fix iteration over object with inherited properties (#2068)

fixes #2055

3 files changed, 22 insertions, 3 deletions

diff --git a/lib/compress.js b/lib/compress.js
index 81b9ccac..5f2ac2b0 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -1419,7 +1419,7 @@ merge(Compressor.prototype, {
             });
             if (value && typeof value == "object") {
                 var props = [];
-                for (var key in value) {
+                for (var key in value) if (HOP(value, key)) {
                     props.push(make_node(AST_ObjectKeyVal, orig, {
                         key: key,
                         value: to_node(value[key], orig)
diff --git a/lib/minify.js b/lib/minify.js
index 16f5b189..cc638be3 100644
--- a/lib/minify.js
+++ b/lib/minify.js
@@ -86,7 +86,7 @@ function minify(files, options) {
             }
             options.parse = options.parse || {};
             options.parse.toplevel = null;
-            for (var name in files) {
+            for (var name in files) if (HOP(files, name)) {
                 options.parse.filename = name;
                 options.parse.toplevel = parse(files[name], options.parse);
                 if (options.sourceMap && options.sourceMap.content == "inline") {
@@ -134,7 +134,7 @@ function minify(files, options) {
                 if (options.sourceMap.includeSources) {
                     if (files instanceof AST_Toplevel) {
                         throw new Error("original source content unavailable");
-                    } else for (var name in files) {
+                    } else for (var name in files) if (HOP(files, name)) {
                         options.output.source_map.get().setSourceContent(name, files[name]);
                     }
                 }
diff --git a/test/mocha/minify.js b/test/mocha/minify.js
index 519b725c..638e79f7 100644
--- a/test/mocha/minify.js
+++ b/test/mocha/minify.js
@@ -13,6 +13,13 @@ describe("minify", function() {
         assert.strictEqual(result.code, 'function foo(n){return n?3:7}');
     });
 
+    it("Should skip inherited keys from `files`", function() {
+        var files = Object.create({ skip: this });
+        files[0] = "alert(1 + 1)";
+        var result = Uglify.minify(files);
+        assert.strictEqual(result.code, "alert(2);");
+    });
+
     describe("keep_quoted_props", function() {
         it("Should preserve quotes in object literals", function() {
             var js = 'var foo = {"x": 1, y: 2, \'z\': 3};';
@@ -207,5 +214,17 @@ describe("minify", function() {
             assert.ok(err instanceof Error);
             assert.strictEqual(err.stack.split(/\n/)[0], "Error: Can't handle expression: debugger");
         });
+        it("should skip inherited properties", function() {
+            var foo = Object.create({ skip: this });
+            foo.bar = 42;
+            var result = Uglify.minify("alert(FOO);", {
+                compress: {
+                    global_defs: {
+                        FOO: foo
+                    }
+                }
+            });
+            assert.strictEqual(result.code, "alert({bar:42});");
+        });
     });
 });