New visibility handling in Clutter

Instead of listing every public symbol inside an ancillary file, we can
use compiler annotations. This scheme is also used by GLib and GTK+.

The symbols file is left in tree until the Visual Studio rules are
fixed, but it's not used any more during distcheck.

I double-checked that the exposed ABI is the same before and after this
change, except for symbols that were never meant to be public in the
first place, and that escaped our attention when we generated the first
version of the symbols file.

clutter/Makefile.am

@@ -29,6 +29,7 @@ AM_CPPFLAGS = \
 	$(CLUTTER_DEPRECATED_CFLAGS)		\
 	$(CLUTTER_DEBUG_CFLAGS)			\
 	$(CLUTTER_PROFILE_CFLAGS)		\
+	$(CLUTTER_HIDDEN_VISIBILITY_CFLAGS)	\
 	$(NULL)
 
 AM_CFLAGS = $(CLUTTER_CFLAGS) $(MAINTAINER_CFLAGS)
@@ -850,7 +851,6 @@ libclutter_@CLUTTER_API_VERSION@_la_LDFLAGS = \
 	$(CLUTTER_LINK_FLAGS) \
 	$(CLUTTER_LT_LDFLAGS) \
 	-export-dynamic \
-	-export-symbols-regex "^(clutter|cally).*" \
 	-rpath $(libdir) \
 	$(win32_resources_ldflag) \
 	$(NULL)

configure.ac

@@ -193,6 +193,36 @@ AC_ARG_ENABLE([Bsymbolic],
 AS_IF([test "x$enable_Bsymbolic" = "xyes"], [CLUTTER_LINK_FLAGS=-Wl[,]-Bsymbolic-functions])
 AC_SUBST(CLUTTER_LINK_FLAGS)
 
+# Check for the visibility flags
+CLUTTER_HIDDEN_VISIBILITY_CFLAGS=""
+case "$host" in
+  *-*-mingw*)
+    dnl on mingw32 we do -fvisibility=hidden and __declspec(dllexport)
+    AC_DEFINE([_CLUTTER_EXTERN], [__attribute__((visibility("default"))) __declspec(dllexport) extern],
+              [defines how to decorate public symbols while building])
+    CFLAGS="${CFLAGS} -fvisibility=hidden"
+    ;;
+  *)
+    dnl on other compilers, check if we can do -fvisibility=hidden
+    SAVED_CFLAGS="${CFLAGS}"
+    CFLAGS="-fvisibility=hidden"
+    AC_MSG_CHECKING([for -fvisibility=hidden compiler flag])
+    AC_TRY_COMPILE([], [int main (void) { return 0; }],
+                   AC_MSG_RESULT(yes)
+                   enable_fvisibility_hidden=yes,
+                   AC_MSG_RESULT(no)
+                   enable_fvisibility_hidden=no)
+    CFLAGS="${SAVED_CFLAGS}"
+
+    AS_IF([test "${enable_fvisibility_hidden}" = "yes"], [
+      AC_DEFINE([_CLUTTER_EXTERN], [__attribute__((visibility("default"))) extern],
+                [defines how to decorate public symbols while building])
+      CLUTTER_HIDDEN_VISIBILITY_CFLAGS="-fvisibility=hidden"
+    ])
+    ;;
+esac
+AC_SUBST(CLUTTER_HIDDEN_VISIBILITY_CFLAGS)
+
 AC_CACHE_SAVE
 
 dnl ========================================================================