Merge pull request #1972 from alexlamsl/harmony-v3.0.9

Merging from master for 3.0.9

README.md

@@ -459,6 +459,9 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 - `unsafe_proto` (default: false) -- optimize expressions like
   `Array.prototype.slice.call(a)` into `[].slice.call(a)`
 
+- `unsafe_regexp` (default: false) -- enable substitutions of variables with
+  `RegExp` values the same way as if they are constants.
+
 - `conditionals` -- apply optimizations for `if`-s and conditional
   expressions
 
@@ -550,9 +553,9 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
   being compressed into `1/0`, which may cause performance issues on Chrome.
 
 - `side_effects` -- default `true`. Pass `false` to disable potentially dropping
-functions marked as "pure".  A function call is marked as "pure" if a comment
-annotation `/*@__PURE__*/` or `/*#__PURE__*/` immediately precedes the call. For
-example: `/*@__PURE__*/foo()`;
+  functions marked as "pure".  A function call is marked as "pure" if a comment
+  annotation `/*@__PURE__*/` or `/*#__PURE__*/` immediately precedes the call. For
+  example: `/*@__PURE__*/foo();`
 
 ## Mangle options
 

lib/compress.js

@@ -84,6 +84,7 @@ function Compressor(options, false_by_default) {
         unsafe_comps  : false,
         unsafe_math   : false,
         unsafe_proto  : false,
+        unsafe_regexp : false,
         unused        : !false_by_default,
         warnings      : false,
     }, true);
@@ -545,11 +546,11 @@ merge(Compressor.prototype, {
         return lhs instanceof AST_SymbolRef && lhs.definition().orig[0] instanceof AST_SymbolLambda;
     }
 
-    function is_reference_const(ref) {
+    function is_ref_of(ref, type) {
         if (!(ref instanceof AST_SymbolRef)) return false;
         var orig = ref.definition().orig;
         for (var i = orig.length; --i >= 0;) {
-            if (orig[i] instanceof AST_SymbolConst) return true;
+            if (orig[i] instanceof type) return true;
         }
     }
 
@@ -828,7 +829,7 @@ merge(Compressor.prototype, {
                     }
                 } else {
                     var lhs = expr[expr instanceof AST_Assign ? "left" : "expression"];
-                    return !is_reference_const(lhs) && lhs;
+                    return !is_ref_of(lhs, AST_SymbolConst) && lhs;
                 }
             }
 
@@ -2056,7 +2057,7 @@ merge(Compressor.prototype, {
                     && node instanceof AST_Assign
                     && node.operator == "="
                     && node.left instanceof AST_SymbolRef
-                    && !is_reference_const(node.left)
+                    && !is_ref_of(node.left, AST_SymbolBlockDeclaration)
                     && scope === self) {
                     node.right.walk(tw);
                     return true;
@@ -3160,7 +3161,6 @@ merge(Compressor.prototype, {
                     // Symbol's argument is only used for debugging.
                     self.args = [];
                     return self;
-                    break;
                 }
             }
             else if (exp instanceof AST_Dot && exp.property == "toString" && self.args.length == 0) {
@@ -3343,7 +3343,7 @@ merge(Compressor.prototype, {
                     && (left.operator == "++" || left.operator == "--")) {
                     left = left.expression;
                 } else left = null;
-                if (!left || is_lhs_read_only(left) || is_reference_const(left)) {
+                if (!left || is_lhs_read_only(left) || is_ref_of(left, AST_SymbolConst)) {
                     expressions[++i] = cdr;
                     continue;
                 }
@@ -3912,7 +3912,7 @@ merge(Compressor.prototype, {
             if (fixed) {
                 if (d.should_replace === undefined) {
                     var init = fixed.evaluate(compressor);
-                    if (init !== fixed) {
+                    if (init !== fixed && (compressor.option("unsafe_regexp") || !(init instanceof RegExp))) {
                         init = make_node_from_constant(init, fixed);
                         var value_length = init.optimize(compressor).print_to_string().length;
                         var fn;

package.json

@@ -4,7 +4,7 @@
   "homepage": "https://github.com/mishoo/UglifyJS2/tree/harmony",
   "author": "Mihai Bazon <mihai.bazon@gmail.com> (http://lisperator.net/)",
   "license": "BSD-2-Clause",
-  "version": "3.0.8",
+  "version": "3.0.9",
   "engines": {
     "node": ">=0.8.0"
   },

test/compress/drop-unused.js

@@ -1253,3 +1253,30 @@ reassign_const: {
     }
     expect_stdout: true
 }
+
+issue_1968: {
+    options = {
+        unused: true,
+    }
+    input: {
+        function f(c) {
+            var a;
+            if (c) {
+                let b;
+                return (a = 2) + (b = 3);
+            }
+        }
+        console.log(f(1));
+    }
+    expect: {
+        function f(c) {
+            if (c) {
+                let b;
+                return 2 + (b = 3);
+            }
+        }
+        console.log(f(1));
+    }
+    expect_stdout: "5"
+    node_version: ">=6"
+}

test/compress/evaluate.js

@@ -1083,3 +1083,50 @@ Infinity_NaN_undefined_LHS: {
         "}",
     ]
 }
+
+issue_1964_1: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        unsafe_regexp: false,
+        unused: true,
+    }
+    input: {
+        function f() {
+            var long_variable_name = /\s/;
+            return "a b c".split(long_variable_name)[1];
+        }
+        console.log(f());
+    }
+    expect: {
+        function f() {
+            var long_variable_name = /\s/;
+            return "a b c".split(long_variable_name)[1];
+        }
+        console.log(f());
+    }
+    expect_stdout: "b"
+}
+
+issue_1964_2: {
+    options = {
+        evaluate: true,
+        reduce_vars: true,
+        unsafe_regexp: true,
+        unused: true,
+    }
+    input: {
+        function f() {
+            var long_variable_name = /\s/;
+            return "a b c".split(long_variable_name)[1];
+        }
+        console.log(f());
+    }
+    expect: {
+        function f() {
+            return "a b c".split(/\s/)[1];
+        }
+        console.log(f());
+    }
+    expect_stdout: "b"
+}