Determine whether t_TYPE is a recognized bsl::variant tag type.

Synopsis

Declared in <bslstl_variant.h>

template<class t_TYPE>
struct Variant_IsTag
    : bsl::false_type

Description

This component‐private metafunction derives from bsl::true_type if (template parameter) t_TYPE is one of the recognized bsl::variant tag types, and from bsl::false_type otherwise.

This metafunction requires any cv and ref qualifications to be removed from the queried type.

Base Classes

Name

Description

bsl::false_type

Metafunction representing the boolean constant false.

Specializations

Name

Description

Variant_IsTag<std::allocator_arg_t>

This explicit specialization derives from bsl::true_type for the bsl::allocator_arg_t tag type.

Variant_IsTag<bsl::in_place_index_t<t_INDEX>>

This partial specialization derives from bsl::true_type for any specialization of the bsl::in_place_index_t tag type.

Variant_IsTag<bsl::in_place_type_t<t_TYPE>>

This partial specialization derives from bsl::true_type for any specialization of the bsl::in_place_type_t tag type.

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