fix: React Native CodeGen integration for 0.64-stable (#31027)

* fix: codegen blank files

* chore: add codegen script back

* chore: restore react_native_pods, prepare_command is still fine

* feat: rework codegen sh setup

* chore: revert unwanted change

* chore: can't overwrite CODEGEN_PATH right now, remove this

* chore: remove extra user-defined envs

Author: grabbou

.gitignore

@@ -100,7 +100,6 @@ package-lock.json
 !/packages/rn-tester/Pods/__offline_mirrors__
 
 # react-native-codegen
-/React/FBReactNativeSpec/FBReactNativeSpec
 /packages/react-native-codegen/lib
 /ReactCommon/react/renderer/components/rncore/
 

React/FBReactNativeSpec/FBReactNativeSpec/FBReactNativeSpec-generated.mm

@@ -105,6 +105,7 @@
     "promise": "^8.0.3",
     "prop-types": "^15.7.2",
     "react-devtools-core": "^4.6.0",
+    "react-native-codegen": "^0.0.7",
     "react-refresh": "^0.4.0",
     "regenerator-runtime": "^0.13.2",
     "scheduler": "^0.20.1",
@@ -155,4 +156,4 @@
       }
     }
   }
-}
+}

React/FBReactNativeSpec/FBReactNativeSpec/FBReactNativeSpec.h

@@ -57,33 +57,19 @@ main() {
   TEMP_OUTPUT_DIR="$TEMP_DIR/out"
   SCHEMA_FILE="$TEMP_DIR/schema.json"
 
-  CODEGEN_REPO_PATH="$RN_DIR/packages/react-native-codegen"
-  CODEGEN_NPM_PATH="$RN_DIR/../react-native-codegen"
-
-if [ -z "$NODE_BINARY" ]; then
+  if [ -z "$NODE_BINARY" ]; then
     echo "Error: Could not find node. Make sure it is in bash PATH or set the NODE_BINARY environment variable." 1>&2
     exit 1
   fi
 
-  if [ -d "$CODEGEN_REPO_PATH" ]; then
-    CODEGEN_PATH=$(cd "$CODEGEN_REPO_PATH" && pwd)
-  elif [ -d "$CODEGEN_NPM_PATH" ]; then
-    CODEGEN_PATH=$(cd "$CODEGEN_NPM_PATH" && pwd)
-  else
-    echo "Error: Could not determine react-native-codegen location. Try running 'yarn install' or 'npm install' in your project root." 1>&2
-    exit 1
-  fi
+  CODEGEN_PATH=$("$NODE_BINARY" -e "console.log(require('path').dirname(require.resolve('react-native-codegen/package.json')))")
 
+  # Special case for running CodeGen from source: build it
   if [ ! -d "$CODEGEN_PATH/lib" ]; then
     describe "Building react-native-codegen package"
     bash "$CODEGEN_PATH/scripts/oss/build.sh"
   fi
 
-  if [ -z "$NODE_BINARY" ]; then
-    echo "Error: Could not find node. Make sure it is in bash PATH or set the NODE_BINARY environment variable." 1>&2
-    exit 1
-  fi
-
   describe "Generating schema from flow types"
   "$NODE_BINARY" "$CODEGEN_PATH/lib/cli/combine/combine-js-to-schema-cli.js" "$SCHEMA_FILE" "$SRCS_DIR"
 

package.json

@@ -21,7 +21,6 @@
     "eslint": "7.14.0",
     "jest": "^26.6.3",
     "metro-react-native-babel-preset": "^0.64.0",
-    "react-native-codegen": "^0.0.7",
     "react-test-renderer": "17.0.1"
   },
   "jest": {