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* [Bug libstdc++/64658] New: std::atomic_init() undefined
@ 2015-01-18 17:11 redi at gcc dot gnu.org
  2015-01-18 17:25 ` [Bug libstdc++/64658] " redi at gcc dot gnu.org
                   ` (2 more replies)
  0 siblings, 3 replies; 5+ messages in thread
From: redi at gcc dot gnu.org @ 2015-01-18 17:11 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64658

            Bug ID: 64658
           Summary: std::atomic_init() undefined
           Product: gcc
           Version: 4.9.2
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: redi at gcc dot gnu.org

#include <atomic>

int main()
{
  std::atomic_int a;
  atomic_init(&a, 0);
}

$ g++ -std=c++11 at.cc
In file included from at.cc:1:0:
/home/jwakely/gcc/5/include/c++/5.0.0/atomic:924:5: warning: inline function
‘void std::atomic_init(std::atomic<_ITp>*, _ITp) [with _ITp = int]’ used but
never defined
     atomic_init(atomic<_ITp>* __a, _ITp __i) noexcept;
     ^
/tmp/ccZgPnay.o: In function `main':
/tmp/at.cc:6: undefined reference to `void
std::atomic_init<int>(std::atomic<int>*, int)'
collect2: error: ld returned 1 exit status
>From gcc-bugs-return-473732-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sun Jan 18 17:24:22 2015
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From: "redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/64658] std::atomic_init() undefined
Date: Sun, 18 Jan 2015 17:24:00 -0000
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X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 4.9.2
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd658

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-01-18
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Although atomic_init doesn't need to be atomic the simplest way to implement it
is just with a relaxed store:

--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -921,11 +921,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION

   template<typename _ITp>
     inline void
-    atomic_init(atomic<_ITp>* __a, _ITp __i) noexcept;
+    atomic_init(atomic<_ITp>* __a, _ITp __i) noexcept
+    { __a->store(__i, memory_order_relaxed); }

   template<typename _ITp>
     inline void
-    atomic_init(volatile atomic<_ITp>* __a, _ITp __i) noexcept;
+    atomic_init(volatile atomic<_ITp>* __a, _ITp __i) noexcept
+    { __a->store(__i, memory_order_relaxed); }

   template<typename _ITp>
     inline void


A better implementation would make atomic_init friend of std::atomic so it can
set the private data member directly.


^ permalink raw reply	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2015-01-27 20:50 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-01-18 17:11 [Bug libstdc++/64658] New: std::atomic_init() undefined redi at gcc dot gnu.org
2015-01-18 17:25 ` [Bug libstdc++/64658] " redi at gcc dot gnu.org
2015-01-20 11:51 ` redi at gcc dot gnu.org
2015-01-27 12:49 ` redi at gcc dot gnu.org
2015-01-27 20:50   ` Jon Chesterfield

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