[GHC] #15149: Identical distinct type family fields miscompiled

[GHC]

#15149: Identical distinct type family fields miscompiled
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        Reporter:  NeilMitchell      |                Owner:  adamgundry
            Type:  bug               |               Status:  patch
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler          |              Version:  8.4.2
      Resolution:                    |             Keywords:  ORF
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHC rejects       |            Test Case:
  valid program                      |  rename/should_compile/T15149
      Blocked By:                    |             Blocking:
 Related Tickets:  #14747            |  Differential Rev(s):  Phab:D4821
       Wiki Page:                    |
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Comment (by simonpj):

 > Moving field label resolution to the typechecker still might be worth
 doing, because it should get rid of quite a bit of duplication. But it's
 not a small task (e.g. because of dot-dot patterns) so I think it's worth
 pursuing the small fix first.

 I agree with this point, but we should still do it!  Then we could get rid
 of `tcg_field_env` altogether, which would be very worthwhile.

 Maybe open a fresh ticket for it?

-- 
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/15149#comment:11>
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