Code bloat caused by lack of nounwind attr on `drop_in_place`

Hang on, is panicking in Drop actually guaranteed not to unwind? Panicking during unwinding results in an abort, which means panic-in-Drop is ill-advised, but I'm not sure the language has actually ruled it out.

Nothing in

• Panic - The Rust Reference
• Drop in std::ops - Rust
• Destructors - The Rust Reference
• panic in std - Rust

even mentions that panicking while already unwinding results in an abort, let alone that panicking in Drop is always forbidden. Thus, as far as I can tell, panicking in Drop is legal, as long as it never happens in practice while another panic is being processed. (But hopefully I've just missed the appropriate reference!)