fix(transformer): correct symbol flags for lowered enums by Dunqing · Pull Request #24269 · oxc-project/oxc

Dunqing · 2026-07-07T15:11:28Z

Closes #24226 — the first commit is @camc314's fix from there.

Lowered enums kept their RegularEnum/ConstEnum symbol flags, so the flags no longer matched the emitted JavaScript:

Top-level enums become var → FunctionScopedVariable.
Exported and nested enums become let → BlockScopedVariable.
Merged enums lowered to an assignment only lose their enum bits.

This removes over 1,000 stale symbol-flag mismatches from the snapshots.

Unlike #24226 there is no pending state: enum member inlining now identifies enums through EnumData (#24268) instead of SymbolFlags, so the flags can be updated right when the enum is lowered.

codspeed-hq · 2026-07-07T15:15:37Z

Merging this PR will not alter performance

✅ 52 untouched benchmarks
⏩ 19 skipped benchmarks¹

_{Comparing transformer-enum-flags-immediate (84eeb55) with semantic-record-const-enums (f5a5104)²}

19 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩
No successful run was found on semantic-record-const-enums (1b829d8) during the generation of this report, so 8295b04 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

Dunqing · 2026-07-07T15:26:46Z

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graphite-app · 2026-07-07T16:47:55Z

Merge activity

Jul 7, 4:47 PM UTC: camc314 added this pull request to the Graphite merge queue.
Jul 7, 4:54 PM UTC: Merged by the Graphite merge queue.

@camc314

Closes #24226 — the first commit is @camc314's fix from there. Lowered enums kept their `RegularEnum`/`ConstEnum` symbol flags, so the flags no longer matched the emitted JavaScript: - Top-level enums become `var` → `FunctionScopedVariable`. - Exported and nested enums become `let` → `BlockScopedVariable`. - Merged enums lowered to an assignment only lose their enum bits. This removes over 1,000 stale symbol-flag mismatches from the snapshots. Unlike #24226 there is no pending state: enum member inlining now identifies enums through `EnumData` (#24268) instead of `SymbolFlags`, so the flags can be updated right when the enum is lowered.

Record which enums are `const` in `EnumData` and expose it as `Scoping::is_const_enum`. Same pattern as the existing `no_side_effects` set. The transformer needs to tell const enums apart even after lowering, but #24269 makes lowering rewrite the enum's `SymbolFlags`, so the flags can no longer answer that. `EnumData` stays valid for the whole transform. The small `allocs_semantic.snap` bump is the new hash set. Needed by #24269.

