#14813: EmptyCase thinks pattern match involving type family is not exhaustive, when it actually is -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.2 Resolution: | Keywords: | PatternMatchWarnings Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect | Unknown/Multiple error/warning at compile-time | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by RyanGlScott): Replying to [comment:3 simonpj]:
Why do you think the typechecker "isn't giving the correct type"
Like I said in comment:2, what I meant by "correct type" is "insufficiently type-family–free type".
and would would be consequences of that be?
The consequences are this very ticket! As explained in comment:1, `F False a` and `Void` can produce different results in the pattern-match coverage checker, so it's critical that we use the latter whenever possible. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14813#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler