source: trunk/src/gcc/config/acinclude.m4@ 54

dnl This file is included into all any other acinclude file that needs
dnl to use these macros.

dnl This is copied from autoconf 2.12, but does calls our own AC_PROG_CC_WORKS,
dnl and doesn't call AC_PROG_CXX_GNU, cause we test for that in  AC_PROG_CC_WORKS.
dnl We are probably using a cross compiler, which will not be able to fully
dnl link an executable.  This should really be fixed in autoconf itself.
dnl Find a working G++ cross compiler. This only works for the GNU C++ compiler.
AC_DEFUN(CYG_AC_PROG_CXX_CROSS,
[AC_BEFORE([$0], [AC_PROG_CXXCPP])
AC_CHECK_PROGS(CXX, $CCC c++ g++ gcc CC cxx cc++, gcc)

CYG_AC_PROG_GXX_WORKS

if test $ac_cv_prog_gxx = yes; then
  GXX=yes
dnl Check whether -g works, even if CXXFLAGS is set, in case the package
dnl plays around with CXXFLAGS (such as to build both debugging and
dnl normal versions of a library), tasteless as that idea is.
  ac_test_CXXFLAGS="${CXXFLAGS+set}"
  ac_save_CXXFLAGS="$CXXFLAGS"
  CXXFLAGS=
  AC_PROG_CXX_G
  if test "$ac_test_CXXFLAGS" = set; then
    CXXFLAGS="$ac_save_CXXFLAGS"
  elif test $ac_cv_prog_cxx_g = yes; then
    CXXFLAGS="-g -O2"
  else
    CXXFLAGS="-O2"
  fi
else
  GXX=
  test "${CXXFLAGS+set}" = set || CXXFLAGS="-g"
fi
])

dnl See if the G++ compiler we found works.
AC_DEFUN(CYG_AC_PROG_GXX_WORKS,
[AC_MSG_CHECKING([whether the G++ compiler ($CXX $CXXFLAGS $LDFLAGS) actually works])
AC_LANG_SAVE
AC_LANG_CPLUSPLUS
dnl Try a test case. We only compile, because it's close to impossible
dnl to get a correct fully linked executable with a cross compiler. For
dnl most cross compilers, this test is bogus. For G++, we can use various
dnl other compile line options to get a decent idea that the cross compiler
dnl actually does work, even though we can't produce an executable without
dnl more info about the target it's being compiled for. This only works
dnl for the GNU C++ compiler.

dnl Transform the name of the compiler to it's cross variant, unless
dnl CXX is set. This is also what CXX gets set to in the generated
dnl Makefile.
if test x"${CXX}" = xc++ ; then
    CXX=`echo gcc | sed -e "${program_transform_name}"`
fi

dnl Get G++'s full path to libgcc.a
libgccpath=`${CXX} --print-libgcc`

dnl If we don't have a path with libgcc.a on the end, this isn't G++.
if test `echo $libgccpath | sed -e 's:/.*/::'` = libgcc.a ; then
   ac_cv_prog_gxx=yes
else
   ac_cv_prog_gxx=no
fi

dnl If we are using G++, look for the files that need to exist if this
dnl compiler works.
if test x"${ac_cv_prog_gxx}" = xyes ; then
    gccfiles=`echo $libgccpath | sed -e 's:/libgcc.a::'`
    if test -f ${gccfiles}/specs -a -f ${gccfiles}/cpp -a -f ${gccfiles}/cc1plus; then
        gccfiles=yes
    else
        gccfiles=no
    fi
    gcclibs=`echo $libgccpath | sed -e 's:lib/gcc-lib/::' -e 's:/libgcc.a::' -e 's,\(.*\)/.*,\1,g'`/lib
    if test -d ${gcclibs}/ldscripts -a -f ${gcclibs}/libc.a -a -f ${gcclibs}/libstdc++.a ; then
        gcclibs=yes
    else
        gcclibs=no
    fi
fi

dnl If everything is OK, then we can safely assume the compiler works.
if test x"${gccfiles}" = xno -o x"${gcclibs}" = xno; then
    ac_cv_prog_cxx_works=no
    AC_MSG_ERROR(${CXX} is a non-working cross compiler)
else
   ac_cv_prog_cxx_works=yes 
fi

AC_LANG_RESTORE
AC_MSG_RESULT($ac_cv_prog_cxx_works)
if test x"$ac_cv_prog_cxx_works" = xno; then
  AC_MSG_ERROR([installation or configuration problem: C++ compiler cannot create executables.])
fi
AC_MSG_CHECKING([whether the G++ compiler ($CXX $CXXFLAGS $LDFLAGS) is a cross-compiler])
AC_MSG_RESULT($ac_cv_prog_cxx_cross)
cross_compiling=$ac_cv_prog_cxx_cross
AC_SUBST(CXX)
])

dnl ====================================================================
dnl Find a working GCC cross compiler. This only works for the GNU gcc compiler.
dnl This is based on the macros above for G++.
AC_DEFUN(CYG_AC_PROG_CC_CROSS,
[AC_BEFORE([$0], [AC_PROG_CCPP])
AC_CHECK_PROGS(CC, cc, gcc)