fix(isolated-declarations): preserve const context in literal type inference by camc314 · Pull Request #19178 · oxc-project/oxc

camc314 · 2026-02-09T12:14:25Z

TypeScript:

Us before: (we incorrectly add readonly on a when readonly should only be on the top level object

Us after:

camc314 · 2026-02-09T12:14:41Z

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

0-merge - adds this PR to the back of the merge queue
hotfix - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

_{An organization admin has enabled the Graphite Merge Queue in this repository.} _{Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.}

This stack of pull requests is managed by Graphite. Learn more about stacking.

codspeed-hq · 2026-02-09T12:20:00Z

CodSpeed Performance Report

Merging this PR will not alter performance

_{Comparing c/02-09-fix_isolated-declarations_preserve_const_context_in_literal_type_inference (2067621) with main (e19bc45)¹}

Summary

✅ 47 untouched benchmarks
⏩ 3 skipped benchmarks²

No successful run was found on c/02-09-fix_isolated-declarations_preserve_readonly_literal_initializers (02df6a1) during the generation of this report, so main (e19bc45) was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩
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. ↩

camc314 · 2026-02-09T12:27:02Z

Monitor Oxc

suite	result
Isolated Declarations	✅
(codegen)	✅
(mangler)	❌
(transformer)	❌
(compressor)	❌
(formatter)	❌
(whitespace)	❌
(formatter_dcr)	✅
(dce)	❌

Copilot

Pull request overview

This PR fixes isolated declarations’ literal type inference to correctly preserve const context (e.g., through as const and parentheses), improving the emitted .d.ts types to better match TypeScript behavior—especially for object/array literals under const assertions.

Changes:

Introduces explicit “const context” propagation for expression-to-TS-type transformation (including parentheses, tuples/arrays, and object literals).
Updates handling of as const / type assertions so const assertions trigger const-literal inference while non-const assertions yield the asserted type.
Expands the readonly class property initializer fixture + snapshot to cover direct/parenthesized objects and nested const-asserted objects.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
crates/oxc_isolated_declarations/src/types.rs	Adds const-context-aware expression→type transformation and propagates const context through arrays/objects/parentheses and const assertions.
crates/oxc_isolated_declarations/src/inferrer.rs	Aligns inference for `as const` and `TSTypeAssertion` to use the new const-context transformation.
crates/oxc_isolated_declarations/tests/fixtures/readonly-class-property-initializer.ts	Adds object/nested-object readonly initializer cases (including `as const`) for regression coverage.
crates/oxc_isolated_declarations/tests/snapshots/readonly-class-property-initializer.snap	Updates expected `.d.ts` output to reflect correct const-context inference for the new fixture cases.

Dunqing · 2026-02-10T02:02:53Z

Good job!

Dunqing · 2026-02-10T02:05:53Z

Merge activity

Feb 10, 2:05 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Feb 10, 2:05 AM UTC: Dunqing added this pull request to the Graphite merge queue.
Feb 10, 2:13 AM UTC: Merged by the Graphite merge queue.

…ference (#19178) TypeScript: ![Screenshot 2026-02-09 at 12.23.39.png](https://app.graphite.com/user-attachments/assets/0f4738f8-9ab8-42be-a737-d5eaf9674997.png) Us before: (we incorrectly add `readonly` on `a` when `readonly `should only be on the top level object ![Screenshot 2026-02-09 at 12.23.55.png](https://app.graphite.com/user-attachments/assets/7d56a8dc-30a1-40b6-8c7d-b9a595fd8889.png) Us after: ![Screenshot 2026-02-09 at 12.25.03.png](https://app.graphite.com/user-attachments/assets/a5a95deb-0e5a-4c62-9170-16c451a88507.png)

