[Animats]

Yes. There isn't Rust language support for this.

Order of initialization can be supported at various levels:

- Completely random (OK if interdependence are locked out, otherwise bad)

- Consistent, but sorted by something such as alphabetical name (meh.)

- Manual, controlled in linker scripts (headache)

- True dependency tree order, including diagnosing loops (seen in the Modula family).

General comment: yes, you can, and you probably shouldn't unless you have profiling data that indicates a significant performance improvement for a critical use case.

[ameliaquining]

I think these things are used more for developer experience than for performance, since you can always just do the initialization in main if you really have to.

[Animats]

It's something of an issue if you have some crate that needs to set itself up at load time without a call from main. But those are very rare. Even "simplelog" needs a call at startup to do anything.

[ameliaquining]

Yeah, I think of avoiding the call from main as a devex consideration rather than a performance one, since either way the initialization code runs once at process startup.

[rcxdude]

But it can cause problems when there's multiple crates trying to do it. If the call is explicit, the application developer can sequence the calls appropriately (or at least deterministically), as opposed to having the order determined by details of the implementation (something that was learned from the C++ 'static initialization order fiasco')

[Animats]

I'm trying to think of any useful crate that really uses this. "Tracy", the profiling crate, used to self-start on loading, but that was changed to require a call to get it going.