Tracing warning with invalid expansion

[Noratrieb]

extern "C" {
  thread_local! {
    static FOO: u32 = 0;
  }
}

This is of course invalid, thread_local expands to a static item with an initializer.

WARN rustc_errors::emitter Invalid span src/main.rs:4:12: 110:22 (#15), error=DistinctSources(DistinctSources { begin: (Real(LocalPath("src/main.rs")), BytePos(0)), end: (Real(Remapped { local_path: None, virtual_name: "/rustc/5ae769f06bbe2afc50cde219757a5915e61ba365/library/std/src/sys/common/thread_local/fast_local.rs" }), BytePos(415220)) })
error: extern items cannot be `const`
 --> src/main.rs:4:12
  |
4 |       static FOO: u32 = 0;
  |  ____________-^^
5 | |   }
6 | | }
7 | | }); }
... |
  |
  = note: for more information, visit https://doc.rust-lang.org/std/keyword.extern.html

error: incorrect `static` inside `extern` block
 --> src/main.rs:4:12
  |
2 |   extern "C" {
  |   ---------- `extern` blocks define existing foreign statics and statics inside of them cannot have a body
3 | /   thread_local! {
4 | |     static FOO: u32 = 0;
  | |            ^^^ cannot have a body
5 | |   }
  | |___- the invalid body
  |
  = note: for more information, visit https://doc.rust-lang.org/std/keyword.extern.html

something's having fun with the span there