Panic with promoted types that Typeable doesn't support
The following program panics on GHC 8.2 and later:
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE ImpredicativeTypes #-}
{-# LANGUAGE RankNTypes #-}
{-# LANGUAGE TypeApplications #-}
module Bug where
import Type.Reflection
newtype Foo = MkFoo (forall a. a)
foo :: TypeRep MkFoo
foo = typeRep @MkFoo
$ /opt/ghc/8.6.1/bin/ghc Bug.hs
[1 of 1] Compiling Bug ( Bug.hs, Bug.o )
GHC error in desugarer lookup in Bug:
attempting to use module ‘main:Bug’ (Bug.hs) which is not loaded
ghc: panic! (the 'impossible' happened)
(GHC version 8.6.1 for x86_64-unknown-linux):
initDs
Trac metadata
Trac field | Value |
---|---|
Version | 8.6.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |