[commit: packages/integer-gmp] master: Hackishly fix parallel build failure with in-tree GMP (8ed8ac5)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/integer-gmp

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/8ed8ac58b4a5c8654fccee4436ca62bf7c690474/integer-gmp

>---------------------------------------------------------------

commit 8ed8ac58b4a5c8654fccee4436ca62bf7c690474
Author: Austin Seipp <austin at well-typed.com>
Date:   Tue Jan 7 03:52:38 2014 -0600

    Hackishly fix parallel build failure with in-tree GMP
    
    See the comments and #8102. The basic gist of it seems to be that the
    build system follows an implied rule from somewhere to directly build a
    C file, which doesn't have a dependency on the in-tree gmp.h that we
    build. As a result, the C file compilation races against the GMP build,
    causing an error.
    
    This is a pretty unsatisfactory hack, but for Windows and OS X machines
    where we more often build in-tree GMPs, it's quite important.
    
    Authored-by: Kazu Yamamoto <kazu at iij.ad.jp>
    Signed-off-by: Austin Seipp <austin at well-typed.com>


>---------------------------------------------------------------

8ed8ac58b4a5c8654fccee4436ca62bf7c690474
 mkGmpDerivedConstants/ghc.mk |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mkGmpDerivedConstants/ghc.mk b/mkGmpDerivedConstants/ghc.mk
index 6c06224..1729b1a 100644
--- a/mkGmpDerivedConstants/ghc.mk
+++ b/mkGmpDerivedConstants/ghc.mk
@@ -26,7 +26,14 @@ $(GmpDerivedConstants_HEADER): $(mkGmpDerivedConstants_INPLACE)
 
 ifneq "$(HaveLibGmp)" "YES"
 ifneq "$(HaveFrameworkGMP)" "YES"
-$(libraries/integer-gmp/mkGmpDerivedConstants_dist_depfile_c_asm): libraries/integer-gmp/gmp/gmp.h
+# NOTE: we should really be referring to the depfile generated by the build
+# system here, but due to an awkward contortion I can't figure out, the build
+# system follows an implied from somewhere else to directly build the C file
+# instead (independent of the depfile rules), which doesn't have a built gmp.h
+# dependency. This race causes the parallel build to fail.
+#
+# See #8102
+libraries/integer-gmp/mkGmpDerivedConstants/mkGmpDerivedConstants.c: libraries/integer-gmp/gmp/gmp.h
 endif
 endif