diff --git a/clippy_lints/src/suspicious_trait_impl.rs b/clippy_lints/src/suspicious_trait_impl.rs index 6d1d083fa8d4..502fffc5e6c6 100644 --- a/clippy_lints/src/suspicious_trait_impl.rs +++ b/clippy_lints/src/suspicious_trait_impl.rs @@ -64,26 +64,22 @@ impl<'tcx> LateLintPass<'tcx> for SuspiciousImpl { | hir::BinOpKind::Gt => return, _ => {}, } - // Check if the binary expression is part of another bi/unary expression - // or operator assignment as a child node - let mut parent_expr = cx.tcx.hir().get_parent_node(expr.hir_id); - while parent_expr != hir::CRATE_HIR_ID { - if let hir::Node::Expr(e) = cx.tcx.hir().get(parent_expr) { - match e.kind { - hir::ExprKind::Binary(..) - | hir::ExprKind::Unary(hir::UnOp::UnNot | hir::UnOp::UnNeg, _) - | hir::ExprKind::AssignOp(..) => return, - _ => {}, + + // Check for more than one binary operation in the implemented function + // Linting when multiple operations are involved can result in false positives + if_chain! { + let parent_fn = cx.tcx.hir().get_parent_item(expr.hir_id); + if let hir::Node::ImplItem(impl_item) = cx.tcx.hir().get(parent_fn); + if let hir::ImplItemKind::Fn(_, body_id) = impl_item.kind; + let body = cx.tcx.hir().body(body_id); + let mut visitor = BinaryExprVisitor { nb_binops: 0 }; + + then { + walk_expr(&mut visitor, &body.value); + if visitor.nb_binops > 1 { + return; } } - parent_expr = cx.tcx.hir().get_parent_node(parent_expr); - } - // as a parent node - let mut visitor = BinaryExprVisitor { in_binary_expr: false }; - walk_expr(&mut visitor, expr); - - if visitor.in_binary_expr { - return; } if let Some(impl_trait) = check_binop( @@ -181,7 +177,7 @@ fn check_binop( } struct BinaryExprVisitor { - in_binary_expr: bool, + nb_binops: u32, } impl<'tcx> Visitor<'tcx> for BinaryExprVisitor { @@ -191,12 +187,13 @@ impl<'tcx> Visitor<'tcx> for BinaryExprVisitor { match expr.kind { hir::ExprKind::Binary(..) | hir::ExprKind::Unary(hir::UnOp::UnNot | hir::UnOp::UnNeg, _) - | hir::ExprKind::AssignOp(..) => self.in_binary_expr = true, + | hir::ExprKind::AssignOp(..) => self.nb_binops += 1, _ => {}, } walk_expr(self, expr); } + fn nested_visit_map(&mut self) -> NestedVisitorMap { NestedVisitorMap::None } diff --git a/tests/ui/suspicious_arithmetic_impl.rs b/tests/ui/suspicious_arithmetic_impl.rs index 1f5b98118870..60c2f3ec9b65 100644 --- a/tests/ui/suspicious_arithmetic_impl.rs +++ b/tests/ui/suspicious_arithmetic_impl.rs @@ -88,3 +88,33 @@ fn main() {} fn do_nothing(x: u32) -> u32 { x } + +struct MultipleBinops(u32); + +impl Add for MultipleBinops { + type Output = MultipleBinops; + + // OK: multiple Binops in `add` impl + fn add(self, other: Self) -> Self::Output { + let mut result = self.0 + other.0; + if result >= u32::max_value() { + result -= u32::max_value(); + } + MultipleBinops(result) + } +} + +impl Mul for MultipleBinops { + type Output = MultipleBinops; + + // OK: multiple Binops in `mul` impl + fn mul(self, other: Self) -> Self::Output { + let mut result: u32 = 0; + let size = std::cmp::max(self.0, other.0) as usize; + let mut v = vec![0; size + 1]; + for i in 0..size + 1 { + result *= i as u32; + } + MultipleBinops(result) + } +}