fix: add an error for collisions

Author: Ivan Kuchaev

src/cli/moduleId.js

@@ -6,10 +6,10 @@ const crypto = require('crypto')
  * @param {string} path - The file path to hash.
  * @returns {number} - The hash number not exceeding Number.MAX_SAFE_INTEGER.
  */
-function moduleId(path) {
+function moduleId(path, maxNumber = Number.MAX_SAFE_INTEGER) {
   const hash = crypto.createHash('sha256').update(path).digest('hex')
 
-  return parseInt(hash.substring(0, 15), 16) % Number.MAX_SAFE_INTEGER
+  return parseInt(hash.substring(0, 15), 16) % maxNumber
 }
 
 module.exports = {

src/metro-config/createModuleIdFactory.js

@@ -4,16 +4,23 @@ const { moduleId } = require('../cli/moduleId')
 const root = process.cwd()
 
 // https://github.com/facebook/metro/blob/ed84760a8db1afc1a938c6ef005365bcf68df554/packages/metro/src/lib/createModuleIdFactory.js#L14
-function createModuleIdFactory() {
-  const modules = {}
-  return (pathToFile) => {
-    if (modules[pathToFile]) {
-      return modules[pathToFile]
+const createCreateModuleIdFactory =
+  ({ moduleIdMaxNumber } = {}) =>
+  () => {
+    const modules = {}
+    const hashes = {}
+    return (pathToFile) => {
+      if (modules[pathToFile]) {
+        return modules[pathToFile]
+      }
+      const id = moduleId(path.relative(root, pathToFile), moduleIdMaxNumber)
+      if (hashes[id] && hashes[id] !== pathToFile) {
+        throw new Error(`${pathToFile} collides with ${hashes[id]}`)
+      }
+      modules[pathToFile] = id
+      hashes[id] = pathToFile
+      return id
     }
-    const id = moduleId(path.relative(root, pathToFile))
-    modules[pathToFile] = id
-    return id
   }
-}
 
-module.exports = createModuleIdFactory
+module.exports = createCreateModuleIdFactory

src/metro-config/withChunksConfig.js

@@ -1,6 +1,6 @@
 const path = require('path')
 const { minimatch } = require('minimatch')
-const createModuleIdFactory = require('./createModuleIdFactory')
+const createCreateModuleIdFactory = require('./createModuleIdFactory')
 const { getChunksConfig } = require('../cli/getChunksConfig')
 const { getOutputDir } = require('../cli/utils')
 const { MetroSerializer } = require('./MetroSerializer')
@@ -23,13 +23,13 @@ const bootstraps = [
  *
  * @param {import('metro-config').MetroConfig} config
  */
-const serializeChunks = (config, chunksConfig, chunkId) => {
+const serializeChunks = (config, chunksConfig, chunkId, options) => {
   const customSerializer = MetroSerializer({ isChunkBundle })
   let result = {
     ...config.serializer,
     getRunModuleStatement: customSerializer.getRunModuleStatement,
     customSerializer: customSerializer,
-    createModuleIdFactory: createModuleIdFactory,
+    createModuleIdFactory: createCreateModuleIdFactory(options),
   }
   if (!isChunkBundle) {
     return result
@@ -114,7 +114,7 @@ const serializeChunks = (config, chunksConfig, chunkId) => {
  *
  * @param {import('metro-config').MetroConfig} config
  */
-function withChunksConfig(config) {
+function withChunksConfig(config, options) {
   const chunksConfig = isChunkBundle ? getChunksConfig({ root }) : null
 
   return {
@@ -124,7 +124,7 @@ function withChunksConfig(config) {
       assetExts: [...config.resolver.assetExts, 'chunk'],
       resolveRequest: resolveRequest(config, chunksConfig, chunkId),
     },
-    serializer: serializeChunks(config, chunksConfig, chunkId),
+    serializer: serializeChunks(config, chunksConfig, chunkId, options),
   }
 }