fix(semantic): allow reserved keywords in typescript ambient contexts #15495

sapphi-red · 2025-11-08T17:19:55Z

Reserved keywords are allowed as an identifier in ambient contexts.

declare const private: number

This is allowed.

sapphi-red · 2025-11-08T17:20:10Z

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codspeed-hq · 2025-11-08T17:29:04Z

CodSpeed Performance Report

Merging #15495 will not alter performance

_{Comparing 11-09-fix_semantic_allow_reserved_keywords_in_typescript_ambient_contexts (bace84d) with main (4fe3aac)}

Summary

✅ 42 untouched
⏩ 3 skipped¹

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. ↩

sapphi-red · 2025-11-08T18:04:29Z

This probably should be solved in a different way...

crates/oxc_semantic/src/checker/javascript.rs

overlookmotel · 2025-11-09T23:14:58Z

This probably should be solved in a different way...

The "look up ancestors" part only applies to BindingIdentifiers, right? If so, I think you can look up the VariableDeclaration with Scoping::symbol_declaration (or maybe it's not built yet?)

crates/oxc_semantic/src/checker/javascript.rs

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Pull Request Overview

This PR allows reserved keywords (like private, await) to be used as identifiers in TypeScript ambient contexts by relaxing keyword restrictions for declare variable declarations. The change fixes parsing of TypeScript declaration files where reserved keywords may appear as variable names.

Adds logic to check if a binding identifier is part of a declare variable declaration
Updates test coverage snapshots to reflect one additional passing test
Fixes the topLevelAwait.3.ts test case which previously had errors

Reviewed Changes

Copilot reviewed 1 out of 9 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
`crates/oxc_semantic/src/checker/javascript.rs`	Adds new helper function and extends ambient context checks to include `declare` variable declarations
`tasks/coverage/misc/pass/declare-let-private.ts`	New test case demonstrating `private` keyword usage in declare statement
`tasks/coverage/snapshots/transformer_misc.snap`	Updated test counts (49→50)
`tasks/coverage/snapshots/parser_misc.snap`	Updated test counts (49→50)
`tasks/coverage/snapshots/formatter_misc.snap`	Updated test counts (49→50)
`tasks/coverage/snapshots/codegen_misc.snap`	Updated test counts (49→50)
`tasks/coverage/snapshots/semantic_misc.snap`	Updated test counts (49→50) and shows semantic error for new test
`tasks/coverage/snapshots/semantic_typescript.snap`	Removes error for `topLevelAwait.3.ts` and updates pass count
`tasks/coverage/snapshots/parser_typescript.snap`	Removes parsing error for `topLevelAwait.3.ts` and updates pass count

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Dunqing · 2025-11-12T02:53:12Z

I think we can simplify it more by checking whether the binding is flagged with the Ambient symbol flag.

See Oxc Playground

tasks/coverage/snapshots/semantic_misc.snap

tasks/coverage/snapshots/semantic_typescript.snap

Dunqing · 2025-11-18T08:10:33Z

I tweaked a little bit to improve the identifier in a BindingIdentifier situation, which already has a symbol ID, so that we can avoid getting a symbol ID again from AstKind::BindingIdentifier. I hope you don't mind that I modified the PR directly without conversation because I think the PR has been left here for a long time, so I don't want to delay it anyway!

Dunqing · 2025-11-18T08:11:04Z

Merge activity

Nov 18, 8:11 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Nov 18, 8:11 AM UTC: Dunqing added this pull request to the Graphite merge queue.
Nov 18, 8:16 AM UTC: Merged by the Graphite merge queue.

…#15495) Reserved keywords are allowed as an identifier in ambient contexts. ```ts declare const private: number ``` This is allowed.

@license

### 💥 BREAKING CHANGES - cbb27fd ast: [**BREAKING**] Add `TSGlobalDeclaration` type (#15712) (overlookmotel) ### 🚀 Features - 0c1f82b linter/plugins: Add `tokens` property to `Program` (#16020) (overlookmotel) - 6cff132 span: Add `Span::merge_within` method (#15869) (sapphi-red) - 102365d allocator/vec: Add `Vec::into_bump_slice` method (#15770) (Dunqing) ### 🐛 Bug Fixes - e2ca770 codegen: Add support for printing type arguments in new expressions (#15963) (Ives van Hoorne) - 2bd3cb6 apps, editors, napi: Fix `oxlint-disable` comments (#16014) (overlookmotel) - 622cb5e parser: Preserve legal comments with @preserve/@license when preceded by other annotations (#15929) (copilot-swe-agent) - 7c46a9e transformer/tagged-template-transform: Handle `\n` escape sequences (#15830) (Dunqing) - f386efc minifier: Avoid generating invalid spans (#15778) (sapphi-red) - d4ff004 parser: Forbid invalid modifiers on `module` and `global` (#15723) (overlookmotel) - 2191ae9 semantic: Allow reserved keywords in typescript ambient contexts (#15495) (sapphi-red) - 7d1ebad isolated-declarations: Incorrect nested namespace output in isolated declarations (#15800) (copilot-swe-agent) ### ⚡ Performance - b4b0ed8 transformer/typescript: Reverse order of checks (#15722) (overlookmotel) ### 📚 Documentation - c81a331 data_structures: Doc comments on fields of `Stack` (#15793) (overlookmotel) - cfae31d allocator: Use `allocator` as var name in examples (#15781) (overlookmotel) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

github-actions bot added A-semantic Area - Semantic C-bug Category - Bug labels Nov 8, 2025

This was referenced Nov 8, 2025

test(tasks/coverage/typescript): Update 2541-2999 error codes handling #15492

Merged

test(tasks/coverage/typescript): Update 1xxx error codes handling #15493

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This was referenced Nov 8, 2025

test(tasks/coverage/typescript): parse as module if export {} is present #15494

Closed

test(tasks/coverage/typescript): collect more error files #15496

Merged

sapphi-red changed the base branch from 11-09-test_coverage_typescript_parse_as_module_if_export_is_present to graphite-base/15495 November 8, 2025 17:31

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sapphi-red marked this pull request as ready for review November 10, 2025 15:35

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fix(semantic): allow reserved keywords in typescript ambient contexts (…

2191ae9

…#15495) Reserved keywords are allowed as an identifier in ambient contexts. ```ts declare const private: number ``` This is allowed.

graphite-app bot force-pushed the 11-09-fix_semantic_allow_reserved_keywords_in_typescript_ambient_contexts branch from bace84d to 2191ae9 Compare November 18, 2025 08:11

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Boshen mentioned this pull request Nov 24, 2025

release(crates): oxc v0.99.0 #16037

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fix(semantic): allow reserved keywords in typescript ambient contexts #15495

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