isUnliftedType GHC panic on pattern with True :: Maybe
{-# LANGUAGE PatternSynonyms #-}
{-# LANGUAGE ScopedTypeVariables #-}
module Oops where
pattern What = True :: MaybeFails on 8.4.3 with:
ghc: panic! (the 'impossible' happened)
(GHC version 8.4.3 for x86_64-unknown-linux):
isUnliftedType
(Maybe |> {co_a1Dg3}) :: TYPE t_a1Dg9[tau:1]
Call stack:
CallStack (from HasCallStack):
callStackDoc, called at compiler/utils/Outputable.hs:1150:37 in ghc:Outputable
pprPanic, called at compiler/types/Type.hs:1939:10 in ghc:Type
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabugI'm currently cloning from git, and will try to get around to check it with HEAD over the next days. BTW, it's not a show-stopper for me.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.4.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | low |
| Resolution | Unresolved |
| Component | Compiler (Type checker) |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture | aarch64 |