[GHC] #5970: Type checker hangs

[GHC]

#5970: Type checker hangs
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    Reporter:  Lemming                  |       Owner:                              
        Type:  bug                      |      Status:  new                         
    Priority:  normal                   |   Milestone:                              
   Component:  Compiler (Type checker)  |     Version:  7.4.1                       
    Keywords:                           |          Os:  Linux                       
Architecture:  x86                      |     Failure:  Compile-time performance bug
  Difficulty:  Unknown                  |    Testcase:                              
   Blockedby:                           |    Blocking:                              
     Related:                           |  
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Comment(by simonpj@…):

 commit 516d3138473d7b097cc572901bd02fce9509f1b8
 {{{
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Wed Mar 28 09:56:14 2012 +0100

     Add a crucial forkM on the superclass context of IfaceClass in
 tcIfaceDecl

     The absence of this was causing a loop when typechecking an interface
     where the superclass context mentioned an associated type
        class C (T a) => D a where
          data T a

     Fixes Trac #5970

  compiler/iface/BuildTyCl.lhs   |    7 +++----
  compiler/iface/LoadIface.lhs   |    2 +-
  compiler/iface/TcIface.lhs     |   36
 +++++++++++++++++++++++++-----------
  compiler/typecheck/FamInst.lhs |    3 +++
  4 files changed, 32 insertions(+), 16 deletions(-)
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5970#comment:4>
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