[GHC] #5929: Exciting arity warning when compiling with optimizations

[GHC]

#5929: Exciting arity warning when compiling with optimizations
-----------------------------------------------+----------------------------
 Reporter:  passalaqua                         |          Owner:                  
     Type:  bug                                |         Status:  new             
 Priority:  normal                             |      Component:  Compiler        
  Version:  7.4.1                              |       Keywords:  Exciting arity  
       Os:  Unknown/Multiple                   |   Architecture:  Unknown/Multiple
  Failure:  Incorrect warning at compile-time  |       Testcase:                  
Blockedby:                                     |       Blocking:                  
  Related:                                     |  
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 When trying to compile a file generated by UUAG
 (http://www.cs.uu.nl/wiki/HUT/AttributeGrammarSystem) using optimizations
 on GHC 7.2.1 (Windows), 7.2.2 (Mac) or 7.4.1 (Windows) I get a line that
 says only "Exciting arity" followed by some GHC internal code (maybe GHC
 Core?).

 The code still compiles and executes as expected, however this warning
 clearly indicates that something (either in the code or in ghc) is not
 working as expected.

 Changing the code sometimes eliminates that warning, sometimes it doesn't.
 The version attached was the smallest I could get that still got me the
 warnings (and does not depend on any 3rd party libraries, if anyone's
 interested in reproducing it).

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5929>
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