Re: [GHC] #14045: Data family instances must list all patterns of family, despite documentation's claims to the contrary

2 Aug 2017

      #14045: Data family instances must list all patterns of family, despite
documentation's claims to the contrary
-------------------------------------+-------------------------------------
        Reporter:  RyanGlScott       |                Owner:  (none)
            Type:  bug               |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Compiler (Type    |              Version:  8.3
  checker)                           |
      Resolution:                    |             Keywords:  TypeFamilies
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  GHC rejects       |            Test Case:  indexed-
  valid program                      |  types/should_compile/T14045,
                                     |  indexed-types/should_fail/T14045a
      Blocked By:                    |             Blocking:
 Related Tickets:  #12369            |  Differential Rev(s):  Phab:D3804
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Ryan Scott ):

 In [changeset:"d74983ef0c4a5b47a53d2821f8be9ebbf86e9257/ghc"
 d74983ef/ghc]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="d74983ef0c4a5b47a53d2821f8be9ebbf86e9257"
 Get the roles right for newtype instances

 This was a simple slip, that gave rise to the bug reported in
 comment:13 of Trac #14045.  We were supplying roles to mkAlgTyCon
 that didn't match the tyvars.
 }}}

-- 
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14045#comment:17
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler