On 17 January 2013 00:21, Jonathan Wakely wrote:
> This fixes a regression since 4.6 when -Wsystem-headers is used. The
> initialization of the __atomic_flag_base base class has a narrowing
> conversion from int (the macro) to either bool or unsigned char. The
> patch fixes it by calling a constexpr function which implicitly
> converts the value to the return type instead of doing the conversion
> inside a braced-init-list. Doing that requires naming the return
> type, so I defined a new typedef for to avoid duplicating the
> preprocessor conditional. The patch also adds a missing assignment
> operator in atomic<bool>.
>
> PR libstdc++/56012
> * include/bits/atomic_base.h (atomic_flag): Fix narrowing conversion.
> * testsuite/29_atomics/atomic/operators/56012.cc: New.
>
> PR libstdc++/56011
> * include/std/atomic (atomic<bool>::operator=(bool) volatile): Add
> missing overload.
> * testsuite/29_atomics/atomic/operators/56011.cc: New.
>
> Tested x86_64-linux, it's a regression so I want to commit it to the
> trunk and 4.7 branch, any objections from the atomics experts?
Committed to trunk, 4.7 to follow soon.
commit 9f33378b56382e14dce6279d40d44c268de714f8
Author: Jonathan Wakely <jwakely....@gmail.com>
Date: Tue Feb 26 23:40:56 2013 +0000
PR libstdc++/56012
* include/bits/atomic_base.h (atomic_flag): Fix narrowing conversion.
* testsuite/29_atomics/atomic/operators/56012.cc: New.
PR libstdc++/56011
* include/std/atomic (atomic<bool>::operator=(bool) volatile): Add
missing overload.
* testsuite/29_atomics/atomic/operators/56011.cc: New.
diff --git a/libstdc++-v3/include/bits/atomic_base.h
b/libstdc++-v3/include/bits/atomic_base.h
index b44e990..609fe8b 100644
--- a/libstdc++-v3/include/bits/atomic_base.h
+++ b/libstdc++-v3/include/bits/atomic_base.h
@@ -239,6 +239,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
struct atomic<_Tp*>;
+ /* The target's "set" value for test-and-set may not be exactly 1. */
+#if __GCC_ATOMIC_TEST_AND_SET_TRUEVAL == 1
+ typedef bool __atomic_flag_data_type;
+#else
+ typedef unsigned char __atomic_flag_data_type;
+#endif
/**
* @brief Base type for atomic_flag.
@@ -254,12 +260,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
struct __atomic_flag_base
{
- /* The target's "set" value for test-and-set may not be exactly 1. */
-#if __GCC_ATOMIC_TEST_AND_SET_TRUEVAL == 1
- bool _M_i;
-#else
- unsigned char _M_i;
-#endif
+ __atomic_flag_data_type _M_i;
};
_GLIBCXX_END_EXTERN_C
@@ -277,7 +278,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Conversion to ATOMIC_FLAG_INIT.
constexpr atomic_flag(bool __i) noexcept
- : __atomic_flag_base({ __i ? __GCC_ATOMIC_TEST_AND_SET_TRUEVAL : 0 })
+ : __atomic_flag_base{ _S_init(__i) }
{ }
bool
@@ -313,6 +314,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__atomic_clear (&_M_i, __m);
}
+
+ private:
+ static constexpr __atomic_flag_data_type
+ _S_init(bool __i)
+ { return __i ? __GCC_ATOMIC_TEST_AND_SET_TRUEVAL : 0; }
};
diff --git a/libstdc++-v3/include/std/atomic b/libstdc++-v3/include/std/atomic
index 8ed53eb..813f574 100644
--- a/libstdc++-v3/include/std/atomic
+++ b/libstdc++-v3/include/std/atomic
@@ -69,6 +69,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
operator=(bool __i) noexcept
{ return _M_base.operator=(__i); }
+ bool
+ operator=(bool __i) volatile noexcept
+ { return _M_base.operator=(__i); }
+
operator bool() const noexcept
{ return _M_base.load(); }
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic/operators/56011.cc
b/libstdc++-v3/testsuite/29_atomics/atomic/operators/56011.cc
new file mode 100644
index 0000000..1d77a55
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic/operators/56011.cc
@@ -0,0 +1,29 @@
+// { dg-options "-std=gnu++0x" }
+// { dg-do compile }
+
+// Copyright (C) 2013 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <atomic>
+void test01()
+{
+ using namespace std;
+ volatile atomic<bool> ab1 __attribute__((unused));
+ ab1 = true;
+ volatile atomic_bool ab2 __attribute__((unused));
+ ab2 = true;
+}
diff --git a/libstdc++-v3/testsuite/29_atomics/atomic_flag/cons/56012.cc
b/libstdc++-v3/testsuite/29_atomics/atomic_flag/cons/56012.cc
new file mode 100644
index 0000000..64f3b972
--- /dev/null
+++ b/libstdc++-v3/testsuite/29_atomics/atomic_flag/cons/56012.cc
@@ -0,0 +1,26 @@
+// { dg-options "-std=gnu++0x -Wsystem-headers -Wnarrowing" }
+// { dg-do compile }
+
+// Copyright (C) 2013 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3. If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <atomic>
+void test01()
+{
+ using namespace std;
+ atomic_flag af __attribute__((unused)) = ATOMIC_FLAG_INIT;
+}
