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ax_gcc_option

Synopsis

AX_GCC_OPTION(OPTION,EXTRA-OPTIONS,TEST-PROGRAM,ACTION-IF-SUCCESSFUL,ACTION-IF-NOT-SUCCESFUL)

Description

AX_GCC_OPTION checks wheter gcc accepts the passed OPTION. If it accepts the OPTION then ACTION-IF-SUCCESSFUL will be executed, otherwise ACTION-IF-UNSUCCESSFUL.

NOTE: This macro will be obsoleted by AX_C_CHECK_FLAG AX_CXX_CHECK_FLAG, AX_CPP_CHECK_FLAG, AX_CXXCPP_CHECK_FLAG and AX_LD_CHECK_FLAG.

A typical usage should be the following one:

  AX_GCC_OPTION([-fomit-frame-pointer],[],[],[
    AC_MSG_NOTICE([The option is supported])],[
    AC_MSG_NOTICE([No luck this time])
  ])

The macro doesn't discriminate between languages so, if you are testing for an option that works for C++ but not for C you should use '-x c++' as EXTRA-OPTIONS:

  AX_GCC_OPTION([-fno-rtti],[-x c++],[],[ ... ],[ ... ])

OPTION is tested against the following code:

  int main()
  {
          return 0;
  }

The optional TEST-PROGRAM comes handy when the default main() is not suited for the option being checked

So, if you need to test for -fstrict-prototypes option you should probably use the macro as follows:

  AX_GCC_OPTION([-fstrict-prototypes],[-x c++],[
    int main(int argc, char ** argv)
    {
        (void) argc;
        (void) argv;

        return 0;
    }
  ],[ ... ],[ ... ])

Note that the macro compiles but doesn't link the test program so it is not suited for checking options that are passed to the linker, like:

  -Wl,-L<a-library-path>

In order to avoid such kind of problems you should think about usinguse the AX_*_CHECK_FLAG family macros

Authors

Francesco Salvestrini <salvestrini@users.sourceforge.net> and Bogdan Drozdowski <bogdandr@op.pl>.

Last Modified

2008-04-12

Cross References

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M4 Source Code

AC_DEFUN([AX_GCC_OPTION], [
  AC_REQUIRE([AC_PROG_CC])

  AC_MSG_CHECKING([if gcc accepts $1 option])

  AS_IF([ test "x$GCC" = "xyes" ],[
    AS_IF([ test -z "$3" ],[
      ax_gcc_option_test="int main()
{
        return 0;
}"
    ],[
      ax_gcc_option_test="$3"
    ])

    # Dump the test program to file
    cat <<EOF > conftest.c
$ax_gcc_option_test
EOF

    # Dump back the file to the log, useful for debugging purposes
    AC_TRY_COMMAND(cat conftest.c 1>&AS_MESSAGE_LOG_FD)

    AS_IF([ AC_TRY_COMMAND($CC $2 $1 -c conftest.c 1>&AS_MESSAGE_LOG_FD) ],[
                AC_MSG_RESULT([yes])
        $4
    ],[
                AC_MSG_RESULT([no])
        $5
    ])
  ],[
    AC_MSG_RESULT([no gcc available])
  ])
])

License

Copyright © 2008 Francesco Salvestrini <salvestrini@users.sourceforge.net>
Copyright © 2008 Bogdan Drozdowski <bogdandr@op.pl>

This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.

As a special exception, the respective Autoconf Macro's copyright owner gives unlimited permission to copy, distribute and modify the configure scripts that are the output of Autoconf when processing the Macro. You need not follow the terms of the GNU General Public License when using or distributing such scripts, even though portions of the text of the Macro appear in them. The GNU General Public License (GPL) does govern all other use of the material that constitutes the Autoconf Macro.

This special exception to the GPL applies to versions of the Autoconf Macro released by the Autoconf Macro Archive. When you make and distribute a modified version of the Autoconf Macro, you may extend this special exception to the GPL to apply to your modified version as well.