fix(parser): detect TS1363 error for type-only imports with mixed default and named/namespace bindings by Copilot · Pull Request #17712 · oxc-project/oxc

Copilot · 2026-01-06T10:51:19Z

The parser was not detecting import type foo, {} from 'bar'; and import type A, * as NS from 'mod'; as errors. TypeScript's TS1363 requires that type-only imports specify either a default import or named/namespace bindings, but not both—even when the named bindings list is empty.

Changes

Parser: Added TS1363 check in parse_import_declaration_specifiers when encountering LCurly or Star token after a type-only default import
Module record: Removed redundant TS1363 validation that couldn't detect empty {} cases
Error span: Now points at the default specifier instead of the entire import statement

Examples

The following patterns now correctly error with TS1363:

// Empty named bindings
import type foo, {} from 'bar';

// Named bindings with specifiers
import type foo, { bar } from 'baz';

// Namespace import
import type A, * as NS from 'mod';

The parser-level check is comprehensive and catches all cases including empty braces and namespace imports, which weren't being detected previously.

Testing

✅ All parser unit tests pass (54/54)
✅ Added test cases for both empty named bindings and namespace imports
✅ Updated conformance test snapshots
✅ Memory allocation snapshots updated with just allocs

Original prompt

This section details on the original issue you should resolve

<issue_title>parser: missing error for mixed type + non type imports</issue_title>
<issue_description>Missed
import type foo, {  } from 'bar';
https://www.typescriptlang.org/play/?#code/JYWwDg9gTgLgBDAnmApnAZhCAaOBvOOAXwyghDgHIAjAQykoG4g

Originally posted by @fisker in #17609 (comment)

cc @Sysix

we might have to move this check directly into the parser where we know if there's the {}</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes parser: missing error for mixed type + non type imports #17684

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

- Add error detection in parse_import_declaration_specifiers for TS1363 - Remove redundant check from module_record.rs (now handled in parser) - Add test case for empty named imports: import-type-mixed-empty.ts - Improve error span to point at default specifier instead of whole statement Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

crates/oxc_parser/src/module_record.rs

Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

codspeed-hq · 2026-01-06T11:27:14Z

CodSpeed Performance Report

Merging #17712 will not alter performance

_{Comparing copilot/fix-missing-error-imports (34884e9) with main (2bd2d5a)}

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. ↩

camc314 · 2026-01-06T11:34:05Z

@copilot fix CI

you need to run just allocs as well as all tests

Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

Copilot · 2026-01-06T11:42:03Z

@copilot fix CI

you need to run just allocs as well as all tests

Fixed in 07903b1. Updated allocation snapshots with cargo allocs. All tests pass.

Sysix · 2026-01-06T11:44:03Z

@camc314 thanks for fixing this :) Because the code targets Curly, I am not sure if namespaces will be reported too:
#17609 (comment)

camc314 · 2026-01-06T11:45:27Z

@copilot import type A, * as NS from 'mod' should also report an error

camc314 · 2026-01-06T11:45:37Z

@copilot import type A, * as NS from 'mod' should also report an error

fix this

camc314 · 2026-01-06T11:45:53Z

@camc314 thanks for fixing this :) Because the code targets Curly, I am not sure if namespaces will be reported too: #17609 (comment)

copilot is doing my dirty work 🙂

Also report error for `import type A, * as NS from 'mod'` pattern Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

Copilot · 2026-01-06T11:54:10Z

@copilot import type A, * as NS from 'mod' should also report an error

fix this

Fixed in 84d4ee9. Now reports TS1363 error for import type A, * as NS from 'mod' pattern as well.

crates/oxc_parser/src/js/module.rs

Signed-off-by: Cameron <cameron.clark@hey.com>

camc314

I didn't bother getting the spans to be correct - maybe point to the whole import statement, as it's a decent amount of work, for not much gain

Copilot

Pull request overview

This PR fixes a parser bug where TypeScript's TS1363 error was not being detected for type-only imports that mix default imports with empty named bindings or namespace imports. The fix moves error detection from the module record builder (which couldn't detect empty {} cases) to the parser itself, enabling comprehensive validation including empty braces.

