From 2668390454bc0efe52a262eb2faa4a2bd5a062e2 Mon Sep 17 00:00:00 2001 From: Philip Withnall Date: Fri, 1 Apr 2022 13:47:19 +0100 Subject: [PATCH 2/2] gatomic: Add a C++ variant of g_atomic_int_compare_and_exchange() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The C++ variant implements type safety differently, to avoid warnings from C++ compilers about: ``` ../../../gnome-commander-1.14.2/src/intviewer/searcher.cc:303:5: error: cannot initialize a parameter of type 'gint *' (aka 'int *') with an rvalue of type 'void *' g_atomic_int_compare_and_exchange ((gint*)&src->priv->progress_value, oldval, (gint)d); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ /mnt/b/yoe/master/build/tmp/work/cortexa72-yoe-linux/gnome-commander/1.14.2-r0/recipe-sysroot/usr/include/glib-2.0/glib/gatomic.h:160:44: note: expanded from macro 'g_atomic_int_compare_and_exchange' __atomic_compare_exchange_n ((atomic), (void *) (&(gaicae_oldval)), (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \ ^~~~~~~~~~~~~~~~~~~~~~~~~~~ ``` This complements the existing C++ variant for `g_atomic_pointer_compare_and_exchange()`, and fixes a regression on C++ from https://gitlab.gnome.org/GNOME/glib/-/merge_requests/2114. With the addition of the unit tests in the previous commit, this is effectively tested by the FreeBSD and macOS CI jobs, as they use `clang++` in C++ mode. `g++` doesn’t seem to emit a warning about this. Signed-off-by: Philip Withnall Fixes: #2625 Upstream-Status: Submitted [https://gitlab.gnome.org/GNOME/glib/-/merge_requests/2578] Signed-off-by: Khem Raj --- glib/gatomic.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/glib/gatomic.h b/glib/gatomic.h index 5eba1dbc7..8b2b880c8 100644 --- a/glib/gatomic.h +++ b/glib/gatomic.h @@ -152,6 +152,17 @@ G_END_DECLS (void) (0 ? *(atomic) ^ *(atomic) : 1); \ __atomic_fetch_sub ((atomic), 1, __ATOMIC_SEQ_CST) == 1; \ })) +#if defined(glib_typeof) && defined(__cplusplus) && __cplusplus >= 201103L +/* See comments below about equivalent g_atomic_pointer_compare_and_exchange() + * shenanigans for type-safety when compiling in C++ mode. */ +#define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \ + (G_GNUC_EXTENSION ({ \ + glib_typeof (*(atomic)) gaicae_oldval = (oldval); \ + G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ + (void) (0 ? *(atomic) ^ (newval) ^ (oldval) : 1); \ + __atomic_compare_exchange_n ((atomic), &gaicae_oldval, (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \ + })) +#else /* if !(defined(glib_typeof) && defined(__cplusplus) && __cplusplus >= 201103L) */ #define g_atomic_int_compare_and_exchange(atomic, oldval, newval) \ (G_GNUC_EXTENSION ({ \ gint gaicae_oldval = (oldval); \ @@ -159,6 +170,7 @@ G_END_DECLS (void) (0 ? *(atomic) ^ (newval) ^ (oldval) : 1); \ __atomic_compare_exchange_n ((atomic), (void *) (&(gaicae_oldval)), (newval), FALSE, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST) ? TRUE : FALSE; \ })) +#endif /* defined(glib_typeof) */ #define g_atomic_int_add(atomic, val) \ (G_GNUC_EXTENSION ({ \ G_STATIC_ASSERT (sizeof *(atomic) == sizeof (gint)); \ -- 2.35.1