it's safe to negate expression in !EXP only in boolean context

#kendo

lib/compress.js

@@ -53,6 +53,7 @@ function Compressor(options, false_by_default) {
         dead_code     : !false_by_default,
         drop_debugger : !false_by_default,
         unsafe        : !false_by_default,
+        unsafe_comps  : false,
         conditionals  : !false_by_default,
         comparisons   : !false_by_default,
         evaluate      : !false_by_default,
@@ -427,13 +428,24 @@ merge(Compressor.prototype, {
             var ret = [], prev = null;
             statements.forEach(function(stat){
                 if (prev) {
-                    if (stat instanceof AST_For && stat.init && !(stat.init instanceof AST_Definitions)) {
+                    if (stat instanceof AST_For) {
+                        var opera = {};
+                        try {
+                            prev.body.walk(new TreeWalker(function(node){
+                                if (node instanceof AST_Binary && node.operator == "in")
+                                    throw opera;
+                            }));
+                            if (stat.init && !(stat.init instanceof AST_Definitions)) {
                                 stat.init = cons_seq(stat.init);
                             }
-                    else if (stat instanceof AST_For && !stat.init) {
+                            else if (!stat.init) {
                                 stat.init = prev.body;
                                 ret.pop();
                             }
+                        } catch(ex) {
+                            if (ex !== opera) throw ex;
+                        }
+                    }
                     else if (stat instanceof AST_If) {
                         stat.condition = cons_seq(stat.condition);
                     }
@@ -692,7 +704,7 @@ merge(Compressor.prototype, {
         });
         def(AST_Binary, function(compressor){
             var self = this.clone(), op = this.operator;
-            if (compressor.option("comparisons") && compressor.option("unsafe")) {
+            if (compressor.option("unsafe_comps")) {
                 switch (op) {
                   case "<=" : self.operator = ">"  ; return self;
                   case "<"  : self.operator = ">=" ; return self;
@@ -1434,10 +1446,10 @@ merge(Compressor.prototype, {
                 compressor.warn("Boolean expression always true [{file}:{line},{col}]", self.start);
                 return make_node(AST_True, self);
             }
-        }
+            if (e instanceof AST_Binary && self.operator == "!") {
-        if (e instanceof AST_Binary) {
                 self = best_of(self, e.negate(compressor));
             }
+        }
         return self.evaluate(compressor)[0];
     });
 

lib/scope.js

@@ -115,7 +115,14 @@ AST_Toplevel.DEFMETHOD("figure_out_scope", function(){
             node.init_scope_vars();
         }
         if (node instanceof AST_SymbolLambda) {
-            scope.def_function(node);
+            //scope.def_function(node);
+            //
+            // https://github.com/mishoo/UglifyJS2/issues/24 — MSIE
+            // leaks function expression names into the containing
+            // scope.  Don't like this fix but seems we can't do any
+            // better.  IE: please die. Please!
+            (node.scope = scope.parent_scope).def_function(node);
+
             node.init.push(tw.parent());
         }
         else if (node instanceof AST_SymbolDefun) {

package.json

@@ -3,7 +3,7 @@
     "description": "JavaScript parser, mangler/compressor and beautifier toolkit",
     "homepage": "http://lisperator.net/uglifyjs",
     "main": "tools/node.js",
-    "version": "2.1.3",
+    "version": "2.1.5",
     "engines": { "node" : ">=0.4.0" },
     "maintainers": [{
         "name": "Mihai Bazon",

test/compress/sequences.js

@@ -127,3 +127,35 @@ lift_sequences_4: {
         x = baz;
     }
 }
+
+for_sequences: {
+    options = { sequences: true };
+    input: {
+        // 1
+        foo();
+        bar();
+        for (; false;);
+        // 2
+        foo();
+        bar();
+        for (x = 5; false;);
+        // 3
+        x = (foo in bar);
+        for (; false;);
+        // 4
+        x = (foo in bar);
+        for (y = 5; false;);
+    }
+    expect: {
+        // 1
+        for (foo(), bar(); false;);
+        // 2
+        for (foo(), bar(), x = 5; false;);
+        // 3
+        x = (foo in bar);
+        for (; false;);
+        // 4
+        x = (foo in bar);
+        for (y = 5; false;);
+    }
+}

tools/node.js

@@ -9,7 +9,9 @@ var fs = require("fs");
 // but by the time you can set that the `path` module is already
 // loaded and `path.existsSync` is already changed to display that
 // warning, therefore here's the poor solution:
+if (fs.existsSync) {
     path.existsSync = fs.existsSync;
+}
 
 var vm = require("vm");
 var sys = require("util");