[GHC] #8474: Extremely slow compilation of a program with multiply implicit parameters

[GHC]

#8474: Extremely slow compilation of a program with multiply implicit parameters
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        Reporter:  akamaus                  |            Owner:
            Type:  bug                      |           Status:  new
        Priority:  normal                   |        Milestone:
       Component:  Compiler (Type checker)  |          Version:  7.6.3
      Resolution:                           |         Keywords:
Operating System:  Unknown/Multiple         |     Architecture:
 Type of failure:  None/Unknown             |  Unknown/Multiple
       Test Case:                           |       Difficulty:  Unknown
        Blocking:                           |       Blocked By:
                                            |  Related Tickets:
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Comment (by Simon Peyton Jones <simonpj@…>):

 In [changeset:"54717c8218cb27b1f1f56ba019c17494556f766c/ghc"]:
 {{{
 #!CommitTicketReference repository="ghc"
 revision="54717c8218cb27b1f1f56ba019c17494556f766c"
 Be more careful when iterating the constraint-simpifier loop (fixes Trac
 #8474)

 We were (uselessly) iterating the simplification loop an exponential
 number of times.  Lovely simple test case showed this up.

 See Note [Cutting off simpl_loop] in TcSimplify
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8474#comment:2>
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