### 💥 BREAKING CHANGES - 2bf7293 mangler: [**BREAKING**] Enable `top_level` by default for modules and commonjs (#18278) (sapphi-red) - 48b0542 span: [**BREAKING**] SourceType::ts should set module to unambigious (#18873) (Boshen) ### 🚀 Features - 500d071 minifier: Local traverse ctx and generated minifier traverse (#19106) (Boshen) - 142a1be parser: Detect binary files with TS1490 error (#19047) (Boshen) - e316857 allocator/bitset: Add `Ones` iterator to `BitSet` (#19027) (sapphi-red) - 742ad3f minifier: Default `invalid_import_side_effects` to `false` (#18916) (sapphi-red) - 0eff6be parser: Error JSX-like type assertions and generics in `.mts`/`.cts` (#18910) (Boshen) - 18320c6 span: Store file extension in `SourceType` (#18893) (Boshen) ### 🐛 Bug Fixes - a7514e4 isolated-declarations: Preserve const context in literal type inference (#19178) (camc314) - 312e756 isolated-declarations: Preserve readonly literal initializers (#19177) (camc314) - d0ca8d0 isolated-declarations: Skip parenthesis when inferring type (#19176) (camc314) - 110c300 oxc_ecmascript: `+[false]` and `+[true]` should evaluate to `NaN` (#19174) (copilot-swe-agent) - f32ea19 semantic: Report redeclaration error for import bindings conflicting with value declarations (#19068) (Boshen) - 3aeba7a semantic: Report redeclaration error for `function a() {} var a` in module mode (#19041) (Boshen) - 35e32c6 coverage: Match Babel's options.json inheritance for test fixtures (#19002) (Boshen) - 463d60d semantic: Skip TS2391 for standalone computed-name class methods (#19025) (Boshen) - 56c086b parser: Add modifier ordering validation (TS1029) (#19024) (Boshen) - 6067a49 linter/jsdoc: False positive in `check-tag-names` for `@` in email addresses and npm scopes (#19021) (Boshen) - b13bb70 semantic/jsdoc: Inline tags like `{@link}` break jsdoc parsing (#19019) (Boshen) - e3609e3 regular_expression: Preserve UnicodeEscape CharacterKind in string literals (#18998) (Boshen) - 57917ee parser: Parse decorators on rest parameters (#18938) (Boshen) - 487601b napi: Disable mimalloc on Windows to fix worker_threads crash (#18923) (Boshen) - 1f6b193 parser: Validate TypeScript import type options (#18889) (Boshen) - 1663184 parser: Allow conditional types in function type parameters (#18886) (Boshen) - 5758046 parser: Error on property access after instantiation expression (#18887) (Boshen) - 5eb4a94 parser: Handle `<<` as two `<` tokens in type argument contexts (#18885) (Boshen) ### ⚡ Performance - ed8c054 oxc_str: Add precomputed hash to Ident for fast HashMap lookups (#19143) (Boshen) - d4a0867 transformer_plugins: Switch ReplaceGlobalDefines from Traverse to VisitMut (#19146) (Boshen) - 9eb16b3 syntax: Pack ASCII identifier tables into single bitflag table (#19088) (Boshen) - e7595d1 mangler: Use BitSet for exported symbols set (#19023) (sapphi-red) - 2537924 semantic: Optimize scope resolution with fast paths and inlining (#19029) (Boshen) - 69a8d85 mangler: Use BitSet for keep_names symbols set (#19028) (sapphi-red) - f78c525 parser: Try hybrid parsing for jsx children and closing element/fragments (#18789) (camchenry) Co-authored-by: camc314 <[email protected]>

