fix(parser): error on property access after instantiation expression by Boshen · Pull Request #18887 · oxc-project/oxc

Boshen · 2026-02-03T12:32:29Z

Summary

Add TypeScript error TS1477: "An instantiation expression cannot be followed by a property access"
Check for TSInstantiationExpression before parsing property access (static . or computed [])

This fixes parsing of invalid syntax like:

a.c (static member access)
a?.c (optional static member access)
a?.[c] (optional computed member access)
a?.b<c>.d (chained)

Valid syntax like a?.(c) (optional call) and (a).c (parenthesized) are not affected.

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Pull request overview

This PR adds TypeScript error TS1477 to correctly report when an instantiation expression is followed by a property access, which is invalid TypeScript syntax. The parser now properly detects and reports errors for patterns like a.c, a?.c, and a?.[c], while still allowing valid constructs like optional calls a?.(c) and parenthesized property access (a).c.

Changes:

Added new diagnostic ts_instantiation_expression_cannot_be_followed_by_property_access with error code TS1477
Added validation checks in the parser before static and computed member access to detect instantiation expressions
Increased negative test pass rates (TypeScript: 1514/2557, Babel: 1656/1689)

Reviewed changes

Copilot reviewed 2 out of 4 changed files in this pull request and generated no comments.

File	Description
crates/oxc_parser/src/diagnostics.rs	Adds the new TS1477 error diagnostic function for instantiation expression property access errors
crates/oxc_parser/src/js/expression.rs	Adds checks before static and computed member expression parsing to detect and error on TSInstantiationExpression followed by property access
tasks/coverage/snapshots/parser_typescript.snap	Updates test coverage showing 3 additional negative tests now passing with proper error messages
tasks/coverage/snapshots/parser_babel.snap	Updates test coverage showing 1 additional negative test now passing with proper error message

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TypeScript error TS1477: An instantiation expression cannot be followed by a property access. This fixes parsing of invalid syntax like: - `a.c` (static member access) - `a?.c` (optional static member access) - `a?.[c]` (optional computed member access) - `a?.b<c>.d` (chained) Valid syntax like `a?.(c)` (optional call) and `(a).c` (parenthesized) are not affected. Co-Authored-By: Claude Opus 4.5 <[email protected]>

Boshen · 2026-02-03T12:47:00Z

Merge activity

Feb 3, 12:47 PM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
Feb 3, 12:52 PM UTC: Boshen added this pull request to the Graphite merge queue.

codspeed-hq · 2026-02-03T12:52:31Z

Merging this PR will not alter performance

✅ 46 untouched benchmarks
⏩ 3 skipped benchmarks¹

_{Comparing fix/parser-instantiation-expression-property-access (1701a15) with main (5eb4a94)}

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. ↩

### 💥 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]>

Copilot AI review requested due to automatic review settings February 3, 2026 12:32

github-actions bot added A-parser Area - Parser C-bug Category - Bug labels Feb 3, 2026

Copilot started reviewing on behalf of Boshen February 3, 2026 12:32 View session

Copilot AI reviewed Feb 3, 2026

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Boshen force-pushed the fix/parser-instantiation-expression-property-access branch from cdbbc88 to 50d0b82 Compare February 3, 2026 12:36

Boshen force-pushed the fix/parser-instantiation-expression-property-access branch from 50d0b82 to 1701a15 Compare February 3, 2026 12:46

Boshen added the 0-merge Merge with Graphite Merge Queue label Feb 3, 2026

Boshen merged commit 5758046 into main Feb 3, 2026
30 checks passed

Boshen deleted the fix/parser-instantiation-expression-property-access branch February 3, 2026 12:58

This was referenced Feb 9, 2026

release(crates): oxc v0.113.0 #19167

Closed

release(crates): oxc v0.113.0 #19210

Merged

Boshen mentioned this pull request Feb 10, 2026

release(crates): oxc v0.113.0 #19215

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fix(parser): error on property access after instantiation expression#18887

fix(parser): error on property access after instantiation expression#18887
Boshen merged 1 commit intomainfrom
fix/parser-instantiation-expression-property-access

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Boshen commented Feb 3, 2026

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codspeed-hq bot commented Feb 3, 2026

Merging this PR will not alter performance

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Boshen commented Feb 3, 2026 •

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