--- /dev/null
+AC_DEFUN([AC_FUNC_GCC_VISIBILITY],
+ [AC_CACHE_CHECK(whether __attribute__((visibility())) is supported,
+ libc_cv_visibility_attribute,
+ [cat > conftest.c <<EOF
+ int foo __attribute__ ((visibility ("hidden"))) = 1;
+ int bar __attribute__ ((visibility ("protected"))) = 1;
+EOF
+ libc_cv_visibility_attribute=no
+ if ${CC-cc} -Werror -S conftest.c -o conftest.s \
+ >/dev/null 2>&1; then
+ if grep '\.hidden.*foo' conftest.s >/dev/null; then
+ if grep '\.protected.*bar' conftest.s >/dev/null; then
+ libc_cv_visibility_attribute=yes
+ fi
+ fi
+ fi
+ rm -f conftest.[cs]
+ ])
+ if test $libc_cv_visibility_attribute = yes; then
+ AC_DEFINE(HAVE_VISIBILITY_ATTRIBUTE)
+ fi
+ ])