Field exposed-modules is not allowed in common stanza

[fendor]

Common stanzas may not define exposed-modules field.
E.g. this cabal file:

cabal-version:      3.8
name:               some-dir
version:            0.1.0.0

common warnings
    ghc-options: -Wall

common mods
    exposed-modules:
        MyLib

library
    import:           warnings, mods
    build-depends:    base
    hs-source-dirs:   src
    default-language: Haskell2010

is not what you want and you get the following:

> cabal repl
Resolving dependencies...
Build profile: -w ghc-8.10.7 -O1
In order, the following will be built (use -v for more details):
 - some-dir-0.1.0.0 (lib) (first run)
Warning: some-dir.cabal:9:5: Unknown field: "exposed-modules"
Configuring library for some-dir-0.1.0.0..
Preprocessing library for some-dir-0.1.0.0..
Warning: No exposed modules
GHCi, version 8.10.7: https://www.haskell.org/ghc/  :? for help
Prelude> :q
Leaving GHCi.

Idk whether this is simply an oversight or a design decision, but it should probably be documented here https://cabal.readthedocs.io/en/stable/cabal-package.html?highlight=common#common-stanzas

[ulysses4ever]

The reason it doesn't work currently, I believe, is the same as what's discussed in #6117. Time long have come to get more specialized version of common stanzas.

[fendor]

Closing this in favour of #6117