m4/visibility_hidden.m4

   1 AC_DEFUN([AC_FUNC_GCC_VISIBILITY],
   2   [AC_CACHE_CHECK(whether __attribute__((visibility())) is supported,
   3                   libc_cv_visibility_attribute,
   4                   [cat > conftest.c <<EOF
   5                    int foo __attribute__ ((visibility ("hidden"))) = 1;
   6                    int bar __attribute__ ((visibility ("protected"))) = 1;
   7 EOF
   8                   libc_cv_visibility_attribute=no
   9                   if ${CC-cc} -Werror -S conftest.c -o conftest.s \
  10                         >/dev/null 2>&1; then
  11                     if grep '\.hidden.*foo' conftest.s >/dev/null; then
  12                       if grep '\.protected.*bar' conftest.s >/dev/null; then
  13                         libc_cv_visibility_attribute=yes
  14                       fi
  15                     fi
  16                   fi
  17                   rm -f conftest.[cs]
  18                   ])
  19    if test $libc_cv_visibility_attribute = yes; then
  20      AC_DEFINE(HAVE_VISIBILITY_ATTRIBUTE, [], [GCC supports visibility attributes])
  21    fi
  22   ])