Fix EII

[AsakuraMizu]

Fix support for EII functions with defaults and EII statics. Now all tests/ui/eii tests pass.

[antoyo]

It seems there's some interactions with the inline attribute that should be handled as well.
For instance:

#![crate_type = "rlib"]
#![feature(extern_item_impls)]
#[eii(eii1)]
#[inline]
pub fn decl1(x: u64) {
    println!("default {x}");
}

panics with this warning:

libgccjit.so: warning: : inline function ‘_RNvCslJaV4vr0Uxj_9test_rust5decl1’ declared weak [-Wattributes]

Please add this as a test in tests/run and fix this issue.

[AsakuraMizu]

It seems there's some interactions with the inline attribute that should be handled as well.

Hi, thanks for your review.

I investigated this further and found that this isn't only a attribute interaction issue with cg_gcc; it could also lead to unexpected behavior on cg_llvm. I've reported this upstream: rust-lang/rust#161650.

bjorn3 suggested denying #[inline] on EII declarations altogether: rust-lang/rust#161650 (comment)

Therefore if we add this check in rustc, the given example will produce a compile error before reaching cg_gcc instead of triggering an ICE.

Would you prefer to wait for the upstream fix for now?

[antoyo]

I'm OK with merging this PR now.
Is this ready to merge?

[AsakuraMizu]

Is this ready to merge?

Yes it's ready. Thanks! 😃

[antoyo]

Thanks for your contribution!

[GuillaumeGomez]

Nice work!