[GHC] #8683: add "cpp program" and "cpp program options" to settings file

[GHC]

#8683: add "cpp program" and "cpp program options" to settings file
-------------------------------------+------------------------------------
        Reporter:  carter            |            Owner:
            Type:  feature request   |           Status:  patch
        Priority:  normal            |        Milestone:  7.8.1
       Component:  Compiler          |          Version:  7.7
      Resolution:                    |         Keywords:
Operating System:  Unknown/Multiple  |     Architecture:  Unknown/Multiple
 Type of failure:  None/Unknown      |       Difficulty:  Unknown
       Test Case:                    |       Blocked By:
        Blocking:                    |  Related Tickets:  #8439
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Comment (by trommler):

 Replying to [comment:16 carter]:
 OK, I see what the issue is:
 > here an error from
 > ./configure --with-gcc=clang --with-cpp=gcc
 >
 > (where i try to add the cpp flags to mk/config.in with a patch i've not
 pushed yet)
 >
 > [...]
 > with the associated log  being
 >
 > {{{
 > This file contains any messages produced by compilers while
 > running configure, to aid debugging if configure makes a mistake.
 >
 > It was created by Haskell terminfo package configure 0.2, which was
 > generated by GNU Autoconf 2.69.  Invocation command line was
 >
 >   $ ./configure --with-compiler=ghc CFLAGS= -m64 -fno-stack-protector
 LDFLAGS= -m64   CPPFLAGS= -m64 -E -undef -traditional    --with-cc=gcc
 --with-gcc=/Users/carter/bin/gcc
 >
 > [...]
 > configure:2413: checking whether the C compiler works
 > configure:2435: gcc  -m64 -fno-stack-protector     -m64 -E -undef
 -traditional     -m64   conftest.c  >&5
 >[...]
 > }}}

 {{{$CPPFLAGS}}} will be used in compiler commands too. The compiler
 command configure tests is something like {{{$CC $CFLAGS $CPPFLAGS
 $LDFLAGS}}}.

 {{{-E}}} must not be part of CPPFLAGS but CPP should be set to {{{$CC
 -E}}} unless you specify the preprocessor ({{{/usr/bin/cpp}}} on my
 system) directly. If you call the preprocessor through a compiler driver
 like {{{gcc}}} or {{{clang}}} then {{{$CPP}}} should include the {{{-E}}}
 flag. I think the user should be required to specify {{{--with-cpp="gcc
 -E"}}} rather than {{{--with-cpp=gcc}}} and likewise for clang.

 I'll prepare a new pull request.

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/8683#comment:20>
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