Fixes issues with uglify.js usage

Summary: Adds flow type defs for uglify, and fixes the two issues found

Reviewed By: jeanlauliac

Differential Revision: D5029190

fbshipit-source-id: eb5947b051844938da241e002b727edc1384e3a6

flow/uglify.js

@@ -0,0 +1,71 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+'use strict';
+
+type _SourceMap = {
+  file?: string,
+  mappings: string,
+  names: Array<string>,
+  sourceRoot?: string,
+  sources: Array<string>,
+  sourcesContent?: Array<?string>,
+  version: number,
+};
+
+type _Result<MapT> = {
+  code: string,
+  map: MapT,
+};
+
+type _Options = {
+  compress?: false | {||},
+  fromString?: boolean,
+  inSourceMap?: string | ?_SourceMap,
+  mangle?: boolean | {|
+    except?: Array<string>,
+    toplevel?: boolean,
+    eval?: boolean,
+    keep_fnames?: boolean,
+  |},
+  mangleProperties?: boolean | {|
+    regex?: RegExp,
+    ignore_quoted?: boolean,
+    debug?: false | string,
+  |},
+  outFileName?: string,
+  output?: {|
+    ascii_only?: boolean,
+    screw_ie8?: boolean,
+  |},
+  parse?: {|
+    strict?: boolean,
+    bare_returns?: boolean,
+    filename?: string,
+  |},
+  sourceMapUrl?: string,
+  sourceRoot?: string,
+  warnings?: boolean,
+};
+
+type _Input =
+  | string // code or file name
+  | Array<string> // array of file names
+  | {[filename: string]: string}; // file names and corresponding code
+
+declare module 'uglify-js' {
+  declare function minify(
+    fileOrFilesOrCode: _Input,
+    options?: _Options & {outSourceMap?: ?false | ''},
+  ): _Result<void>;
+  declare function minify(
+    fileOrFilesOrCode: _Input,
+    options?: _Options & {outSourceMap: true | string},
+  ): _Result<string>;
+}

packager/src/JSTransformer/worker/minify.js

@@ -15,17 +15,19 @@ const uglify = require('uglify-js');
 
 const {UGLIFY_JS_OUTPUT_OPTIONS} = require('./JsMinification');
 
-function minify(filename: string, code: string, sourceMap: ?string) {
+import type {MappingsMap} from '../../lib/SourceMap';
-  const minifyResult = uglify.minify(code, {
+
+function minify(filename: string, inputCode: string, sourceMap: ?MappingsMap) {
+  let {code, map} = uglify.minify(inputCode, {
     fromString: true,
     inSourceMap: sourceMap,
     outSourceMap: true,
     output: UGLIFY_JS_OUTPUT_OPTIONS,
   });
 
-  minifyResult.map = JSON.parse(minifyResult.map);
+  map = JSON.parse(map);
-  minifyResult.map.sources = [filename];
+  map.sources = [filename];
-  return minifyResult;
+  return {code, map};
 }
 
 module.exports = minify;

packager/src/JSTransformer/worker/worker.js

@@ -166,7 +166,7 @@ exports.transformAndExtractDependencies = (
 exports.minify = (
   filename: string,
   code: string,
-  sourceMap: string,
+  sourceMap: MappingsMap,
   callback: (error: ?Error, result: mixed) => mixed,
 ) => {
   var result;

packager/src/ModuleGraph/types.flow.js

@@ -110,7 +110,7 @@ export type TransformResult = {|
   code: string,
   dependencies: Array<string>,
   dependencyMapName?: string,
-  map: ?Object,
+  map: ?MappingsMap,
 |};
 
 export type TransformResults = {[string]: TransformResult};

packager/src/ModuleGraph/worker/optimize-module.js

@@ -19,6 +19,7 @@ const minify = require('../../JSTransformer/worker/minify');
 const sourceMap = require('source-map');
 
 import type {TransformedSourceFile, TransformResult} from '../types.flow';
+import type {MappingsMap, SourceMap} from '../../lib/SourceMap';
 
 export type OptimizationOptions = {|
   dev: boolean,
@@ -71,7 +72,7 @@ function optimize(transformed, file, originalCode, options): TransformResult {
     gen.code,
     inputMap && mergeSourceMaps(file, inputMap, gen.map),
   );
-  return {code: min.code, map: inputMap && min.map, dependencies};
+  return {code: min.code, map: min.map, dependencies};
 }
 
 function optimizeCode(code, map, filename, inliningOptions) {
@@ -86,7 +87,11 @@ function optimizeCode(code, map, filename, inliningOptions) {
   });
 }
 
-function mergeSourceMaps(file, originalMap, secondMap) {
+function mergeSourceMaps(
+  file: string,
+  originalMap: SourceMap,
+  secondMap: SourceMap,
+): MappingsMap {
   const merged = new sourceMap.SourceMapGenerator();
   const inputMap = new sourceMap.SourceMapConsumer(originalMap);
   new sourceMap.SourceMapConsumer(secondMap)