* testsuite/20_util/variant/compile.cc: Fix narrowing test for ILP32
targets. Add more cases from P0608R3.
* testsuite/20_util/variant/run.cc: Add more cases from P0608R3.
From-SVN: r271325
* include/std/variant (__overload_set): Remove.
(_Arr): New helper.
(_Build_FUN): New class template to define a single FUN overload,
with specializations to prevent unwanted conversions, as per P0608R3.
(_Build_FUNs): New class template to build an overload set of FUN.
(_FUN_type): New alias template to perform overload resolution.
(__accepted_type): Use integer_constant base for failure case. Use
_FUN_type for successful case.
(variant::__accepted_index): Use _Tp instead of _Tp&&.
(variant::variant(_Tp&&)): Likewise.
(variant::operator=(_Tp&&)): Likewise.
From-SVN: r271296
The std::variant move assignment operator should not be trivial if the
variant is not trivially move constructible.
* include/std/variant (__detail::__variant::_Traits): Make
_S_trivial_copy_assign depend on _S_trivial_copy_ctor and make
_S_trivial_move_assign depend on _S_trivial_move_ctor, as per
P0602R4.
(__detail::__variant::_Copy_assign_alias): Only depend on
_S_trivial_copy_assign, which subsumes _S_trivial_copy_ctor now.
* testsuite/20_util/variant/compile.cc: Correct checks for trivial
move assignment operators.
From-SVN: r270510
Also refactor some constraints slightly to be more readable.
PR libstdc++/90165
* include/std/variant (variant::__not_self): New helper for the
is_same_v<remove_cvref_t<T>, variant>==false constraints.
(variant::__to_type_impl): Remove.
(variant::__to_type): Add default argument to check pack size, instead
of using __to_type_impl.
(variant::__accepted_type): Add default argument using __not_self.
(variant::__is_in_place_tag, variant::__not_in_place_tag): New helpers
for variant(T&&) constructor constraint.
(variant::variant(T&&)): Use __not_in_place_tag in constraints.
Extract __accepted_type into a named template parameter for reuse in
other constraints and in the exception specification.
(variant::variant(in_place_type_t<T>, Args&&...))
(variant::variant(in_place_type_t<T>, initializer_list<U>, Args&&...))
(variant::variant(in_place_index_t<T>, Args&&...))
(variant::variant(in_place_index_t<T>, initializer_list<U>, Args&&...))
(variant::operator=T&&)): Remove redundant && from trait arguments.
* testsuite/20_util/variant/compile.cc: Check variant(T&&) constructor
isn't used for in_place_type or in_place_index arguments.
From-SVN: r270509
A regression was introduced by the recent changes to provide the strong
exception safety guarantee for "never valueless" types that have O(1),
non-throwing move assignment. The problematic code is:
else if constexpr (__detail::__variant::_Never_valueless_alt<type>())
{
// This construction might throw:
variant __tmp(in_place_index<_Np>, __il,
std::forward<_Args>(__args)...);
// But _Never_valueless_alt<type> means this won't:
*this = std::move(__tmp);
}
When the variant is not assignable, the assignment is ill-formed, so
should not be attempted. When the variant has a copy assignment operator
but not a move assignment operator, the assignment performs a copy
assignment and that could throw, so should not be attempted.
The solution is to only take that branch when the variant has a move
assignment operator, which is determined by the _Traits::_S_move_assign
constant. When that is false the strong exception safety guarantee is
not possible, and so the __never_valueless function should also depend
on _S_move_assign.
While testing the fixes for this I noticed that the partial
specialization _Never_valueless_alt<basic_string<C,T,A>> incorrectly
assumed that is_nothrow_move_constructible<basic_string<C,T,A>> is
always true, but that's wrong for fully-dynamic COW strings. Fix the
partial specialization, and improve the comment describing
_Never_valueless_alt to be clear it depends on move construction as well
as move assignment.
Finally, I also observed that _Variant_storage<false, T...>::_M_valid()
was not taking advantage of the __never_valueless<T...>() function to
avoid a runtime check. Only the _Variant_storage<true, T...>::_M_valid()
function was using __never_valueless. That is also fixed.
PR libstdc++/87431
* include/bits/basic_string.h (_Never_valueless_alt): Make partial
specialization also depend on is_nothrow_move_constructible.
* include/std/variant (__detail::__variant::__never_valueless()):
Only true if the variant would have a move assignment operator.
(__detail::__variant::_Variant_storage<false, T...>::_M_valid()):
Check __never_valueless<T...>().
