f1a677789a
Fix soundness issue in scoped threads. This was discovered in https://github.com/rust-lang/rust/pull/94559#discussion_r820116323 The `scope()` function returns when all threads are finished, but I accidentally considered a thread 'finished' before dropping their panic payload or ignored return value. So if a thread returned (or panics with) something that in its `Drop` implementation still uses borrowed stuff, it goes wrong. https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=2a1f19ac4676cdabe43e24e536ff9358