Pluggable panic implementations (tracking issue for RFC 1513)

[nikomatsakis]

Tracking issue for rust-lang/rfcs#1513.

-C panic=abort is now stable, but the ability to create customized panic implementations is still unstable.

[alexcrichton]

I'm working on an implementation.

[mrpollo]

is there a branch we can track? @alexcrichton, thanks!

[alexcrichton]

Sure! -- https://github.com/alexcrichton/rust/tree/panic2abort

[ketsuban]

Will I still need a dummy eh_personality lang item after this goes through? Some googling suggests -Z no-landing-pads was supposed to remove the need for it (for example, this regression report led to this issue which was resolved by this PR) but I only started using Rust for OSdev since it went stable and I've always needed eh_personality even with -Z no-landing-pads.

[alexcrichton]

@ketsuban it depends. If you use any library compiled with -C panic=unwind (like the binaries we ship) then you'll need to define eh_personality. If, however, you compile everything with -C panic=abort then you shouldn't need to define a personality.

[alexcrichton]

I've opened a PR for this.