Cabal check incorrectly assumes package has -Wall -Werror #8257
Description
Describe the bug
In some cases (I believe when ghc-options: -Werror is given), cabal check reports a warning about 'ghc-options: -Wall -Werror', although -Wall is not set. This makes it, for example, impossible to upload such a package to hackage (see haskell/hackage-server#1088).
To Reproduce
Steps to reproduce the behavior:
$ mkdir tmp
$ cd tmp
$ cabal init
$ echo " ghc-options: -W -Werror" >> tmp.cabal
$ cabal check
Warning: These warnings may cause trouble when distributing the package:
Warning: No 'category' field.
Warning: The following errors will cause portability problems on other
environments:
Warning: No 'synopsis' or 'description' field.
Warning: The 'license' field is missing or is NONE.
Warning: 'ghc-options: -Wall -Werror' makes the package very easy to break
with future GHC versions because new GHC versions often add new warnings. Use
just 'ghc-options: -Wall' instead. Alternatively, if you want to use this,
make it conditional based on a Cabal configuration flag (with 'manual: True'
and 'default: False') and enable that flag during development.
Warning: Hackage would reject this package.
Let us disregard the warnings about the missing fields, those are fine. I'm worried about Warning: 'ghc-options: -Wall -Werror' makes the package very easy to break [...].
Expected behavior
Either no warning, or a correct warning message (e.g. warning about -Werror together with any enabled warning flag). I think it's fairer to have no warning here. -W -Werror is less likely to break in future GHC versions than -Wall -Werror, and should be allowed. (Maybe even good practice.)
System information
- Operating system: NixOS unstable
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 9.0.2
$ cabal --version
cabal-install version 3.6.2.0
compiled using version 3.6.3.0 of the Cabal library