Pattern synonyms defined through other pattern synonyms produce `impossible happened` in ghci/runhaskell
This module content (Bug.hs)
{-# language PatternSynonyms #-}
data A a = A a
pattern B a = A a
pattern C a = B a
causes ghci/runhaskell to fail:
> :l Bug
[1 of 1] Compiling Main ( Bug.hs, interpreted )
ghc: panic! (the 'impossible' happened)
(GHC version 8.0.1 for x86_64-unknown-linux):
kindPrimRep.go rep_a1r0
Please report this as a GHC bug: http://www.haskell.org/ghc/reportabug
When using ghc everything compiles and even works, so adding the code
main = do
let C a = A 1
print a
produced executable that prints "1".
Trac metadata
Trac field | Value |
---|---|
Version | 8.0.1 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |