no way to disable exception handling with static/dynamic linking

[thestinger]

There's no equivalent to -Z no-landing-pads for static/dynamic libraries. Since it's not possible to mark foreign functions as not throwing like it is with __attribute__((nothrow)), Rust will always output lots of unwinding tables with a Rust-specific unwinding personality/calls. This would be a lot less bad if Rust actually read the C library headers with libclang and dealt with the attributes like nothrow.

[brson]

Can -Z no-landing-pads work for static and dynamic libraries?

This is similar to #11871 where we have a language feature that has a runtime dependency, but it can't be turned off, and you wouldn't want to accidentally combine crates with the wrong options. Perhaps we can add something to the metadata to record which runtime features were in use, and start adding these options.

[thestinger]

I think adding a flag to the metadata is the best idea. It would be really nice to omit the landing pads and invoke calls in the first place too.

[thestinger]

Closing in favour of #18511.