Importantly these aren't types they're operations.
So it's not that you have a "release/acquire atomic variable" but you have an atomic variable and it so happens you choose to do a Release store to that variable, in other code maybe you do a Relaxed fetch from the same variable, elsewhere you have a compare exchange with different ordering rules
Since we're talking about Mutex here, here's the entirety of Rust's "try_lock" for Mutex on a Linux-like platform:
That's a single atomic operation, in which we hope the futex is UNLOCKED, if it is we store LOCKED to it with Acquire ordering, but, if it wasn't we use a Relaxed load to find out what it was instead of UNLOCKED.
We actually don't do anything with that load, but the Ordering for both operations is specified here, not when the variable was typed.
So it's not that you have a "release/acquire atomic variable" but you have an atomic variable and it so happens you choose to do a Release store to that variable, in other code maybe you do a Relaxed fetch from the same variable, elsewhere you have a compare exchange with different ordering rules
Since we're talking about Mutex here, here's the entirety of Rust's "try_lock" for Mutex on a Linux-like platform:
That's a single atomic operation, in which we hope the futex is UNLOCKED, if it is we store LOCKED to it with Acquire ordering, but, if it wasn't we use a Relaxed load to find out what it was instead of UNLOCKED.We actually don't do anything with that load, but the Ordering for both operations is specified here, not when the variable was typed.