Do we want to codegen pointer-providence-related casts differently?

[tedinski]

In codegen_rvalue we used to handle two kinds of Rvalue::Cast: CastKind::Misc and CastKind::Pointer

Rust introduced in a couple PRs new variants that distinguish (from CastKind::Misc) casts that turn pointers into numbers or vice versa. This is likely due to the need to think specially about these, since they need to invent (or forget) pointer providence.

We currently do not take advantage of this. Should we?

Rust PRs:

• Add a pointer to address cast kind rust-lang/rust#97582
• add cast kind of from_exposed_addr (int-to-ptr casts) rust-lang/rust#97653

[tedinski]

I believe this got further broken out in a later rust toolchain update, and CastKind:Misc no longer exists, in favor of recording explicit kinds for everything. I don't think there's anything special to do here anymore. If we should be handling this differently, it'd be a different issue to support a specific aim.