Skip to content

Serve ESM type declarations to ESM importers of @tailwindcss/postcss#20228

Merged
RobinMalfait merged 2 commits into
tailwindlabs:mainfrom
truffle-dev:fix/postcss-esm-types-condition
Jun 12, 2026
Merged

Serve ESM type declarations to ESM importers of @tailwindcss/postcss#20228
RobinMalfait merged 2 commits into
tailwindlabs:mainfrom
truffle-dev:fix/postcss-esm-types-condition

Conversation

@truffle-dev

@truffle-dev truffle-dev commented Jun 12, 2026

Copy link
Copy Markdown
Contributor

Summary

Fixes #20219.

The @tailwindcss/postcss exports map serves the CJS-shaped dist/index.d.ts (export = _default) for both the import and require conditions, while the correct ESM declaration file dist/index.d.mts (export { _default as default }) is built and published but never referenced. Type checkers that treat the import condition as ESM reject the default import with TS1192 — concretely, deno check on Deno 2.8.3+ (which ships TypeScript 6.0) fails on import tailwindcss from "@tailwindcss/postcss".

This splits the export entry into per-condition types blocks so ESM importers resolve index.d.mts and CJS consumers keep index.d.ts — the same shape @tailwindcss/vite already uses ("types": "./dist/index.d.mts").

Two notes on the issue as filed:

  • Stock tsc with NodeNext does not reproduce the error (declaration file format follows the file extension and package type, not the matched condition), so I didn't take the suggested export = → export default change in index.d.ts — that would break CJS consumers, and the correct ESM declarations already ship.
  • @tailwindcss/node has the same single-types exports shape; happy to follow up there if you want parity.

Test plan

Against @tailwindcss/postcss@4.3.0 with the published exports map, then again with only this package.json change applied to the installed package:

# Deno 2.8.3 (TypeScript 6.0), nodeModulesDir: auto
deno check main.ts   # before: TS1192 "Module ... index.d.ts has no default export" — after: passes
# typescript@6.0.0-dev (NodeNext), one ESM importer + one .cts require importer
tsc --noEmit         # passes both before and after (no regression for npm consumers)

@arethetypeswrong/cli:

published 4.3.0 with this change
node16 (from ESM) 🎭 Masquerading as CJS 🟢 (ESM)
node16 (from CJS) 🟢 (CJS) 🟢 (CJS)
bundler 🟢 🟢

@truffle-dev
Serve ESM type declarations to ESM importers of @tailwindcss/postcss
aaf8ad6 
The exports map served the CJS-shaped `dist/index.d.ts` (`export =`)
for both the `import` and `require` conditions, while the correct
ESM declaration file `dist/index.d.mts` was built and published but
never referenced. Type checkers that treat the import condition as
ESM (TypeScript 6.0 via `deno check` in Deno 2.8.3+) reject the
default import with TS1192.

Split the export entry into per-condition blocks so ESM importers get
`index.d.mts` and CJS consumers keep `index.d.ts`, mirroring the
shape `@tailwindcss/vite` already uses.

Fixes tailwindlabs#20219
@truffle-dev truffle-dev requested a review from a team as a code owner June 12, 2026 14:12
@greptile-apps

greptile-apps Bot commented Jun 12, 2026

Copy link
Copy Markdown
Contributor

Confidence Score: 5/5

Safe to merge — the exports map change is minimal, exactly parallels how other packages in this repo are structured, and both generated declaration files already exist in the published artifact.

Both dist/index.d.mts and dist/index.d.ts are already produced by the existing tsup build (ESM entry from src/index.ts, CJS entry from src/index.cts), so no build changes are needed. The restructuring only affects how type checkers resolve declarations under each module condition — CJS consumers see no change, and ESM consumers get the correctly-shaped declaration file they were previously missing.

No files require special attention. The single package.json export map change is straightforward, and the CHANGELOG entry is accurate.

Reviews (1): Last reviewed commit: "Add changelog entry" | Re-trigger Greptile

@coderabbitai

coderabbitai Bot commented Jun 12, 2026 •
edited
Loading

Copy link
Copy Markdown
Contributor

Review Change Stack

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info
⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 795655e0-0799-4a97-b349-6c8a6899590d

📥 Commits

Reviewing files that changed from the base of the PR and between aaf8ad6 and c9fae30.

📒 Files selected for processing (1)
  • CHANGELOG.md
✅ Files skipped from review due to trivial changes (1)
  • CHANGELOG.md

Walkthrough

This PR updates the export map in the @tailwindcss-postcss package to use conditional sub-exports. The exports["."] field is restructured so that both ESM (import) and CommonJS (require) conditions now specify their own types and default entry points separately, rather than using a single flat types field. This ensures type definitions and runtime entries are resolved correctly for each module format.

🚥 Pre-merge checks | ✅ 4
✅ Passed checks (4 passed)
Check name Status Explanation
Title check ✅ Passed The title accurately summarizes the main change: serving ESM type declarations to ESM importers of @tailwindcss/postcss by updating the exports map.
Description check ✅ Passed The description comprehensively explains the issue, the solution, testing approach, and includes notes on why alternative approaches were not taken.
Linked Issues check ✅ Passed The PR fulfills the requirements from #20219 by updating package.json exports to serve ESM type declarations (index.d.mts) to ESM importers while maintaining CJS declarations for require conditions.
Out of Scope Changes check ✅ Passed All changes are scoped to fixing the export map for @tailwindcss/postcss per the linked issue; no unrelated modifications were introduced.

✏️ Tip: You can configure your own custom pre-merge checks in the settings.

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

Comment @coderabbitai help to get the list of available commands and usage tips.

@RobinMalfait RobinMalfait enabled auto-merge (squash) June 12, 2026 14:28
RobinMalfait
RobinMalfait approved these changes Jun 12, 2026
View reviewed changes

@RobinMalfait RobinMalfait left a comment

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Thanks!

@RobinMalfait RobinMalfait merged commit 522288c into tailwindlabs:main Jun 12, 2026
8 checks passed
@SisyphusZheng SisyphusZheng mentioned this pull request Jun 12, 2026
Open
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@RobinMalfait RobinMalfait RobinMalfait approved these changes

Assignees

No one assigned

Labels

None yet

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

types: export = in @tailwindcss/postcss contradicts exports.import in package.json

2 participants

@truffle-dev @RobinMalfait