[GHC] #5424: Validate error under 7.2.1 caused by incomplete pattern warnings in new code gen (GADTs)

[GHC]

#5424: Validate error under 7.2.1 caused by incomplete pattern warnings in new
code gen (GADTs)
---------------------------------+------------------------------------------
    Reporter:  dterei            |       Owner:                     
        Type:  bug               |      Status:  new                
    Priority:  normal            |   Component:  Compiler           
     Version:  7.2.1             |    Keywords:                     
    Testcase:                    |   Blockedby:                     
          Os:  Unknown/Multiple  |    Blocking:                     
Architecture:  Unknown/Multiple  |     Failure:  Building GHC failed
---------------------------------+------------------------------------------
 the files compiler/cmm/Cmm.hs, compiler/cmm/CmmNode.hs and
 compiler/cmm/CmmStackLayout.hs all contain the following lines at the top:

 {{{
 {-# OPTIONS_GHC -fno-warn-incomplete-patterns #-}
 #if __GLASGOW_HASKELL__ >= 701
 -- GHC 7.0.1 improved incomplete pattern warnings with GADTs
 {-# OPTIONS_GHC -fwarn-incomplete-patterns #-}
 #endif
 }}}

 This causes a validation error when building with 7.2.1 as this version of
 GHC still seems to incorrectly warn about incorrect patterns despite the
 above comment. (The above comment is wrong anyway as the cpp if statement
 only triggers with GHC 7.2.1 and greater, not with GHC 7.0.1).

 For now I've dealt with this simply by changing the cpp if statement to
 be:

 {{{
 #if __GLASGOW_HASKELL__ >= 703
 ...
 }}}

 Someone more familiar with the code and the state of '-fwarn-incomplete-
 patterns' should actually fix this up though.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5424>
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