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fix(parser): handle << as two < tokens in type argument contexts#18885

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fix/parser-type-arguments-bit-shift-left
Feb 3, 2026
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fix(parser): handle << as two < tokens in type argument contexts#18885
graphite-app[bot] merged 1 commit intomainfrom
fix/parser-type-arguments-bit-shift-left

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@Boshen Boshen commented Feb 3, 2026

Summary

  • Fix parsing of type arguments that start with < (generic function types), which creates what looks like a bit-shift-left operator (<<)
  • Call re_lex_ts_l_angle() in try_parse_type_arguments() to re-lex << back to a single <, matching the behavior already used in parse_type_arguments_of_type_reference()

This fixes parsing of:

  • class extends f<<T>(v: T) => void>
  • interface I extends f<<T>(v: T) => void>
  • <Component<<T>(v: T) => void> />

🤖 Generated with Claude Code

Copilot AI review requested due to automatic review settings February 3, 2026 11:51
@github-actions github-actions bot added A-parser Area - Parser C-bug Category - Bug labels Feb 3, 2026
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Pull request overview

Fixes TypeScript parsing for type argument lists that begin with < (e.g., generic function types), where the lexer can initially produce a << (shift-left) token, by re-lexing it back into < tokens in the relevant parsing path.

Changes:

  • Update try_parse_type_arguments() to call re_lex_ts_l_angle() so << can be interpreted as two < tokens in type-argument contexts.
  • Update coverage snapshots to reflect improved parsing/coverage outcomes for affected Babel/TS fixtures.

Reviewed changes

Copilot reviewed 1 out of 4 changed files in this pull request and generated no comments.

File Description
crates/oxc_parser/src/ts/types.rs Uses re_lex_ts_l_angle() when attempting to parse type arguments, matching existing behavior in other TS type-argument parsers.
tasks/coverage/snapshots/parser_babel.snap Snapshot updates showing fewer panics / improved parse pass counts for Babel parser fixtures.
tasks/coverage/snapshots/semantic_babel.snap Snapshot updates reflecting improved semantic coverage results after parsing fix.
tasks/coverage/snapshots/estree_typescript.snap Snapshot updates reflecting improved positive pass counts for TypeScript ESTree coverage.

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codspeed-hq bot commented Feb 3, 2026 •
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Merging this PR will not alter performance

✅ 46 untouched benchmarks
⏩ 3 skipped benchmarks1

Comparing fix/parser-type-arguments-bit-shift-left (90ef814) with main (be89007)2

Open in CodSpeed

Footnotes

  1. 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. ↩

  2. No successful run was found on main (c0d26c7) during the generation of this report, so be89007 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

@Boshen Boshen force-pushed the fix/parser-type-arguments-bit-shift-left branch 2 times, most recently from 3264491 to 90ef814 Compare February 3, 2026 12:14
@Boshen Boshen added the 0-merge Merge with Graphite Merge Queue label Feb 3, 2026
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Boshen commented Feb 3, 2026 •
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@Boshen
fix(parser): handle << as two < tokens in type argument contexts (#…
5eb4a94 
…18885)

## Summary

- Fix parsing of type arguments that start with `<` (generic function types), which creates what looks like a bit-shift-left operator (`<<`)
- Call `re_lex_ts_l_angle()` in `try_parse_type_arguments()` to re-lex `<<` back to a single `<`, matching the behavior already used in `parse_type_arguments_of_type_reference()`

This fixes parsing of:
- `class extends f<<T>(v: T) => void>`
- `interface I extends f<<T>(v: T) => void>`
- `<Component<<T>(v: T) => void> />`

🤖 Generated with [Claude Code](https://claude.com/claude-code)
@graphite-app graphite-app bot force-pushed the fix/parser-type-arguments-bit-shift-left branch from 90ef814 to 5eb4a94 Compare February 3, 2026 12:21
@graphite-app graphite-app bot merged commit 5eb4a94 into main Feb 3, 2026
22 checks passed
@graphite-app graphite-app bot deleted the fix/parser-type-arguments-bit-shift-left branch February 3, 2026 12:27
@graphite-app graphite-app bot removed the 0-merge Merge with Graphite Merge Queue label Feb 3, 2026
This was referenced Feb 9, 2026
Closed
Merged
camc314 added a commit that referenced this pull request Feb 10, 2026
@Boshen @camc314
release(crates): oxc v0.113.0 (#19210)
acdb40e 
### 💥 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]>
@Boshen Boshen mentioned this pull request Feb 10, 2026
Closed
owjs3901 pushed a commit to owjs3901/oxc that referenced this pull request Feb 11, 2026
@Boshen @camc314 @owjs3901
release(crates): oxc v0.113.0 (oxc-project#19210)
68e76fb 
### 💥 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]>
OskarLebuda pushed a commit to OskarLebuda/oxc that referenced this pull request Feb 17, 2026
@Boshen @camc314 @OskarLebuda
release(crates): oxc v0.113.0 (oxc-project#19210)
ea5f1e2 
### 💥 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]>
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