Static EII defaults are currently unsupported on macOS

[AsakuraMizu]

Static EII defaults currently fail to link on macOS targets.

Example:

#![feature(extern_item_impls)]

#[eii(eii1)]
pub static DECL1: u64 = 5;

fn main() {
    println!("{DECL1}");
}

This appears to be caused by LLVM's Mach-O alias emission. See #156583 (comment) for details and links to the related LLVM issue / PR.

Until the LLVM fix reaches rustc, rustc should reject static EII defaults on macOS targets with a diagnostic that points here.

This issue tracks that temporary restriction and its eventual removal.

Related

• Tracking issue: Tracking Issue for externally implementable items #125418
• PR adding static EII defaults: Support defaults for static EIIs #156583

[AsakuraMizu]

@rustbot label +F-external-item_impls

[rustbot]

Error: Unknown labels: F-external-item_impls

Please file an issue on GitHub at triagebot if there's a problem with this bot, or reach out on #triagebot on Zulip.

[AsakuraMizu]

@rustbot label +F-extern_item_impls +T-compiler +O-macos +A-linkage