### 🚀 Features - 616bfa2 minifier: Remove unreachable code after terminating statements (#24441) (Dunqing) - ddab89a data_structures: Add `likely` and `unlikely` functions (#24368) (overlookmotel) - a3a39f9 react_compiler: Implement enableEmitHookGuards codegen (#24329) (Boshen) - b79eef7 minifier: Apply De Morgan's law to negated comparison chains in jump guards and loop tests (#24279) (Dunqing) - 34ff7b4 minifier: Drop write-only property assignments to unused local bindings by default (#24112) (Dunqing) - 1b829d8 semantic: Record const enums in EnumData (#24268) (Dunqing) - ba0944c semantic: Add `Scoping::set_symbol_span` (#24221) (camc314) ### 🐛 Bug Fixes - 7d33363 minifier: Preserve guaranteed throws from class heritage evaluation (#24349) (Dunqing) - 058a62f semantic: Track ambient contexts in `SemanticBuilder` (#24327) (camc314) - 721eb0b transformer/decorator: Scope accessor class binding (#24330) (camc314) - 1ebdce3 semantic: Allow reserved keywords in ambient declaration types (#24325) (camc314) - 460176a track-memory-allocations: Exclude arena chunks from Sys allocs (#24292) (Dunqing) - af4922b transformer: Clear lowered namespace redeclarations (#24300) (camc314) - ffd2765 semantic: Mark declared computed `MethodDefinition`s as type references (#24296) (camc314) - f17514b isolated-declarations: Emit const readonly fields as types (#24288) (camc314) - 40f769d minifier: Make `__proto__` write tracking execution-order independent (#24280) (Dunqing) - 6371fed transformer: Remove stale enum member bindings (#24272) (camc314) - f05dfab transformer: Correct symbol flags for lowered namespaces (#24271) (Dunqing) - 84eeb55 transformer: Correct symbol flags for lowered enums (#24269) (Dunqing) - c3057da transformer: Preserve generated class binding spans (#24220) (camc314) - 8260096 transformer: Correct span for lowered namespace symbol (#24222) (camc314) - 42d00d3 semantic: Mark declared class heritage as type references (#24237) (camc314) - 588d997 semantic: Mark TS `PropertyDefinition`s computed fields as type references (#24233) (camc314) - 9b95632 semantic: Mark computed method keys in `TSMethodSignature`s as type references (#24232) (camc314) ### ⚡ Performance - 5b26643 transformer_plugins: Dispatch global defines by trailing name (#23666) (Boshen) - dce0f29 react_compiler: Replace all compiled functions in a single AST walk (#24403) (Boshen) - f85f0d8 ast: Delegate inherited enum variants in clone_in and estree derives (#23555) (Boshen) - 3ff0234 allocator: Remove `unwrap` from `ReplaceWith` (#24365) (overlookmotel) - ab22e80 transformer: Fix Rust 1.97 performance regression (#24354) (camc314) - b47585c parser: Use `ReplaceWith` instead of `TakeIn` (#24018) (overlookmotel) - b227a06 minifier: Use `ReplaceWith` instead of `TakeIn` (#24017) (overlookmotel) Co-authored-by: Boshen <[email protected]>

Dunqing mentioned this pull request Jul 7, 2026

feat(semantic): record const enums in EnumData #24268

Merged

github-actions Bot added the A-transformer Area - Transformer / Transpiler label Jul 7, 2026

Dunqing force-pushed the transformer-enum-flags-immediate branch from 4d1f444 to f8d3de1 Compare July 7, 2026 15:26

Dunqing force-pushed the semantic-record-const-enums branch from 28fd65d to 3d3b24e Compare July 7, 2026 15:26

Dunqing changed the title ~~refactor(transformer): set lowered enum symbol flags in place~~ fix(transformer): correct symbol flags for lowered enums Jul 7, 2026

Dunqing mentioned this pull request Jul 7, 2026

fix(transformer): correct symbol flags for lowered namespaces #24271

Merged

Dunqing force-pushed the semantic-record-const-enums branch from 3d3b24e to f5a5104 Compare July 7, 2026 16:17

Dunqing force-pushed the transformer-enum-flags-immediate branch from f8d3de1 to 89a3dda Compare July 7, 2026 16:17

Dunqing marked this pull request as ready for review July 7, 2026 16:26

Dunqing assigned camc314 Jul 7, 2026

camc314 approved these changes Jul 7, 2026

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graphite-app Bot force-pushed the semantic-record-const-enums branch from f5a5104 to 1b829d8 Compare July 7, 2026 16:48

graphite-app Bot requested a review from overlookmotel as a code owner July 7, 2026 16:48

graphite-app Bot force-pushed the transformer-enum-flags-immediate branch from 89a3dda to 84eeb55 Compare July 7, 2026 16:48

Base automatically changed from semantic-record-const-enums to main July 7, 2026 16:53

graphite-app Bot merged commit 84eeb55 into main Jul 7, 2026
39 checks passed

graphite-app Bot deleted the transformer-enum-flags-immediate branch July 7, 2026 16:54

oxc-guard Bot mentioned this pull request Jul 13, 2026

release(crates): oxc v0.140.0 #24453

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fix(transformer): correct symbol flags for lowered enums#24269

fix(transformer): correct symbol flags for lowered enums#24269
graphite-app[bot] merged 1 commit into
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