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Add std::string constructor for substring of string_view (LWG 2742) 

* doc/xml/manual/intro.xml: Document LWG 2742 status.
	* doc/html/*: Regenerate.
	* include/bits/basic_string.h
	(basic_string(const T&, size_type, size_type, const Allocator&)): Add
	constructor for substring of basic_string_view, as per LWG 2742 but
	with additional constraint to fix ambiguity.
	* testsuite/21_strings/basic_string/cons/char/9.cc: New test.
	* testsuite/21_strings/basic_string/cons/wchar_t/9.cc: New test.

From-SVN: r242416
This commit is contained in:
Jonathan Wakely 2016-11-15 14:33:20 +00:00 committed by Jonathan Wakely
parent 8b99f005cb
commit bf56b0b838
6 changed files with 137 additions and 3 deletions
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9
libstdc++-v3/ChangeLog
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@ -1,5 +1,14 @@
2016-11-15 Jonathan Wakely <jwakely@redhat.com>
* doc/xml/manual/intro.xml: Document LWG 2742 status.
* doc/html/*: Regenerate.
* include/bits/basic_string.h
(basic_string(const T&, size_type, size_type, const Allocator&)): Add
constructor for substring of basic_string_view, as per LWG 2742 but
with additional constraint to fix ambiguity.
* testsuite/21_strings/basic_string/cons/char/9.cc: New test.
* testsuite/21_strings/basic_string/cons/wchar_t/9.cc: New test.
* doc/xml/manual/intro.xml: Document LWG 2748 status.
* include/std/optional (optional<T>::swap): Use is_nothrow_swappable_v
for exception specification.

12
libstdc++-v3/doc/html/manual/bugs.html
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@ -496,11 +496,21 @@
</span></dt><dd><p>Avoid using <code class="code">dynamic_cast</code> when it would be
ill-formed.
</p></dd><dt><span class="term"><a class="link" href="../ext/lwg-defects.html#2583" target="_top">2583</a>:
<span class="emphasis"><em>There is no way to supply an allocator for <code class="code"> basic_string(str, pos)</code>
<span class="emphasis"><em>There is no way to supply an allocator for <code class="code">basic_string(str, pos)</code>
</em></span>
</span></dt><dd><p>Add new constructor
</p></dd><dt><span class="term"><a class="link" href="../ext/lwg-defects.html#2684" target="_top">2684</a>:
<span class="emphasis"><em><code class="code">priority_queue</code> lacking comparator typedef
</em></span>
</span></dt><dd><p>Define the <code class="code">value_compare</code> typedef.
</p></dd><dt><span class="term"><a class="link" href="../ext/lwg-defects.html#2742" target="_top">2742</a>:
<span class="emphasis"><em>Inconsistent <code class="code">string</code> interface taking <code class="code">string_view</code>
</em></span>
</span></dt><dd><p>Add the new constructor and additionally constrain it
to avoid ambiguities with non-const <code class="code">charT*</code>.
</p></dd><dt><span class="term"><a class="link" href="../ext/lwg-defects.html#2748" target="_top">2748</a>:
<span class="emphasis"><em>swappable traits for optionals
</em></span>
</span></dt><dd><p>Disable the non-member <code class="code">swap</code> overload when
the contained object is not swappable.
</p></dd></dl></div></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="license.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="status.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="setup.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">License </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 2. Setup</td></tr></table></div></body></html>

8
libstdc++-v3/doc/xml/manual/intro.xml
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@ -1107,6 +1107,14 @@ requirements of the license of GCC.
<listitem><para>Define the <code>value_compare</code> typedef.
</para></listitem></varlistentry>
<varlistentry><term><link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="../ext/lwg-defects.html#2742">2742</link>:
<emphasis>Inconsistent <code>string</code> interface taking <code>string_view</code>
</emphasis>
</term>
<listitem><para>Add the new constructor and additionally constrain it
to avoid ambiguities with non-const <code>charT*</code>.
</para></listitem></varlistentry>
<varlistentry><term><link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="../ext/lwg-defects.html#2748">2748</link>:
<emphasis>swappable traits for optionals
</emphasis>

19
libstdc++-v3/include/bits/basic_string.h
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@ -585,13 +585,28 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
{ _M_construct(__beg, __end); }
#if __cplusplus > 201402L
/**
* @brief Construct string from a substring of a string_view.
* @param __t Source string view.
* @param __pos The index of the first character to copy from __t.
* @param __n The number of characters to copy from __t.
* @param __a Allocator to use.
*/
template<typename _Tp, typename =
_Require<is_convertible<_Tp, __sv_type>,
__not_<is_convertible<const _Tp&, const _CharT*>>>>
basic_string(const _Tp& __t, size_type __pos, size_type __n,
const _Alloc& __a = _Alloc())
: basic_string(__sv_type(__t).substr(__pos, __n), __a) { }
/**
* @brief Construct string from a string_view.
* @param __sv Source string view.
* @param __a Allocator to use (default is default allocator).
*/
explicit basic_string(__sv_type __sv, const _Alloc& __a = _Alloc())
: basic_string(__sv.data(), __sv.size(), __a) {}
explicit
basic_string(__sv_type __sv, const _Alloc& __a = _Alloc())
: basic_string(__sv.data(), __sv.size(), __a) { }
#endif // C++17
/**

46
libstdc++-v3/testsuite/21_strings/basic_string/cons/char/9.cc Normal file
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@ -0,0 +1,46 @@
// Copyright (C) 2016 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++17" }
// { dg-do run { target c++1z } }
#include <string>
#include <testsuite_hooks.h>
void
test01()
{
using C = char;
using string_type = std::basic_string<C>;
using view_type = std::basic_string_view<C>;
std::allocator<C> alloc;
VERIFY( string_type(view_type("string")) == "string" );
VERIFY( string_type(view_type("string"), alloc) == "string" );
// LWG 2742
VERIFY( string_type("substring", 3, 6) == "string" );
VERIFY( string_type("substring", 3, 6, alloc) == "string" );
VERIFY( string_type(view_type("substring"), 3, 6) == "string" );
VERIFY( string_type(view_type("substring"), 3, 6, alloc) == "string" );
}
int
main()
{
test01();
}

46
libstdc++-v3/testsuite/21_strings/basic_string/cons/wchar_t/9.cc Normal file
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@ -0,0 +1,46 @@
// Copyright (C) 2016 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++17" }
// { dg-do run { target c++1z } }
#include <string>
#include <testsuite_hooks.h>
void
test01()
{
using C = wchar_t;
using string_type = std::basic_string<C>;
using view_type = std::basic_string_view<C>;
std::allocator<C> alloc;
VERIFY( string_type(view_type(L"string")) == L"string" );
VERIFY( string_type(view_type(L"string"), alloc) == L"string" );
// LWG 2742
VERIFY( string_type(L"substring", 3, 6) == L"string" );
VERIFY( string_type(L"substring", 3, 6, alloc) == L"string" );
VERIFY( string_type(view_type(L"substring"), 3, 6) == L"string" );
VERIFY( string_type(view_type(L"substring"), 3, 6, alloc) == L"string" );
}
int
main()
{
test01();
}