[compiler] Add meta internal option for useMemoCache import (#31654)

Adds `target: 'donotuse_meta_internal'`, which inserts useMemoCache
imports directly from `react`. Note that this is only valid for Meta
bundles, as others do not [re-export the `c`
function](https://github.com/facebook/react/blob/5b0ef217ef32333a8e56f39be04327c89efa346f/packages/react/index.fb.js#L68-L70).

```js
// target=donotuse_meta_internal
import {c as _c} from 'react';

// target=19
import {c as _c} from 'react/compiler-runtime';

// target=17,18
import {c as _c} from 'react-compiler-runtime';
```

Meta is a bit special in that react runtime and compiler are guaranteed
to be up-to-date and compatible. It also has its own bundling and module
resolution logic, which makes importing from `react/compiler-runtime`
tricky.

I'm also fine with implementing the alternative which adds an internal
stub for `react-compiler-runtime` and
[bundles](https://github.com/facebook/react/blob/5b0ef217ef32333a8e56f39be04327c89efa346f/scripts/rollup/bundles.js#L120)
the runtime for internal builds.

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

@@ -121,7 +121,22 @@ export type PluginOptions = {
   target: CompilerReactTarget;
 };
 
-const CompilerReactTargetSchema = z.enum(['17', '18', '19']);
+const CompilerReactTargetSchema = z.union([
+  z.literal('17'),
+  z.literal('18'),
+  z.literal('19'),
+  /**
+   * Used exclusively for Meta apps which are guaranteed to have compatible
+   * react runtime and compiler versions. Note that only the FB-internal bundles
+   * re-export useMemoCache (see
+   * https://github.com/facebook/react/blob/5b0ef217ef32333a8e56f39be04327c89efa346f/packages/react/index.fb.js#L68-L70),
+   * so this option is invalid / creates runtime errors for open-source users.
+   */
+  z.object({
+    kind: z.literal('donotuse_meta_internal'),
+    runtimeModule: z.string().default('react'),
+  }),
+]);
 export type CompilerReactTarget = z.infer<typeof CompilerReactTargetSchema>;
 
 const CompilationModeSchema = z.enum([

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

@@ -1123,30 +1123,23 @@ 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, {
+function getReactCompilerRuntimeModule(opts: PluginOptions): string {
+  if (opts.target === '19') {
+    return 'react/compiler-runtime'; // from react namespace
+  } else if (opts.target === '17' || opts.target === '18') {
+    return 'react-compiler-runtime'; // npm package
+  } else {
+    CompilerError.invariant(
+      opts.target != null &&
+        opts.target.kind === 'donotuse_meta_internal' &&
+        typeof opts.target.runtimeModule === 'string',
+      {
         reason: 'Expected target to already be validated',
         description: null,
         loc: null,
         suggestions: null,
-      });
+      },
+    );
+    return opts.target.runtimeModule;
   }
-  return moduleName;
 }

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

@@ -0,0 +1,43 @@
+
+## Input
+
+```javascript
+// @target="donotuse_meta_internal"
+
+function Component() {
+  return <div>Hello world</div>;
+}
+
+export const FIXTURE_ENTRYPOINT = {
+  fn: Component,
+  params: [],
+  isComponent: true,
+};
+
+```
+
+## Code
+
+```javascript
+import { c as _c } from "react"; // @target="donotuse_meta_internal"
+
+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,
+};
+
+```
+      

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

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

compiler/packages/snap/src/SproutTodoFilter.ts

@@ -504,6 +504,7 @@ const skipFilter = new Set([
   // Depends on external functions
   'idx-method-no-outlining-wildcard',
   'idx-method-no-outlining',
+  'target-flag-meta-internal',
 
   // needs to be executed as a module
   'meta-property',

compiler/packages/snap/src/compiler.ts

@@ -18,6 +18,7 @@ import type {
   LoggerEvent,
   PanicThresholdOptions,
   PluginOptions,
+  CompilerReactTarget,
 } from 'babel-plugin-react-compiler/src/Entrypoint';
 import type {Effect, ValueKind} from 'babel-plugin-react-compiler/src/HIR';
 import type {
@@ -55,7 +56,7 @@ function makePluginOptions(
   let validatePreserveExistingMemoizationGuarantees = false;
   let customMacros: null | Array<Macro> = null;
   let validateBlocklistedImports = null;
-  let target = '19' as const;
+  let target: CompilerReactTarget = '19';
 
   if (firstLine.indexOf('@compilationMode(annotation)') !== -1) {
     assert(
@@ -81,8 +82,15 @@ function makePluginOptions(
 
   const targetMatch = /@target="([^"]+)"/.exec(firstLine);
   if (targetMatch) {
-    // @ts-ignore
-    target = targetMatch[1];
+    if (targetMatch[1] === 'donotuse_meta_internal') {
+      target = {
+        kind: targetMatch[1],
+        runtimeModule: 'react',
+      };
+    } else {
+      // @ts-ignore
+      target = targetMatch[1];
+    }
   }
 
   if (firstLine.includes('@panicThreshold(none)')) {