From f4a27f24ec5df32f28c3279e445200dded327585 Mon Sep 17 00:00:00 2001
From: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
Date: Mon, 6 Aug 2012 18:16:58 +0200
Subject: configure: check for visibility attribute.

Add a check for GCC "visibility" attribute. Also define DLL_HIDDEN helper
so that to declare functions as internal to a particular shared library.

Signed-off-by: Gwenole Beauchesne <gwenole.beauchesne@intel.com>
---
 configure.ac | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

(limited to 'configure.ac')

diff --git a/configure.ac b/configure.ac
index 9f37d90..1f958a8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -171,6 +171,28 @@ if test "$enable_docs" = "yes"; then
 fi
 AM_CONDITIONAL(ENABLE_DOCS, test "$enable_docs" = "yes")
 
+# Check for __attribute__((visibility()))
+AC_CACHE_CHECK([whether __attribute__((visibility())) is supported],
+    ac_cv_have_gnuc_visibility_attribute,
+    [cat > conftest.c <<EOF
+int foo __attribute__ ((visibility ("hidden"))) = 1;
+int bar __attribute__ ((visibility ("protected"))) = 1;
+EOF
+    ac_cv_have_gnuc_visibility_attribute="no"
+    if ${CC-cc} -Werror -S conftest.c -o conftest.s >/dev/null 2>&1; then
+        if grep '\.hidden.*foo' conftest.s >/dev/null; then
+            if grep '\.protected.*bar' conftest.s >/dev/null; then
+                ac_cv_have_gnuc_visibility_attribute="yes"
+            fi
+        fi
+    fi
+    rm -f conftest.[cs]
+])
+if test "$ac_cv_have_gnuc_visibility_attribute" = "yes"; then
+    AC_DEFINE([HAVE_GNUC_VISIBILITY_ATTRIBUTE], [1],
+              [Defined to 1 if GCC visibility attribute is supported])
+fi
+
 # Check for X11
 USE_X11="no"
 if test "$enable_x11" = "yes"; then
-- 
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