diff --git a/clippy_lints/src/unnecessary_sort_by.rs b/clippy_lints/src/unnecessary_sort_by.rs index 8b00d29ac..9b6a9075a 100644 --- a/clippy_lints/src/unnecessary_sort_by.rs +++ b/clippy_lints/src/unnecessary_sort_by.rs @@ -1,5 +1,4 @@ use crate::utils; -use crate::utils::paths; use crate::utils::sugg::Sugg; use if_chain::if_chain; use rustc_errors::Applicability; @@ -171,12 +170,22 @@ fn mirrored_exprs( } fn detect_lint(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option { + // NOTE: Vectors of references are not supported. In order to avoid hitting https://github.com/rust-lang/rust/issues/34162, + // (different unnamed lifetimes for closure arg and return type) we need to make sure the suggested + // closure parameter is not a reference in case we suggest `Reverse`. Trying to destructure more + // than one level of references would add some extra complexity as we would have to compensate + // in the closure body. + if_chain! { if let ExprKind::MethodCall(name_ident, _, args, _) = &expr.kind; if let name = name_ident.ident.name.to_ident_string(); if name == "sort_by" || name == "sort_unstable_by"; if let [vec, Expr { kind: ExprKind::Closure(_, _, closure_body_id, _, _), .. }] = args; - if utils::match_type(cx, &cx.typeck_results().expr_ty(vec), &paths::VEC); + let vec_ty = cx.typeck_results().expr_ty(vec); + if utils::is_type_diagnostic_item(cx, vec_ty, sym!(vec_type)); + let ty = vec_ty.walk().nth(1).unwrap().expect_ty(); // T in Vec + if !matches!(&ty.kind(), ty::Ref(..)); + if utils::is_copy(cx, ty); if let closure_body = cx.tcx.hir().body(*closure_body_id); if let &[ Param { pat: Pat { kind: PatKind::Binding(_, _, left_ident, _), .. }, ..}, diff --git a/tests/ui/unnecessary_sort_by.fixed b/tests/ui/unnecessary_sort_by.fixed index 31c2ba0f9..ad0d0387d 100644 --- a/tests/ui/unnecessary_sort_by.fixed +++ b/tests/ui/unnecessary_sort_by.fixed @@ -25,17 +25,25 @@ fn unnecessary_sort_by() { vec.sort_by(|_, b| b.cmp(&5)); vec.sort_by(|_, b| b.cmp(c)); vec.sort_unstable_by(|a, _| a.cmp(c)); + + // Ignore vectors of references + let mut vec: Vec<&&&isize> = vec![&&&3, &&&6, &&&1, &&&2, &&&5]; + vec.sort_by(|a, b| (***a).abs().cmp(&(***b).abs())); + vec.sort_unstable_by(|a, b| (***a).abs().cmp(&(***b).abs())); + vec.sort_by(|a, b| b.cmp(a)); + vec.sort_unstable_by(|a, b| b.cmp(a)); } -// Should not be linted to avoid hitting https://github.com/rust-lang/rust/issues/34162 +// Do not suggest returning a reference to the closure parameter of `Vec::sort_by_key` mod issue_5754 { - struct Test(String); + #[derive(Clone, Copy)] + struct Test(usize); #[derive(PartialOrd, Ord, PartialEq, Eq)] - struct Wrapper<'a>(&'a str); + struct Wrapper<'a>(&'a usize); impl Test { - fn name(&self) -> &str { + fn name(&self) -> &usize { &self.0 } @@ -60,7 +68,33 @@ mod issue_5754 { } } +// `Vec::sort_by_key` closure parameter is `F: FnMut(&T) -> K` +// The suggestion is destructuring T and we know T is not a reference, so test that non-Copy T are +// not 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 = vec![]; + + // Forward + args.sort_by(|a, b| a.name().cmp(&b.name())); + args.sort_unstable_by(|a, b| a.name().cmp(&b.name())); + // Reverse + args.sort_by(|a, b| b.name().cmp(&a.name())); + args.sort_unstable_by(|a, b| b.name().cmp(&a.name())); + } +} + fn main() { unnecessary_sort_by(); issue_5754::test(); + issue_6001::test(); } diff --git a/tests/ui/unnecessary_sort_by.rs b/tests/ui/unnecessary_sort_by.rs index a3c8ae468..9746f6e68 100644 --- a/tests/ui/unnecessary_sort_by.rs +++ b/tests/ui/unnecessary_sort_by.rs @@ -25,17 +25,25 @@ fn unnecessary_sort_by() { vec.sort_by(|_, b| b.cmp(&5)); vec.sort_by(|_, b| b.cmp(c)); vec.sort_unstable_by(|a, _| a.cmp(c)); + + // Ignore vectors of references + let mut vec: Vec<&&&isize> = vec![&&&3, &&&6, &&&1, &&&2, &&&5]; + vec.sort_by(|a, b| (***a).abs().cmp(&(***b).abs())); + vec.sort_unstable_by(|a, b| (***a).abs().cmp(&(***b).abs())); + vec.sort_by(|a, b| b.cmp(a)); + vec.sort_unstable_by(|a, b| b.cmp(a)); } -// Should not be linted to avoid hitting https://github.com/rust-lang/rust/issues/34162 +// Do not suggest returning a reference to the closure parameter of `Vec::sort_by_key` mod issue_5754 { - struct Test(String); + #[derive(Clone, Copy)] + struct Test(usize); #[derive(PartialOrd, Ord, PartialEq, Eq)] - struct Wrapper<'a>(&'a str); + struct Wrapper<'a>(&'a usize); impl Test { - fn name(&self) -> &str { + fn name(&self) -> &usize { &self.0 } @@ -60,7 +68,33 @@ mod issue_5754 { } } +// `Vec::sort_by_key` closure parameter is `F: FnMut(&T) -> K` +// The suggestion is destructuring T and we know T is not a reference, so test that non-Copy T are +// not 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 = vec![]; + + // Forward + args.sort_by(|a, b| a.name().cmp(&b.name())); + args.sort_unstable_by(|a, b| a.name().cmp(&b.name())); + // Reverse + args.sort_by(|a, b| b.name().cmp(&a.name())); + args.sort_unstable_by(|a, b| b.name().cmp(&a.name())); + } +} + fn main() { unnecessary_sort_by(); issue_5754::test(); + issue_6001::test(); }