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| author | Patrick Palka <ppalka@redhat.com> | 2024-02-01 14:56:02 -0500 |
|---|---|---|
| committer | Patrick Palka <ppalka@redhat.com> | 2024-02-01 14:56:02 -0500 |
| commit | 87d162383ed68c55311a55784f6b40e979945c00 (patch) | |
| tree | 4e69e6575ae5ad4f05f58516c3e8c6732baf6731 | |
| parent | b14209715e659f6d3ca0f9eef9a4851e7bd6e373 (diff) | |
| download | gcc-87d162383ed68c55311a55784f6b40e979945c00.zip gcc-87d162383ed68c55311a55784f6b40e979945c00.tar.gz gcc-87d162383ed68c55311a55784f6b40e979945c00.tar.bz2 | |
libstdc++/pair: Factor out const-assignability helper for C++20
This is consistent with std::tuple's __const_assignable helper, and will
be useful for implementing the new pair::operator= overloads from P2165R4.
libstdc++-v3/ChangeLog:
* include/bits/stl_pair.h (pair::_S_const_assignable): Define,
factored out from ...
(pair::operator=): ... the constraints of the const overloads.
Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
| -rw-r--r-- | libstdc++-v3/include/bits/stl_pair.h | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/libstdc++-v3/include/bits/stl_pair.h b/libstdc++-v3/include/bits/stl_pair.h index acd0c7b..b81b479 100644 --- a/libstdc++-v3/include/bits/stl_pair.h +++ b/libstdc++-v3/include/bits/stl_pair.h @@ -406,6 +406,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _U1, typename _U2> static constexpr bool + _S_const_assignable() + { + if constexpr (is_assignable_v<const _T1&, _U1>) + return is_assignable_v<const _T2&, _U2>; + return false; + } + + template<typename _U1, typename _U2> + static constexpr bool _S_nothrow_assignable() { if constexpr (is_nothrow_assignable_v<_T1&, _U1>) @@ -468,8 +477,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION /// Copy assignment operator (const) constexpr const pair& operator=(const pair& __p) const - requires is_copy_assignable_v<const first_type> - && is_copy_assignable_v<const second_type> + requires (_S_const_assignable<const first_type&, const second_type&>()) { first = __p.first; second = __p.second; @@ -479,8 +487,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION /// Move assignment operator (const) constexpr const pair& operator=(pair&& __p) const - requires is_assignable_v<const first_type&, first_type> - && is_assignable_v<const second_type&, second_type> + requires (_S_const_assignable<first_type, second_type>()) { first = std::forward<first_type>(__p.first); second = std::forward<second_type>(__p.second); @@ -491,8 +498,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _U1, typename _U2> constexpr const pair& operator=(const pair<_U1, _U2>& __p) const - requires is_assignable_v<const first_type&, const _U1&> - && is_assignable_v<const second_type&, const _U2&> + requires (_S_const_assignable<const _U1&, const _U2&>()) { first = __p.first; second = __p.second; @@ -503,8 +509,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION template<typename _U1, typename _U2> constexpr const pair& operator=(pair<_U1, _U2>&& __p) const - requires is_assignable_v<const first_type&, _U1> - && is_assignable_v<const second_type&, _U2> + requires (_S_const_assignable<_U1, _U2>()) { first = std::forward<_U1>(__p.first); second = std::forward<_U2>(__p.second); |