diff options
Diffstat (limited to 'testsuite/tests/wcompat-warnings/WCompatWarningsNotOn.hs')
| -rw-r--r-- | testsuite/tests/wcompat-warnings/WCompatWarningsNotOn.hs | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/testsuite/tests/wcompat-warnings/WCompatWarningsNotOn.hs b/testsuite/tests/wcompat-warnings/WCompatWarningsNotOn.hs index 24cab851c9..64a19e5cf9 100644 --- a/testsuite/tests/wcompat-warnings/WCompatWarningsNotOn.hs +++ b/testsuite/tests/wcompat-warnings/WCompatWarningsNotOn.hs @@ -6,9 +6,21 @@ module WCompatWarningsNotOn 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 Semi.Monoid S where + S a `mappend` S b = S (a+b) + mempty = S 0 |