dead_code fails to consider reexports of foreign items

[huonw]

#![crate_type = "lib"]
pub use x = foo;
extern { fn foo(); }

playpen

<anon>:3:10: 3:19 warning: code is never used: `foo`, #[warn(dead_code)] on by default
<anon>:3 extern { fn foo(); }
                  ^~~~~~~~~
[...]

[ktt3ja]

Is there a reason why foo is not in the exported items set? If it's supposed to be, then changing self.prev_exported && a.vis == ast::Public here to (self.prev_exported && a.vis == ast::Public) || self.reexports.contains(&a.id) would fix this error as well:

rust/src/librustc/middle/privacy.rs

Line 329 in 02adaca

if self.prev_exported && a.vis == ast::Public {

[huonw]

// crate_a.rs
#![crate_type = "lib"]
pub use foo = abort;

extern { fn abort() -> !; }

// crate_b.rs
extern crate crate_a;

fn main() {
    unsafe { crate_a::foo(); }
}

Both compile and run fine (i.e. crate_b aborts correctly), so it seems that it's being exported correctly somehow.