-- Test purpose: -- Ensure that -Wno-compat disables a previously set -Wcompat {-# OPTIONS_GHC -Wcompat #-} {-# OPTIONS_GHC -Wno-compat #-} module WCompatWarningsOnOff where import qualified Data.Semigroup as Semi monadFail :: Monad m => m a monadFail = do Just _ <- undefined undefined (<>) = undefined -- Semigroup warnings -- -fwarn-noncanonical-monoid-instances newtype S = S Int instance Semi.Semigroup S where (<>) = mappend instance Monoid S where S a `mappend` S b = S (a+b) mempty = S 0