On 28/12/14 13:47 +0100, Eelis wrote:
On 2014-12-28 00:18, Eelis wrote:
Trivial fix attached.
Please don't commit this patch.
I just noticed that the assignability test is wrong in an additional way: it
should look at assignability of /output/ elements, not /input/ elements.
As a result, this code is currently rejected (because uninitialized_copy
doesn't notice in time that chars can't be assigned to Xs):
struct X
{
X() = default;
X(char) {}
X(X const &) = default;
X & operator=(X const&) = default;
X & operator=(char) = delete;
};
#include <memory>
int main()
{
char a[100];
X b[100];
std::uninitialized_copy(a, a+10, b);
}
Updated fix attached. With it, the code is accepted again. Testing as we speak.
Index: stl_uninitialized.h
===================================================================
--- stl_uninitialized.h (revision 219070)
+++ stl_uninitialized.h (working copy)
@@ -104,30 +104,30 @@
*/
template<typename _InputIterator, typename _ForwardIterator>
inline _ForwardIterator
uninitialized_copy(_InputIterator __first, _InputIterator __last,
_ForwardIterator __result)
{
typedef typename iterator_traits<_InputIterator>::value_type
_ValueType1;
typedef typename iterator_traits<_ForwardIterator>::value_type
_ValueType2;
#if __cplusplus < 201103L
const bool __assignable = true;
#else
// trivial types can have deleted assignment
- typedef typename iterator_traits<_InputIterator>::reference _RefType;
- const bool __assignable = is_assignable<_ValueType1, _RefType>::value;
+ typedef typename iterator_traits<_ForwardIterator>::reference _RefType;
+ const bool __assignable = is_assignable<_RefType, _ValueType1>::value;
#endif
This is still wrong, because it tests for assigning an rvalue to the
result sequence, but dereferencing the _InputIterator doesn't
necessarily produce an rvalue, and the output type might behave
differently for assignment from lvalues and rvalues.
My first attempt to fix it was simply:
#else
// trivial types can have deleted assignment
typedef typename iterator_traits<_InputIterator>::reference _RefType;
- const bool __assignable = is_assignable<_ValueType1, _RefType>::value;
+ const bool __assignable = is_assignable<_ValueType2, _RefType>::value;
#endif
But even that is wrong if the target type has a ref-qualified
assignment from the source type. The attached patch should be correct.
Tested x86_64-linux, committed to trunk and 4.9.
commit 8ba322dd71cca830b3641002b4c1bf132f195741
Author: Jonathan Wakely <jwak...@redhat.com>
Date: Fri Jan 9 15:51:20 2015 +0000
PR libstdc++/64476
* include/bits/stl_uninitialized.h (uninitialized_copy): Fix
is_assignable arguments.
* testsuite/20_util/specialized_algorithms/uninitialized_copy/64476.cc:
New.
diff --git a/libstdc++-v3/include/bits/stl_uninitialized.h b/libstdc++-v3/include/bits/stl_uninitialized.h
index 00659e9..61a1561 100644
--- a/libstdc++-v3/include/bits/stl_uninitialized.h
+++ b/libstdc++-v3/include/bits/stl_uninitialized.h
@@ -115,8 +115,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
const bool __assignable = true;
#else
// trivial types can have deleted assignment
- typedef typename iterator_traits<_InputIterator>::reference _RefType;
- const bool __assignable = is_assignable<_ValueType1, _RefType>::value;
+ typedef typename iterator_traits<_InputIterator>::reference _RefType1;
+ typedef typename iterator_traits<_ForwardIterator>::reference _RefType2;
+ const bool __assignable = is_assignable<_RefType2, _RefType1>::value;
#endif
return std::__uninitialized_copy<__is_trivial(_ValueType1)
diff --git a/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/64476.cc b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/64476.cc
new file mode 100644
index 0000000..6369b17
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/specialized_algorithms/uninitialized_copy/64476.cc
@@ -0,0 +1,65 @@
+// Copyright (C) 2015 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/>.
+
+// { dg-options "-std=gnu++11" }
+
+#include <memory>
+#include <testsuite_hooks.h>
+
+struct X
+{
+ X() = default;
+ X(X const &) = default;
+ X& operator=(X const&) = delete;
+};
+
+static_assert(__is_trivial(X), "X is trivial");
+
+int constructed = 0;
+int assigned = 0;
+
+struct Y
+{
+ Y() = default;
+ Y(Y const &) = default;
+ Y& operator=(Y const&) = default;
+
+ Y(const X&) { ++constructed; }
+ Y& operator=(const X&)& { ++assigned; return *this; }
+ Y& operator=(const X&)&& = delete;
+ Y& operator=(X&&) = delete;
+};
+
+static_assert(__is_trivial(Y), "Y is trivial");
+
+void
+test01()
+{
+ X a[100];
+ Y b[100];
+
+ std::uninitialized_copy(a, a+10, b);
+
+ VERIFY(constructed == 0);
+ VERIFY(assigned == 10);
+}
+
+int
+main()
+{
+ test01();
+}
