False positive of lint similar-names for identifiers with trailing underscore

[fmease]

I tried this code:

#![allow(unused_variables)]
#![warn(clippy::similar_names)]

fn main() {
    let types = [1, 2, 3];
    let type_ = 3;
}

I expected Clippy to not emit any warnings since types and type_ are visually distinct (in my eyes).
Instead, Clippy reported similar_names suggesting to change type_ to type__ which does not make much sense to me.

Edit: Together with types, I use the identifier type_ quite a lot in my code base, which is a compiler. The unusual name obviously stems from the fact that type is a keyword in Rust and thus I cannot use it (but I prefer it to typ or r#type). All that to say, this is not an artificial corner case.

Meta

• clippy 0.0.212 (1c389ff 2020-11-24)
• rustc 1.50.0-nightly (1c389ffef 2020-11-24)

Full Standard Error

warning: binding's name is too similar to existing binding
 --> src/main.rs:6:9
  |
6 |     let type_ = 3;
  |         ^^^^^
  |
note: the lint level is defined here
 --> src/main.rs:2:9
  |
2 | #![warn(clippy::similar_names)]
  |         ^^^^^^^^^^^^^^^^^^^^^
note: existing binding defined here
 --> src/main.rs:5:9
  |
5 |     let types = [1, 2, 3];
  |         ^^^^^
help: separate the discriminating character by an underscore like: `type__`
 --> src/main.rs:6:9
  |
6 |     let type_ = 3;
  |         ^^^^^
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#similar_names

warning: 1 warning emitted

[th1000s]

Fixed in PR #7221 by comparing it to a (hardcoded) list of known keywords.

[arieluy]

Should this be closed?

[fmease]

I guess it should.
Closed via #7221.