diff --git a/clippy_lints/src/loops/same_item_push.rs b/clippy_lints/src/loops/same_item_push.rs index 62c131968e7a..b3d784474c82 100644 --- a/clippy_lints/src/loops/same_item_push.rs +++ b/clippy_lints/src/loops/same_item_push.rs @@ -1,11 +1,13 @@ use super::SAME_ITEM_PUSH; use clippy_utils::diagnostics::span_lint_and_help; +use clippy_utils::path_to_local; use clippy_utils::source::snippet_with_macro_callsite; use clippy_utils::ty::{implements_trait, is_type_diagnostic_item}; use if_chain::if_chain; +use rustc_data_structures::fx::FxHashSet; use rustc_hir::def::{DefKind, Res}; use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor}; -use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, Node, Pat, PatKind, Stmt, StmtKind}; +use rustc_hir::{BindingAnnotation, Block, Expr, ExprKind, HirId, Node, Pat, PatKind, Stmt, StmtKind}; use rustc_lint::LateContext; use rustc_middle::hir::map::Map; use rustc_span::symbol::sym; @@ -41,59 +43,55 @@ pub(super) fn check<'tcx>( } // Determine whether it is safe to lint the body - let mut same_item_push_visitor = SameItemPushVisitor { - should_lint: true, - vec_push: None, - cx, - }; + let mut same_item_push_visitor = SameItemPushVisitor::new(cx); walk_expr(&mut same_item_push_visitor, body); - if same_item_push_visitor.should_lint { - if let Some((vec, pushed_item)) = same_item_push_visitor.vec_push { - let vec_ty = cx.typeck_results().expr_ty(vec); - let ty = vec_ty.walk().nth(1).unwrap().expect_ty(); - if cx - .tcx - .lang_items() - .clone_trait() - .map_or(false, |id| implements_trait(cx, ty, id, &[])) - { - // Make sure that the push does not involve possibly mutating values - match pushed_item.kind { - ExprKind::Path(ref qpath) => { - match cx.qpath_res(qpath, pushed_item.hir_id) { - // immutable bindings that are initialized with literal or constant - Res::Local(hir_id) => { - let node = cx.tcx.hir().get(hir_id); - if_chain! { - if let Node::Binding(pat) = node; - if let PatKind::Binding(bind_ann, ..) = pat.kind; - if !matches!(bind_ann, BindingAnnotation::RefMut | BindingAnnotation::Mutable); - let parent_node = cx.tcx.hir().get_parent_node(hir_id); - if let Some(Node::Local(parent_let_expr)) = cx.tcx.hir().find(parent_node); - if let Some(init) = parent_let_expr.init; - then { - match init.kind { - // immutable bindings that are initialized with literal - ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item), - // immutable bindings that are initialized with constant - ExprKind::Path(ref path) => { - if let Res::Def(DefKind::Const, ..) = cx.qpath_res(path, init.hir_id) { - emit_lint(cx, vec, pushed_item); - } + if_chain! { + if same_item_push_visitor.should_lint(); + if let Some((vec, pushed_item)) = same_item_push_visitor.vec_push; + let vec_ty = cx.typeck_results().expr_ty(vec); + let ty = vec_ty.walk().nth(1).unwrap().expect_ty(); + if cx + .tcx + .lang_items() + .clone_trait() + .map_or(false, |id| implements_trait(cx, ty, id, &[])); + then { + // Make sure that the push does not involve possibly mutating values + match pushed_item.kind { + ExprKind::Path(ref qpath) => { + match cx.qpath_res(qpath, pushed_item.hir_id) { + // immutable bindings that are initialized with literal or constant + Res::Local(hir_id) => { + let node = cx.tcx.hir().get(hir_id); + if_chain! { + if let Node::Binding(pat) = node; + if let PatKind::Binding(bind_ann, ..) = pat.kind; + if !matches!(bind_ann, BindingAnnotation::RefMut | BindingAnnotation::Mutable); + let parent_node = cx.tcx.hir().get_parent_node(hir_id); + if let Some(Node::Local(parent_let_expr)) = cx.tcx.hir().find(parent_node); + if let Some(init) = parent_let_expr.init; + then { + match init.kind { + // immutable bindings that are initialized with literal + ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item), + // immutable bindings that are initialized with constant + ExprKind::Path(ref path) => { + if let Res::Def(DefKind::Const, ..) = cx.qpath_res(path, init.hir_id) { + emit_lint(cx, vec, pushed_item); } - _ => {}, } + _ => {}, } } - }, - // constant - Res::Def(DefKind::Const, ..) => emit_lint(cx, vec, pushed_item), - _ => {}, - } - }, - ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item), - _ => {}, - } + } + }, + // constant + Res::Def(DefKind::Const, ..) => emit_lint(cx, vec, pushed_item), + _ => {}, + } + }, + ExprKind::Lit(..) => emit_lint(cx, vec, pushed_item), + _ => {}, } } } @@ -101,10 +99,38 @@ pub(super) fn check<'tcx>( // Scans the body of the for loop and determines whether lint should be given struct SameItemPushVisitor<'a, 'tcx> { - should_lint: bool, + non_deterministic_expr: bool, + multiple_pushes: bool, // this field holds the last vec push operation visited, which should be the only push seen vec_push: Option<(&'tcx Expr<'tcx>, &'tcx Expr<'tcx>)>, cx: &'a LateContext<'tcx>, + used_locals: FxHashSet, +} + +impl<'a, 'tcx> SameItemPushVisitor<'a, 'tcx> { + fn new(cx: &'a LateContext<'tcx>) -> Self { + Self { + non_deterministic_expr: false, + multiple_pushes: false, + vec_push: None, + cx, + used_locals: FxHashSet::default(), + } + } + + fn should_lint(&self) -> bool { + if_chain! { + if !self.non_deterministic_expr; + if !self.multiple_pushes; + if let Some((vec, _)) = self.vec_push; + if let Some(hir_id) = path_to_local(vec); + then { + !self.used_locals.contains(&hir_id) + } else { + false + } + } + } } impl<'a, 'tcx> Visitor<'tcx> for SameItemPushVisitor<'a, 'tcx> { @@ -113,9 +139,14 @@ impl<'a, 'tcx> Visitor<'tcx> for SameItemPushVisitor<'a, 'tcx> { fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { match &expr.kind { // Non-determinism may occur ... don't give a lint - ExprKind::Loop(..) | ExprKind::Match(..) => self.should_lint = false, + ExprKind::Loop(..) | ExprKind::Match(..) | ExprKind::If(..) => self.non_deterministic_expr = true, ExprKind::Block(block, _) => self.visit_block(block), - _ => {}, + _ => { + if let Some(hir_id) = path_to_local(expr) { + self.used_locals.insert(hir_id); + } + walk_expr(self, expr); + }, } } @@ -140,7 +171,7 @@ impl<'a, 'tcx> Visitor<'tcx> for SameItemPushVisitor<'a, 'tcx> { self.vec_push = vec_push_option; } else { // There are multiple pushes ... don't lint - self.should_lint = false; + self.multiple_pushes = true; } } } diff --git a/tests/ui/same_item_push.rs b/tests/ui/same_item_push.rs index a37c8782ec33..9d420ec672a2 100644 --- a/tests/ui/same_item_push.rs +++ b/tests/ui/same_item_push.rs @@ -148,4 +148,11 @@ fn main() { }; vec.push(item); } + + // Fix #6987 + let mut vec = Vec::new(); + for _ in 0..10 { + vec.push(1); + vec.extend(&[2]); + } }