[GHC] #10079: Coercible solver regression: Couldn't match rep of () with Const () b

[GHC]

#10079: Coercible solver regression: Couldn't match rep of () with Const () b
-------------------------------------+-------------------------------------
        Reporter:  glguy             |                   Owner:  goldfire
            Type:  bug               |                  Status:  new
        Priority:  high              |               Milestone:  7.10.1
       Component:  Compiler (Type    |                 Version:  7.10.1-rc1
  checker)                           |                Keywords:
      Resolution:                    |            Architecture:
Operating System:  Unknown/Multiple  |  Unknown/Multiple
 Type of failure:  GHC rejects       |               Test Case:  indexed-
  valid program                      |  types/should_compile/T10079
      Blocked By:                    |                Blocking:
 Related Tickets:  #7788, #8550      |  Differential Revisions:  Phab:D653
-------------------------------------+-------------------------------------

Comment (by simonpj):

 Richard and I had a Skype chat.  Conclusions:

  * We worked out what to do about Phab:D653, but there are lots of
 changes, and 7.10 is very close.

  * Edward's 117 coerces are already fixed, in 7.10 (see comment:14)

  * So we will not fix anything further in 7.10.

  * That leaves un-done the right fix for this ticket (hence some lurking
 bugs).

  * Also remaining un-done are #7788, #8550, #9554, and #10139.  However
 none are blocking correct code from compiling and running.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10079#comment:25>
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