f3a9de9b08
Prevent `__rust_begin_short_backtrace` frames from being tail-call optimised away I've stumbled across some situations where there (unexpectedly) was no `__rust_begin_short_backtrace` frame on the stack during unwinding. On closer examination, it appeared that the calls to that function had been tail-call optimised away. This PR follows [@bjorn3's suggestion on Zulip](https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic/Disabling.20tail.20call.20optimisation.3F/near/205699133), by adding calls to `black_box` that hint to rustc not to perform TCO. Fixes #47429