bug: missing transitive `postcss` peer dependency

[rtritto]

What version of daisyUI are you using?

v4.12.10

Which browsers are you seeing the problem on?

No response

Reproduction URL

NA

Describe your issue

postcss-js has postcss as peer dependency.
daisyui use postcss-js dependency and it should also include postcss as dependency or peer dependency.

yarn explain peer-requirements
...
p95141 → ✘ daisyui@npm:4.12.10 doesn't provide postcss to postcss-js@npm:4.0.1 [983eb]
...

[github-actions]

Thank you @rtritto for reporting issues. It helps daisyUI a lot 💚
I'll be working on issues one by one. I will help with this one as soon as a I find a solution.
In the meantime providing more details and reproduction links would be helpful.

[saadeghi]

Can you please describe the issue?

Offering a solution needs describing the problem first.

[rtritto]

daisyui use postcss-js dependency with no postcss dependency (postcss is a peer dependency of postcss-js).
If you use a dependency, you must also add all peer dependencies of that dependency (transitive dependencies).

[saadeghi]

My friend, are you having an issue on installation in any environment?

[rtritto]

I'm using yarn berry and with yarn explain peer-requirements, I got the warning as missing dependency (not-compliant).

peer-dependency

I have to use a workaround for that issue (missing dependency):

.yarnrc.yml

+packageExtensions:
+  daisyui@*:
+    peerDependencies:
+      postcss: '*'

[rtritto]

Probably you are using a package manager that autoinstall transitive peer dependencies (shadow behavior) and the issue is hidden.

[saadeghi]

Thanks for more explanation.
Is this warning preventing daisyUI to work?

Because what you're suggesting is not logical. A dependency can not possibly list all the peer dependencies of its dependencies as peer dependency.
Each dependency is a independent project. They can add or remove their dependencies any time. Does it make sense that a dependant package should monitor and list all peer dependencies of all dependencies and sub dependencies and...??

[rtritto]

Is this warning preventing daisyUI to work?

It's a warning, so no, it's not blocking. I can use the workaroud until the fix.

Because what you're suggesting is not logical. A dependency can not possibly list all the peer dependencies of its dependencies as peer dependency.
Each dependency is a independent project. They can add or remove their dependencies any time. Does it make sense that a dependant package should monitor and list all peer dependencies of all dependencies and sub dependencies and...??

Peer dependencies aren't installed by all package managers. That's why you see a peer dependency also in the dev dependencies (the peer dependency is used in tests or in build).

All plugin libraries have that logic. E.g.:

• in a project, you add the dependency A and you want add the plugin B for the dependency A
• plugin B have dependency A in peer dependencies (so the issue will not appear)
• plugin B can't work without dependency A (when you add B you must also add A)

All projects work using that logic as standard.

From answer https://stackoverflow.com/a/68575682 and source https://yarnpkg.com/advanced/error-codes#yn0002---missing_peer_dependency

# bad
project
├─D> packagePeer
└─D> packageA
     └─P> packageB
          └─P> packagePeer

# good
project
├─D> packagePeer
└─D> packageA
     ├─P> packagePeer
     └─D> packageB
          └─P> packagePeer

[rtritto]

@saadeghi if it's not enough, I can tag other expert users to exaplain better this issue
Thanks for your support

[saadeghi]

Post CSS is not required for daisyUI to work.

postcss-js does not require postcss to work, neither does daisyui

So I think you should either ignore the warning, or disable it.

Warning ≠ Error.
Warnings exist to warn you about a potential problem, but if you know it's not a problem, you shouldn't pay attention. It's a console log after all. It's not that smart 😅

[rtritto]

postcss-js does not require postcss to work, neither does daisyui

package.json of postcss-js include in peer dependencies:

https://github.com/postcss/postcss-js/blob/b3db658b932b42f6ac14ca0b1d50f50c4569805b/package.json#L48-L50

  "peerDependencies": {
    "postcss": "^8.4.21"
  },

To have postcss as optional peer dependency, we need this:

  "peerDependenciesMeta": {
    "postcss": {
      "optional": true
    }
  }

[rtritto]

Warning ≠ Error.
Warnings exist to warn you about a potential problem, but if you know it's not a problem, you shouldn't pay attention. It's a console log after all. It's not that smart 😅

That's because yarn berry autoinstall missing peer dependencies to not break dependency tree resolution.
The warning says that something isn't how should be.

[saadeghi]

Even if it doesn't install postcss , nothing would break. daisyUI doesn't depend on postcss.
If it was depending, I would've add it to dependencies. Like other dependencies.

[rtritto]

Even if it doesn't install postcss , nothing would break. daisyUI doesn't depend on postcss.
If it was depending, I would've add it to dependencies. Like other dependencies.

postcss-js depends on postcss (package.json of postcss-js have postcss in peer dependencies).
In a project, if you want use postcss-js dependency, you need also include postcss as dependency.

So, if DaisyUI uses postcss-js dependency, postcss must be added in dependencies.