Non-exhaustive patterns in case in GHCi with quantified class contexts
This appears in the wip/T2893 branch.
To reproduce, create the following module
{-# LANGUAGE ConstraintKinds, GADTs, KindSignatures, QuantifiedConstraints #-}
module Bug where
import GHC.Exts
data Foo :: (* -> Constraint) -> * where
MkFoo :: (forall a . c a => c (f a), c a) => (f a) -> Foo c
and load it into GHCi:
Bug> foo = MkFoo "foo" :: Foo Show
*** Exception: compiler/typecheck/TcType.hs:(1965,9)-(1985,76): Non-exhaustive patterns in case
Putting the same declaration into the module itself does not seem to trigger the bug.
Trac metadata
Trac field | Value |
---|---|
Version | 8.5 |
Type | Bug |
TypeOfFailure | OtherFailure |
Priority | normal |
Resolution | Unresolved |
Component | Compiler |
Test case | |
Differential revisions | |
BlockedBy | |
Related | |
Blocking | |
CC | |
Operating system | |
Architecture |