### 💥 BREAKING CHANGES - 2bf7293 mangler: [**BREAKING**] Enable `top_level` by default for modules and commonjs (oxc-project#18278) (sapphi-red) - 48b0542 span: [**BREAKING**] SourceType::ts should set module to unambigious (oxc-project#18873) (Boshen) ### 🚀 Features - 500d071 minifier: Local traverse ctx and generated minifier traverse (oxc-project#19106) (Boshen) - 142a1be parser: Detect binary files with TS1490 error (oxc-project#19047) (Boshen) - e316857 allocator/bitset: Add `Ones` iterator to `BitSet` (oxc-project#19027) (sapphi-red) - 742ad3f minifier: Default `invalid_import_side_effects` to `false` (oxc-project#18916) (sapphi-red) - 0eff6be parser: Error JSX-like type assertions and generics in `.mts`/`.cts` (oxc-project#18910) (Boshen) - 18320c6 span: Store file extension in `SourceType` (oxc-project#18893) (Boshen) ### 🐛 Bug Fixes - a7514e4 isolated-declarations: Preserve const context in literal type inference (oxc-project#19178) (camc314) - 312e756 isolated-declarations: Preserve readonly literal initializers (oxc-project#19177) (camc314) - d0ca8d0 isolated-declarations: Skip parenthesis when inferring type (oxc-project#19176) (camc314) - 110c300 oxc_ecmascript: `+[false]` and `+[true]` should evaluate to `NaN` (oxc-project#19174) (copilot-swe-agent) - f32ea19 semantic: Report redeclaration error for import bindings conflicting with value declarations (oxc-project#19068) (Boshen) - 3aeba7a semantic: Report redeclaration error for `function a() {} var a` in module mode (oxc-project#19041) (Boshen) - 35e32c6 coverage: Match Babel's options.json inheritance for test fixtures (oxc-project#19002) (Boshen) - 463d60d semantic: Skip TS2391 for standalone computed-name class methods (oxc-project#19025) (Boshen) - 56c086b parser: Add modifier ordering validation (TS1029) (oxc-project#19024) (Boshen) - 6067a49 linter/jsdoc: False positive in `check-tag-names` for `@` in email addresses and npm scopes (oxc-project#19021) (Boshen) - b13bb70 semantic/jsdoc: Inline tags like `{@link}` break jsdoc parsing (oxc-project#19019) (Boshen) - e3609e3 regular_expression: Preserve UnicodeEscape CharacterKind in string literals (oxc-project#18998) (Boshen) - 57917ee parser: Parse decorators on rest parameters (oxc-project#18938) (Boshen) - 487601b napi: Disable mimalloc on Windows to fix worker_threads crash (oxc-project#18923) (Boshen) - 1f6b193 parser: Validate TypeScript import type options (oxc-project#18889) (Boshen) - 1663184 parser: Allow conditional types in function type parameters (oxc-project#18886) (Boshen) - 5758046 parser: Error on property access after instantiation expression (oxc-project#18887) (Boshen) - 5eb4a94 parser: Handle `<<` as two `<` tokens in type argument contexts (oxc-project#18885) (Boshen) ### ⚡ Performance - ed8c054 oxc_str: Add precomputed hash to Ident for fast HashMap lookups (oxc-project#19143) (Boshen) - d4a0867 transformer_plugins: Switch ReplaceGlobalDefines from Traverse to VisitMut (oxc-project#19146) (Boshen) - 9eb16b3 syntax: Pack ASCII identifier tables into single bitflag table (oxc-project#19088) (Boshen) - e7595d1 mangler: Use BitSet for exported symbols set (oxc-project#19023) (sapphi-red) - 2537924 semantic: Optimize scope resolution with fast paths and inlining (oxc-project#19029) (Boshen) - 69a8d85 mangler: Use BitSet for keep_names symbols set (oxc-project#19028) (sapphi-red) - f78c525 parser: Try hybrid parsing for jsx children and closing element/fragments (oxc-project#18789) (camchenry) Co-authored-by: camc314 <[email protected]>

…ference (oxc-project#19178) TypeScript: ![Screenshot 2026-02-09 at 12.23.39.png](https://app.graphite.com/user-attachments/assets/0f4738f8-9ab8-42be-a737-d5eaf9674997.png) Us before: (we incorrectly add `readonly` on `a` when `readonly `should only be on the top level object ![Screenshot 2026-02-09 at 12.23.55.png](https://app.graphite.com/user-attachments/assets/7d56a8dc-30a1-40b6-8c7d-b9a595fd8889.png) Us after: ![Screenshot 2026-02-09 at 12.25.03.png](https://app.graphite.com/user-attachments/assets/a5a95deb-0e5a-4c62-9170-16c451a88507.png)

