False positive in `map_identity` with lifetimes

[human-0]

Summary

Mapping with an identity closure (|x| x) is sometimes required to fix lifetimes.

Lint Name

map_identity

Reproducer

I tried this code:

pub fn test<'a, I>(iter: I)
where
    I: IntoIterator<Item = &'a i32>
{
    let local = 0;
    let _ = std::iter::once(&local).chain(iter.into_iter().map(|x| x));
}

Removing the map results in a compile error. I saw this happen:

warning: unnecessary map of the identity function
 --> src/lib.rs:6:59
  |
6 |     let _ = std::iter::once(&local).chain(iter.into_iter().map(|x| x));
  |                                                           ^^^^^^^^^^^ help: remove the call to `map`
  |
  = note: `#[warn(clippy::map_identity)]` on by default
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#map_identity

I expected to see this happen: No warning, as the map cannot be removed without causing a compile error. This happens on both stable and nightly.

Version

rustc 1.64.0-nightly (0f4bcadb4 2022-07-30)
binary: rustc
commit-hash: 0f4bcadb46006bc484dad85616b484f93879ca4e
commit-date: 2022-07-30
host: x86_64-pc-windows-msvc
release: 1.64.0-nightly
LLVM version: 14.0.6

Additional Labels

@rustbot label +I-suggestion-causes-error