[GHC] #14605: Core Lint error

[GHC]

#14605: Core Lint error
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        Reporter:  Iceland_jack      |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler          |              Version:  8.2.2
      Resolution:                    |             Keywords:  TypeInType,
                                     |  DeferredTypeErrors
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #14584            |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by simonpj):

 Richard and I decided that the simple way to do this is to switch off
 deferred type errors when inside a forall-unification.

 One could also imagine using the enclosing value bindings, but the
 necessary variables won't be in scope there.

 We could instead bind a bogus coercion in the outside scope, with a
 vanilla type like `() ~ ()` and then unsafe-corece it to the one we need.
 But it's more complicated and doesn't seem with the pain unless we get
 user pressure.

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14605#comment:5>
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