From af4d01b51b282af95e7841d7c02f73ece8cef541 Mon Sep 17 00:00:00 2001
From: Thomas Haller <thaller@redhat.com>
Date: Mon, 2 Nov 2020 10:08:09 +0100
Subject: [PATCH] shared: add a compat implementation for
 g_atomic_pointer_get()

With glib2-2.67.0-1.fc34.x86_64.rpm, clang-11.0.0-2.fc34.x86_64.rpm, we
get a failure for g_atomic_pointer_get():

    ../shared/nm-glib-aux/nm-hash-utils.c:38:9: error: passing 'typeof (*(&global_seed)) *' (aka 'const unsigned char *volatile *') to parameter of type 'const guint8 **' (aka 'const unsigned char **') discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
        g = g_atomic_pointer_get(&global_seed);
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    /usr/include/glib-2.0/glib/gatomic.h:112:38: note: expanded from macro 'g_atomic_pointer_get'
        __atomic_load (gapg_temp_atomic, &gapg_temp_newval, __ATOMIC_SEQ_CST); \
                                         ^~~~~~~~~~~~~~~~~
    ../shared/nm-glib-aux/nm-hash-utils.c:109:32: error: passing 'typeof (*(&global_seed)) *' (aka 'const unsigned char *volatile *') to parameter of type 'const guint8 **' (aka 'const unsigned char **') discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
        return ((*((const guint *) _get_hash_key())) ^ static_seed) ?: 3679500967u;
                                   ^~~~~~~~~~~~~~~
    ../shared/nm-glib-aux/nm-hash-utils.c:84:14: note: expanded from macro '_get_hash_key'
            _g = g_atomic_pointer_get(&global_seed); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    /usr/include/glib-2.0/glib/gatomic.h:112:38: note: expanded from macro 'g_atomic_pointer_get'
        __atomic_load (gapg_temp_atomic, &gapg_temp_newval, __ATOMIC_SEQ_CST); \
                                         ^~~~~~~~~~~~~~~~~
    ../shared/nm-glib-aux/nm-hash-utils.c:123:9: error: passing 'typeof (*(&global_seed)) *' (aka 'const unsigned char *volatile *') to parameter of type 'const guint8 **' (aka 'const unsigned char **') discards qualifiers [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
        g = _get_hash_key();
            ^~~~~~~~~~~~~~~
    ../shared/nm-glib-aux/nm-hash-utils.c:84:14: note: expanded from macro '_get_hash_key'
            _g = g_atomic_pointer_get(&global_seed); \
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    /usr/include/glib-2.0/glib/gatomic.h:112:38: note: expanded from macro 'g_atomic_pointer_get'
        __atomic_load (gapg_temp_atomic, &gapg_temp_newval, __ATOMIC_SEQ_CST); \
                                         ^~~~~~~~~~~~~~~~~

(cherry picked from commit 5e57ea37f0944bfa3441a51afb1bd5e81b8c5b41)
(cherry picked from commit 1e4cfba6dc583ebe071506c42f2a04a9915959b0)
(cherry picked from commit 446cac18ccb209334644d1347f300599da14c0b9)
---
 shared/nm-glib-aux/nm-glib.h | 41 ++++++++++++++++++++++++++++++------
 1 file changed, 35 insertions(+), 6 deletions(-)

diff --git a/shared/nm-glib-aux/nm-glib.h b/shared/nm-glib-aux/nm-glib.h
index 2df5179566..5cac30e12a 100644
--- a/shared/nm-glib-aux/nm-glib.h
+++ b/shared/nm-glib-aux/nm-glib.h
@@ -565,6 +565,30 @@ _nm_g_value_unset (GValue *value)
 
 /*****************************************************************************/
 
+/* g_atomic_pointer_get() is implemented as a macro, and it is also used for
+ * (gsize *) arguments. However, that leads to compiler warnings in certain
+ * configurations. Work around it, by redefining the macro. */
+static inline gpointer
+_g_atomic_pointer_get (void **atomic)
+{
+	return g_atomic_pointer_get (atomic);
+}
+#undef g_atomic_pointer_get
+#define g_atomic_pointer_get(atomic) \
+	({ \
+		typeof (*atomic) *const _atomic = (atomic); \
+		\
+		/* g_atomic_pointer_get() is used by glib also for (gsize *) pointers,
+		 * not only pointers to pointers. We thus don't enforce that (*atomic)
+		 * is a pointer, but of suitable size/alignment. */ \
+		\
+		G_STATIC_ASSERT (sizeof (*_atomic) == sizeof (gpointer)); \
+		G_STATIC_ASSERT (_nm_alignof (*_atomic) == _nm_alignof (gpointer)); \
+		(void) (0 ? (gpointer) * (_atomic) : NULL); \
+		\
+		(typeof (*_atomic)) _g_atomic_pointer_get ((void **) _atomic); \
+	})
+
 /* Glib implements g_atomic_pointer_compare_and_exchange() as a macro.
  * For one, to inline the atomic operation and also to perform some type checks
  * on the arguments.
@@ -573,20 +597,25 @@ _nm_g_value_unset (GValue *value)
  * pointers there. Reimplement the macro to get that right, but with stronger
  * type checks (as we use typeof()). Had one job. */
 static inline gboolean
-_g_atomic_pointer_compare_and_exchange (volatile void *atomic,
-                                        gconstpointer oldval,
-                                        gconstpointer newval)
+_g_atomic_pointer_compare_and_exchange (void **atomic,
+                                        void *oldval,
+                                        void *newval)
 {
-	return g_atomic_pointer_compare_and_exchange ((void **) atomic, (void *) oldval, (void *) newval);
+    return g_atomic_pointer_compare_and_exchange (atomic, oldval, newval);
 }
 #undef g_atomic_pointer_compare_and_exchange
 #define g_atomic_pointer_compare_and_exchange(atomic, oldval, newval) \
 	({ \
-		typeof (atomic) const _atomic = (atomic); \
+		typeof (*atomic) *const _atomic = (atomic); \
 		typeof (*_atomic) const _oldval = (oldval); \
 		typeof (*_atomic) const _newval = (newval); \
+		_nm_unused gconstpointer const _val_type_check = _oldval; \
 		\
-		_g_atomic_pointer_compare_and_exchange (_atomic, _oldval, _newval); \
+		(void) (0 ? (gpointer) * (_atomic) : NULL); \
+		\
+		_g_atomic_pointer_compare_and_exchange ((void **) _atomic, \
+		                                        (void *) _oldval, \
+		                                        (void *) _newval); \
 	})
 
 /*****************************************************************************/