ghc panic: runtimeRepLevity_maybe
An ill-typed program triggers a panic while printing an error message.
Steps to reproduce
module Bug where import GHC.Exts (TYPE) data T (a :: TYPE r) = MkT f :: T @(f a b) () -> () f MkT = ()
GHC tries to print an error message (as can be seen from the error code
GHC-83865) but then panics:
Bug.hs:7:17: error: [GHC-83865]ghc: panic! (the 'impossible' happened) GHC version 9.7.20230110: runtimeRepLevity_maybe 'BoxedRep Call stack: CallStack (from HasCallStack): callStackDoc, called at compiler/GHC/Utils/Panic.hs:189:37 in ghc:GHC.Utils.Panic pprPanic, called at compiler/GHC/Core/Type.hs:796:22 in ghc:GHC.Core.Type
A proper error message.
- GHC version used: HEAD.
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