src/tools/clippy/tests/ui/map_flatten_fixable.fixed

   1 // run-rustfix
   2
   3 #![warn(clippy::all, clippy::pedantic)]
   4 #![allow(clippy::let_underscore_drop)]
   5 #![allow(clippy::missing_docs_in_private_items)]
   6 #![allow(clippy::map_identity)]
   7 #![allow(clippy::redundant_closure)]
   8 #![allow(clippy::unnecessary_wraps)]
   9 #![feature(result_flattening)]
  10
  11 fn main() {
  12     // mapping to Option on Iterator
  13     fn option_id(x: i8) -> Option<i8> {
  14         Some(x)
  15     }
  16     let option_id_ref: fn(i8) -> Option<i8> = option_id;
  17     let option_id_closure = |x| Some(x);
  18     let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(option_id).collect();
  19     let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(option_id_ref).collect();
  20     let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(option_id_closure).collect();
  21     let _: Vec<_> = vec![5_i8; 6].into_iter().filter_map(|x| x.checked_add(1)).collect();
  22
  23     // mapping to Iterator on Iterator
  24     let _: Vec<_> = vec![5_i8; 6].into_iter().flat_map(|x| 0..x).collect();
  25
  26     // mapping to Option on Option
  27     let _: Option<_> = (Some(Some(1))).and_then(|x| x);
  28
  29     // mapping to Result on Result
  30     let _: Result<_, &str> = (Ok(Ok(1))).and_then(|x| x);
  31
  32     issue8734();
  33     issue8878();
  34 }
  35
  36 fn issue8734() {
  37     //     let _ = [0u8, 1, 2, 3]
  38     //         .into_iter()
  39     //         .map(|n| match n {
  40     //             1 => [n
  41     //                 .saturating_add(1)
  42     //                 .saturating_add(1)
  43     //                 .saturating_add(1)
  44     //                 .saturating_add(1)
  45     //                 .saturating_add(1)
  46     //                 .saturating_add(1)
  47     //                 .saturating_add(1)
  48     //                 .saturating_add(1)],
  49     //             n => [n],
  50     //         })
  51     //         .flatten();
  52 }
  53
  54 #[allow(clippy::bind_instead_of_map)] // map + flatten will be suggested to `and_then`, but afterwards `map` is suggested again
  55 #[rustfmt::skip] // whitespace is important for this one
  56 fn issue8878() {
  57     std::collections::HashMap::<u32, u32>::new()
  58         .get(&0)
  59         .and_then(|_| {
  60 // we need some newlines
  61 // so that the span is big enough
  62 // we need some newlines
  63 // so that the span is big enough
  64 // for a splitted output of the diagnostic
  65             Some("")
  66  // whitespace beforehand is important as well
  67         });
  68 }