Re: [GHC] #15144: Type inference regression between GHC 8.0.2 and 8.2.2

18 May 2018

      #15144: Type inference regression between GHC 8.0.2 and 8.2.2
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:  8.6.1
       Component:  Compiler (Type    |              Version:  8.2.2
  checker)                           |
      Resolution:                    |             Keywords:  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Simon Peyton Jones ):

 In [changeset:"ae292c6d1362f34117be75a2553049cec7022244/ghc"
 ae292c6d/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="ae292c6d1362f34117be75a2553049cec7022244"
 Do not unify representational equalities

 This patch is an easy fix to Trac #15144, which was caused
 by accidentally unifying a representational equality in the
 unflattener.  (The main code in TcInteract was always careful
 not to do so, but I'd missed the test in the unflattener.)

 See Note [Do not unify representational equalities]
 in TcInteract
 }}}

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15144#comment:4
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler