[GHC] #11715: There's something fishy going on with Constraint

[GHC]

#11715: There's something fishy going on with Constraint
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        Reporter:  bgamari           |                Owner:
            Type:  bug               |               Status:  new
        Priority:  high              |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Description changed by bgamari:

@@ -2,1 +2,1 @@
- #11334. Consider this testcase,
+ #11334. Consider this testcase (`-O0` is sufficient),

New description:

 I first noticed something was a bit odd with `Constraint` when chasing
 #11334. Consider this testcase (`-O0` is sufficient),
 {{{#!hs
 import Data.Typeable

 main = do
     print $ typeRep (Proxy :: Proxy Eq)
     print $ typeOf (Proxy :: Proxy Eq)
 }}}
 With `ghc-8.0` this will produce,
 {{{
 Eq
 Proxy (* -> *) Eq
 }}}
 Notice the second line; GHC seems to be claiming that `Eq :: * -> *`,
 which is clearly nonsense.

 I believe this issue may be the cause of some of the testsuite failures
 that I'm seeing on #11011. Unfortunately I haven't the foggiest where this
 issue might originate.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11715#comment:3>
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