fix(compiler-sfc): add resolution trying for `.mts/.cts` files by Gehbt · Pull Request #14402 · vuejs/core

Gehbt · 2026-02-02T18:40:59Z

Summary by CodeRabbit

Bug Fixes
- Improved module-aware import resolution to better recognize ESM/CJS variants and additional TypeScript extensions (.mts/.cts and declaration variants), improving import precedence and reliability in mixed JS/TS projects.
- Extended parser recognition to include new TypeScript language variants for correct parsing behavior.
Tests
- Added tests covering modular JS/TS extension combinations to validate type resolution and runtime prop mapping.

coderabbitai · 2026-02-02T18:41:26Z

📝 Walkthrough

Walkthrough

Detects module type from filename suffix and expands TypeScript resolution candidates: adds .mts/.d.mts for ESM and .cts/.d.cts for CJS, updates parser language set to include cts, and adds tests for modular JS extensions. No public API changes.

Changes

Cohort / File(s)	Summary
Module resolution logic `packages/compiler-sfc/src/script/resolveType.ts`	Add module-type-aware extension resolution: detect `.mjs`/`.cjs`, strip JS-family suffix with unified regex, and prepend `.mts`/`.d.mts` (ESM) or `.cts`/`.d.cts` (CJS) candidates ahead of existing `.ts`/`.d.ts` and index fallbacks.
Parser context `packages/compiler-sfc/src/script/context.ts`	Include `cts` in the set of TypeScript-like languages so TypeScript parser plugins are enabled for `cts` files.
Parsing/extension handling `packages/compiler-sfc/src/script/...`	Recognize additional TS-related extensions (`.cts`, `.mtsx`) and adjust runtime declaration-detection regex to `/\.d\.[cm]?ts$/`.
Tests `packages/compiler-sfc/__tests__/compileScript/resolveType.spec.ts`	Add tests exercising modular JS extension resolution and precedence (.mjs/.cjs imports preferring .mts/.cts and `.d.mts`/`.d.cts` over `.d.ts`), asserting correct runtime prop mappings.

Sequence Diagram(s)

(omitted)

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Possibly related PRs

fix(compiler-sfc): check lang before attempt to compile script #13508 — modifies compiler-sfc's script language handling and relates to adding CTS/MTS recognition.
fix(compiler-sfc): simulate allowArbitraryExtensions on resolving type (fix #13295) #13301 — changes type resolution logic for module-aware TypeScript extensions similar to these edits.

Suggested labels

ready to merge, :hammer: p3-minor-bug

Suggested reviewers

LittleSound

Poem

🐰 I sniffed through extensions, small and spry,
Found .mts and .cts waiting nearby.
I hopped in the resolver, nudged them in place,
Now types cross the modules with confident grace.
🥕✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: adding resolution support for `.mts/.cts` file extensions in the compiler-sfc package.
Linked Issues check	✅ Passed	The changes implement module-type aware extension resolution for `.mts` and `.cts` files, enabling the SFC compiler to resolve types from modules using these extensions, directly addressing issue `#2611`'s requirement to resolve RouterLinkProps and similar types.
Out of Scope Changes check	✅ Passed	All changes are focused on adding resolution for `.mts/.cts` extensions and treating `cts` as a TypeScript variant, remaining within scope of the stated objectives.

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✨ Finishing touches

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🧪 Generate unit tests (beta)

Create PR with unit tests
Post copyable unit tests in a comment

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Actionable comments posted: 0

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⚠️ Outside diff range comments (1)

packages/compiler-sfc/src/script/resolveType.ts (1)
988-1011: ⚠️ Potential issue | 🟠 Major

Extensionless imports won't resolve .mts/.cts files.

When moduleType is u (unknown, as with extensionless imports like ./foo), the code skips the .mts/.d.mts and .cts/.d.cts resolution branches and goes directly to trying .ts/.tsx/.d.ts. This means foo.mts and foo.cts will never be found for extensionless imports, breaking TypeScript's ESM/CJS module-kind-by-extension detection.

