[GHC] #9924: libffi configure script does not detect MSYS2 Windows 10 x86_64

[GHC]

#9924: libffi configure script does not detect MSYS2 Windows 10 x86_64
-------------------------------------+-------------------------------------
       Reporter:  luite              |                   Owner:
           Type:  bug                |                  Status:  new
       Priority:  normal             |               Milestone:
      Component:  Compiler           |                 Version:  7.10.1-rc1
       Keywords:                     |        Operating System:  Windows
   Architecture:  Unknown/Multiple   |         Type of failure:
     Difficulty:  Unknown            |  None/Unknown
     Blocked By:                     |               Test Case:
Related Tickets:                     |                Blocking:
                                     |  Differential Revisions:
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 When building GHC 7.10 RC 1 on Windows 10 Technical Preview, 64 bit, in
 MSYS2, libffi fails with the message that it cannot determine the build
 system, and that `config.guess` and `config.sub` may need to be updated.

 The latest versions do indeed work. Unfortunately the scripts are stored
 in the `libffi.tar` file, if we don't want to change the file we'll need
 some way to get the correct versions in place.

 I have a very hacky workaround that downloads the latest versions after
 unpacking the tar, which is obviously not how it should be solved, but
 might help some people get their RC1 to build before we have a proper fix:

 {{{
 diff --git a/libffi/ghc.mk b/libffi/ghc.mk
 index ec37f0c..fbd2e5e 100644
 --- a/libffi/ghc.mk
 +++ b/libffi/ghc.mk
 @@ -89,6 +89,9 @@ $(libffi_STAMP_CONFIGURE): $(TOUCH_DEP)
         cd libffi && \
             $(LIBFFI_PATH_MANGLE) \
             cd build && \
 +            autoreconf -f && \
 +            wget -O config.guess
 "http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.guess;hb=HEAD"
 && \
 +            wget -O config.sub
 "http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=config.sub;hb=HEAD"
 && \
             CC=$(CC_STAGE1) \
             CXX=$(CC_STAGE1) \
             LD=$(LD) \
 }}}

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9924>
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