std::is_corresponding_member
From cppreference.com
| Defined in header <type_traits>
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| template< class S1, class S2, class M1, class M2 > constexpr bool is_corresponding_member( M1 S1::* mp, M2 S2::* mq ) noexcept; |
(since C++20) | |
Determines whether mp and mq refer corresponding members in the common initial sequence of S1 and S2. The program is ill-formed if either S1 or S2 is an incomplete type.
If either S1 or S2 is not a StandardLayoutType, or either M1 or M2 is not an object type, or either mp or mq is equal to nullptr, the result is always false.
Parameters
| mp, mq | - | pointers-to-member to detect |
Return value
true if mp and mq refer corresponding members in the common initial sequence of S1 and S2, otherwise false.
Notes
The type of a pointer-to-member expression &S::m is not always M S::*, where m is of type M, because m may be a member inherited from a base class of S. The template arguments can be specified in order to avoid potentially surprising results.
Example
Run this code
#include <type_traits> struct Foo { int x; double d; }; struct Bar { int y; double z; }; struct Baz : Foo, Bar {}; // not standard-layout static_assert( std::is_same_v<decltype(&Baz::x), int Foo::*> == true && std::is_same_v<decltype(&Baz::y), int Bar::*> == true && std::is_corresponding_member(&Foo::x, &Bar::y) == true && std::is_corresponding_member(&Foo::d, &Bar::z) == true && std::is_corresponding_member(&Baz::x, &Baz::y) == true && std::is_corresponding_member<Baz, Baz, int, int>(&Baz::x, &Baz::y) == false ); int main() {}
See also
| (C++11) |
checks if a type is a standard-layout type (class template) |
| (C++20) |
checks if two types are layout-compatible (class template) |
| (C++11) |
checks if a type is a non-static member object pointer (class template) |