Adds TS1363 validation directly in the parser when encountering { or * after a type-only default import
Removes redundant module-record-level validation that couldn't catch empty braces
Improves error span to point at the default specifier instead of the entire import statement

Reviewed changes

Copilot reviewed 6 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
crates/oxc_parser/src/js/module.rs	Added TS1363 error detection in `parse_import_declaration_specifiers` when type-only default import is followed by `{` or `*` tokens
crates/oxc_parser/src/module_record.rs	Removed previous TS1363 validation logic that operated on import entries (couldn't detect empty braces)
tasks/coverage/misc/fail/import-type-mixed-empty.ts	New test case for `import type foo, {} from 'bar';`
tasks/coverage/misc/fail/import-type-mixed-star.ts	New test case for `import type A, * as NS from 'mod';`
tasks/coverage/snapshots/parser_misc.snap	Updated snapshot showing correct TS1363 errors with improved spans
tasks/coverage/snapshots/parser_typescript.snap	Updated snapshot showing improved error span (pointing at default specifier)
tasks/coverage/snapshots/parser_babel.snap	Updated snapshot showing improved error span (pointing at default specifier)
crates/oxc_linter/src/rules/unicorn/require_module_specifiers.rs	Commented out test cases that are now invalid TypeScript syntax due to TS1363
crates/oxc_linter/src/rules/import/no_empty_named_blocks.rs	Commented out test cases that are now invalid TypeScript syntax due to TS1363
crates/oxc_linter/src/snapshots/unicorn_require_module_specifiers.snap	Removed snapshot entries for now-invalid TypeScript patterns
tasks/track_memory_allocations/allocs_parser.snap	Updated memory allocation counts (reduced by 8 system allocations for cal.com.tsx)

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crates/oxc_linter/src/rules/unicorn/require_module_specifiers.rs

crates/oxc_linter/src/rules/import/no_empty_named_blocks.rs

### 🚀 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>

# Oxlint ### 🚀 Features - 9699a1b linter/prefer-global-this: Add suggestion (#17873) (Mikhail Baev) - 51c2815 linter/no-invalid-regexp: Add labels and help text to flag diagnostics (#17865) (camchenry) - 344d77d linter/no-ex-assign: Improve diagnostic with more detail (#17864) (camchenry) - 7d280e0 linter: Add fixer for `unicorn/no-useless-error-capture-stack-trace` rule (#17839) (Mikhail Baev) - af1d0e3 linter/prefer-optional-chain: Add rule (#17831) (camc314) - e3c4108 vscode: Add more supported languages to extension (#17812) (Alexander Lichter) - 4a46678 vscode: Activate extension on more languages (#17717) (Sysix) - b1298fc vscode: Sync formatter with supported files (#17615) (Alexander Lichter) - c7f0848 linte/rno-required-prop-with-default: Implement suggestion (#17747) (Minsu Lee) - 0e8127e linter/vue: Implement no-lifecycle-after-await (#17701) (yefan) - 3567304 linter/vitest: Implement `consistent-each-for` (#17601) (Said Atrahouch) - 883e156 linter: Add fixer for `unicorn/no-useless-collection-argument` rule (#17594) (Mikhail Baev) - 4eb335c linter/vitest: Implemented prefer-called-once (#17674) (Said Atrahouch) - 2bd2d5a linter/vitest: Implement hoisted-apis-on-top (#17658) (Said Atrahouch) - cfb2bcc linter/vue: Implement no-arrow-functions-in-watch (#17672) (yefan) - a68208a linter/eslint-plugin-vitest: Implements `prefer-describe-function-title` (#17677) (Said Atrahouch) - efa029f linter/vitest: Implement no-unneeded-async-expect-function (#17494) (Minsu Lee) ### 🐛 Bug Fixes - 49cf66e lsp: Fix workspace worker selection for nested and similar-named workspaces (#17853) (Copilot) - 84f4f3c linter: Add doc url for tsgolint diagnostics (#17879) (Sysix) - 76c903f linter/consistent-indexed-object-style: Skip fixing default exported interface (#17874) (Copilot) - 7e87d16 linter/tabindex-no-positive: Improve diagnostic phrasing (#17849) (connorshea) - 28f9fba vscode: Fix nested search for binaries (#17832) (Sysix) - 8ca2cd2 linter: Move jsx-a11y/no-static-element-interactions rule to nursery. (#17818) (connorshea) - dc9fdd6 linter/consistent-indexed-object-style: Re-port test cases and fix some bugs (#17802) (camc314) - 7bbd880 linter: Update prefer-destructuring rule metadata (#17642) (Hamir Mahal) - 3c45185 linter/consistent-indexed-object-style: False positive with circular reference (#17789) (heygsc) - bd186b4 vscode: Search for `oxlint` and `oxfmt` in every workspace directory (#17760) (Sysix) - 3e0dff7 linter/no-hooks: Add punctuation to diagnostic message (#17751) (camc314) - 6ae21f9 linter/prefer-called-once: Avoid panic on trailing comma (#17735) (Said Atrahouch) - 32c3901 oxlint: Do not panic on invalid `no-unused-vars` configuration (#17719) (Sysix) - 59a6228 parser: Detect TS1363 error for type-only imports with mixed default and named/namespace bindings (#17712) (Copilot) ### ⚡ Performance - f87a1e2 linter: Check for giving reserved plugin name before calling `load_plugin` on napi side (#17841) (Sysix) ### 📚 Documentation - a2b3a24 linter/no-caller: Improve docs and diagnostic for rule. (#17890) (connorshea) - aa48247 linter/no-unsafe-finally: Improve rule docs. (#17891) (connorshea) - 1b0bdee linter: Tweak docs for no-useless-constructor and hoisted-apis-on-top (#17888) (connorshea) - 8f24fa9 vscode: Remove mention of a built-in server (#17836) (Sysix) - e81a306 linter: Update the tsconfig flag mention for the import plugin. (#17778) (connorshea) # Oxfmt ### 🚀 Features - 539b350 formatter/sort_imports: Update `NODE_BUILTINS` modules (#17771) (nilptr) - 2e03ebf oxfmt/lsp: Use `SourceFormatter` to support non-JS files and napi features (#17655) (leaysgur) - 623f7eb oxfmt/sort_package_json: Use `options.sort_scripts` (#17740) (leaysgur) - 86c0168 oxfmt/sort_package_json: Handle `oxfmtrc.sort_scripts` option (#17738) (leaysgur) - 256636a oxfmt/lsp: Add `.editorconfig` to `get_watcher_patterns` (#17694) (leaysgur) - 3f3db39 oxfmt/lsp: Use `ConfigResolver` to align with CLI (#17654) (leaysgur) ### 🐛 Bug Fixes - fdd1e1e formatter: Don't wrap parenthesis for type assertion when it's an declaration of export default (#17878) (Dunqing) - f0813ad formatter: Incorrect type annotation check for short argument (#17877) (Dunqing) - 9e89389 formatter/tailwindcss: Nested class string doesn't respect `singleQuote: true` (#17838) (Dunqing) - e2f534c formatter/sort_imports: Handle alignable comment with JsLabels (#17791) (leaysgur) - f0cedd4 formatter/tailwindcss: Class name is broken after sorting when its contains single quotes with `singleQuote: true` (#17790) (Dunqing) - 1864142 oxfmt/tailwindcss: Bundle `prettier/plugins/*` (#17782) (leaysgur) - 3a9d43b oxfmt: Ignore explicit positional path which is ignored by directory (#17732) (leaysgur) - 0563217 formatter: Classes will be stripped out when both `experimentalTailwindcss` and `experimentalSortImports` are enabled (#17726) (Dunqing) ### ⚡ Performance - d1bc514 formatter: Optimize RegExpLiteral formatting to avoid heap allocations (#17797) (Dunqing) ### 📚 Documentation - 62b7a01 formatter: Clarify `experimentalTailwindcss` configuration comments (#17898) (Dunqing) Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>

