[Pkg-javascript-commits] [uglifyjs] 82/491: introduce `unsafe_regexp` (#1970)

[Jonas Smedegaard]

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js pushed a commit to annotated tag debian/3.3.10-1
in repository uglifyjs.

commit eae26756f1419e7e601bae8b44d69f4e80dd0d61
Author: Alex Lam S.L <alexlamsl at gmail.com>
Date:   Fri May 19 09:06:29 2017 +0800

    introduce `unsafe_regexp` (#1970)
    
    fixes #1964
---
 README.md                 | 11 +++++++----
 lib/compress.js           |  3 ++-
 test/compress/evaluate.js | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index a2997b7..a763509 100644
--- a/README.md
+++ b/README.md
@@ -462,6 +462,9 @@ 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
 
@@ -552,10 +555,10 @@ If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.u
 - `keep_infinity` -- default `false`. Pass `true` to prevent `Infinity` from
   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()`;
+- `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();`
 
 ## Mangle options
 
diff --git a/lib/compress.js b/lib/compress.js
index f168b94..f6bf3d0 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -83,6 +83,7 @@ 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);
@@ -3765,7 +3766,7 @@ 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;
diff --git a/test/compress/evaluate.js b/test/compress/evaluate.js
index b807756..a1e3d0b 100644
--- a/test/compress/evaluate.js
+++ b/test/compress/evaluate.js
@@ -990,3 +990,50 @@ 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"
+}

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