config/no-executables.m4

   1 # GCC_NO_EXECUTABLES
   2 # -----------------
   3 # FIXME: The GCC team has specific needs which the current Autoconf
   4 # framework cannot solve elegantly.  This macro implements a dirty
   5 # hack until Autoconf is able to provide the services its users
   6 # need.
   7 #
   8 # Several of the support libraries that are often built with GCC can't
   9 # assume the tool-chain is already capable of linking a program: the
  10 # compiler often expects to be able to link with some of such
  11 # libraries.
  12 #
  13 # In several of these libraries, workarounds have been introduced to
  14 # avoid the AC_PROG_CC_WORKS test, that would just abort their
  15 # configuration.  The introduction of AC_EXEEXT, enabled either by
  16 # libtool or by CVS autoconf, have just made matters worse.
  17 #
  18 # Unlike the previous AC_NO_EXECUTABLES, this test does not
  19 # disable link tests at autoconf time, but at configure time.
  20 # This allows AC_NO_EXECUTABLES to be invoked conditionally.
  21 AC_DEFUN_ONCE([GCC_NO_EXECUTABLES],
  22 [m4_divert_push([KILL])
  23
  24 AC_BEFORE([$0], [_AC_COMPILER_EXEEXT])
  25 AC_BEFORE([$0], [AC_LINK_IFELSE])
  26
  27 m4_define([_AC_COMPILER_EXEEXT],
  28 [AC_LANG_CONFTEST([AC_LANG_PROGRAM(
  29                      [#include <stdio.h>],
  30                      [printf ("hello world\n");])])
  31 # FIXME: Cleanup?
  32 AS_IF([AC_TRY_EVAL(ac_link)], [gcc_no_link=no], [gcc_no_link=yes])
  33 if test x$gcc_no_link = xyes; then
  34   # Setting cross_compile will disable run tests; it will
  35   # also disable AC_CHECK_FILE but that's generally
  36   # correct if we can't link.
  37   cross_compiling=yes
  38   EXEEXT=
  39 else
  40   ]m4_defn([_AC_COMPILER_EXEEXT])dnl
  41 fi
  42 )
  43
  44 m4_define([AC_LINK_IFELSE],
  45 if test x$gcc_no_link = xyes; then
  46   AC_MSG_ERROR([Link tests are not allowed after [[$0]].])
  47 fi
  48 m4_defn([AC_LINK_IFELSE]))
  49
  50 dnl This is a shame.  We have to provide a default for some link tests,
  51 dnl similar to the default for run tests.
  52 m4_define([AC_FUNC_MMAP],
  53 if test x$gcc_no_link = xyes; then
  54   if test "x${ac_cv_func_mmap_fixed_mapped+set}" != xset; then
  55     ac_cv_func_mmap_fixed_mapped=no
  56   fi
  57 fi
  58 if test "x${ac_cv_func_mmap_fixed_mapped}" != xno; then
  59   m4_defn([AC_FUNC_MMAP])
  60 fi)
  61
  62 m4_divert_pop()dnl
  63 ])# GCC_NO_EXECUTABLES
  64
  65 # Use the strongest available test out of AC_TRY_COMPILE and AC_TRY_LINK.
  66 AC_DEFUN([GCC_TRY_COMPILE_OR_LINK],
  67 [if test x$gcc_no_link = xyes; then
  68   AC_TRY_COMPILE([$1], [$2], [$3], [$4])
  69 else
  70   AC_TRY_LINK([$1], [$2], [$3], [$4])
  71 fi])