compiler_fence does not cause a panic but a compilation error

[CatCode79]

Location (URL)

https://doc.rust-lang.org/std/sync/atomic/fn.compiler_fence.html

Summary

Halfway through the page it says ‘Panics if order is Relaxed’, but since compiler_fence is, as the name suggests, evaluated at compile time, it seemed strange to me.
In fact, I quickly checked with the line:
compiler_fence(Ordering::Relaxed);

and got a compilation error:
error: memory fences cannot have Relaxed ordering
--> src\main.rs:34:20
|
34 | compiler_fence(Ordering::Relaxed);
| ^^^^^^^^^^^^^^^^^
|
= help: consider using ordering modes Acquire, Release, AcqRel or SeqCst
= note: #[deny(invalid_atomic_ordering)] on by default

[CatCode79]

Sorry, I’m being stupid, I hadn’t considered that the ordering can be passed at runtime. I’m still surprised that the function isn’t const or that there isn’t a more aggressive constant evaluation.