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libstdc++: Simplify noexcept-specifiers for move constructors

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This puts the logic for the noexcept-specifier in one place, and then
reuses it elsewhere. This means checking whether the move constructor
can throw doesn't need to do overload resolution and then check whether
some other constructor can throw, we just get the answer directly.

libstdc++-v3/ChangeLog:

	* include/bits/hashtable.h (_Hashtable::_S_nothrow_move()):
	New function to determine noexcept-specifier for move
	constructors.
	(_Hashtable): Use _S_nothrow_move() on move constructors.
	* testsuite/23_containers/unordered_map/cons/noexcept_move_construct.cc:
	Correct static assertion message.
	* testsuite/23_containers/unordered_multimap/cons/noexcept_move_construct.cc:
	Likewise.
	* testsuite/23_containers/unordered_multiset/cons/noexcept_move_construct.cc:
	Likewise.
	* testsuite/23_containers/unordered_set/cons/noexcept_move_construct.cc:
	Likewise.
This commit is contained in:
Jonathan Wakely 2021-04-08 16:29:11 +01:00
parent 59d09f9fe4
commit 1cbba49e34
5 changed files with 22 additions and 20 deletions
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26
libstdc++-v3/include/bits/hashtable.h
View File

@ -472,10 +472,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__hashtable_alloc(__node_alloc_type(__a))
{ }
template<bool _No_realloc = true>
static constexpr bool
_S_nothrow_move()
{
if _GLIBCXX17_CONSTEXPR (_No_realloc)
if _GLIBCXX17_CONSTEXPR (is_nothrow_copy_constructible<_Hash>())
return is_nothrow_copy_constructible<_Equal>();
return false;
}
_Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
true_type /* alloc always equal */)
noexcept(std::is_nothrow_copy_constructible<_Hash>::value &&
std::is_nothrow_copy_constructible<_Equal>::value);
noexcept(_S_nothrow_move());
_Hashtable(_Hashtable&&, __node_alloc_type&&,
false_type /* alloc always equal */);
@ -508,19 +517,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Use delegating constructors.
_Hashtable(_Hashtable&& __ht)
noexcept( noexcept(
_Hashtable(std::declval<_Hashtable>(),
std::declval<__node_alloc_type>(),
true_type{})) )
noexcept(_S_nothrow_move())
: _Hashtable(std::move(__ht), std::move(__ht._M_node_allocator()),
true_type{})
{ }
_Hashtable(_Hashtable&& __ht, const allocator_type& __a)
noexcept( noexcept(
_Hashtable(std::declval<_Hashtable>(),
std::declval<__node_alloc_type>(),
typename __node_alloc_traits::is_always_equal{})) )
noexcept(_S_nothrow_move<__node_alloc_traits::_S_always_equal()>())
: _Hashtable(std::move(__ht), __node_alloc_type(__a),
typename __node_alloc_traits::is_always_equal{})
{ }
@ -1400,8 +1403,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Hash, _RangeHash, _Unused, _RehashPolicy, _Traits>::
_Hashtable(_Hashtable&& __ht, __node_alloc_type&& __a,
true_type /* alloc always equal */)
noexcept(std::is_nothrow_copy_constructible<_Hash>::value &&
std::is_nothrow_copy_constructible<_Equal>::value)
noexcept(_S_nothrow_move())
: __hashtable_base(__ht),
__map_base(__ht),
__rehash_base(__ht),

4
libstdc++-v3/testsuite/23_containers/unordered_map/cons/noexcept_move_construct.cc
View File

@ -40,7 +40,7 @@ struct not_noexcept_copy_cons_hash
using type2 = std::unordered_map<int, int, not_noexcept_copy_cons_hash>;
static_assert( !std::is_nothrow_move_constructible<type2>::value,
"noexcept move constructor" );
"not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type2, type2&&,
const typename type2::allocator_type&>::value,
"not noexcept move constructor with allocator" );
@ -59,7 +59,7 @@ using type3 = std::unordered_map<int, int, std::hash<int>,
not_noexcept_copy_cons_equal_to>;
static_assert( !std::is_nothrow_move_constructible<type3>::value,
"noexcept move constructor" );
"not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type3, type3&&,
const typename type3::allocator_type&>::value,
"not noexcept move constructor with allocator" );

4
libstdc++-v3/testsuite/23_containers/unordered_multimap/cons/noexcept_move_construct.cc
View File

@ -40,7 +40,7 @@ struct not_noexcept_copy_cons_hash
using type2 = std::unordered_multimap<int, int, not_noexcept_copy_cons_hash>;
static_assert( !std::is_nothrow_move_constructible<type2>::value,
"noexcept move constructor" );
"not not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type2, type2&&,
const typename type2::allocator_type&>::value,
"not noexcept move constructor with allocator" );
@ -59,7 +59,7 @@ using type3 = std::unordered_multimap<int, int, std::hash<int>,
not_noexcept_copy_cons_equal_to>;
static_assert( !std::is_nothrow_move_constructible<type3>::value,
"noexcept move constructor" );
"not not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type3, type3&&,
const typename type3::allocator_type&>::value,
"not noexcept move constructor with allocator" );

4
libstdc++-v3/testsuite/23_containers/unordered_multiset/cons/noexcept_move_construct.cc
View File

@ -40,7 +40,7 @@ struct not_noexcept_copy_cons_hash
using type2 = std::unordered_multiset<int, not_noexcept_copy_cons_hash>;
static_assert( !std::is_nothrow_move_constructible<type2>::value,
"noexcept move constructor" );
"not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type2, type2&&,
const typename type2::allocator_type&>::value,
"not noexcept move constructor with allocator" );
@ -59,7 +59,7 @@ using type3 = std::unordered_multiset<int, std::hash<int>,
not_noexcept_copy_cons_equal_to>;
static_assert( !std::is_nothrow_move_constructible<type3>::value,
"noexcept move constructor" );
"not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type3, type3&&,
const typename type3::allocator_type&>::value,
"not noexcept move constructor with allocator" );

4
libstdc++-v3/testsuite/23_containers/unordered_set/cons/noexcept_move_construct.cc
View File

@ -40,7 +40,7 @@ struct not_noexcept_copy_cons_hash
using type2 = std::unordered_set<int, not_noexcept_copy_cons_hash>;
static_assert( !std::is_nothrow_move_constructible<type2>::value,
"noexcept move constructor" );
"not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type2, type2&&,
const typename type2::allocator_type&>::value,
"not noexcept move constructor with allocator" );
@ -59,7 +59,7 @@ using type3 = std::unordered_set<int, std::hash<int>,
not_noexcept_copy_cons_equal_to>;
static_assert( !std::is_nothrow_move_constructible<type3>::value,
"noexcept move constructor" );
"not noexcept move constructor" );
static_assert( !std::is_nothrow_constructible<type3, type3&&,
const typename type3::allocator_type&>::value,
"not noexcept move constructor with allocator" );