5 /// **What it does:** Detects classic underflow/overflow checks.
7 /// **Why is this bad?** Most classic C underflow/overflow checks will fail in
8 /// Rust. Users can use functions like `overflowing_*` and `wrapping_*` instead.
10 /// **Known problems:** None.
17 pub OVERFLOW_CHECK_CONDITIONAL,
19 "overflow checks inspired by C which are likely to panic"
22 #[derive(Copy, Clone)]
23 pub struct OverflowCheckConditional;
25 impl LintPass for OverflowCheckConditional {
26 fn get_lints(&self) -> LintArray {
27 lint_array!(OVERFLOW_CHECK_CONDITIONAL)
31 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for OverflowCheckConditional {
32 // a + b < a, a > a + b, a < a - b, a - b > a
33 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
35 if let Expr_::ExprBinary(ref op, ref first, ref second) = expr.node;
36 if let Expr_::ExprBinary(ref op2, ref ident1, ref ident2) = first.node;
37 if let Expr_::ExprPath(QPath::Resolved(_, ref path1)) = ident1.node;
38 if let Expr_::ExprPath(QPath::Resolved(_, ref path2)) = ident2.node;
39 if let Expr_::ExprPath(QPath::Resolved(_, ref path3)) = second.node;
40 if path1.segments[0] == path3.segments[0] || path2.segments[0] == path3.segments[0];
41 if cx.tables.expr_ty(ident1).is_integral();
42 if cx.tables.expr_ty(ident2).is_integral();
44 if let BinOp_::BiLt = op.node {
45 if let BinOp_::BiAdd = op2.node {
46 span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span,
47 "You are trying to use classic C overflow conditions that will fail in Rust.");
50 if let BinOp_::BiGt = op.node {
51 if let BinOp_::BiSub = op2.node {
52 span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span,
53 "You are trying to use classic C underflow conditions that will fail in Rust.");
60 if let Expr_::ExprBinary(ref op, ref first, ref second) = expr.node;
61 if let Expr_::ExprBinary(ref op2, ref ident1, ref ident2) = second.node;
62 if let Expr_::ExprPath(QPath::Resolved(_, ref path1)) = ident1.node;
63 if let Expr_::ExprPath(QPath::Resolved(_, ref path2)) = ident2.node;
64 if let Expr_::ExprPath(QPath::Resolved(_, ref path3)) = first.node;
65 if path1.segments[0] == path3.segments[0] || path2.segments[0] == path3.segments[0];
66 if cx.tables.expr_ty(ident1).is_integral();
67 if cx.tables.expr_ty(ident2).is_integral();
69 if let BinOp_::BiGt = op.node {
70 if let BinOp_::BiAdd = op2.node {
71 span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span,
72 "You are trying to use classic C overflow conditions that will fail in Rust.");
75 if let BinOp_::BiLt = op.node {
76 if let BinOp_::BiSub = op2.node {
77 span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span,
78 "You are trying to use classic C underflow conditions that will fail in Rust.");