[GHC] #12881: GHC 8.0.2 regression involving OVERLAP annotations

[GHC]

#12881: GHC 8.0.2 regression involving OVERLAP annotations
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:
            Type:  bug               |               Status:  patch
        Priority:  high              |            Milestone:  8.0.2
       Component:  Compiler          |              Version:  8.0.2-rc1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):  Phab:D2760
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by RyanGlScott):

 Replying to [comment:10 rwbarton]:
 > But happily GHC HEAD already accepts this case, somehow. (Maybe someone
 with 8.0.2-rc1 can confirm.)

 Indeed, GHC 8.0.2-rc1 accepts that program. Luckily, these instances
 aren't sufficiently overlapping to confuse GHC when it uses VTA to apply
 `@(Int, b)` or `@(a, Char)`.

 In any case, I made sure to use a phrase akin to "might fail to type-
 check" instead of "//will// fail to type-check" in Phab:D2760 so as not to
 exaggerate the severity of this problem ;)

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12881#comment:11>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler