[GHC] #9257: CC_CLANG_BACKEND not reconfigured during bindist install

[GHC]

#9257: CC_CLANG_BACKEND not reconfigured during bindist install
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       Reporter:  MtnViewMark        |             Owner:
           Type:  bug                |            Status:  new
       Priority:  normal             |         Milestone:
      Component:  Build System       |           Version:  7.8.2
       Keywords:  clang              |  Operating System:  MacOS X
   Architecture:  Unknown/Multiple   |   Type of failure:  Installing GHC
     Difficulty:  Moderate (less     |  failed
  than a day)                        |         Test Case:
     Blocked By:                     |          Blocking:
Related Tickets:                     |
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 1) build GHC is built on a machine with clang -- project.mk ends up with
 the macro
     CC_CLANG_BACKEND=1
 2) make binary-dist on that machine
 3) bring that bindist to a machine that doesn't use clang
 4) unpack the bindist, ./configure, make install

 This error ensues:

     cc1: error: unrecognized command line option "-Wno-invalid-pp-token"
     cc1: error: unrecognized command line option "-Wno-unicode"

 The problem rests in that there is on gcc invocation during that make
 install:

     /usr/bin/gcc -E   ...   rts/package.conf.in -o
 rts/dist/package.conf.install.raw

 This call is picking up arguments from RAWCPP_FLAGS, set in mk/config.mk,
 based on CC_CLANG_BACKEND, set in mk/project.mk... which was computed at
 build time.

 carter has hypothesized that adding the macro FP_CC_LLVM_BACKEND to
 distrib/configure.ac.in might fix this. In theory that will cause the
 config file that is bunded into the bindist to recompute the
 CC_CLANG_BACKEND flag at dist config time. However, this may not work
 because the only file that emits CC_CLANG_BACKEND is project.mk and that
 doesn't seem to get re-written during dist time config. -- so something
 else will be needed.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/9257>
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