diff options
| -rw-r--r-- | clippy_lints/src/methods/needless_collect.rs | 78 | ||||
| -rw-r--r-- | tests/ui/needless_collect.fixed | 23 | ||||
| -rw-r--r-- | tests/ui/needless_collect.rs | 23 |
3 files changed, 118 insertions, 6 deletions
diff --git a/clippy_lints/src/methods/needless_collect.rs b/clippy_lints/src/methods/needless_collect.rs index 45f79dd44f2..56ff7e2c61b 100644 --- a/clippy_lints/src/methods/needless_collect.rs +++ b/clippy_lints/src/methods/needless_collect.rs @@ -1,3 +1,5 @@ +use std::ops::ControlFlow; + use super::NEEDLESS_COLLECT; use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_hir_and_then}; use clippy_utils::source::{snippet, snippet_with_applicability}; @@ -9,9 +11,9 @@ use clippy_utils::{ }; use rustc_data_structures::fx::FxHashMap; use rustc_errors::{Applicability, MultiSpan}; -use rustc_hir::intravisit::{Visitor, walk_block, walk_expr}; +use rustc_hir::intravisit::{Visitor, walk_block, walk_expr, walk_stmt}; use rustc_hir::{ - BindingMode, Block, Expr, ExprKind, HirId, HirIdSet, LetStmt, Mutability, Node, PatKind, Stmt, StmtKind, + BindingMode, Block, Expr, ExprKind, HirId, HirIdSet, LetStmt, Mutability, Node, Pat, PatKind, Stmt, StmtKind, }; use rustc_lint::LateContext; use rustc_middle::hir::nested_filter; @@ -103,6 +105,12 @@ pub(super) fn check<'tcx>( return; } + if let IterFunctionKind::IntoIter(hir_id) = iter_call.func + && !check_iter_expr_used_only_as_iterator(cx, hir_id, block) + { + return; + } + // Suggest replacing iter_call with iter_replacement, and removing stmt let mut span = MultiSpan::from_span(name_span); span.push_span_label(iter_call.span, "the iterator could be used here instead"); @@ -253,7 +261,7 @@ struct IterFunction { impl IterFunction { fn get_iter_method(&self, cx: &LateContext<'_>) -> String { match &self.func { - IterFunctionKind::IntoIter => String::new(), + IterFunctionKind::IntoIter(_) => String::new(), IterFunctionKind::Len => String::from(".count()"), IterFunctionKind::IsEmpty => String::from(".next().is_none()"), IterFunctionKind::Contains(span) => { @@ -268,7 +276,7 @@ impl IterFunction { } fn get_suggestion_text(&self) -> &'static str { match &self.func { - IterFunctionKind::IntoIter => { + IterFunctionKind::IntoIter(_) => { "use the original Iterator instead of collecting it and then producing a new one" }, IterFunctionKind::Len => { @@ -284,7 +292,7 @@ impl IterFunction { } } enum IterFunctionKind { - IntoIter, + IntoIter(HirId), Len, IsEmpty, Contains(Span), @@ -343,7 +351,7 @@ impl<'tcx> Visitor<'tcx> for IterFunctionVisitor<'_, 'tcx> { } match method_name.ident.name.as_str() { "into_iter" => self.uses.push(Some(IterFunction { - func: IterFunctionKind::IntoIter, + func: IterFunctionKind::IntoIter(expr.hir_id), span: expr.span, })), "len" => self.uses.push(Some(IterFunction { @@ -520,3 +528,61 @@ fn get_captured_ids(cx: &LateContext<'_>, ty: Ty<'_>) -> HirIdSet { set } + +struct IteratorMethodCheckVisitor<'a, 'tcx> { + cx: &'a LateContext<'tcx>, + hir_id_of_expr: HirId, + hir_id_of_let_binding: Option<HirId>, +} + +impl<'tcx> Visitor<'tcx> for IteratorMethodCheckVisitor<'_, 'tcx> { + type Result = ControlFlow<()>; + fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) -> ControlFlow<()> { + if let ExprKind::MethodCall(_method_name, recv, _args, _) = &expr.kind + && (recv.hir_id == self.hir_id_of_expr + || self + .hir_id_of_let_binding + .is_some_and(|hid| path_to_local_id(recv, hid))) + && !is_trait_method(self.cx, expr, sym::Iterator) + { + return ControlFlow::Break(()); + } else