Blocked TODO issues

[joshlf]

The following is a list of external issues which appear in TODO(XXX) comments in our code. If you notice that one of these issues has been closed, please comment here in order to notify someone watching this issue, or if you're feeling up to it, search for the matching TODO comment and put up a PR for whatever change was blocked on the issue in question.

• Tracking issue for #![feature(const_precise_live_drops)] rust-lang/rust#73255
• Tracking issue for &mut T in const contexts (const_mut_refs) rust-lang/rust#57349
• Tracking Issue for strict_provenance rust-lang/rust#95228
• Function used in anonymous constant is not considered used rust-lang/rust#104084
• Tracking Issue: Procedural Macro Diagnostics (RFC 1566) rust-lang/rust#54140