Add back in __gxx_personality_v0

[hoodmane]

See discussion here:
rust-lang/rust#98030

I removed rust's reference to this function
rust-lang/rust#97888
but this hasn't been released yet and it would be helpful to support slightly older versions of rust for a while if it's as easy as leaving this stub function.

[sbc100]

@aheejin what do you think?

I don't think I support adding a random symbol that does nothing just because rust happens to expect it to exist.

However it has been shown IIRC, that at least at the bitcode level clang does generate references to this symbol (that then get removed later).

[sbc100]

Thanks! Looking good!

[aheejin]

@sbc100

@aheejin what do you think?

I think having a dummy symbol is fine, as long as we document it well what it's for and it is meant to be a temporary measure.

However it has been shown IIRC, that at least at the bitcode level clang does generate references to this symbol (that then get removed later).

Clang generates that only because Rust library has that symbol, so I think it's better to remove it from the Rust side eventually.

[hoodmane]

it's better to remove it from the Rust side eventually

Just to be clear this is already done:
rust-lang/rust#97888

[aheejin]

@hoodmane Yeah, I wasn't clear. I mean, it would be good if it can be eventually removed from all supported Rust versions 😅