From 7e5af6263981819655d5725964182516ae847374 Mon Sep 17 00:00:00 2001
From: Alex Hunt <alexeh@meta.com>
Date: Wed, 28 Jun 2023 03:48:43 -0700
Subject: [PATCH] Restore base config merge in metro-config (#38092)
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Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/38092

Reverts https://github.com/facebook/react-native/pull/36777.

This is motivated by reducing user friction when the widespread assumption is for `react-native/metro-config` to export a complete Metro config, as with Expo/rnx-kit, and like previously understood uses of `metro-config`. See https://github.com/facebook/metro/issues/1010#issuecomment-1609215165 for further notes.

Fixes:
- https://github.com/facebook/metro/issues/1010
- https://github.com/facebook/react-native/issues/38069
- https://github.com/kristerkari/react-native-svg-transformer/issues/276

Note that we do not intend for `react-native/metro-config` to directly export `assetExts` etc — these can be accessed on the `resolver` property from the full config object.

Changelog: [General][Changed] `react-native/metro-config` now includes all base config values from `metro-config`

Reviewed By: robhogan

Differential Revision: D47055973

fbshipit-source-id: eedc4698e651645ada46a013d3945a16965bff22
---
 packages/metro-config/index.js | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/packages/metro-config/index.js b/packages/metro-config/index.js
index e88df579040627..c43b46a34b8cf9 100644
--- a/packages/metro-config/index.js
+++ b/packages/metro-config/index.js
@@ -8,9 +8,9 @@
  * @noformat
  */
 
-/*:: import type {MetroConfig} from 'metro-config'; */
+/*:: import type {ConfigT} from 'metro-config'; */
 
-const {mergeConfig} = require('metro-config');
+const {getDefaultConfig: getBaseConfig, mergeConfig} = require('metro-config');
 
 const INTERNAL_CALLSITES_REGEX = new RegExp(
   [
@@ -37,8 +37,8 @@ const INTERNAL_CALLSITES_REGEX = new RegExp(
  */
 function getDefaultConfig(
   projectRoot /*: string */
-) /*: MetroConfig */ {
-  return {
+) /*: ConfigT */ {
+  const config = {
     resolver: {
       resolverMainFields: ['react-native', 'browser', 'main'],
       platforms: ['android', 'ios'],
@@ -76,6 +76,11 @@ function getDefaultConfig(
     },
     watchFolders: [],
   };
+
+  return mergeConfig(
+    getBaseConfig.getDefaultValues(projectRoot),
+    config,
+  );
 }
 
 module.exports = {getDefaultConfig, mergeConfig};