Static LINKER_MESSAGES

pub static LINKER_MESSAGES: &Lint

The linker_messages lint forwards warnings from the linker.

Example

#[warn(linker_messages)]
extern "C" {
  fn foo();
}
fn main () { unsafe { foo(); } }

On Linux, using gcc -Wl,--warn-unresolved-symbols as a linker, this will produce

warning: linker stderr: rust-lld: undefined symbol: foo
         >>> referenced by rust_out.69edbd30df4ae57d-cgu.0
         >>>               rust_out.rust_out.69edbd30df4ae57d-cgu.0.rcgu.o:(rust_out::main::h3a90094b06757803)
  |
note: the lint level is defined here
 --> warn.rs:1:9
  |
1 | #![warn(linker_messages)]
  |         ^^^^^^^^^^^^^^^
warning: 1 warning emitted

Explanation

Linkers emit platform-specific and program-specific warnings that cannot be predicted in advance by the Rust compiler. Such messages are ignored by default for now. While linker warnings could be very useful they have been ignored for many years by essentially all users, so we need to do a bit more work than just surfacing their text to produce a clear and actionable warning of similar quality to our other diagnostics. See this tracking issue for more details: https://github.com/rust-lang/rust/issues/136096.