Missing attribute name and corrupted output for unsafe attribute used without unsafe

[ia0]

Code

# bar/Cargo.toml
[package]
name = "bar"
version = "0.1.0"
edition = "2024"

[lib]
proc-macro = true

[dependencies]
quote = "1.0.37"

// bar/src/lib.rs
use proc_macro::TokenStream;
use quote::quote;

#[proc_macro]
pub fn bar(input: TokenStream) -> TokenStream {
    assert!(input.is_empty());
    quote! {
        #[no_mangle]
        pub extern "C" fn yolo() {}
    }
    .into()
}

# foo/Cargo.toml
[package]
name = "foo"
version = "0.1.0"
edition = "2021"

[dependencies]
bar.path = "../bar"

// foo/src/lib.rs
bar::bar!();

Current output

Running cargo check from the foo directory:

error: unsafe attribute used without unsafe
 --> src/lib.rs:1:1
  |
1 | bar::bar!();
  | ^^^^^^^^^^^ usage of unsafe attribute
  |
  = note: this error originates in the macro `bar::bar` (in Nightly builds, run with -Z macro-backtrace for more info)
help: wrap the attribute in `unsafe(...)`
  |
1 | baunsafe(r::bar!());
  |   +++++++        +

error: could not compile `foo` (lib) due to 1 previous error

Desired output

error: unsafe attribute used without unsafe
 --> src/lib.rs:1:1
  |
1 | bar::bar!();
  | ^^^^^^^^^^^ usage of unsafe attribute
  |
  = note: this error originates in the macro `bar::bar` (in Nightly builds, run with -Z macro-backtrace for more info)
help: wrap the attribute in `unsafe(...)`
  |
1 | #[unsafe(no_mangle)]
  |   +++++++         +

error: could not compile `foo` (lib) due to 1 previous error

Rationale and extra context

Note that the problem occurs only when bar uses edition 2024. It doesn't matter if foo does too.

Other cases

No response

Rust Version

rustc 1.85.0-nightly (d49be02cf 2024-12-02)
binary: rustc
commit-hash: d49be02cf6d2e2a01264fcdef1e20c826710c0f5
commit-date: 2024-12-02
host: x86_64-unknown-linux-gnu
release: 1.85.0-nightly
LLVM version: 19.1.4

Anything else?

No response

[jieyouxu]

I believe this is a duplicate of #133994, thank you for the report.

[ia0]

Indeed, thanks!