From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 17 Aug 2022 19:32:38 +0000 (-0400)
Subject: Fix: add missing unused attribute to _rcu_dereference
X-Git-Tag: v0.12.4~3
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=b0dd3b2579b942971650b228069b3060a4f727ed;p=userspace-rcu.git

Fix: add missing unused attribute to _rcu_dereference

Reproduced with gcc-8, gcc-10, gcc-11 in O2:

14:39:19 In file included from ../../include/urcu/pointer.h:39,
14:39:19                  from ../../include/urcu-pointer.h:1,
14:39:19                  from ../../include/urcu/rcuhlist.h:30,
14:39:19                  from ../../include/urcu/cds.h:28,
14:39:19                  from test_build.c:30:
14:39:19 test_build.c: In function ‘test_build_rcu_dereference’:
14:39:19 ../../include/urcu/static/pointer.h:102:55: warning: variable ‘_________p0’ set but not used [-Wunused-but-set-variable]
14:39:19   102 |                                         __typeof__(p) _________p0 = { 0 };              \
14:39:19       |                                                       ^~~~~~~~~~~
14:39:19 ../../include/urcu/pointer.h:47:33: note: in expansion of macro ‘_rcu_dereference’
14:39:19    47 | #define rcu_dereference         _rcu_dereference
14:39:19       |                                 ^~~~~~~~~~~~~~~~
14:39:19 test_build.c:133:9: note: in expansion of macro ‘rcu_dereference’
14:39:19   133 |         rcu_dereference(opaque_const);
14:39:19       |         ^~~~~~~~~~~~~~~
14:39:19 mv -f .deps/test_urcu_multiflavor_single_unit_dynlink_cxx-test_urcu_multiflavor_single_unit_cxx.Tpo .deps/test_urcu_multiflavor_single_unit_dynlink_cxx-test_urcu_multiflavor_single_unit_cxx.Po
14:39:19 ../../include/urcu/static/pointer.h:102:55: warning: variable ‘_________p0’ set but not used [-Wunused-but-set-variable]
14:39:19   102 |                                         __typeof__(p) _________p0 = { 0 };              \
14:39:19       |                                                       ^~~~~~~~~~~
14:39:19 ../../include/urcu/pointer.h:47:33: note: in expansion of macro ‘_rcu_dereference’
14:39:19    47 | #define rcu_dereference         _rcu_dereference
14:39:19       |                                 ^~~~~~~~~~~~~~~~
14:39:19 test_build.c:135:9: note: in expansion of macro ‘rcu_dereference’
14:39:19   135 |         rcu_dereference(clear_const);
14:39:19       |         ^~~~~~~~~~~~~~~

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Change-Id: If3a78c2ec1c3ae0cab1ea5f9d40ede4e30f9bc81
---

diff --git a/include/urcu/static/pointer.h b/include/urcu/static/pointer.h
index c276e68..9e46a57 100644
--- a/include/urcu/static/pointer.h
+++ b/include/urcu/static/pointer.h
@@ -99,7 +99,7 @@ extern "C" {
 #ifdef __URCU_DEREFERENCE_USE_ATOMIC_CONSUME
 # define _rcu_dereference(p) __extension__ ({						\
 				__typeof__(__extension__ ({				\
-					__typeof__(p) _________p0 = { 0 };		\
+					__typeof__(p) __attribute__((unused)) _________p0 = { 0 }; \
 					_________p0;					\
 				})) _________p1;					\
 				__atomic_load(&(p), &_________p1, __ATOMIC_CONSUME);	\