diff options
Diffstat (limited to 'src/tools/clippy/tests/ui/iter_on_empty_collections.rs')
-rw-r--r-- | src/tools/clippy/tests/ui/iter_on_empty_collections.rs | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/iter_on_empty_collections.rs b/src/tools/clippy/tests/ui/iter_on_empty_collections.rs new file mode 100644 index 000000000..e15ba94bd --- /dev/null +++ b/src/tools/clippy/tests/ui/iter_on_empty_collections.rs @@ -0,0 +1,63 @@ +// run-rustfix +#![warn(clippy::iter_on_empty_collections)] +#![allow(clippy::iter_next_slice, clippy::redundant_clone)] + +fn array() { + assert_eq!([].into_iter().next(), Option::<i32>::None); + assert_eq!([].iter_mut().next(), Option::<&mut i32>::None); + assert_eq!([].iter().next(), Option::<&i32>::None); + assert_eq!(None.into_iter().next(), Option::<i32>::None); + assert_eq!(None.iter_mut().next(), Option::<&mut i32>::None); + assert_eq!(None.iter().next(), Option::<&i32>::None); + + // Don't trigger on non-iter methods + let _: Option<String> = None.clone(); + let _: [String; 0] = [].clone(); + + // Don't trigger on match or if branches + let _ = match 123 { + 123 => [].iter(), + _ => ["test"].iter(), + }; + + let _ = if false { ["test"].iter() } else { [].iter() }; +} + +macro_rules! in_macros { + () => { + assert_eq!([].into_iter().next(), Option::<i32>::None); + assert_eq!([].iter_mut().next(), Option::<&mut i32>::None); + assert_eq!([].iter().next(), Option::<&i32>::None); + assert_eq!(None.into_iter().next(), Option::<i32>::None); + assert_eq!(None.iter_mut().next(), Option::<&mut i32>::None); + assert_eq!(None.iter().next(), Option::<&i32>::None); + }; +} + +// Don't trigger on a `None` that isn't std's option +mod custom_option { + #[allow(unused)] + enum CustomOption { + Some(i32), + None, + } + + impl CustomOption { + fn iter(&self) {} + fn iter_mut(&mut self) {} + fn into_iter(self) {} + } + use CustomOption::*; + + pub fn custom_option() { + None.iter(); + None.iter_mut(); + None.into_iter(); + } +} + +fn main() { + array(); + custom_option::custom_option(); + in_macros!(); +} |