- Previously, it was possible for a thread migration to occur from core A to core B.
- Next, core B waits on a guest lock that must be released by a thread queued for core A.
- Meanwhile, core A is still waiting on the core B's current thread lock - resulting in a deadlock.
- Fix this by try-locking the thread lock.
- Fixes softlocks in FF8 and Pokemon Legends Arceus.
Given these are only used as function existence checks, we can simplify
some usages of declval, given they aren't particularly useful here.
Reduces a few template instantiations, which at most reduces compile
times a tiny bit.
An identifier containing a starting underscore followed by a capital
letter is reserved by the standard. It's trivial to avoid this by moving
the underscore to the end of the identifier.
While the likelihood of clashing here being minimal, we can turn a
"should not break" scenario into a definitive "will not break" one, so
why not?.
- 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.)