From b8f5c8fc3fa146df01a9dca65c475c33cc679bd5 Mon Sep 17 00:00:00 2001
From: Evilebot Tnawi <evilebottnawi@users.noreply.github.com>
Date: Wed, 26 Apr 2017 22:27:59 +0300
Subject: [PATCH] perf: generate source maps only when explicitly set (#478)

---
 lib/loader.js         | 13 ++++++++++---
 lib/processCss.js     |  4 ++--
 test/sourceMapTest.js | 27 +++++++++++++++++++++++++++
 3 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/lib/loader.js b/lib/loader.js
index b55b35f9..ea4d8372 100644
--- a/lib/loader.js
+++ b/lib/loader.js
@@ -16,10 +16,16 @@ module.exports = function(content, map) {
 	var root = query.root;
 	var moduleMode = query.modules || query.module;
 	var camelCaseKeys = query.camelCase || query.camelcase;
+	var sourceMap = query.sourceMap || false;
 	var resolve = createResolver(query.alias);
 
-	if(map !== null && typeof map !== "string") {
-		map = JSON.stringify(map);
+	if(sourceMap) {
+		if (map && typeof map !== "string") {
+			map = JSON.stringify(map);
+		}
+	} else {
+		// Some loaders (example `"postcss-loader": "1.x.x"`) always generates source map, we should remove it
+		map = null;
 	}
 
 	processCss(content, map, {
@@ -28,7 +34,8 @@ module.exports = function(content, map) {
 		to: loaderUtils.getCurrentRequest(this),
 		query: query,
 		minimize: this.minimize,
-		loaderContext: this
+		loaderContext: this,
+		sourceMap: sourceMap
 	}, function(err, result) {
 		if(err) return callback(err);
 
diff --git a/lib/processCss.js b/lib/processCss.js
index 2c2fea6d..34017d5e 100644
--- a/lib/processCss.js
+++ b/lib/processCss.js
@@ -200,12 +200,12 @@ module.exports = function processCss(inputSource, inputMap, options, callback) {
 		// we need a prefix to avoid path rewriting of PostCSS
 		from: "/css-loader!" + options.from,
 		to: options.to,
-		map: {
+		map: options.sourceMap ? {
 			prev: inputMap,
 			sourcesContent: true,
 			inline: false,
 			annotation: false
-		}
+		} : null
 	}).then(function(result) {
 		callback(null, {
 			source: result.css,
diff --git a/test/sourceMapTest.js b/test/sourceMapTest.js
index 23ac5dc8..3bb84f66 100644
--- a/test/sourceMapTest.js
+++ b/test/sourceMapTest.js
@@ -10,6 +10,24 @@ describe("source maps", function() {
 	testWithMap("falsy: undefined map doesn't cause an error", ".class { a: b c d; }", undefined, [
 		[1, ".class { a: b c d; }", ""]
 	]);
+    testWithMap("should don't generate sourceMap when `sourceMap: false` and map exist",
+		".class { a: b c d; }",
+        {
+            file: 'test.css',
+            mappings: 'AAAA,SAAS,SAAS,EAAE',
+            names: [],
+            sourceRoot: '',
+            sources: [ '/folder/test.css' ],
+            sourcesContent: [ '.class { a: b c d; }' ],
+            version: 3
+        },
+		[
+			[1, ".class { a: b c d; }", ""]
+		],
+		{
+            query: "?sourceMap=false"
+		}
+	);
 	testMap("generate sourceMap (1 loader)", ".class { a: b c d; }", undefined, {
 		loaders: [{request: "/path/css-loader"}],
 		options: { context: "/" },
@@ -95,4 +113,13 @@ describe("source maps", function() {
 			version: 3
 		}]
 	]);
+	testMap("don't generate sourceMap (1 loader)", ".class { a: b c d; }", undefined, {
+		loaders: [{request: "/path/css-loader"}],
+		options: { context: "/" },
+		resource: "/folder/test.css",
+		request: "/path/css-loader!/folder/test.css",
+		query: "?sourceMap=false"
+	}, [
+		[1, ".class { a: b c d; }", ""]
+	]);
 });