fix(parser): reject invalid accessor assertions by camc314 · Pull Request #24504 · oxc-project/oxc

camc314 · 2026-07-14T10:02:06Z

Summary

Align auto-accessor definite assignment assertions with TypeScript.
Report TS1263 when an accessor has both ! and an initializer.
Report TS1264 when an accessor has ! but no type annotation.
Report TS1255 for typed definite assertions in static, abstract, and ambient contexts.
Highlight only the ! token, matching TypeScript.

TypeScript behavior

Given:

class A {
    accessor missingType!;
    // ^: TS1264: Declarations with definite assignment assertions must also have type annotations.
    accessor initialized! = 1;
    // ^: TS1263: Declarations with initializers cannot also have definite assignment assertions.
    accessor typed!: number;
    // ^: valid
    static accessor staticTyped!: number;
    // ^: TS1255: A definite assignment assertion '!' is not permitted in this context.
}

TypeScript treats auto-accessors as property declarations and applies the following grammar check:

https://github.com/microsoft/TypeScript/blob/637d5746b70257028fb95aad32ddec6b26ab0a14/src/compiler/checker.ts#L53443-L53452

This establishes the diagnostic precedence:

An initializer produces TS1263.
Otherwise, a missing type annotation produces TS1264.
Otherwise, an invalid context produces TS1255.

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codspeed-hq · 2026-07-14T10:10:33Z

Merging this PR will not alter performance

✅ 62 untouched benchmarks
⏩ 9 skipped benchmarks¹

_{Comparing codex/fix-accessor-definite-assertions (d12fd99) with main (99978a8)}

9 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. ↩

camc314 · 2026-07-14T10:15:33Z

Merge activity

Jul 14, 10:15 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Jul 14, 10:15 AM UTC: camc314 added this pull request to the Graphite merge queue.
Jul 14, 10:22 AM UTC: Merged by the Graphite merge queue.

## Summary - Align auto-accessor definite assignment assertions with TypeScript. - Report TS1263 when an accessor has both `!` and an initializer. - Report TS1264 when an accessor has `!` but no type annotation. - Report TS1255 for typed definite assertions in static, abstract, and ambient contexts. - Highlight only the `!` token, matching TypeScript. fixes #24503. ## TypeScript behavior Given: ```ts class A { accessor missingType!; // ^: TS1264: Declarations with definite assignment assertions must also have type annotations. accessor initialized! = 1; // ^: TS1263: Declarations with initializers cannot also have definite assignment assertions. accessor typed!: number; // ^: valid static accessor staticTyped!: number; // ^: TS1255: A definite assignment assertion '!' is not permitted in this context. } ``` TypeScript treats auto-accessors as property declarations and applies the following grammar check: https://github.com/microsoft/TypeScript/blob/637d5746b70257028fb95aad32ddec6b26ab0a14/src/compiler/checker.ts#L53443-L53452 This establishes the diagnostic precedence: 1. An initializer produces TS1263. 2. Otherwise, a missing type annotation produces TS1264. 3. Otherwise, an invalid context produces TS1255.

oxc-guard · 2026-07-14T10:19:32Z

Monitor Oxc

Commit: c517aa08a8f3

suite	result
Test262	❌
Build	✅
Isolated Declarations	✅
Runtime Bundles	✅
Uglify Corpus	✅
(codegen)	✅
(dce)	✅
(whitespace)	✅
(transformer)	✅
(compressor)	✅
(mangler)	❌
(formatter_dcr)	✅
(formatter)	❌
Runtime (zod)	✅
Runtime (solid)	✅
Runtime (es-toolkit)	✅
Runtime (vue)	✅
Runtime (svelte)	✅

