[GHC] #13804: MonoLocalBinds/RankNTypes type inference regression in GHC 8.2

[GHC]

#13804: MonoLocalBinds/RankNTypes type inference regression in GHC 8.2
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  highest           |            Milestone:
       Component:  Compiler (Type    |              Version:  8.2.1-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:  #11698            |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by simonpj):

 The attached patch does the job, but regresses `perf/compiler/T12227`.

 I'm tied up this week; would anyone like to investigate?

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13804#comment:5>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler