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libstdc++: Fix non-default constructors for hash containers [PR101583]

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When I added the new mixin to _Hashtable, I forgot to explicitly
construct it in each non-default constructor. That means you can't
use any constructors unless all three of the hash function, equality
function, and allocator are all default constructible.

libstdc++-v3/ChangeLog:

	PR libstdc++/101583
	* include/bits/hashtable.h (_Hashtable): Replace mixin with
	_Enable_default_ctor. Construct it explicitly in all
	non-forwarding, non-defaulted constructors.
	* testsuite/23_containers/unordered_map/cons/default.cc: Check
	non-default constructors can be used.
	* testsuite/23_containers/unordered_set/cons/default.cc:
	Likewise.

(cherry picked from commit 8ed6cfbbee)
This commit is contained in:
Jonathan Wakely 2021-07-22 18:49:57 +01:00
parent b4c0226e7b
commit 3bf56cdf5e
3 changed files with 41 additions and 5 deletions
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17
libstdc++-v3/include/bits/hashtable.h
View File

@ -54,11 +54,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// from any other potentially-overlapping subobjects of the hashtable.
template<typename _Equal, typename _Hash, typename _Allocator>
using _Hashtable_enable_default_ctor
= _Enable_special_members<__and_<is_default_constructible<_Equal>,
= _Enable_default_constructor<__and_<is_default_constructible<_Equal>,
is_default_constructible<_Hash>,
is_default_constructible<_Allocator>>{},
true, true, true, true, true,
__detail::_Hash_node_base>;
__detail::_Hash_node_base>;
/**
* Primary class template _Hashtable.
@ -228,6 +227,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Equal, _Hash,
_RangeHash, _Unused,
_RehashPolicy, _Traits>;
using __enable_default_ctor
= _Hashtable_enable_default_ctor<_Equal, _Hash, _Alloc>;
public:
typedef _Key key_type;
@ -482,7 +483,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
_Hashtable(const _Hash& __h, const _Equal& __eq,
const allocator_type& __a)
: __hashtable_base(__h, __eq),
__hashtable_alloc(__node_alloc_type(__a))
__hashtable_alloc(__node_alloc_type(__a)),
__enable_default_ctor(_Enable_default_constructor_tag{})
{ }
template<bool _No_realloc = true>
@ -549,7 +551,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
explicit
_Hashtable(const allocator_type& __a)
: __hashtable_alloc(__node_alloc_type(__a))
: __hashtable_alloc(__node_alloc_type(__a)),
__enable_default_ctor(_Enable_default_constructor_tag{})
{ }
template<typename _InputIterator>
@ -1407,6 +1410,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__rehash_base(__ht),
__hashtable_alloc(
__node_alloc_traits::_S_select_on_copy(__ht._M_node_allocator())),
__enable_default_ctor(__ht),
_M_buckets(nullptr),
_M_bucket_count(__ht._M_bucket_count),
_M_element_count(__ht._M_element_count),
@ -1429,6 +1433,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__map_base(__ht),
__rehash_base(__ht),
__hashtable_alloc(std::move(__a)),
__enable_default_ctor(__ht),
_M_buckets(__ht._M_buckets),
_M_bucket_count(__ht._M_bucket_count),
_M_before_begin(__ht._M_before_begin._M_nxt),
@ -1459,6 +1464,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__map_base(__ht),
__rehash_base(__ht),
__hashtable_alloc(__node_alloc_type(__a)),
__enable_default_ctor(__ht),
_M_buckets(),
_M_bucket_count(__ht._M_bucket_count),
_M_element_count(__ht._M_element_count),
@ -1480,6 +1486,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
__map_base(__ht),
__rehash_base(__ht),
__hashtable_alloc(std::move(__a)),
__enable_default_ctor(__ht),
_M_buckets(nullptr),
_M_bucket_count(__ht._M_bucket_count),
_M_element_count(__ht._M_element_count),

15
libstdc++-v3/testsuite/23_containers/unordered_map/cons/default.cc
View File

@ -31,3 +31,18 @@ static_assert( ! std::is_default_constructible<Map2>{}, "PR libstdc++/100863" );
struct Equal : std::equal_to<int> { Equal(int) { } };
using Map3 = std::unordered_map<int, int, std::hash<int>, Equal>;
static_assert( ! std::is_default_constructible<Map3>{}, "PR libstdc++/100863" );
// PR libstdc++/101583
// verify non-default ctors can still be used
using Map4 = std::unordered_map<int, int, Hash, Equal,
NoDefaultConsAlloc<std::pair<const int, int>>>;
Hash h(1);
Equal eq(1);
Map4::allocator_type a(1);
Map4 m{1, h, eq, a};
Map4 m2{m.begin(), m.end(), m.size(), h, eq, a};
Map4 m3{{{1,1}, {2,2}, {3,3}}, 3, h, eq, a};
Map4 m4{m};
Map4 m5{m, a};
Map4 m6{std::move(m)};
Map4 m7{std::move(m6), a};

14
libstdc++-v3/testsuite/23_containers/unordered_set/cons/default.cc
View File

@ -31,3 +31,17 @@ static_assert( ! std::is_default_constructible<Set2>{}, "PR libstdc++/100863" );
struct Equal : std::equal_to<int> { Equal(int) { } };
using Set3 = std::unordered_set<int, std::hash<int>, Equal>;
static_assert( ! std::is_default_constructible<Set3>{}, "PR libstdc++/100863" );
// PR libstdc++/101583
// verify non-default ctors can still be used
using Set4 = std::unordered_set<int, Hash, Equal, NoDefaultConsAlloc<int>>;
Hash h(1);
Equal eq(1);
Set4::allocator_type a(1);
Set4 s{1, h, eq, a};
Set4 s2{s.begin(), s.end(), s.size(), h, eq, a};
Set4 s3{{1, 2, 3}, 3, h, eq, a};
Set4 s4{s};
Set4 s5{s, a};
Set4 s6{std::move(s)};
Set4 s7{std::move(s6), a};