#14744: Non-exhaustive patterns in case in GHCi with quantified class contexts -------------------------------------+------------------------------------- Reporter: kosmikus | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.5 Keywords: wipT2893, | Operating System: Unknown/Multiple QuantifiedConstraints | Architecture: | Type of failure: None/Unknown Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- 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. -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14744> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler