-Wnoncanonical-monoid-instances

[andreasabel]

src/System/Process/Common.hs:94:5: warning: [GHC-50928] [-Wnoncanonical-monoid-instances]
    Noncanonical ‘mappend’ definition detected
    in the instance declaration for ‘Monoid ExitCode’.
    ‘mappend’ will eventually be removed in favour of ‘(<>)’
    Suggested fix:
      Either remove definition for ‘mappend’ (recommended) or define as ‘mappend = (<>)’
      See also: https://gitlab.haskell.org/ghc/ghc/-/wikis/proposal/semigroup-monoid
   |
94 |     mappend x (ExitFailure 0) = x
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

The warning should be fixed eventually.