### 💥 BREAKING CHANGES - 2bf7293 mangler: [**BREAKING**] Enable `top_level` by default for modules and commonjs (oxc-project#18278) (sapphi-red) - 48b0542 span: [**BREAKING**] SourceType::ts should set module to unambigious (oxc-project#18873) (Boshen) ### 🚀 Features - 500d071 minifier: Local traverse ctx and generated minifier traverse (oxc-project#19106) (Boshen) - 142a1be parser: Detect binary files with TS1490 error (oxc-project#19047) (Boshen) - e316857 allocator/bitset: Add `Ones` iterator to `BitSet` (oxc-project#19027) (sapphi-red) - 742ad3f minifier: Default `invalid_import_side_effects` to `false` (oxc-project#18916) (sapphi-red) - 0eff6be parser: Error JSX-like type assertions and generics in `.mts`/`.cts` (oxc-project#18910) (Boshen) - 18320c6 span: Store file extension in `SourceType` (oxc-project#18893) (Boshen) ### 🐛 Bug Fixes - a7514e4 isolated-declarations: Preserve const context in literal type inference (oxc-project#19178) (camc314) - 312e756 isolated-declarations: Preserve readonly literal initializers (oxc-project#19177) (camc314) - d0ca8d0 isolated-declarations: Skip parenthesis when inferring type (oxc-project#19176) (camc314) - 110c300 oxc_ecmascript: `+[false]` and `+[true]` should evaluate to `NaN` (oxc-project#19174) (copilot-swe-agent) - f32ea19 semantic: Report redeclaration error for import bindings conflicting with value declarations (oxc-project#19068) (Boshen) - 3aeba7a semantic: Report redeclaration error for `function a() {} var a` in module mode (oxc-project#19041) (Boshen) - 35e32c6 coverage: Match Babel's options.json inheritance for test fixtures (oxc-project#19002) (Boshen) - 463d60d semantic: Skip TS2391 for standalone computed-name class methods (oxc-project#19025) (Boshen) - 56c086b parser: Add modifier ordering validation (TS1029) (oxc-project#19024) (Boshen) - 6067a49 linter/jsdoc: False positive in `check-tag-names` for `@` in email addresses and npm scopes (oxc-project#19021) (Boshen) - b13bb70 semantic/jsdoc: Inline tags like `{@link}` break jsdoc parsing (oxc-project#19019) (Boshen) - e3609e3 regular_expression: Preserve UnicodeEscape CharacterKind in string literals (oxc-project#18998) (Boshen) - 57917ee parser: Parse decorators on rest parameters (oxc-project#18938) (Boshen) - 487601b napi: Disable mimalloc on Windows to fix worker_threads crash (oxc-project#18923) (Boshen) - 1f6b193 parser: Validate TypeScript import type options (oxc-project#18889) (Boshen) - 1663184 parser: Allow conditional types in function type parameters (oxc-project#18886) (Boshen) - 5758046 parser: Error on property access after instantiation expression (oxc-project#18887) (Boshen) - 5eb4a94 parser: Handle `<<` as two `<` tokens in type argument contexts (oxc-project#18885) (Boshen) ### ⚡ Performance - ed8c054 oxc_str: Add precomputed hash to Ident for fast HashMap lookups (oxc-project#19143) (Boshen) - d4a0867 transformer_plugins: Switch ReplaceGlobalDefines from Traverse to VisitMut (oxc-project#19146) (Boshen) - 9eb16b3 syntax: Pack ASCII identifier tables into single bitflag table (oxc-project#19088) (Boshen) - e7595d1 mangler: Use BitSet for exported symbols set (oxc-project#19023) (sapphi-red) - 2537924 semantic: Optimize scope resolution with fast paths and inlining (oxc-project#19029) (Boshen) - 69a8d85 mangler: Use BitSet for keep_names symbols set (oxc-project#19028) (sapphi-red) - f78c525 parser: Try hybrid parsing for jsx children and closing element/fragments (oxc-project#18789) (camchenry) Co-authored-by: camc314 <[email protected]>