### 💥 BREAKING CHANGES - 54cc121 ast: [**BREAKING**] Split `MetaProperty` into `ImportMeta` and `NewTarget` (#24557) (camc314) ### 🚀 Features - 4c71560 parser: More friendly error for spread element in dynamic imports (#24705) (sapphi-red) - 7b045cd minfier: Drop last break from last switch case (#24673) (Armano) - 7d3c178 minifier: Remove unreachable recursive functions (#24125) (Dunqing) - 94f99b3 ast: Allow `NONE` to be passed to AST builder methods where `Option<ArenaVec>` is expected (#24629) (overlookmotel) - 77230c5 ast: Accept arrays for `ArenaVec` params of AST builder methods (#24621) (overlookmotel) - f08b152 allocator: Implement `FromIn` for array to `Vec` conversion (#24620) (overlookmotel) - 2338c13 track-memory-allocations: Track heap deallocs, alloc bytes, and peak growth (#24619) (Boshen) - 7aa4739 syntax,transformer: Move JSX entity decoder to `oxc_syntax` (#24617) (camc314) - 2b097c4 str: Export `Str` as `ArenaStr` (#24604) (overlookmotel) - 3acf4c1 minifier: Expand switch optimiation to remove empty cases (#24520) (Armano) - 129b759 parser: Improve diagnostics for unparenthesized LHS on exponential expr (#24569) (camc314) - 4d0c601 minifier: Fold arithmetic over undefined and null operands (#24485) (Dunqing) - 91541dd minifier: Drop empty switch statements (#24527) (Armano) - d05224d ast_visit: Generate VisitJs visitor that skips TypeScript type-space (#24499) (Boshen) - 3d22307 parser: Add `ParseOptions::enable_ident_hashes` (#24491) (Boshen) ### 🐛 Bug Fixes - 64c2241 minifier: Align class heritage removal with assumptions (#24533) (Dunqing) - 48b59f4 parser: Span ambient generator diagnostics (#24711) (camc314) - e750a82 ecmascript: Fix false negative for may_have_side_effects on dynamic property access (#24709) (sapphi-red) - f145d73 minifier: Guard reordered identifier reads (#24698) (Dunqing) - a2ef382 isolated-declarations: Reject `window.Symbol` as global symbol reference (#24689) (camc314) - b1bcf72 minifier: Invalidate facts for redeclared bindings (#24658) (Dunqing) - 921b834 minifier: Don't treat a conditionally-assigned var as write-once (#24650) (Dunqing) - 061af1f minifier: Avoid stale pure function summaries (#24636) (Dunqing) - 40c2f43 allocator: `Vec::from_array_in` do not allocate zero-length array (#24628) (overlookmotel) - 70994ae codegen: Preserve comments before expression operands (#24510) (Dunqing) - 7b4baff parser: Reject new import member access (#23459) (camc314) - 128b385 minifier: Clippy warning with no-debug-assertions (#24547) (camc314) - 8421feb parser: Use first `as` span for imported name (#24537) (leaysgur) - c517aa0 parser: Reject invalid accessor assertions (#24504) (camc314) ### ⚡ Performance - 884d9eb parser: Pre-size cover-grammar assignment target buffers (#24683) (Boshen) - d3f07a0 diagnostics: Box OxcDiagnosticInner to reduce binary size (#24665) (Boshen) - bcc9de0 parser: Defer diagnostic creation until parse exit (#24663) (Boshen) - c35d8ab allocator: Mark `ReplaceWith` panic path cold (#24515) (camc314) - ba65790 semantic, allocator: Branchless `clone_in` for semantic IDs (#24564) (overlookmotel) - 747feec parser: Build AST nodes with the AST builder instead of cloning (#24540) (Boshen) - ba35a0d react_compiler: Use IndexVec for dense id-keyed maps (#24549) (Boshen) - b685062 react_compiler: Keep small hot-path collections inline (#24514) (Marius Schulz) - a149e95 transformer: Outline rare expression exits (#24512) (camc314) - 7808a6e react_compiler: Make aliasing effects cheap to intern and clone (#24506) (Marius Schulz) - 3a36f2a react_compiler: Store AbstractValue reasons as a u16 bitmask (#24480) (Boshen) - 1c96753 react_compiler: Use FxHashMap for the lookup-only aliasing node map (#24490) (Boshen) Co-authored-by: Cameron <[email protected]>

camc314 self-assigned this Jul 14, 2026

github-actions Bot added the A-parser Area - Parser label Jul 14, 2026

camc314 marked this pull request as ready for review July 14, 2026 10:05

Copilot AI review requested due to automatic review settings July 14, 2026 10:05

Copilot AI reviewed Jul 14, 2026

camc314 added the 0-merge Merge with Graphite Merge Queue label Jul 14, 2026

graphite-app Bot force-pushed the codex/fix-accessor-definite-assertions branch from d12fd99 to c517aa0 Compare July 14, 2026 10:16

camc314 added the run-monitor-oxc Add to a PR to dispatch oxc-project/monitor-oxc CI against it label Jul 14, 2026

oxc-guard Bot removed the run-monitor-oxc Add to a PR to dispatch oxc-project/monitor-oxc CI against it label Jul 14, 2026

graphite-app Bot merged commit c517aa0 into main Jul 14, 2026
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graphite-app Bot removed the 0-merge Merge with Graphite Merge Queue label Jul 14, 2026

graphite-app Bot deleted the codex/fix-accessor-definite-assertions branch July 14, 2026 10:22

oxc-guard Bot mentioned this pull request Jul 20, 2026

release(crates): oxc v0.141.0 #24714

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fix(parser): reject invalid accessor assertions#24504

fix(parser): reject invalid accessor assertions#24504
graphite-app[bot] merged 1 commit into
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codex/fix-accessor-definite-assertions

camc314 commented Jul 14, 2026 •

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camc314 commented Jul 14, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

TypeScript behavior

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codspeed-hq Bot commented Jul 14, 2026

Merging this PR will not alter performance

Footnotes

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Monitor Oxc

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camc314 commented Jul 14, 2026 •

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oxc-guard Bot commented Jul 14, 2026 •

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