(variant::emplace): Only perform non-throwing move assignments
for never-valueless alternatives if the variant has a move assignment
operator.
* testsuite/20_util/variant/compile.cc: Check that never-valueless
types can be emplaced into non-assignable variants.
* testsuite/20_util/variant/run.cc: Check that never-valueless types
don't get copied when emplaced into non-assignable variants.
From-SVN: r270502
The standard says the std::variant copy constructor is defined as
deleted unless all alternative types are copy constructible, but we were
making it also depend on move constructible. Fix the condition and
enhance the tests to check the semantics with pathological copy-only
types (i.e. supporting copying but having deleted moves).
The enhanced tests revealed a regression in copy assignment for
non-trivial alternative types, where the assignment would not be
performed because the condition in the _Copy_assign_base visitor is
false: is_same_v<remove_reference_t<T&>, remove_reference_t<const T&>>.
* include/std/variant (__detail::__variant::_Traits::_S_copy_assign):
Do not depend on whether all alternative types are move constructible.
(__detail::__variant::_Copy_assign_base::operator=): Remove cv-quals
from the operand when deciding whether to perform the assignment.
* testsuite/20_util/variant/compile.cc (DeletedMoves): Define type
with deleted move constructor and deleted move assignment operator.
(default_ctor, copy_ctor, move_ctor, copy_assign, move_assign): Check
behaviour of variants with DeletedMoves as an alternative.
* testsuite/20_util/variant/run.cc (DeletedMoves): Define same type.
(move_ctor, move_assign): Check that moving a variant with a
DeletedMoves alternative falls back to copying instead of moving.
From-SVN: r270425
The string literal is optional in C++17 and all these are empty so add
no value.
* testsuite/20_util/variant/compile.cc: Remove empty string literals
from static_assert declarations.
From-SVN: r270424
* testsuite/20_util/variant/compile.cc (MoveCtorOnly): Fix type to
actually match its name.
(MoveCtorAndSwapOnly): Define new type that adds swap to MoveCtorOnly.
(test_swap()): Fix result for MoveCtorOnly and check
MoveCtorAndSwapOnly.
From-SVN: r270423
* include/std/variant (__do_visit): New.
(__variant_cast): Likewise.
(__variant_cookie): Likewise.
(__erased_*): Remove.
(_Variant_storage::_S_vtable): Likewise.
(_Variant_storage::__M_reset_impl): Adjust to use __do_visit.
(_Variant_storage::__M_reset): Adjust.
(__variant_construct): New.
(_Copy_ctor_base(const _Copy_ctor_base&)): Adjust to use
__variant_construct.
(_Move_ctor_base(_Move_ctor_base&&)): Likewise.
(_Move_ctor_base::__M_destructive_copy): New.
(_Move_ctor_base::__M_destructive_move): Adjust to use
__variant_construct.
(_Copy_assign_base::operator=): Adjust to use __do_visit.
(_Copy_assign_alias): Adjust to check both copy assignment
and copy construction for triviality.
(_Move_assign_base::operator=): Adjust to use __do_visit.
(_Multi_array): Add support for visitors that accept and return
a __variant_cookie.
(__gen_vtable_impl::_S_apply_all_alts): Likewise.
(__gen_vtable_impl::_S_apply_single_alt): Likewise.
(__gen_vtable_impl::__element_by_index_or_cookie): New. Generate
a __variant_cookie temporary for a variant that is valueless and..
(__gen_vtable_impl::__visit_invoke): ..adjust here.
(__gen_vtable::_Array_type): Conditionally make space for
the __variant_cookie visitor case.
(__variant_construct_by_index): New.
(get_if): Adjust to use std::addressof.
(relops): Adjust to use __do_visit.
(variant): Add __variant_cast and __variant_construct_by_index
as friends.
(variant::emplace): Use _M_reset() and __variant_construct_by_index
instead of self-destruction.
(variant::swap): Adjust to use __do_visit.
(visit): Reimplement in terms of __do_visit.
(__variant_hash_call_base_impl::operator()): Adjust to use __do_visit.
* testsuite/20_util/variant/compile.cc: Adjust.
* testsuite/20_util/variant/run.cc: Likewise.
From-SVN: r269422
PR libstdc++/80187
* include/std/variant (variant::variant, variant::~variant,
variant::operator=): Implement triviality forwarding for four
special member functions.
* testsuite/20_util/variant/compile.cc: Tests.
From-SVN: r249706
* include/std/variant (visit): Make visit constexpr. Also cleanup
__get_alternative and __storage, since we don't support reference/void
alternatives any more.
* testsuite/20_util/variant/compile.cc: Add tests.
