Improve too_many_arguments: only highlight function arguments instead of entire function

[alexheretic]

Too many arguments lint highlights the entire function which can end up being quite visually noisey. It would be nicer to highlight the arguments / lines with arguments in them or similar.

fn foo(_: u8, _: u8, _: u8, _: u8, _: u8, _: u8, _: u8, _: u8) {
    let _prefectly = "tarred";
    let _fine = "with";
    let _code = "same";
    let _is = "brush";
}
fn main() {
    foo(1, 2, 3, 4, 5, 6, 7, 8);
}

warning: this function has too many arguments (8/7)
 --> src/main.rs:1:1
  |
1 | / fn foo(_: u8, _: u8, _: u8, _: u8, _: u8, _: u8, _: u8, _: u8) {
2 | |     let _prefectly = "tarred";
3 | |     let _fine = "with";
4 | |     let _code = "same";
5 | |     let _is = "brush";
6 | | }
  | |_^
  |
  = note: #[warn(too_many_arguments)] on by default
  = help: for further information visit https://rust-lang-nursery.github.io/rust-clippy/v0.0.186/index.html#too_many_arguments

[camelid]

Seems to be fixed now:

warning: this function has too many arguments (8/7)
 --> src/main.rs:1:1
  |
1 | fn foo(_: u8, _: u8, _: u8, _: u8, _: u8, _: u8, _: u8, _: u8) {
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: `#[warn(clippy::too_many_arguments)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#too_many_arguments

[giraffate]

Thanks! It seems to be fixed by #4053, so I'm closing this.