[GHC] #2937: source file that compiled fine fails to recompile after touching it (yes, another one)

[GHC]

#2937: source file that compiled fine fails to recompile after touching it (yes,
another one)
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    Reporter:  rwbarton          |        Owner:  simonpj         
        Type:  bug               |       Status:  new             
    Priority:  normal            |    Milestone:  6.10.2          
   Component:  Compiler          |      Version:  6.11            
    Severity:  normal            |   Resolution:                  
    Keywords:                    |   Difficulty:  Unknown         
    Testcase:  tc245             |           Os:  Unknown/Multiple
Architecture:  Unknown/Multiple  |  
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Comment (by simonpj):

 Ah.  Its seems that
  * this `fromJust` failure is an example of #2417;
  * which is marked as a dup of #1968
  * which was fixed in the HEAD but not 6.10

 GHC 6.10 doesn't support GADTs in associated types, which this test uses.

 It is a still a bug that 6.10 crashes under such circumstances.   Do we
 care enough?  If 6.10 is long-lived, perhaps we do. So pls create a ticket
 for the absence of a decent error message and we can do a 6.10 only patch.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/2937#comment:3>
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