Which PostCSS version should be used for the peer dependency config?

[romainmenke]

The peer dependency version of PostCSS has started to diverge in plugins.

https://github.com/csstools/postcss-plugins/blob/main/UPDATING_POSTCSS.md?plain=1#L3-L6

see : packages/postcss-tape/package.json

Set the postcss version to match the peer dependency of all plugins.
Set the postcss-oldest-supported depending on community needs. This can be the same as the postcss version.

After some thought I propose we change this to :

• choose the lowest PostCSS version as the peer dependency
• also test the latest PostCSS version
• validate in CI that all plugins have the same version (part of package.json lint?)

If a plugin of ours does not require PostCSS 8.3 and works perfectly fine with the features in 8.2 it should be possible to use PostCSS 8.2. Currently we disable usage with 8.2 arbitrarily.

Overal this should make it easier for users to install and use postcss-preset-env and plugins if they have little or no control over their PostCSS version. (we've seen these versions pinned by frameworks)

[Antonio-Laguna]

So you're proposing to just use PostCSS 8 as peer but keep testing the latest too. I think that's sensible to do and to enforce with the package.json lint too.

Thanks for articulating this!