Wrong suggestion for `unused_variables` accepted by cargo fix

[crumblingstatue]

Seems to originate from #145827.

Test code:

mod m1 {
    const _MAX_FMTVER_X1X_EVENTNUM: i32 = 0;
}

mod m2 {
    fn fun(rough: i32) {}
}

Gives bizarre suggestion:

help: you might have meant to pattern match on the similarly named constant `_MAX_FMTVER_X1X_EVENTNUM`
  |
6 -     fn fun(rough: i32) {}
6 +     fn fun(m1::_MAX_FMTVER_X1X_EVENTNUM: i32) {}

Which is then applied by cargo fix:

warning: failed to automatically apply fixes suggested by rustc to crate `lol`
...
The following errors were reported:
error[E0433]: failed to resolve: use of unresolved module or unlinked crate `m1`
 --> src/lib.rs:6:12
  |
6 |     fn fun(m1::_MAX_FMTVER_X1X_EVENTNUM: i32) {}
  |            ^^ use of unresolved module or unlinked crate `m1`
  |
  = help: if you wanted to use a crate named `m1`, use `cargo add m1` to add it to your `Cargo.toml`
help: consider importing this module
  |
6 +     use crate::m1;

rustc 1.92.0-nightly (5c7ae0c7e 2025-10-02)

This is a regression from stable to nightly.

[Jules-Bertholet]

@rustbot label C-bug A-diagnostics A-suggestion-diagnostics D-invalid-suggestion T-compiler regression-from-stable-to-nightly