single-use lifetime lint warning on expanded automock

[Rosdf]

#[derive(Debug)]
pub struct MyEr;

#[mockall::automock]
pub trait MyTrait {
    /// # Errors
    ///
    /// some stuff
    fn get<'a>(
        &'a mut self,
        data: i32,
    ) -> Result<&'a str, MyEr>;
}

this code after cargo check produces

warning: lifetime parameter `'a` only used once
  --> src/main.rs:13:12
   |
13 |     fn get<'a>(
   |            ^^
   |            |
   |            this lifetime...
   |            ...is used only here
   |
   = note: requested on the command line with `-W single-use-lifetimes`
help: elide the single-use lifetime
   |
13 -     fn get<'a>(
13 +     fn get<'_>(
   |

there is an easy way out by applying #[allow] on this method, but in my project allow is forbidden in favor of except (clippy::allow_attributes)

[asomers]

What Rustc compiler are you using? Please do rustc -Vv.

[Rosdf]

rustc 1.83.0 (90b35a623 2024-11-26)
binary: rustc
commit-hash: 90b35a6239c3d8bdabc530a6a0816f7ff89a0aaf
commit-date: 2024-11-26
host: x86_64-unknown-linux-gnu
release: 1.83.0
LLVM version: 19.1.1

[asomers]

This warning can be suppressed in the generated code. But I'm curious why the issue hasn't arisen already. Is this an off-by-default warning that you enabled in your project?

[Rosdf]

Yes, this lint is allowed by default and set to warn in my project