From-SVN: r243295
* include/std/variant: Remove variant<T&>, variant<void>, variant<> support
to rebase on the post-Issaquah design.
* testsuite/20_util/variant/compile.cc: Likewise.
From-SVN: r242437
Implement P0504R0 (Revisiting in-place tag types for
any/optional/variant).
* include/std/any (any(_ValueType&& __value)): Constrain
the __is_in_place_type with the decayed type.
(make_any): Adjust to use the new tag type.
* include/std/utility (in_place_tag): Remove.
(in_place_t): Turn into a non-reference tag type.
(__in_place, __in_place_type, __in_place_index): Remove.
(in_place): Turn into an inline variable of non-reference
tag type.
(in_place<_Tp>): Remove.
(in_place_index<_Idx>): Remove.
(in_place_type_t): New.
(in_place_type): Turn into a variable template of non-reference
type.
(in_place_index_t): New.
(in_place_index): Turn into a variable template of non-reference
type.
* include/std/variant
(_Variant_storage(in_place_index_t<_Np>, _Args&&...)): Adjust to
use the new tag type.
(_Union(in_place_index_t<0>, _Args&&...)): Likewise.
(_Union(in_place_index_t<_Np>, _Args&&...)): Likewise.
(_Variant_base()): Likewise.
(variant(_Tp&&)): Likewise.
(variant(in_place_type_t<_Tp>, _Args&&...)): Likewise.
(variant(in_place_type_t<_Tp>, initializer_list<_Up>,
_Args&&...)): Likewise.
(variant(in_place_index_t<_Np>, _Args&&...)): Likewise.
(variant(in_place_index_t<_Np>, initializer_list<_Up>,
_Args&&...)): Likewise
(variant(allocator_arg_t, const _Alloc&)): Likewise.
(variant(allocator_arg_t, const _Alloc&, _Tp&&)): Likewise.
(variant(allocator_arg_t, const _Alloc&, in_place_type_t<_Tp>,
_Args&&...)): Likewise.
(variant(allocator_arg_t, const _Alloc&, in_place_type_t<_Tp>,
initializer_list<_Up>, _Args&&...)): Likewise.
(variant(allocator_arg_t, const _Alloc&, in_place_index_t<_Np>,
_Args&&...)): Likewise.
(variant(allocator_arg_t, const _Alloc&, in_place_index_t<_Np>,
initializer_list<_Up>, _Args&&...)): Likewise.
(emplace(_Args&&...)): Likewise.
(emplace(initializer_list<_Up>, _Args&&...)): Likewise.
* testsuite/20_util/any/cons/explicit.cc: Likewise.
* testsuite/20_util/any/cons/in_place.cc: Likewise.
* testsuite/20_util/any/requirements.cc: Add tests to
check that any is not constructible from the new in_place_type_t
of any value category.
* testsuite/20_util/in_place/requirements.cc: Adjust to
use the new tag type.
* testsuite/20_util/variant/compile.cc: Likewise.
* testsuite/20_util/variant/run.cc: Likewise.
From-SVN: r242401
* call.c (build_user_type_conversion_1): Consider conversions from
a single element in an initializer-list.
(build_temp): Undo early_elide_copy change.
(build_over_call): Check that we don't try to copy a TARGET_EXPR
in C++17 mode. Set user_conv_p here.
(convert_like_real): Not here.
(check_self_delegation): Split out from...
(build_special_member_call): ...here. Handle C++17 copy elision.
* cvt.c (early_elide_copy): Remove.
(ocp_convert): Undo early_elide_copy change.
* except.c (build_throw): Likewise.
* init.c (expand_default_init): Likewise.
* typeck.c (cp_build_modify_expr): Likewise.
From-SVN: r240889
PR libstdc++/77641
* include/std/variant (_Variant_storage::_Variant_storage):
Change _Variant_storage's union to be default constructible.
* testsuite/20_util/variant/compile.cc: New test.
From-SVN: r240340
* include/Makefile.am: Add new file std/variant.
* include/Makefile.in: Generated from Makefile.am.
* include/bits/enable_special_members.h: Add a tag type to allow
the construction in non-default constructor.
* include/bits/uses_allocator.h: Add convenience traits to
detect constructibility.
* include/std/variant: Implement <variant>.
* testsuite/20_util/variant/compile.cc: Compile-time tests.
* testsuite/20_util/variant/run.cc: Runtime tests.
From-SVN: r239590
Jakub Jelinek
Jonathan Wakely
Ville Voutilainen
Paolo Carlini
Tim Shen
Jason Merrill
Jonathan Wakely