Confusing error "the trait bound `u8: Termination` is not satisfied" when duplicated function is marked as `#[test]`

[karolzwolak]

Code

#[cfg(test)]
mod tests{
    fn foo() -> u8 {
        0
    }
    
    #[test]
    fn foo() {}
}

Current output

error[E0428]: the name `foo` is defined multiple times
 --> src/lib.rs:8:5
  |
3 |     fn foo() -> u8 {
  |     -------------- previous definition of the value `foo` here
...
8 |     fn foo() {}
  |     ^^^^^^^^ `foo` redefined here
  |
  = note: `foo` must be defined only once in the value namespace of this module

error[E0277]: the trait bound `u8: Termination` is not satisfied
   --> src/lib.rs:8:13
    |
7   |     #[test]
    |     ------- in this procedural macro expansion
8   |     fn foo() {}
    |             ^ the trait `Termination` is not implemented for `u8`
    |
note: required by a bound in `assert_test_result`
   --> /playground/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/test/src/lib.rs:234:30
    |
234 | pub fn assert_test_result<T: Termination>(result: T) -> Result<(), String> {
    |                              ^^^^^^^^^^^ required by this bound in `assert_test_result`
    = note: this error originates in the attribute macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)

Some errors have detailed explanations: E0277, E0428.
For more information about an error, try `rustc --explain E0277`.

Desired output

error[E0428]: the name `foo` is defined multiple times
 --> src/lib.rs:8:5
  |
3 |     fn foo() -> u8 {
  |     -------------- previous definition of the value `foo` here
...
8 |     fn foo() {}
  |     ^^^^^^^^ `foo` redefined here
  |
  = note: `foo` must be defined only once in the value namespace of this module

Some errors have detailed explanations: E0428.
For more information about an error, try `rustc --explain E0428`.

Rationale and extra context

The second error the trait bound `u8: Termination` is not satisfied is confusing, especially because it's reported last (so if you have multiple errors, you might not see you have duplicate functions.

Other cases

No response

Rust Version

rustc 1.85.0 (4d91de4e4 2025-02-17)
binary: rustc
commit-hash: 4d91de4e48198da2e33413efdcd9cd2cc0c46688
commit-date: 2025-02-17
host: x86_64-unknown-linux-gnu
release: 1.85.0
LLVM version: 19.1.7

Anything else?

If the non-test function returns nothing, the weird error doesn't show up.

[asquared31415]

This looks like the compiler is using the signature for the first definition of the name for both of those functions for type checking. This may be more complicated than a simple diagnostics fix.