std::meta::common_reference

 

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Checking string literals is_string_literal Types info meta::exception access_context data_member_options member_offset operators Concepts reflection_range Promoting to static storage reflect_constant_string reflect_constant_array define_static_string define_static_array define_static_object Operator representations operator_of symbol_of u8symbol_of Names and locations has_identifier identifier_of u8identifier_of display_string_of u8display_string_of source_location_of Reflection queries ➜ Member accessibility queries is_accessible has_inaccessible_nonstatic_   data_members has_inaccessible_bases has_inaccessible_subobjects

Scope identification current_function current_class current_namespace Reflection member queries members_of bases_of static_data_members_of nonstatic_data_members_of      subobjects_of enumerators_of Reflection layout queries offset_of size_of alignment_of bit_size_of Annotation reflection annotations_of annotations_of_with_type Value extraction extract Reflection substitution can_substitute substitute Expression result reflection reflect_constant reflect_object reflect_function Class definition generation data_member_spec is_data_member_spec define_aggregate

Primary type categories is_void_type is_null_pointer_type is_integral_type is_floating_point_type is_array_type is_pointer_type is_lvalue_reference_type is_rvalue_reference_type is_member_object_pointer_type is_member_function_pointer_type      is_enum_type is_union_type is_class_type is_function_type is_reflection_type Composite type categories is_reference_type is_arithmetic_type is_fundamental_type is_object_type is_scalar_type is_compound_type is_member_pointer_type Type properties ➜ Type relations is_same_type is_base_of_type is_virtual_base_of_type is_convertible_type is_nothrow_convertible_type is_layout_compatible_type is_pointer_interconvertible_   base_of_type is_invocable_type is_invocable_r_type is_nothrow_invocable_type is_nothrow_invocable_r_type

Const-volatile modifications remove_const remove_volatile remove_cv add_const add_volatile add_cv Reference modifications remove_reference add_lvalue_reference add_rvalue_reference Sign modifications make_signed make_unsigned Array modifications remove_extent remove_all_extents Pointer modifications remove_pointer add_pointer Other transformations remove_cvref decay common_type common_reference underlying_type invoke_result unwrap_reference unwrap_ref_decay tuple_size tuple_element is_applicable_type is_nothrow_applicable_type apply_result variant_size variant_alternative type_order

 

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Reflection queries type_of object_of constant_of is_public is_protected is_private is_virtual is_pure_virtual is_override is_final is_deleted is_defaulted is_user_provided is_user_declared is_explicit is_noexcept is_bit_field is_enumerator is_annotation is_const is_volatile is_mutable_member is_lvalue_reference_qualified is_rvalue_reference_qualified has_static_storage_duration has_thread_storage_duration has_automatic_storage_duration      has_internal_linkage has_module_linkage has_external_linkage has_linkage has_c_language_linkage is_complete_type is_enumerable_type is_variable is_type is_namespace is_type_alias is_namespace_alias is_function is_conversion_function is_operator_function is_literal_operator is_special_member_function is_destructor

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is_polymorphic_type is_abstract_type is_final_type is_aggregate_type is_structural_type is_signed_type is_unsigned_type is_bounded_array_type is_unbounded_array_type is_scoped_enum_type is_constructible_type is_trivially_constructible_type is_nothrow_constructible_type is_default_constructible_type is_trivially_default_constructible_type is_nothrow_default_constructible_type is_copy_constructible_type is_trivially_copy_constructible_type is_nothrow_copy_constructible_type is_move_constructible_type is_trivially_move_constructible_type is_nothrow_move_constructible_type is_assignable_type is_trivially_assignable_type is_nothrow_assignable_type is_copy_assignable_type is_trivially_copy_assignable_type is_nothrow_copy_assignable_type is_move_assignable_type is_trivially_move_assignable_type is_nothrow_move_assignable_type is_swappable_with_type is_swappable_type is_nothrow_swappable_with_type is_nothrow_swappable_type is_destructible_type is_trivially_destructible_type is_nothrow_destructible_type is_implicit_lifetime_type has_virtual_destructor has_unique_object_representations reference_constructs_from_temporary reference_converts_from_temporary Type property queries rank extent

 

Defined in header <meta>
template< std::meta::reflection_range R = std::initializer_list<std::meta::info> > consteval std::meta::info common_reference( R&& types );		(since C++26)

See More

Let T... be a pack of types or type aliases whose elements are represented by the corresponding elements of types.

Determines the common reference type of a sequence of reflected types T..., that is, the type to which all the types in T... can be converted or bound. If such a type exists (as determined according to the rules for std::common_reference), returns the reflection of that type.

Equivalent to return std::meta::dealias(^^std::common_reference<T...>::type);, except that if the member type is not provided throws std::meta::exception.

When given reference types, common_reference attempts to find a reference type to which the supplied reference types can all be bound, but may return a non-reference type if it cannot find such a reference type.

If any type in the pack T... is not a complete type or (possibly cv-qualified) void, the program is ill-formed.

Parameters

types

-

a range of reflected types

Return value

A reflection of the common (maybe reference) type among all types T..., if such a type exists.

Exceptions

Throws std::meta::exception if

• any reflection in types does not represent a type or type alias;
• no common (reference) type exists, as described above.

Example

Run this code

#include <meta>

static_assert(
    (std::meta::common_reference(
    {
        ^^int&, ^^int&&, ^^const int&, ^^const int&&
    })
    == ^^const int&)
    &&
    (std::meta::common_reference(
    {
        ^^short, ^^int&, ^^int&&, ^^const int&, ^^const int&&
    })
    == ^^int)
);

int main() {}

See also

common_type (C++26)	determines the common type of a sequence of reflected types (function template)
common_reference_with (C++20)	specifies that two types share a common reference type (concept)
common_referencebasic_common_reference (C++20)(C++20)	determines the common reference type of a group of types (class template)