From db73113599561eab969be7452bbec3d6056ffdd8 Mon Sep 17 00:00:00 2001
From: "a.gutnikov" <a.gutnikov@corp.badoo.com>
Date: Wed, 9 Nov 2016 18:31:57 +0300
Subject: [PATCH] keep wrapping parens. for function extpressions

---
 bin/uglifyjs  | 6 ++++++
 lib/output.js | 9 +++++++++
 2 files changed, 15 insertions(+)

diff --git a/bin/uglifyjs b/bin/uglifyjs
index ce2e9411..c71c3149 100755
--- a/bin/uglifyjs
+++ b/bin/uglifyjs
@@ -69,6 +69,7 @@ You need to pass an argument to this option to specify the name that your module
     .describe("noerr", "Don't throw an error for unknown options in -c, -b or -m.")
     .describe("bare-returns", "Allow return outside of functions.  Useful when minifying CommonJS modules.")
     .describe("keep-fnames", "Do not mangle/drop function names.  Useful for code relying on Function.prototype.name.")
+    .describe("keep-fparens", "Do not drop parenthesises around function definitions. Useful for marking a function to be compiled eagerly by browser.")
     .describe("quotes", "Quote style (0 - auto, 1 - single, 2 - double, 3 - original)")
     .describe("reserved-file", "File containing reserved names")
     .describe("reserve-domprops", "Make (most?) DOM properties reserved for --mangle-props")
@@ -132,6 +133,7 @@ You need to pass an argument to this option to specify the name that your module
     .boolean("noerr")
     .boolean("bare-returns")
     .boolean("keep-fnames")
+    .boolean("keep-fparens")
     .boolean("reserve-domprops")
     .boolean("wrap-iife")
 
@@ -256,6 +258,10 @@ if (ARGS.wrap_iife) {
     OUTPUT_OPTIONS.wrap_iife = true;
 }
 
+if (ARGS.keep_fparens) {
+    OUTPUT_OPTIONS.keep_fparens = true;
+}
+
 if (BEAUTIFY)
     UglifyJS.merge(OUTPUT_OPTIONS, BEAUTIFY);
 
diff --git a/lib/output.js b/lib/output.js
index 63a78c60..740ef843 100644
--- a/lib/output.js
+++ b/lib/output.js
@@ -69,6 +69,7 @@ function OutputStream(options) {
         quote_style      : 0,
         keep_quoted_props: false,
         wrap_iife        : false,
+        keep_fparens     : false
     }, true);
 
     // Convert comment option to RegExp if neccessary and set up comments filter
@@ -558,6 +559,14 @@ function OutputStream(options) {
             return true;
         }
 
+        // If option is on then keep wrapping parenthesises
+        if (output.option('keep_fparens')) {
+          if (this.start && this.start instanceof AST_Token && this.start.value === '(' &&
+            this.end && this.end instanceof AST_Token && this.end.value === ')') {
+              return true;
+            }
+        }
+
         if (output.option('wrap_iife')) {
             var p = output.parent();
             return p instanceof AST_Call && p.expression === this;