Short live q23::invoke_r!

Add an implementation of C++23's std::invoke_r. Will need it in our
implementation of function_ref.

Differences to std::invoke_r:

- only constexpr in C++20, not in C++17 (to fix, we'd need to
  implement our own q20::invoke just to add the constexpr keyword;
  let's first see whether we need this).

Task-number: QTBUG-103739
Change-Id: Id864f83f27ed499849b6bde0c34353127e37e7ed
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Andrei Golubev <andrei.golubev@qt.io>

0 files changed, 0 insertions, 0 deletions