#5686: 'impossible' happened when deriving Functor on a type with a type family
application
--------------------------------+-------------------------------------------
Reporter: patrick_premont | Owner:
Type: bug | Status: new
Priority: normal | Component: Compiler
Version: 7.2.1 | Keywords:
Os: Unknown/Multiple | Architecture: Unknown/Multiple
Failure: Compile-time crash | Testcase:
Blockedby: | Blocking:
Related: |
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The following should fail with an appropriate error message.
I discovered this by accident when I changed the definition of type 'U'
and forgot to remove 'deriving Functor'.
{{{
> {-# LANGUAGE TypeFamilies, DeriveFunctor #-}
> data U a = U (G a) deriving Functor
>
> class A a where
> type G a
}}}
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5686>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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