if let ExprKind::Assign(place, value, _span) = &expr.kind + && value.hir_id == self.hir_id_of_expr + && let Some(id) = path_to_local(place) + { + // our iterator was directly assigned to a variable + self.hir_id_of_let_binding = Some(id); + } + walk_expr(self, expr) + } + fn visit_stmt(&mut self, stmt: &'tcx Stmt<'tcx>) -> ControlFlow<()> { + if let StmtKind::Let(LetStmt { + init: Some(expr), + pat: + Pat { + kind: PatKind::Binding(BindingMode::NONE | BindingMode::MUT, id, _, None), + .. + }, + .. + }) = &stmt.kind + && expr.hir_id == self.hir_id_of_expr + { + // our iterator was directly assigned to a variable + self.hir_id_of_let_binding = Some(*id); + } + walk_stmt(self, stmt) + } +} + +fn check_iter_expr_used_only_as_iterator<'tcx>( + cx: &LateContext<'tcx>, + hir_id_of_expr: HirId, + block: &'tcx Block<'tcx>, +) -> bool { + let mut visitor = IteratorMethodCheckVisitor { + cx, + hir_id_of_expr, + hir_id_of_let_binding: None, + }; + visitor.visit_block(block).is_continue() +} diff --git a/tests/ui/needless_collect.fixed b/tests/ui/needless_collect.fixed index bad8c307586..6551fa56b42 100644 --- a/tests/ui/needless_collect.fixed +++ b/tests/ui/needless_collect.fixed @@ -98,6 +98,29 @@ fn main() { let mut out = vec![]; values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); let _y = values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); // this is fine + + // Don't write a warning if we call `clone()` on the iterator + // https://github.com/rust-lang/rust-clippy/issues/13430 + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let _cloned = my_collection.into_iter().clone(); + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let my_iter = my_collection.into_iter(); + let _cloned = my_iter.clone(); + // Same for `as_slice()`, for same reason. + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let _sliced = my_collection.into_iter().as_slice(); + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let my_iter = my_collection.into_iter(); + let _sliced = my_iter.as_slice(); + // Assignment outside of main scope + { + let x; + { + let xxx: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + x = xxx.into_iter(); + for i in x.as_slice() {} + } + } } fn foo(_: impl IntoIterator<Item = usize>) {} diff --git a/tests/ui/needless_collect.rs b/tests/ui/needless_collect.rs index 3dfb5194f40..973c41c6875 100644 --- a/tests/ui/needless_collect.rs +++ b/tests/ui/needless_collect.rs @@ -98,6 +98,29 @@ fn main() { let mut out = vec![]; values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); let _y = values.iter().cloned().map(|x| out.push(x)).collect::<Vec<_>>(); // this is fine + + // Don't write a warning if we call `clone()` on the iterator + // https://github.com/rust-lang/rust-clippy/issues/13430 + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let _cloned = my_collection.into_iter().clone(); + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let my_iter = my_collection.into_iter(); + let _cloned = my_iter.clone(); + // Same for `as_slice()`, for same reason. + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let _sliced = my_collection.into_iter().as_slice(); + let my_collection: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + let my_iter = my_collection.into_iter(); + let _sliced = my_iter.as_slice(); + // Assignment outside of main scope + { + let x; + { + let xxx: Vec<()> = vec![()].into_iter().map(|()| {}).collect(); + x = xxx.into_iter(); + for i in x.as_slice() {} + } + } } fn foo(_: impl IntoIterator<Item = usize>) {} |