This formats all copyright comments according to SPDX formatting guidelines.
Additionally, this resolves the remaining GPLv2 only licensed files by relicensing them to GPLv2.0-or-later.
- For `std::same_as`, add missing include of `<concepts>`.
- For `std::convertible_to`, create a replacement in `common/concepts.h`
and use that instead.
This would also be found in `<concepts>`, but unlike `std::same_as`,
`std::convertible_to` is not yet implemented in libc++, LLVM's STL
implementation - not even in master. (In fact, `std::same_as` is the
*only* concept currently implemented. For some reason.)
This makes it more inline with its currently unavailable standardized
analogue std::derived_from.
While we're at it, we can also make the template match the requirements
of the standardized variant as well.
* ipc: Allow all trivially copyable objects to be passed directly into WriteBuffer
With the support of C++20, we can use concepts to deduce if a type is an STL container or not.
* More agressive concept for stl containers
* Add -fconcepts
* Move to common namespace
* Add Common::IsBaseOf