can't allow a single needless_collect

[matthiaskrgr]

I tried this code:

fn main() {
    let v = vec![1, 2, 3, 2, 4];
    #[allow(clippy::needless_collect)]
    let v: Vec<i32> = v.into_iter().map(|x| x * 2).collect();
}

This code should not warn but it does.

warning: unused variable: `v`
 --> src/main.rs:4:9
  |
4 |     let v: Vec<i32> = v.into_iter().map(|x| x * 2).collect();
  |         ^ help: if this is intentional, prefix it with an underscore: `_v`
  |
  = note: `#[warn(unused_variables)]` on by default

warning: avoid using `collect()` when not needed
 --> src/main.rs:4:52
  |
4 |     let v: Vec<i32> = v.into_iter().map(|x| x * 2).collect();
  |                       -------------                ^^^^^^^
  |                       |
  |                       the iterator could be used here instead
  |
  = note: `#[warn(clippy::needless_collect)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_collect
help: use the original Iterator instead of collecting it and then producing a new one
  |
4 |     v.into_iter().map(|x| x * 2).map(|x| x * 2).collect();
  |    --                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: 2 warnings emitted

    Finished dev [unoptimized + debuginfo] target(s) in 0.68s

A global #![allow(clippy::needless_collect)] works though.. 🤔

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clippy 0.1.54 (881c1ac 2021-05-08)