//@run-rustfix #![allow(clippy::stable_sort_primitive, clippy::useless_vec)] use std::cell::Ref; fn unnecessary_sort_by() { fn id(x: isize) -> isize { x } let mut vec: Vec<isize> = vec![3, 6, 1, 2, 5]; // Forward examples vec.sort(); vec.sort_unstable(); vec.sort_by_key(|a| (a + 5).abs()); vec.sort_unstable_by_key(|a| id(-a)); // Reverse examples vec.sort_by(|a, b| b.cmp(a)); // not linted to avoid suggesting `Reverse(b)` which would borrow vec.sort_by_key(|b| std::cmp::Reverse((b + 5).abs())); vec.sort_unstable_by_key(|b| std::cmp::Reverse(id(-b))); // Negative examples (shouldn't be changed) let c = &7; vec.sort_by(|a, b| (b - a).cmp(&(a - b))); vec.sort_by(|_, b| b.cmp(&5)); vec.sort_by(|_, b| b.cmp(c)); vec.sort_unstable_by(|a, _| a.cmp(c)); // Vectors of references are fine as long as the resulting key does not borrow let mut vec: Vec<&&&isize> = vec![&&&3, &&&6, &&&1, &&&2, &&&5]; vec.sort_by_key(|a| (***a).abs()); vec.sort_unstable_by_key(|a| (***a).abs()); // `Reverse(b)` would borrow in the following cases, don't lint vec.sort_by(|a, b| b.cmp(a)); vec.sort_unstable_by(|a, b| b.cmp(a)); // No warning if element does not implement `Ord` let mut vec: Vec<Ref<usize>> = Vec::new(); vec.sort_unstable_by(|a, b| a.cmp(b)); } // Do not suggest returning a reference to the closure parameter of `Vec::sort_by_key` mod issue_5754 { #[derive(Clone, Copy)] struct Test(usize); #[derive(PartialOrd, Ord, PartialEq, Eq)] struct Wrapper<'a>(&'a usize); impl Test { fn name(&self) -> &usize { &self.0 } fn wrapped(&self) -> Wrapper<'_> { Wrapper(&self.0) } } pub fn test() { let mut args: Vec<Test> = vec![]; // Forward args.sort_by(|a, b| a.name().cmp(b.name())); args.sort_by(|a, b| a.wrapped().cmp(&b.wrapped())); args.sort_unstable_by(|a, b| a.name().cmp(b.name())); args.sort_unstable_by(|a, b| a.wrapped().cmp(&b.wrapped())); // Reverse args.sort_by(|a, b| b.name().cmp(a.name())); args.sort_by(|a, b| b.wrapped().cmp(&a.wrapped())); args.sort_unstable_by(|a, b| b.name().cmp(a.name())); args.sort_unstable_by(|a, b| b.wrapped().cmp(&a.wrapped())); } } // The closure parameter is not dereferenced anymore, so non-Copy types can be linted mod issue_6001 { struct Test(String); impl Test { // Return an owned type so that we don't hit the fix for 5754 fn name(&self) -> String { self.0.clone() } } pub fn test() { let mut args: Vec<Test> = vec![]; // Forward args.sort_by_key(|a| a.name()); args.sort_unstable_by_key(|a| a.name()); // Reverse args.sort_by_key(|b| std::cmp::Reverse(b.name())); args.sort_unstable_by_key(|b| std::cmp::Reverse(b.name())); } } fn main() { unnecessary_sort_by(); issue_5754::test(); issue_6001::test(); }