camc314 mentioned this pull request Feb 9, 2026

fix(isolated-declarations): skip parenthesis when inferring type #19176

Merged

camc314 mentioned this pull request Feb 9, 2026

fix(isolated-declarations): preserve readonly literal initializers #19177

Merged

github-actions bot added A-isolated-declarations Isolated Declarations C-bug Category - Bug labels Feb 9, 2026

camc314 marked this pull request as ready for review February 9, 2026 12:25

camc314 requested a review from Dunqing as a code owner February 9, 2026 12:25

Copilot AI review requested due to automatic review settings February 9, 2026 12:25

camc314 assigned Dunqing Feb 9, 2026

Copilot started reviewing on behalf of camc314 February 9, 2026 12:26 View session

Copilot AI reviewed Feb 9, 2026

View reviewed changes

Dunqing approved these changes Feb 10, 2026

View reviewed changes

Dunqing added the 0-merge Merge with Graphite Merge Queue label Feb 10, 2026

graphite-app bot force-pushed the c/02-09-fix_isolated-declarations_preserve_readonly_literal_initializers branch from 02df6a1 to 312e756 Compare February 10, 2026 02:06

graphite-app bot force-pushed the c/02-09-fix_isolated-declarations_preserve_const_context_in_literal_type_inference branch from 2067621 to a7514e4 Compare February 10, 2026 02:07

graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Feb 10, 2026

Base automatically changed from c/02-09-fix_isolated-declarations_preserve_readonly_literal_initializers to main February 10, 2026 02:13

graphite-app bot merged commit a7514e4 into main Feb 10, 2026
22 checks passed

graphite-app bot deleted the c/02-09-fix_isolated-declarations_preserve_const_context_in_literal_type_inference branch February 10, 2026 02:13

Boshen mentioned this pull request Feb 10, 2026

release(crates): oxc v0.113.0 #19210

Merged

Boshen mentioned this pull request Feb 10, 2026

release(crates): oxc v0.113.0 #19215

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

fix(isolated-declarations): preserve const context in literal type inference#19178

fix(isolated-declarations): preserve const context in literal type inference#19178
graphite-app[bot] merged 1 commit intomainfrom
c/02-09-fix_isolated-declarations_preserve_const_context_in_literal_type_inference

camc314 commented Feb 9, 2026 •

edited

Loading

Uh oh!

camc314 commented Feb 9, 2026 •

edited

Loading

Uh oh!

codspeed-hq bot commented Feb 9, 2026

Uh oh!

camc314 commented Feb 9, 2026 •

edited by Boshen

Loading

Uh oh!

Copilot AI left a comment

Uh oh!

Dunqing commented Feb 10, 2026

Uh oh!

Dunqing commented Feb 10, 2026 •

edited by graphite-app bot

Loading

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Comments

Uh oh!

Conversation

camc314 commented Feb 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

camc314 commented Feb 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

How to use the Graphite Merge Queue

Uh oh!

codspeed-hq bot commented Feb 9, 2026

CodSpeed Performance Report

Merging this PR will not alter performance

Summary

Footnotes

Uh oh!

camc314 commented Feb 9, 2026 • edited by Boshen Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Monitor Oxc

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Dunqing commented Feb 10, 2026

Uh oh!

Dunqing commented Feb 10, 2026 • edited by graphite-app bot Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Merge activity

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

2 participants

Comments

camc314 commented Feb 9, 2026 •

edited

Loading

camc314 commented Feb 9, 2026 •

edited

Loading

camc314 commented Feb 9, 2026 •

edited by Boshen

Loading

Dunqing commented Feb 10, 2026 •

edited by graphite-app bot

Loading