Error on name collisions

Summary: @​public
This moves us from warnings on name collisions to errors. If the error happens in initialization it will fatal out.

However, if the error happens while working (after initialization) then I did my best to make it recoverable. The rational behind this is that if you're working and you're changing names, you may introduce a duplication while moving things around. It will suck if you have to restart the server every time you do that.

Reviewed By: @frantic

Differential Revision: D2493098

packager/react-packager/src/DependencyResolver/DependencyGraph/HasteMap.js

@@ -8,9 +8,9 @@
  */
 'use strict';
 
-const chalk = require('chalk');
 const path = require('path');
 const getPlatformExtension = require('../../lib/getPlatformExtension');
+const Promise = require('promise');
 
 const GENERIC_PLATFORM = 'generic';
 
@@ -19,11 +19,11 @@ class HasteMap {
     this._fastfs = fastfs;
     this._moduleCache = moduleCache;
     this._helpers = helpers;
-    this._map = Object.create(null);
-    this._warnedAbout = Object.create(null);
   }
 
   build() {
+    this._map = Object.create(null);
+
     let promises = this._fastfs.findFilesByExt('js', {
       ignore: (file) => this._helpers.isNodeModulesDir(file)
     }).map(file => this._processHasteModule(file));
@@ -39,20 +39,15 @@ class HasteMap {
 
   processFileChange(type, absPath) {
     return Promise.resolve().then(() => {
-      // Rewarn after file changes.
-      this._warnedAbout = Object.create(null);
-
       /*eslint no-labels: 0 */
       if (type === 'delete' || type === 'change') {
         loop: for (let name in this._map) {
           const modulesMap = this._map[name];
           for (let platform in modulesMap) {
-            const modules = modulesMap[platform];
-            for (var i = 0; i < modules.length; i++) {
-              if (modules[i].path === absPath) {
-                modules.splice(i, 1);
-                break loop;
-              }
+            const module = modulesMap[platform];
+            if (module.path === absPath) {
+              delete modulesMap[platform];
+              break loop;
             }
           }
         }
@@ -82,38 +77,15 @@ class HasteMap {
     // If no platform is given we choose the generic platform module list.
     // If a platform is given and no modules exist we fallback
     // to the generic platform module list.
-    let modules;
     if (platform == null) {
-      modules = modulesMap[GENERIC_PLATFORM];
+      return modulesMap[GENERIC_PLATFORM];
     } else {
-      modules = modulesMap[platform];
-      if (modules == null) {
-        modules = modulesMap[GENERIC_PLATFORM];
+      let module = modulesMap[platform];
+      if (module == null) {
+        module = modulesMap[GENERIC_PLATFORM];
       }
+      return module;
     }
-
-    if (modules == null) {
-      return null;
-    }
-
-    if (modules.length > 1) {
-      if (!this._warnedAbout[name]) {
-        this._warnedAbout[name] = true;
-        console.warn(
-          chalk.yellow(
-            '\nWARNING: Found multiple haste modules or packages ' +
-            'with the name `%s`. Please fix this by adding it to ' +
-            'the blacklist or deleting the modules keeping only one.\n'
-          ),
-          name,
-          modules.map(m => m.path).join('\n'),
-        );
-      }
-
-      return modules[0];
-    }
-
-    return modules[0];
   }
 
   _processHasteModule(file) {
@@ -147,11 +119,14 @@ class HasteMap {
     const moduleMap = this._map[name];
     const modulePlatform = getPlatformExtension(mod.path) || GENERIC_PLATFORM;
 
-    if (!moduleMap[modulePlatform]) {
-      moduleMap[modulePlatform] = [];
+    if (moduleMap[modulePlatform]) {
+      throw new Error(
+        `Naming collision detected: ${mod.path} ` +
+        `collides with ${moduleMap[modulePlatform].path}`
+      );
     }
 
-    moduleMap[modulePlatform].push(mod);
+    moduleMap[modulePlatform] = mod;
   }
 }