[GHC] #11608: Possible type-checker regression in GHC 8.0 when compiling `microlens`

[GHC]

#11608: Possible type-checker regression in GHC 8.0 when compiling `microlens`
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        Reporter:  hvr               |                Owner:
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:  8.0.1
       Component:  Compiler (Type    |              Version:  8.0.1-rc2
  checker)                           |
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
 Type of failure:  GHC rejects       |  Unknown/Multiple
  valid program                      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by hvr):

 I've temporarily reverted e1631b3b58b7440d3d5a8bf72f1490df635792fb in the
 `ghc-8.0` branch ''only'', via 881b6ccf5c1dbc09d1d16b1b4643e3dec9387047.

 I'm not reverting this in GHC HEAD yet, waiting for Richard to comment how
 we should proceed here.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11608#comment:6>
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