ASSERT failed! on T16135
{-# LANGUAGE ExistentialQuantification, ApplicativeDo #-}
module Bug where
data T f = forall a. MkT (f a)
runf :: forall f. Functor f => IO (T f)
runf = do
return ()
MkT fa <- runf
return $ MkT fa
Leads to assertion failure
ghc: panic! (the 'impossible' happened)
GHC version 9.3.20220221:
ASSERT failed!
2
1
a_aEs[tau:1]
a_aEe[ssk:2]
Call stack:
CallStack (from HasCallStack):
massertPpr, called at compiler/GHC/Tc/Utils/TcMType.hs:1027:10 in ghc:GHC.Tc.Utils.TcMType
Please report this as a GHC bug: https://www.haskell.org/ghc/reportabug
Related to #21113 (closed)