This has not been adopted by LEWG/LWG yet, but was submitted
as a proposed resolution for a new LWG issue; optional<const T> can't
current be compared to a T, and an optional<T> can't be compared
to something non-T that is comparable to a T. This approach fixes
both of those problems, allowing optional's comparisons to actually
work like the comparisons of the underlying type.
Tested on Linux-x64.
2017-02-19 Ville Voutilainen <ville.voutilai...@gmail.com>
Make optional's comparisons be two-parameter templates.
* include/std/optional
(operator==(const optional<_Tp>&, const optional<_Tp>&)):
Turn into operator==(const optional<_Tp>&, const optional<_Up>&).
(operator!=(const optional<_Tp>&, const optional<_Tp>&)):
Turn into operator!=(const optional<_Tp>&, const optional<_Up>&).
(operator<(const optional<_Tp>&, const optional<_Tp>&)):
Turn into operator<(const optional<_Tp>&, const optional<_Up>&.
(operator>(const optional<_Tp>&, const optional<_Tp>&)):
Turn into operator>(const optional<_Tp>&, const optional<_Up>&.
(operator<=(const optional<_Tp>&, const optional<_Tp>&)):
Turn into operator<=(const optional<_Tp>&, const optional<_Up>&).
(operator>=(const optional<_Tp>&, const optional<_Tp>&)):
Turn into operator>=(const optional<_Tp>&, const optional<_Up>&).
(operator==(const optional<_Tp>&, const _Tp&)):
Turn into operator==(const optional<_Tp>&, const _Up&).
(operator==(const _Tp&, const optional<_Tp>&)):
Turn into operator==(const _Up&, const optional<_Tp>&).
(operator!=(const optional<_Tp>&, const _Tp&)):
Turn into operator!=(const optional<_Tp>&, const _Up&).
(operator!=(const _Tp&, const optional<_Tp>&)):
Turn into operator!=(const _Up&, const optional<_Tp>&).
(operator<(const optional<_Tp>&, const _Tp&)):
Turn into operator<(const optional<_Tp>&, const _Up&).
(operator<(const _Tp&, const optional<_Tp>&)):
Turn into operator<(const _Up&, const optional<_Tp>&).
(operator>(const optional<_Tp>&, const _Tp&)):
Turn into operator>(const optional<_Tp>&, const _Up&).
(operator>(const _Tp&, const optional<_Tp>&)):
Turn into operator>(const _Up&, const optional<_Tp>&).
(operator<=(const optional<_Tp>&, const _Tp&)):
Turn into operator<=(const optional<_Tp>&, const _Up&).
(operator<=(const _Tp&, const optional<_Tp>&)):
Turn into operator<=(const _Up&, const optional<_Tp>&).
(operator>=(const optional<_Tp>&, const _Tp&)):
Turn into operator>=(const optional<_Tp>&, const _Up&).
(operator>=(const _Tp&, const optional<_Tp>&)):
Turn into operator>=(const _Up&, const optional<_Tp>&).
* testsuite/20_util/optional/relops/7.cc: New.
diff --git a/libstdc++-v3/include/std/optional
b/libstdc++-v3/include/std/optional
index 905bc0a..c700515 100644
--- a/libstdc++-v3/include/std/optional
+++ b/libstdc++-v3/include/std/optional
@@ -737,52 +737,52 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
enable_if_t<is_convertible<_Tp, bool>::value, bool>;
// Comparisons between optional values.
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator==(const optional<_Tp>& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() == declval<_Tp>())>
+ operator==(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() == declval<_Up>())>
{
return static_cast<bool>(__lhs) == static_cast<bool>(__rhs)
&& (!__lhs || *__lhs == *__rhs);
}
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator!=(const optional<_Tp>& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() != declval<_Tp>())>
+ operator!=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() != declval<_Up>())>
{
return static_cast<bool>(__lhs) != static_cast<bool>(__rhs)
|| (static_cast<bool>(__lhs) && *__lhs != *__rhs);
}
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator<(const optional<_Tp>& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() < declval<_Tp>())>
+ operator<(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() < declval<_Up>())>
{
return static_cast<bool>(__rhs) && (!__lhs || *__lhs < *__rhs);
}
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator>(const optional<_Tp>& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() > declval<_Tp>())>
+ operator>(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() > declval<_Up>())>
{
return static_cast<bool>(__lhs) && (!__rhs || *__lhs > *__rhs);
}
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator<=(const optional<_Tp>& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() <= declval<_Tp>())>
+ operator<=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() <= declval<_Up>())>
{
return !__lhs || (static_cast<bool>(__rhs) && *__lhs <= *__rhs);
}
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator>=(const optional<_Tp>& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() >= declval<_Tp>())>
+ operator>=(const optional<_Tp>& __lhs, const optional<_Up>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() >= declval<_Up>())>
{
return !__rhs || (static_cast<bool>(__lhs) && *__lhs >= *__rhs);
}
@@ -849,76 +849,76 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return !__rhs; }
// Comparisons with value type.
