ negate_iife_5_off: {
         })();
     }
     expect: {
-        !function(){ return true }() ? bar(false) : foo(true), function(){
+        !function(){ return t }() ? bar(false) : foo(true), function(){
             console.log("something");
         }();
     }
diff --git a/test/compress/reduce_vars.js b/test/compress/reduce_vars.js
index 0ee201c0..e38c317b 100644
--- a/test/compress/reduce_vars.js
+++ b/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);
+    }
+}
diff --git a/test/mocha/minify.js b/test/mocha/minify.js
index baac2a41..51c46b28 100644
--- a/test/mocha/minify.js
+++ b/test/mocha/minify.js
@@ -155,7 +155,7 @@ describe("minify", function() {
             assert.strictEqual(code, "//  comment1   comment2\nbar();");
         });
         it("should not drop #__PURE__ hint if function is retained", function() {
-            var result = Uglify.minify("var a = /*#__PURE__*/(function(){return 1})();", {
+            var result = Uglify.minify("var a = /*#__PURE__*/(function(){ foo(); })();", {
                 fromString: true,
                 output: {
                     comments: "all",
@@ -163,7 +163,7 @@ describe("minify", function() {
                 }
             });
             var code = result.code;
-            assert.strictEqual(code, "var a=/*#__PURE__*/function(){return 1}();");
+            assert.strictEqual(code, "var a=/*#__PURE__*/function(){foo()}();");
         })
     });
 
@@ -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)}");
+        });
+    })
+
 });