fix(loader): make webpack peer dependency optional and update Rspack example

[yslpn]

Description

Extend @lingui/loader peer dependency metadata for Rspack and Rsbuild environments, and update the loader docs to describe Webpack-compatible usage more clearly.

UPD:

Made webpack optional peerDependencies and updated the rspack example

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Examples update

Fixes # (issue)

Checklist

• I have read the CONTRIBUTING and CODE_OF_CONDUCT docs
• I have added tests that prove my fix is effective or that my feature works
• I have added the necessary documentation (if appropriate)

[vercel]

@yslpn is attempting to deploy a commit to the Crowdin Team on Vercel.

A member of the Team first needs to authorize it.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.01%. Comparing base (dd43fb0) to head (2d8ec9f).
⚠️ Report is 335 commits behind head on next.

Additional details and impacted files

@@             Coverage Diff             @@
##             next    #2475       +/-   ##
===========================================
+ Coverage   76.66%   89.01%   +12.35%     
===========================================
  Files          81      118       +37     
  Lines        2083     3315     +1232     
  Branches      532      978      +446     
===========================================
+ Hits         1597     2951     +1354     
+ Misses        375      329       -46     
+ Partials      111       35       -76     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[timofei-iatsenko]

@yslpn does it work without adding them into peer dependencies? I'm questioning what the reason of adding it explicitly? Usually we add something if we use (require or import) something from there, so package manager would build a correct graph.

But in this case it used only as a metadata to specify what version range of rsbuild/rspack is supported?

Maybe it would be just enough to update the docs?

[yslpn]

@yslpn does it work without adding them into peer dependencies? I'm questioning what the reason of adding it explicitly? Usually we add something if we use (require or import) something from there, so package manager would build a correct graph.

But in this case it used only as a metadata to specify what version range of rsbuild/rspack is supported?

Maybe it would be just enough to update the docs?

It works but I'd like to remove warnings from package managers for projects that don't require webpack.

❯ yarn install
➤ YN0000: ┌ Resolution step
➤ YN0002: │ rspack-react-ts-starter@workspace:. doesn't provide webpack (p82fb2), requested by @lingui/loader
➤ YN0000: │ Some peer dependencies are incorrectly met; run yarn explain peer-requirements <hash> for details, where <hash> is the six-letter p-prefixed code
➤ YN0000: └ Completed
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0008: │ esbuild@npm:0.25.12 must be rebuilt because its dependency tree changed

[yslpn]

Should I add "@lingui/loader" to the rspack example?

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
js-lingui	Ready	Preview	Apr 15, 2026 7:50am

[timofei-iatsenko]

@yslpn does it work without adding them into peer dependencies? I'm questioning what the reason of adding it explicitly? Usually we add something if we use (require or import) something from there, so package manager would build a correct graph.
But in this case it used only as a metadata to specify what version range of rsbuild/rspack is supported?
Maybe it would be just enough to update the docs?

It works but I'd like to remove warnings from package managers for projects that don't require webpack.

❯ yarn install
➤ YN0000: ┌ Resolution step
➤ YN0002: │ rspack-react-ts-starter@workspace:. doesn't provide webpack (p82fb2), requested by @lingui/loader
➤ YN0000: │ Some peer dependencies are incorrectly met; run yarn explain peer-requirements <hash> for details, where <hash> is the six-letter p-prefixed code
➤ YN0000: └ Completed
➤ YN0000: ┌ Fetch step
➤ YN0000: └ Completed
➤ YN0000: ┌ Link step
➤ YN0008: │ esbuild@npm:0.25.12 must be rebuilt because its dependency tree changed

Got it, so basically it's more about seting a webpack as optional. Maybe then let's just do that? Set webpack as optional without adding rspack and friends as peer deps.

Should I add "@lingui/loader" to the rspack example?

Yes please.

[yslpn]

Got it, so basically it's more about seting a webpack as optional. Maybe then let's just do that? Set webpack as optional without adding rspack and friends as peer deps.

I don't mind, but I want to understand. Are you concerned that specifying rspack/rsbuild will lead to new code additions and make maintenance more difficult?

On the other hand, I see benefits in defining acceptable versions.

Should I add "@lingui/loader" to the rspack example?

Yes please.

Done

[timofei-iatsenko]

I don't mind, but I want to understand. Are you concerned that specifying rspack/rsbuild will lead to new code additions and make maintenance more difficult?

This list is not completed, we will also need to specify turbopack version as webpack compatible (anything else what i'm not aware of?) and maintain the ranges unnecessarily. I believe all these webpack compatible tools is compatible with latest webpack api, so it's on their side to maintain compatibility - not on ours.

[yslpn]

I don't mind, but I want to understand. Are you concerned that specifying rspack/rsbuild will lead to new code additions and make maintenance more difficult?

This list is not completed, we will also need to specify turbopack version as webpack compatible (anything else what i'm not aware of?) and maintain the ranges unnecessarily. I believe all these webpack compatible tools is compatible with latest webpack api, so it's on their side to maintain compatibility - not on ours.

Done. Pull request description updated.

[timofei-iatsenko]

@andrii-bodnar all good let's merge this one