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator==(const optional<_Tp>& __lhs, const _Tp& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() == declval<_Tp>())>
+ operator==(const optional<_Tp>& __lhs, const _Up& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() == declval<_Up>())>
{ return __lhs && *__lhs == __rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator==(const _Tp& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() == declval<_Tp>())>
+ operator==(const _Up& __lhs, const optional<_Tp>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Up>() == declval<_Tp>())>
{ return __rhs && __lhs == *__rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator!=(const optional<_Tp>& __lhs, const _Tp& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() != declval<_Tp>())>
+ operator!=(const optional<_Tp>& __lhs, const _Up& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() != declval<_Up>())>
{ return !__lhs || *__lhs != __rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator!=(const _Tp& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() != declval<_Tp>())>
+ operator!=(const _Up& __lhs, const optional<_Tp>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Up>() != declval<_Tp>())>
{ return !__rhs || __lhs != *__rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator<(const optional<_Tp>& __lhs, const _Tp& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() < declval<_Tp>())>
+ operator<(const optional<_Tp>& __lhs, const _Up& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() < declval<_Up>())>
{ return !__lhs || *__lhs < __rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator<(const _Tp& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() < declval<_Tp>())>
+ operator<(const _Up& __lhs, const optional<_Tp>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Up>() < declval<_Tp>())>
{ return __rhs && __lhs < *__rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator>(const optional<_Tp>& __lhs, const _Tp& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() > declval<_Tp>())>
+ operator>(const optional<_Tp>& __lhs, const _Up& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() > declval<_Up>())>
{ return __lhs && *__lhs > __rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator>(const _Tp& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() > declval<_Tp>())>
+ operator>(const _Up& __lhs, const optional<_Tp>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Up>() > declval<_Tp>())>
{ return !__rhs || __lhs > *__rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator<=(const optional<_Tp>& __lhs, const _Tp& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() <= declval<_Tp>())>
+ operator<=(const optional<_Tp>& __lhs, const _Up& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() <= declval<_Up>())>
{ return !__lhs || *__lhs <= __rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator<=(const _Tp& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() <= declval<_Tp>())>
+ operator<=(const _Up& __lhs, const optional<_Tp>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Up>() <= declval<_Tp>())>
{ return __rhs && __lhs <= *__rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator>=(const optional<_Tp>& __lhs, const _Tp& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() >= declval<_Tp>())>
+ operator>=(const optional<_Tp>& __lhs, const _Up& __rhs)
+ -> __optional_relop_t<decltype(declval<_Tp>() >= declval<_Up>())>
{ return __lhs && *__lhs >= __rhs; }
- template<typename _Tp>
+ template<typename _Tp, typename _Up>
constexpr auto
- operator>=(const _Tp& __lhs, const optional<_Tp>& __rhs)
- -> __optional_relop_t<decltype(declval<_Tp>() >= declval<_Tp>())>
+ operator>=(const _Up& __lhs, const optional<_Tp>& __rhs)
+ -> __optional_relop_t<decltype(declval<_Up>() >= declval<_Tp>())>
{ return !__rhs || __lhs >= *__rhs; }
// Swap and creation functions.
diff --git a/libstdc++-v3/testsuite/20_util/optional/relops/7.cc
b/libstdc++-v3/testsuite/20_util/optional/relops/7.cc
new file mode 100644
index 0000000..04b4cda
--- /dev/null
+++ b/libstdc++-v3/testsuite/20_util/optional/relops/7.cc
@@ -0,0 +1,72 @@
+// { dg-options "-std=gnu++17" }
+// { dg-do run }
+
+// 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 <optional>
+#include <testsuite_hooks.h>
+#include <string>
+
+int main()
+{
+ std::optional<int> o = 42;
+ std::optional<const int> o2 = 666;
+ VERIFY(o == 42);
+ VERIFY(o != 43);
+ VERIFY(o < 43);
+ VERIFY(o > 41);
+ VERIFY(o <= 43);
+ VERIFY(o >= 41);
+ VERIFY(o2 == 666);
+ VERIFY(o2 != 667);
+ VERIFY(o2 < 667);
+ VERIFY(o2 > 665);
+ VERIFY(o2 <= 667);
+ VERIFY(o2 >= 665);
+ VERIFY(42 == o);
+ VERIFY(43 != o);
+ VERIFY(41< o);
+ VERIFY(43 > o);
+ VERIFY(41 <= o);
+ VERIFY(43 >= o);
+ VERIFY(666 == o2);
+ VERIFY(667 != o2);
+ VERIFY(665 < o2);
+ VERIFY(667 > o2);
+ VERIFY(665 <= o2);
+ VERIFY(667 >= o2);
+ std::optional<std::string> os = "jones";
+ VERIFY(os == "jones");
+ VERIFY(os != "bones");
+ VERIFY(os < "kones");
+ VERIFY(os > "hones");
+ VERIFY(os <= "kones");
+ VERIFY(os >= "hones");
+ VERIFY("jones" == os);
+ VERIFY("bones" != os);
+ VERIFY("hones" < os);
+ VERIFY("kones" > os);
+ VERIFY("hones" <= os);
+ VERIFY("kones" >= os);
+ std::optional<int> oi = 42;
+ std::optional<long int> ol = 666;
+ VERIFY(!(oi == ol));
+ VERIFY(!(ol == oi));
+ VERIFY(oi != ol);
+ VERIFY(ol != oi);
+}
