1 use clippy_utils::consts::constant_simple;
2 use clippy_utils::diagnostics::span_lint;
4 use rustc_lint::{LateContext, LateLintPass};
5 use rustc_session::{declare_tool_lint, impl_lint_pass};
6 use rustc_span::source_map::Span;
10 /// Checks for integer arithmetic operations which could overflow or panic.
12 /// Specifically, checks for any operators (`+`, `-`, `*`, `<<`, etc) which are capable
13 /// of overflowing according to the [Rust
14 /// Reference](https://doc.rust-lang.org/reference/expressions/operator-expr.html#overflow),
15 /// or which can panic (`/`, `%`). No bounds analysis or sophisticated reasoning is
18 /// ### Why is this bad?
19 /// Integer overflow will trigger a panic in debug builds or will wrap in
20 /// release mode. Division by zero will cause a panic in either mode. In some applications one
21 /// wants explicitly checked, wrapping or saturating arithmetic.
28 #[clippy::version = "pre 1.29.0"]
29 pub INTEGER_ARITHMETIC,
31 "any integer arithmetic expression which could overflow or panic"
34 declare_clippy_lint! {
36 /// Checks for float arithmetic.
38 /// ### Why is this bad?
39 /// For some embedded systems or kernel development, it
40 /// can be useful to rule out floating-point numbers.
47 #[clippy::version = "pre 1.29.0"]
50 "any floating-point arithmetic statement"
53 #[derive(Copy, Clone, Default)]
54 pub struct NumericArithmetic {
55 expr_span: Option<Span>,
56 /// This field is used to check whether expressions are constants, such as in enum discriminants
58 const_span: Option<Span>,
61 impl_lint_pass!(NumericArithmetic => [INTEGER_ARITHMETIC, FLOAT_ARITHMETIC]);
63 impl<'tcx> LateLintPass<'tcx> for NumericArithmetic {
64 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
65 if self.expr_span.is_some() {
69 if let Some(span) = self.const_span {
70 if span.contains(expr.span) {
75 hir::ExprKind::Binary(op, l, r) | hir::ExprKind::AssignOp(op, l, r) => {
79 | hir::BinOpKind::BitAnd
80 | hir::BinOpKind::BitOr
81 | hir::BinOpKind::BitXor
87 | hir::BinOpKind::Gt => return,
91 let (l_ty, r_ty) = (cx.typeck_results().expr_ty(l), cx.typeck_results().expr_ty(r));
92 if l_ty.peel_refs().is_integral() && r_ty.peel_refs().is_integral() {
94 hir::BinOpKind::Div | hir::BinOpKind::Rem => match &r.kind {
95 hir::ExprKind::Lit(_lit) => (),
96 hir::ExprKind::Unary(hir::UnOp::Neg, expr) => {
97 if let hir::ExprKind::Lit(lit) = &expr.kind {
98 if let rustc_ast::ast::LitKind::Int(1, _) = lit.node {
99 span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
100 self.expr_span = Some(expr.span);
105 span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
106 self.expr_span = Some(expr.span);
110 span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
111 self.expr_span = Some(expr.span);
114 } else if r_ty.peel_refs().is_floating_point() && r_ty.peel_refs().is_floating_point() {
115 span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
116 self.expr_span = Some(expr.span);
119 hir::ExprKind::Unary(hir::UnOp::Neg, arg) => {
120 let ty = cx.typeck_results().expr_ty(arg);
121 if constant_simple(cx, cx.typeck_results(), expr).is_none() {
122 if ty.is_integral() {
123 span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
124 self.expr_span = Some(expr.span);
125 } else if ty.is_floating_point() {
126 span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
127 self.expr_span = Some(expr.span);
135 fn check_expr_post(&mut self, _: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
136 if Some(expr.span) == self.expr_span {
137 self.expr_span = None;
141 fn check_body(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) {
142 let body_owner = cx.tcx.hir().body_owner_def_id(body.id());
144 match cx.tcx.hir().body_owner_kind(body_owner) {
145 hir::BodyOwnerKind::Static(_) | hir::BodyOwnerKind::Const => {
146 let body_span = cx.tcx.def_span(body_owner);
148 if let Some(span) = self.const_span {
149 if span.contains(body_span) {
153 self.const_span = Some(body_span);
155 hir::BodyOwnerKind::Fn | hir::BodyOwnerKind::Closure => (),
159 fn check_body_post(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) {
160 let body_owner = cx.tcx.hir().body_owner(body.id());
161 let body_span = cx.tcx.hir().span(body_owner);
163 if let Some(span) = self.const_span {
164 if span.contains(body_span) {
168 self.const_span = None;