fix(semantic): report duplicate private identifier for static and instance elements by camc314 · Pull Request #17591 · oxc-project/oxc

camc314 · 2026-01-02T14:22:51Z

Previously, TypeScript files with both a static private identifier and an instance private identifier with the same name (e.g., static #m and #m()) were not being reported as errors.

Closes #17518

camc314 · 2026-01-02T14:23:11Z

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Pull request overview

This PR fixes a bug where TypeScript files with both static and instance private identifiers with the same name (e.g., #foo and static #foo) were not being reported as errors, which violates the ECMAScript specification and TypeScript's type checking rules.

Key changes:

Added a new diagnostic static_and_instance_private_identifier for TS error 2804
Updated duplicate class element detection logic to correctly identify when private identifiers with the same name have different static status
Fixed the logic to ensure private identifiers follow JavaScript rules even in TypeScript (static and instance elements cannot share the same private name)

Reviewed changes

Copilot reviewed 2 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/oxc_semantic/src/diagnostics.rs	Added new diagnostic function `static_and_instance_private_identifier` for TS(2804) error with appropriate error message and labels
crates/oxc_semantic/src/checker/javascript.rs	Updated duplicate detection logic to correctly handle private identifiers with different static status, ensuring they are reported as errors in both JavaScript and TypeScript
tasks/coverage/snapshots/parser_typescript.snap	Updated to show newly detected errors for static/instance private identifier conflicts; Negative Passed count increased from 1496 to 1497
tasks/coverage/snapshots/parser_test262.snap	Updated error messages from generic "Identifier has already been declared" to specific TS(2804) error for static/instance private name conflicts
tasks/coverage/snapshots/parser_babel.snap	Updated error messages from generic "Identifier has already been declared" to specific TS(2804) error for static/instance private name conflicts

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codspeed-hq · 2026-01-02T14:28:43Z

Merging this PR will not alter performance

Summary

✅ 42 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing c/01-02-fix_semantic_report_duplicate_private_identifier_for_static_and_instance_elements (d8129a7) with main (3a452b8)²}

3 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 main (f3ec67c) during the generation of this report, so 3a452b8 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

Dunqing

The check logic looks good; it just needs to improve the error message.

tasks/coverage/snapshots/parser_babel.snap

crates/oxc_semantic/src/checker/javascript.rs

Dunqing

Nice work!

Dunqing · 2026-01-08T02:52:27Z

Merge activity

Jan 8, 2:52 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Jan 8, 2:52 AM UTC: Dunqing added this pull request to the Graphite merge queue.
Jan 8, 3:09 AM UTC: Merged by the Graphite merge queue.

…tance elements (#17591) Previously, TypeScript files with both a static private identifier and an instance private identifier with the same name (e.g., `static #m` and `#m()`) were not being reported as errors. Closes #17518

### 🚀 Features - 10426af codegen: Print soft space between inline block comments on the same line (#17799) (camc314) - 2261e6e semantic: Improve error message to add `#` for private identifiers (#17779) (Dunqing) ### 🐛 Bug Fixes - 7422b7e parser/trivia: Correctly mark whether a block comment is on a newline (#17754) (camc314) - c32e8d5 codegen: Wrap `TSAsExpression` in parens when used with in/instanceof operators (#17752) (camc314) - 5755b2d semantic: Report duplicate private identifier for static and instance elements (#17591) (camc314) - 0600df3 isolated_declarations: Only print jsdoc comments (#17748) (camc314) - ef7e014 parser: Preserve `@__NO_SIDE_EFFECTS__` annotation with parenthesized expressions (#17711) (camc314) - 59a6228 parser: Detect TS1363 error for type-only imports with mixed default and named/namespace bindings (#17712) (Copilot) ### ⚡ Performance - 864f1fa semantic: Mark duplicate class element error reporting as cold (#17746) (camc314) - 3a452b8 semantic: Use smallvec for storing reference IDs (#17731) (camchenry) - d5979dc minifier: Do not allocate when checking to convert `const` to `let` (#17730) (camchenry) - 3f4429c parser: Do not re-allocate TS interface heritage (#17692) (camchenry) ### 📚 Documentation - 120a27c minifier: Add prettier-ignore for js-in-md part (#17687) (leaysgur) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

github-actions bot added A-semantic Area - Semantic C-bug Category - Bug labels Jan 2, 2026

camc314 marked this pull request as ready for review January 2, 2026 14:24

camc314 requested a review from Dunqing as a code owner January 2, 2026 14:24

Copilot AI review requested due to automatic review settings January 2, 2026 14:24

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camc314 force-pushed the c/01-02-fix_semantic_report_duplicate_private_identifier_for_static_and_instance_elements branch from cb74908 to d8129a7 Compare January 7, 2026 10:18

camc314 mentioned this pull request Jan 7, 2026

perf(semantic): mark duplicate class element error reporting as cold #17746

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camc314 assigned Dunqing Jan 7, 2026

camc314 mentioned this pull request Jan 7, 2026

fix(isolated_declarations): only print jsdoc comments #17748

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Dunqing approved these changes Jan 8, 2026

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Dunqing added the 0-merge Merge with Graphite Merge Queue label Jan 8, 2026

graphite-app bot force-pushed the c/01-02-fix_semantic_report_duplicate_private_identifier_for_static_and_instance_elements branch from d8129a7 to 5755b2d Compare January 8, 2026 03:02

graphite-app bot merged commit 5755b2d into main Jan 8, 2026
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graphite-app bot deleted the c/01-02-fix_semantic_report_duplicate_private_identifier_for_static_and_instance_elements branch January 8, 2026 03:09

graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Jan 8, 2026

Boshen mentioned this pull request Jan 12, 2026

release(crates): oxc v0.108.0 #17920

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fix(semantic): report duplicate private identifier for static and instance elements#17591

fix(semantic): report duplicate private identifier for static and instance elements#17591
graphite-app[bot] merged 1 commit intomainfrom
c/01-02-fix_semantic_report_duplicate_private_identifier_for_static_and_instance_elements

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Merging this PR will not alter performance

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