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Re: [PATCH, libstdc++]: Avoid "libsupc++/guard.cc:118:18: warning: variable â__pâ set but not used" warning


On 01/07/15 12:22 +0200, Uros Bizjak wrote:
Hello!

2015-07-01  Uros Bizjak  <ubizjak@gmail.com>

   * libsupc++/guard.cc (__test_and_acquire): Use __p after __atomic_load
   to avoid unused variable warning.
   (__set_and_release): Use __p after __atomic_store to avoid unused
   variable warning.

Bootstrapped and regression tested on x86_64-linux-gnu.

OK for mainline?

Yes, OK, although I was wondering if this should really be fixed in
the front end, the warning is spurious, isn't it? __p is not unused,
because the load is done through it.

Index: libsupc++/guard.cc
===================================================================
--- libsupc++/guard.cc	(revision 225221)
+++ libsupc++/guard.cc	(working copy)
@@ -117,6 +117,7 @@ __test_and_acquire (__cxxabiv1::__guard *g)
  unsigned char __c;
  unsigned char *__p = reinterpret_cast<unsigned char *>(g);
  __atomic_load (__p, &__c,  __ATOMIC_ACQUIRE);
+  (void) __p;
  return _GLIBCXX_GUARD_TEST(&__c);
}
#  define _GLIBCXX_GUARD_TEST_AND_ACQUIRE(G) __test_and_acquire (G)
@@ -132,6 +133,7 @@ __set_and_release (__cxxabiv1::__guard *g)
  unsigned char *__p = reinterpret_cast<unsigned char *>(g);
  unsigned char val = 1;
  __atomic_store (__p, &val, __ATOMIC_RELEASE);
+  (void) __p;
}
#  define _GLIBCXX_GUARD_SET_AND_RELEASE(G) __set_and_release (G)
# endif


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