From: Thierry Reding <treding@xxxxxxxxxx>
Checks whether or not the compiler supports the -fvisibility option. If
so it sets the VISIBILITY_CFLAGS variable which can be added to the per
directory AM_CFLAGS where appropriate.
Libraries can use the HAVE_VISIBILITY preprocessor definition to check
for availability and use something like this:
#if defined(HAVE_VISIBILITY)
# define drm_private __attribute__((visibility("hidden")))
# define drm_public __attribute__((visibility("default")))
#else
# define drm_private
# define drm_public
#endif
By default all symbols will be hidden via the VISIBILITY_CFLAGS. Only
symbols explicitly marked drm_public will be exported.
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
configure.ac | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/configure.ac b/configure.ac
index d2d19d66dc17..3f4164238494 100644
--- a/configure.ac
+++ b/configure.ac
@@ -365,6 +365,26 @@ AC_ARG_WITH([kernel-source],
[kernel_source="$with_kernel_source"])
AC_SUBST(kernel_source)
+dnl Add flags for gcc and g++
+if test "x$GCC" = xyes; then
+ # Enable -fvisibility=hidden if using a gcc that supports it
+ save_CFLAGS="$CFLAGS"
+ AC_MSG_CHECKING([whether $CC supports -fvisibility=hidden])
+ VISIBILITY_CFLAGS="-fvisibility=hidden"
+ CFLAGS="$CFLAGS $VISIBILITY_CFLAGS"
+ AC_LINK_IFELSE([AC_LANG_PROGRAM()], AC_MSG_RESULT([yes]),
+ [VISIBILITY_CFLAGS=""; AC_MSG_RESULT([no])]);
+
+ # Restore CFLAGS; VISIBILITY_CFLAGS are added to it where needed.
+ CFLAGS=$save_CFLAGS
+
+ if test "x$VISIBILITY_CFLAGS" != x; then
+ AC_DEFINE(HAVE_VISIBILITY, 1, [Compiler has -fvisibility support])
+ fi
+
+ AC_SUBST([VISIBILITY_CFLAGS])
+fi
+
AC_SUBST(WARN_CFLAGS)
AC_CONFIG_FILES([
Makefile
--
1.8.4.2
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