[GHC] #7592: Building the latest master branch on FreeBSD 9.1 fails

[GHC]

#7592: Building the latest master branch on FreeBSD 9.1 fails
---------------------------------+------------------------------------------
    Reporter:  kazu-yamamoto     |       Owner:  pgj                
        Type:  bug               |      Status:  new                
    Priority:  normal            |   Milestone:                     
   Component:  Build System      |     Version:  7.7                
    Keywords:                    |          Os:  FreeBSD            
Architecture:  Unknown/Multiple  |     Failure:  Building GHC failed
  Difficulty:  Unknown           |    Testcase:                     
   Blockedby:                    |    Blocking:                     
     Related:                    |  
---------------------------------+------------------------------------------

Comment(by igloo):

 Here are the stat outputs:
 {{{
 First time rules fires:
 Before copy:
 100 10437839 -rwxr-xr-x 1 kazu kazu 20851248 9446798 "Feb  3 05:22:22
 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:21 2013"
 32768 18560 0 utils/ghc-cabal/dist/build/tmp/ghc-cabal
 (inplace/bin/ghc-cabal doesn't exist)

 After copy:
 100 10437839 -rwxr-xr-x 1 kazu kazu 20851248 9446798 "Feb  3 05:22:22
 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:21 2013"
 32768 18560 0 utils/ghc-cabal/dist/build/tmp/ghc-cabal
 100  9395816 -rwxr-xr-x 1 kazu kazu 18824736 9446798 "Feb  3 05:22:22
 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013"
 32768 18560 0 inplace/bin/ghc-cabal

 Second time rules fires:
 Before copy:
 100 10437839 -rwxr-xr-x 1 kazu kazu 20851248 9446798 "Feb  3 05:22:22
 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:21 2013"
 32768 18560 0 utils/ghc-cabal/dist/build/tmp/ghc-cabal
 100  9395816 -rwxr-xr-x 1 kazu kazu 18824736 9446798 "Feb  3 05:22:48
 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013"
 32768 18560 0 inplace/bin/ghc-cabal

 After copy:
 100 10437839 -rwxr-xr-x 1 kazu kazu 20851248 9446798 "Feb  3 05:22:50
 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:22 2013" "Feb  3 05:22:21 2013"
 32768 18560 0 utils/ghc-cabal/dist/build/tmp/ghc-cabal
 100  9395816 -rwxr-xr-x 1 kazu kazu 18821696 9446798 "Feb  3 05:22:48
 2013" "Feb  3 05:22:50 2013" "Feb  3 05:22:50 2013" "Feb  3 05:22:22 2013"
 32768 18560 0 inplace/bin/ghc-cabal
 }}}

 I can't see anything wrong there. I've just looked at the make 3.82 code,
 and it certainly looks like a dependency needs to be strictly newer than
 the target for it to be considered changed:
 {{{
 d->changed |= noexist || d_mtime > this_mtime;
 }}}

 I think this will need someone who can reproduce the problem to diagnose
 exactly what's going on (it might be easiest to make a cut-down testcase
 first). One possibility is that the filesystem has sub-second precision,
 `stat` is ignoring the extra precision, and `cp` is giving inconsistent
 times (perhaps truncating the extra precision in the file it creates).
 Another is that the `stat` syscall is giving the wrong result for some
 reason. It's also not impossible that this is a `make` bug.

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/7592#comment:12>
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