[GHC] #7050: stage 1 compiler crashes when the "quickest" build flavour is chosen

[GHC]

#7050: stage 1 compiler crashes when the "quickest" build flavour is chosen
-------------------------------+--------------------------------------------
    Reporter:  ilya            |       Owner:                     
        Type:  bug             |      Status:  merge              
    Priority:  normal          |   Milestone:                     
   Component:  Compiler        |     Version:  7.5                
    Keywords:                  |          Os:  MacOS X            
Architecture:  x86_64 (amd64)  |     Failure:  Building GHC failed
  Difficulty:  Unknown         |    Testcase:                     
   Blockedby:                  |    Blocking:                     
     Related:                  |  
-------------------------------+--------------------------------------------
Changes (by simonpj):

  * status:  new => merge


Comment:

 OK, the commit that broke this was
 {{{
 commit 792449f555bb4dfa8e718079f6d42dc9babe938a
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Sat Jun 11 14:26:34 2011 +0100

     Ignore UNPACK pragmas with OmitInterfacePragmas is on (fixes Trac
 #5252)

     The point here is that if a data type chooses a representation that
     unpacks an argument field, the representation of the argument field
     must be visible to clients.  And it may not be if OmitInterfacePragmas
     is on.

  compiler/typecheck/TcTyClsDecls.lhs |   44
 +++++++++++++++++------------------
  1 file changed, 22 insertions(+), 22 deletions(-)
 }}}
 However, it was fixed on the HEAD by
 {{{
 commit ba8fd081ba9b222dd5f93604d7deeaca372e4511
 Author: Simon Peyton Jones <simonpj at microsoft.com>
 Date:   Mon Sep 17 18:22:10 2012 +0100

     Make the call to chooseBoxingStrategy lazy again
 }}}
 (Confusingly the latter patch attributes the introduction of the bug to
 the wrong patch.)

 The basic solution is to apply the fix on the branch too.  It may not
 apply cleanly because there are some intermediate patches on HEAD, but I
 think it should be obvious what to do.  The important thing is that in
 `tcConArg` we should see
 {{{
         ; let strict_mark = chooseBoxingStrategy dflags arg_ty
 (getBangStrictness bty)
 }}}
 or something like that, NOT `strict_mark <- chooseBoxingStrategy...`.

 Ian, can you fix this up please?  I'll add a test for HEAD.

 Simon

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7050#comment:2>
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