false negative on clippy::filter_next when filter and next wraps map

[meltinglava]

False negative when filter and next is wrapped around a map.

There might be a few other methods like map that will have the same effect.

I tried this code:

    v.windows(3)
        .enumerate()
        .filter(|(_, a)| a == &[true, false, true])
        .map(|(v, _)| v + 1)
        .next()
        .unwrap()

I expected to see this happen: Clippy to suggest

    v.windows(3)
        .enumerate()
        .find(|(_, a)| a == &[true, false, true])
        .map(|(v, _)| v + 1)
        .unwrap()

Instead, this happened: Nothing

Meta

• cargo clippy -V: e.g. clippy 0.0.212 (1c389ff 2020-11-24)rust
• rustc -Vv:

  rustc 1.50.0-nightly (1c389ffef 2020-11-24)
  binary: rustc
  commit-hash: 1c389ffeff814726dec325f0f2b0c99107df2673
  commit-date: 2020-11-24
  host: x86_64-unknown-linux-gnu
  release: 1.50.0-nightly
  

[flip1995]

We could even suggest using find_map here.

[meltinglava]

We could even suggest using find_map here.

#4193 will have the same prolem here. I think its always correct to suggest find, and when the conservativness of find_map is figured out it can be applied here.