FP redundant_closure

[matthiaskrgr]

use std::io::{self, ErrorKind};
use std::path::{Path, PathBuf};

pub fn main() {
    let path = &PathBuf::from("a");
    do_op(path, "remove file", |p| std::fs::remove_file(p)); // redundant closure
}

fn do_op<F>(path: &Path, _desc: &str, mut f: F)
where
    F: FnMut(&Path) -> io::Result<()>,
{
    match f(path) {
        Ok(()) => {}
        Err(ref _e) => {}
        Err(_e) => {}
    }
}

Clippy suggests removing the marked closure, to std::fs::remove_file but this causes a compiler error:

error[E0308]: mismatched types
 --> src/main.rs:6:5
  |
6 |     do_op(path, "remove file", std::fs::remove_file);
  |     ^^^^^ one type is more general than the other
  |
  = note: expected type `std::ops::FnOnce<(&std::path::Path,)>`
             found type `std::ops::FnOnce<(&std::path::Path,)>`

Code found in rustc bootstrap crate.
clippy 0.0.212 (e15510c 2020-08-20)

[DutchGhost]

I hit this as well with pico_args for argument parsing,

#[derive(Debug)]
struct Cli {
    config: PathBuf,
}

impl Cli {
    fn from_args(mut args: pico_args::Arguments) -> Result<Self, BoxedError> {
        let config = args.value_from_fn("--config", |s| PathBuf::try_from(s))?;

        Ok(Self { config })
    }
}

Clippy suggest PathBuf::try_from over the closure, resulting in the same error as the post above

[ThibsG]

Looks like the same as #5594