[compiler] Remove fallback compilation pipeline dead code

[everettbu]

Mirror of facebook/react#35827
Original author: josephsavona

---

Remove dead code left behind after the removal of retryCompileFunction, enableFire, and inferEffectDependencies:

• Delete ValidateNoUntransformedReferences.ts (always a no-op)
• Remove CompileProgramMetadata type and retryErrors from ProgramContext
• Remove 'client-no-memo' output mode
• Change compileProgram return type from CompileProgramMetadata | null to void

[greptile-apps]

Greptile Summary

This PR removes dead code from the React Compiler that was left behind after the removal of retryCompileFunction, enableFire, and inferEffectDependencies. The changes are well-scoped and consistent:

• Deletes ValidateNoUntransformedReferences.ts, which was always a no-op since moduleLoadChecks was initialized as an empty map and never populated
• Removes CompileProgramMetadata type and retryErrors from ProgramContext, since they were only used by the now-removed retry pipeline
• Removes the client-no-memo output mode from the schema and all switch cases in Environment.ts
• Simplifies compileProgram return type from CompileProgramMetadata | null to void

No remaining references to any of the removed constructs were found across the codebase. One minor nit: the @returns JSDoc on compileProgram is now stale.

Confidence Score: 5/5

• This PR is safe to merge — it only removes dead code with no behavioral changes.
• All changes are strictly deletions of dead code (unused types, a no-op validation function, an unused output mode). No remaining references to any removed constructs exist in the codebase. The exhaustive switch statements in Environment.ts correctly handle the reduced set of output modes. The only finding is a stale JSDoc comment, which is cosmetic.
• No files require special attention

Important Files Changed

Filename	Overview
compiler/packages/babel-plugin-react-compiler/src/Babel/BabelPlugin.ts	Removed import and call to validateNoUntransformedReferences, and dropped the return value from compileProgram. Clean removal with no issues.
compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Imports.ts	Removed unused BabelFn import and retryErrors field from ProgramContext. No remaining references to either.
compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Options.ts	Removed client-no-memo from CompilerOutputModeSchema enum. No remaining references in the codebase.
compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts	Removed CompileProgramMetadata type and changed compileProgram return type to void. Stale @returns JSDoc remains.
compiler/packages/babel-plugin-react-compiler/src/Entrypoint/ValidateNoUntransformedReferences.ts	File deleted entirely. The function was always a no-op (moduleLoadChecks was always empty). No remaining imports or references.
compiler/packages/babel-plugin-react-compiler/src/HIR/Environment.ts	Removed client-no-memo cases from enableDropManualMemoization, enableMemoization, and enableValidations switch statements. The assertExhaustive default cases will correctly catch any invalid output modes.

_{Last reviewed commit: e52b267}

[greptile-apps]

_{6 files reviewed, 1 comment}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Additional Comments (1)

compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts
Stale @returns JSDoc
The @returns tag still says "Compilation results or null if compilation was skipped" but the function now returns void. This should be updated or removed to match the new signature.

 * Main entrypoint for React Compiler.
 *
 * @param program The Babel program node to compile
 * @param pass Compiler configuration and context
 */

Prompt To Fix With AI

This is a comment left during a code review.
Path: compiler/packages/babel-plugin-react-compiler/src/Entrypoint/Program.ts
Line: 353-359

Comment:
**Stale `@returns` JSDoc**
The `@returns` tag still says "Compilation results or null if compilation was skipped" but the function now returns `void`. This should be updated or removed to match the new signature.

```suggestion
 * Main entrypoint for React Compiler.
 *
 * @param program The Babel program node to compile
 * @param pass Compiler configuration and context
 */
```

How can I resolve this? If you propose a fix, please make it concise.

[everettbu]

Upstream PR was closed or merged. Code is synced via branch mirror.