[rcr] Update default runtimeModule to react-compiler-runtime (#31144)

Updates the compiler to always import from `react-compiler-runtime` by
default. The runtime then decides whether to use the official or
userspace implementation of useMemoCache.

Author: poteto

compiler/apps/playground/babel.config.js

@@ -13,7 +13,7 @@ module.exports = function (api) {
       [
         'babel-plugin-react-compiler',
         {
-          runtimeModule: 'react-compiler-runtime',
+          target: '18',
         },
       ],
     ],

compiler/packages/babel-plugin-react-compiler/package.json

@@ -8,6 +8,7 @@
     "dist"
   ],
   "scripts": {
+    "postinstall": "./scripts/link-react-compiler-runtime.sh",
     "build": "rimraf dist && rollup --config --bundleConfigAsCjs",
     "test": "yarn snap:ci",
     "jest": "yarn build && ts-node node_modules/.bin/jest",

compiler/packages/babel-plugin-react-compiler/scripts/link-react-compiler-runtime.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+set -eo pipefail
+
+yarn --silent workspace react-compiler-runtime link
+yarn --silent workspace babel-plugin-react-compiler link react-compiler-runtime

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts

@@ -298,7 +298,6 @@ export function compileProgram(
     return;
   }
   const useMemoCacheIdentifier = program.scope.generateUidIdentifier('c');
-  const moduleName = pass.opts.runtimeModule ?? 'react/compiler-runtime';
 
   /*
    * Record lint errors and critical errors as depending on Forget's config,
@@ -605,7 +604,7 @@ export function compileProgram(
     if (needsMemoCacheFunctionImport) {
       updateMemoCacheFunctionImport(
         program,
-        moduleName,
+        getReactCompilerRuntimeModule(pass.opts),
         useMemoCacheIdentifier.name,
       );
     }
@@ -638,8 +637,12 @@ function shouldSkipCompilation(
     }
   }
 
-  const moduleName = pass.opts.runtimeModule ?? 'react/compiler-runtime';
-  if (hasMemoCacheFunctionImport(program, moduleName)) {
+  if (
+    hasMemoCacheFunctionImport(
+      program,
+      getReactCompilerRuntimeModule(pass.opts),
+    )
+  ) {
     return true;
   }
   return false;
@@ -1126,3 +1129,31 @@ function checkFunctionReferencedBeforeDeclarationAtTopLevel(
 
   return errors.details.length > 0 ? errors : null;
 }
+
+type ReactCompilerRuntimeModule =
+  | 'react/compiler-runtime' // from react namespace
+  | 'react-compiler-runtime'; // npm package
+function getReactCompilerRuntimeModule(
+  opts: PluginOptions,
+): ReactCompilerRuntimeModule {
+  let moduleName: ReactCompilerRuntimeModule | null = null;
+  switch (opts.target) {
+    case '17':
+    case '18': {
+      moduleName = 'react-compiler-runtime';
+      break;
+    }
+    case '19': {
+      moduleName = 'react/compiler-runtime';
+      break;
+    }
+    default:
+      CompilerError.invariant(moduleName != null, {
+        reason: 'Expected target to already be validated',
+        description: null,
+        loc: null,
+        suggestions: null,
+      });
+  }
+  return moduleName;
+}

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/target-flag.expect.md

@@ -0,0 +1,45 @@
+
+## Input
+
+```javascript
+// @target="18"
+
+function Component() {
+  return <div>Hello world</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+  isComponent: true,
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react-compiler-runtime"; // @target="18"
+
+function Component() {
+  const $ = _c(1);
+  let t0;
+  if ($[0] === Symbol.for("react.memo_cache_sentinel")) {
+    t0 = <div>Hello world</div>;
+    $[0] = t0;
+  } else {
+    t0 = $[0];
+  }
+  return t0;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+  isComponent: true,
+};
+
+```
+      
+### Eval output
+(kind: ok) <div>Hello world</div>

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/target-flag.js

@@ -0,0 +1,11 @@
+// @target="18"
+
+function Component() {
+  return <div>Hello world</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+  isComponent: true,
+};

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/userspace-use-memo-cache.expect.md

@@ -2,18 +2,22 @@
 ## Input
 
 ```javascript
-// @runtimeModule="react-forget-runtime"
+// @runtimeModule="react-compiler-runtime"
+import {useState} from 'react';
+
 function Component(props) {
   const [x, setX] = useState(1);
   let y;
   if (props.cond) {
     y = x * 2;
   }
   return (
-    <Button
+    <button
       onClick={() => {
         setX(10 * y);
-      }}></Button>
+      }}>
+      Click me
+    </button>
   );
 }
 
@@ -28,7 +32,9 @@ export const FIXTURE_ENTRYPOINT = {
 ## Code
 
 ```javascript
-import { c as _c } from "react-forget-runtime"; // @runtimeModule="react-forget-runtime"
+import { c as _c } from "react/compiler-runtime"; // @runtimeModule="react-compiler-runtime"
+import { useState } from "react";
+
 function Component(props) {
   const $ = _c(5);
   const [x, setX] = useState(1);
@@ -48,11 +54,13 @@ function Component(props) {
   let t1;
   if ($[3] !== t0) {
     t1 = (
-      <Button
+      <button
         onClick={() => {
           setX(10 * y);
         }}
-      />
+      >
+        Click me
+      </button>
     );
     $[3] = t0;
     $[4] = t1;

compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/userspace-use-memo-cache.js

@@ -1,15 +1,19 @@
-// @runtimeModule="react-forget-runtime"
+// @runtimeModule="react-compiler-runtime"
+import {useState} from 'react';
+
 function Component(props) {
   const [x, setX] = useState(1);
   let y;
   if (props.cond) {
     y = x * 2;
   }
   return (
-    <Button
+    <button
       onClick={() => {
         setX(10 * y);
-      }}></Button>
+      }}>
+      Click me
+    </button>
   );
 }