PR libstdc++/79162 implement LWG 2946 and LWG 2758

2017-09-04  Daniel Kruegler  <daniel.kruegler@gmail.com>

	PR libstdc++/79162
	Implement LWG 2946, LWG 2758's resolution missed further corrections
	* include/bits/basic_string.h (basic_string::compare): Add missing
	required noexcept specifications.
	(basic_string): Introduce internal _S_to_string_view and __sv_wrapper
	for implicit string_view conversion.
	(basic_string::basic_string): Fix explicit string_view conversion by
	implicit conversion using _S_to_string_view and __sv_wrapper.
	(basic_string): Introduce internal basic_string(__sv_wrapper, Alloc)
	constructor.
	(basic_string): Fix operator=(T) template by operator=(const T&)
	template for uncopyable types (PR 79162).
	(basic_string::operator+=, basic_string::append, basic_string::assign)
	(basic_string::insert, basic_string::replace, basic_string::find)
	(basic_string::rfind, basic_string::find_first_of)
	(basic_string::find_last_of, basic_string::find_first_not_of)
	(basic_string::find_last_not_of, basic_string::compare): Replace
	__sv_type argument by template const T& (LWG 2946) and correct
	documentation describing __sv_type argument.
	(basic_string::find, basic_string::rfind, basic_string::find_first_of)
	(basic_string::find_last_of, basic_string::find_first_not_of)
	(basic_string::find_last_not_of, basic_string::compare): Replace
	unconditional noexcept specification by conditional noexcept
	specification to partially balance the removal of noexcept by LWG 2946.
	* testsuite/21_strings/basic_string/79162.cc: New.
	* testsuite/21_strings/basic_string/lwg2946.cc: New.

From-SVN: r251664

libstdc++-v3/ChangeLog

+2017-09-04  Daniel Kruegler  <daniel.kruegler@gmail.com>
+
+	PR libstdc++/79162
+	Implement LWG 2946, LWG 2758's resolution missed further corrections
+	* include/bits/basic_string.h (basic_string::compare): Add missing
+	required noexcept specifications.
+	(basic_string): Introduce internal _S_to_string_view and __sv_wrapper
+	for implicit string_view conversion.
+	(basic_string::basic_string): Fix explicit string_view conversion by
+	implicit conversion using _S_to_string_view and __sv_wrapper.
+	(basic_string): Introduce internal basic_string(__sv_wrapper, Alloc)
+	constructor.
+	(basic_string): Fix operator=(T) template by operator=(const T&)
+	template for uncopyable types (PR 79162).
+	(basic_string::operator+=, basic_string::append, basic_string::assign)
+	(basic_string::insert, basic_string::replace, basic_string::find)
+	(basic_string::rfind, basic_string::find_first_of)
+	(basic_string::find_last_of, basic_string::find_first_not_of)
+	(basic_string::find_last_not_of, basic_string::compare): Replace
+	__sv_type argument by template const T& (LWG 2946) and correct
+	documentation describing __sv_type argument.
+	(basic_string::find, basic_string::rfind, basic_string::find_first_of)
+	(basic_string::find_last_of, basic_string::find_first_not_of)
+	(basic_string::find_last_not_of, basic_string::compare): Replace
+	unconditional noexcept specification by conditional noexcept
+	specification to partially balance the removal of noexcept by LWG 2946.
+	* testsuite/21_strings/basic_string/79162.cc: New.
+	* testsuite/21_strings/basic_string/lwg2946.cc: New.
+
 2017-08-31  Jonathan Wakely  <jwakely@redhat.com>
 
 	PR c++/82039

libstdc++-v3/testsuite/21_strings/basic_string/79162.cc

+// { dg-options "-std=gnu++17" }
+// { dg-do compile }
+
+// Copyright (C) 2017 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 <string>
+
+template <class DataType>
+class opt : public DataType
+{
+  opt(const opt &) = delete;
+  opt &operator=(const opt &) = delete;
+public:
+  opt() {}
+};
+
+int main()
+{
+  opt<std::string> PGOTestProfileFile;
+  std::string ProfileFileName;
+  ProfileFileName = PGOTestProfileFile;
+}

libstdc++-v3/testsuite/21_strings/basic_string/lwg2946.cc

+// { dg-options "-std=gnu++17" }
+// { dg-do compile }
+
+// Copyright (C) 2017 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 <string>
+
+int main()
+{
+  std::string s({"abc", 1});
+  s = {"abc", 1};
+  s += {"abc", 1};
+  s.append({"abc", 1});
+  s.assign({"abc", 1});
+  s.insert(0, {"abc", 1});
+  s.replace(0, 1, {"abc", 1});
+  s.replace(s.cbegin(), s.cbegin(), {"abc", 1});
+  s.find({"abc", 1});
+  s.rfind({"abc", 1});
+  s.find_first_of({"abc", 1});
+  s.find_last_of({"abc", 1});
+  s.find_first_not_of({"abc", 1});
+  s.find_last_not_of({"abc", 1});
+  s.compare({"abc", 1});
+  s.compare(0, 1, {"abc", 1});
+}