Re: [GHC] #9371: Overlapping type families, segafult

29 Jul 2014

      #9371: Overlapping type families, segafult
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              Reporter:  pingu          |            Owner:  goldfire
                  Type:  bug            |           Status:  new
              Priority:  normal         |        Milestone:
             Component:  Compiler       |          Version:  7.8.3
            Resolution:                 |         Keywords:
      Operating System:  Linux          |     Architecture:  x86_64 (amd64)
       Type of failure:  Runtime crash  |       Difficulty:  Unknown
             Test Case:                 |       Blocked By:
              Blocking:                 |  Related Tickets:
Differential Revisions:                 |
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Changes (by simonpj):

 * owner:   => goldfire

Comment:

 So, to be concrete, Richard might you do this?

 It's not clear that two equations conflict just because their LHSs differ.
 Eg
 {{{
    F x = Maybe
    F x Int = Maybe Int
 }}}
 But it's certainly safe to say "there's a conflict", and in fact the
 lengths only differ for data families in which case each RHS is a fresh
 data type.

 This is somewhat urgent because what we have now is actually unsound.

 If you can't do it, yell, and I will.

 Simon

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/9371#comment:8
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