FN useless_format: write!(f,"{}",format!())

[matthiaskrgr]

        write!(
            f,
            "{}",
            format!(
                "Cargo cache '{}/':\n\n",
                &self.cargo_cache_paths.cargo_home.display()
            )
        )?;

should just be

        write!(
            f,
            "Cargo cache '{}/':\n\n",
            &self.cargo_cache_paths.cargo_home.display()
        )?;

but clippy doesn't warn apparently.
clippy 0.0.212 (cafef7b 2018-09-06)

[flip1995]

This also applies to print!(), println!() and writeln!().

This could either be a new lint and would fit in clippy_lints/src/write.rs or an extension of the USELESS_FORMAT lint in clippy_lints/src/format.rs. Whatever seems easier to do.

[camsteffen]

Added in #7743