Add fallback resolution for .mts/.d.mts and .cts/.d.cts when moduleType === 'u' (and consider .mtsx/.ctsx JSX variants for consistency with the existing .tsx fallback):
🛠️ Proposed fix
  return (
    tryResolve(filename) ||
    (moduleType === 'm' &&
      (tryResolve(filename + `.mts`) || tryResolve(filename + `.d.mts`))) ||
    (moduleType === 'c' &&
      (tryResolve(filename + `.cts`) || tryResolve(filename + `.d.cts`))) ||
+   (moduleType === 'u' &&
+     (tryResolve(filename + `.mts`) ||
+       tryResolve(filename + `.mtsx`) ||
+       tryResolve(filename + `.d.mts`) ||
+       tryResolve(filename + `.cts`) ||
+       tryResolve(filename + `.ctsx`) ||
+       tryResolve(filename + `.d.cts`))) ||
    tryResolve(filename + `.ts`) ||
    tryResolve(filename + `.tsx`) ||
    tryResolve(filename + `.d.ts`) ||

edison1105 · 2026-02-03T08:43:50Z

Could you please add a test case?

github-actions · 2026-02-04T08:15:12Z

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	103 kB	39.1 kB	35.2 kB
vue.global.prod.js	161 kB	59.1 kB	52.6 kB

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	47 kB	18.3 kB	16.8 kB
createApp	55.1 kB	21.4 kB	19.6 kB
createSSRApp	59.4 kB	23.2 kB	21.1 kB
defineCustomElement	60.8 kB	23.1 kB	21.1 kB
overall	69.5 kB	26.7 kB	24.3 kB

Gehbt · 2026-02-08T12:02:10Z

Test case has been added @edison1105 .

edison1105 · 2026-02-09T01:28:23Z

Thanks for the PR. However, there are some issues with the resolution order. For example, when both foo.ts and foo.mts (or foo.d.ts and foo.d.mts) exist, foo.mjs incorrectly resolves to .d.ts. I verified locally using typescript.resolveModuleName that under TS NodeNext, it actually prioritizes .d.mts (and .d.cts for cjs). I have made the fix: 0517575

node -e "
const ts = require('typescript');

const files = {
  '/foo.d.ts': 'export type X = number;',
  '/foo.d.mts': 'export type X = string;',
};

const host = {
  fileExists: (f) => f in files,
  readFile: (f) => files[f] || '',
  directoryExists: () => true,
  getDirectories: () => [],
  realpath: (f) => f,
};

const result = ts.resolveModuleName(
  './foo.mjs',
  '/test.mts',
  { moduleResolution: ts.ModuleResolutionKind.NodeNext },
  host
);

console.log('TS NodeNext resolves ./foo.mjs to:', result.resolvedModule?.resolvedFileName); // foo.d.mts
"

pkg-pr-new · 2026-02-09T01:37:35Z

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commit: 0517575

edison1105 · 2026-02-09T01:46:18Z

/ecosystem-ci run

vue-bot · 2026-02-09T01:53:07Z

📝 Ran ecosystem CI: Open

suite	result	latest scheduled
language-tools	✅ success	✅ success
pinia	✅ success	✅ success
nuxt	✅ success	✅ success
radix-vue	✅ success	✅ success
test-utils	✅ success	✅ success
vue-macros	✅ success	✅ success
vant	❌ failure	✅ success
vueuse	✅ success	✅ success
primevue	✅ success	✅ success
router	❌ failure	✅ success
vuetify	✅ success	✅ success
vite-plugin-vue	✅ success	✅ success
quasar	✅ success	✅ success
vitepress	✅ success	✅ success
vue-simple-compiler	✅ success	✅ success
vue-i18n	✅ success	✅ success

fix(compiler-sfc): add resolution trying for .mts/.cts files

9430f27

coderabbitai bot reviewed Feb 2, 2026

View reviewed changes

change the order and reverse logic

50814a0

edison1105 added need test The PR has missing test cases. scope: sfc labels Feb 3, 2026

Gehbt added 2 commits February 3, 2026 12:45

enable cts type to parse

2ac8588

test: add test suits

2b3bb6a

edison1105 added 2 commits February 8, 2026 20:40

Merge branch 'main' into feat/resolve-cmts

f61ee04

fix(compiler-sfc): align .mjs/.cjs type resolution with TS NodeNext

0517575

edison1105 added ready to merge The PR is ready to be merged. and removed need test The PR has missing test cases. labels Feb 9, 2026

edison1105 merged commit c09d41f into vuejs:main Feb 9, 2026
18 of 19 checks passed

Gehbt deleted the feat/resolve-cmts branch February 9, 2026 09:36

claude bot mentioned this pull request Feb 12, 2026

chore(deps): update dependency vue to v3.5.28 - autoclosed cbcoutinho/nextcloud-mcp-server#554

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