Initial plan

aba7f79

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Copilot AI changed the title ~~[WIP] Fix missing error for mixed type and non-type imports~~ parser: detect TS1363 error for type-only imports with empty named bindings Jan 6, 2026

Copilot AI requested a review from camc314 January 6, 2026 11:07

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Remove comment and simplify condition in module_record.rs

2666532

Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

Copilot finished work on behalf of camc314 January 6, 2026 11:12

github-actions bot added the A-parser Area - Parser label Jan 6, 2026

camc314 changed the title ~~parser: detect TS1363 error for type-only imports with empty named bindings~~ fix(parser): detect TS1363 error for type-only imports with empty named bindings Jan 6, 2026

github-actions bot added the C-bug Category - Bug label Jan 6, 2026

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Update allocation snapshots after parser changes

07903b1

Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

Copilot AI requested a review from camc314 January 6, 2026 11:43

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camc314 reopened this Jan 6, 2026

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Add TS1363 error for type imports with namespace specifier

84d4ee9

Also report error for `import type A, * as NS from 'mod'` pattern Co-authored-by: camc314 <18101008+camc314@users.noreply.github.com>

Copilot AI changed the title ~~fix(parser): detect TS1363 error for type-only imports with empty named bindings~~ fix(parser): detect TS1363 error for type-only imports with mixed default and named/namespace bindings Jan 6, 2026

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camc314 added 2 commits January 6, 2026 11:55

Apply suggestions from code review

2607d56

Signed-off-by: Cameron <cameron.clark@hey.com>

u

39f1648

github-actions bot added the A-linter Area - Linter label Jan 6, 2026

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camc314 requested a review from Sysix January 6, 2026 14:29

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camc314 marked this pull request as ready for review January 6, 2026 14:36

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Merge branch 'main' into copilot/fix-missing-error-imports

34884e9

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camc314 merged commit 59a6228 into main Jan 6, 2026
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camc314 deleted the copilot/fix-missing-error-imports branch January 6, 2026 14:45

This was referenced Jan 12, 2026

release(crates): oxc v0.108.0 #17920

Merged

release(apps): oxlint v1.39.0 && oxfmt v0.24.0 #17921

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CodSpeed Performance Report

Merging #17712 will not alter performance

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