[GHC] #12533: Internal error using redundant forall with default signature

[GHC]

#12533: Internal error using redundant forall with default signature
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        Reporter:  dfeuer            |                Owner:
            Type:  bug               |               Status:  merge
        Priority:  normal            |            Milestone:  8.0.2
       Component:  Compiler (Type    |              Version:  8.0.1
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  Compile-time      |            Test Case:
  crash                              |  rename/should_compile/T12533
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by bgamari):

 The trouble with merging comment:3 is that it requires
 d2958bd08a049b61941f078e51809c7e63bc3354, which fixes #12220 but which we
 were thinking on not merging as it causes #12466.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12533#comment:6>
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