| use rustc::lint::*; |
| use rustc::hir::*; |
| use utils::{span_lint}; |
| |
| /// **What it does:** This lint finds classic underflow / overflow checks. |
| /// |
| /// **Why is this bad?** Most classic C underflow / overflow checks will fail in Rust. Users can use functions like `overflowing_*` and `wrapping_*` instead. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** `a + b < a` |
| |
| declare_lint!(pub OVERFLOW_CHECK_CONDITIONAL, Warn, |
| "Using overflow checks which are likely to panic"); |
| |
| #[derive(Copy, Clone)] |
| pub struct OverflowCheckConditional; |
| |
| impl LintPass for OverflowCheckConditional { |
| fn get_lints(&self) -> LintArray { |
| lint_array!(OVERFLOW_CHECK_CONDITIONAL) |
| } |
| } |
| |
| impl LateLintPass for OverflowCheckConditional { |
| // a + b < a, a > a + b, a < a - b, a - b > a |
| fn check_expr(&mut self, cx: &LateContext, expr: &Expr) { |
| if_let_chain! {[ |
| let Expr_::ExprBinary(ref op, ref first, ref second) = expr.node, |
| let Expr_::ExprBinary(ref op2, ref ident1, ref ident2) = first.node, |
| let Expr_::ExprPath(_,ref path1) = ident1.node, |
| let Expr_::ExprPath(_, ref path2) = ident2.node, |
| let Expr_::ExprPath(_, ref path3) = second.node, |
| (&path1.segments[0]).identifier == (&path3.segments[0]).identifier || (&path2.segments[0]).identifier == (&path3.segments[0]).identifier, |
| cx.tcx.expr_ty(ident1).is_integral(), |
| cx.tcx.expr_ty(ident2).is_integral() |
| ], { |
| if let BinOp_::BiLt = op.node { |
| if let BinOp_::BiAdd = op2.node { |
| span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span, "You are trying to use classic C overflow conditions that will fail in Rust."); |
| } |
| } |
| if let BinOp_::BiGt = op.node { |
| if let BinOp_::BiSub = op2.node { |
| span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span, "You are trying to use classic C underflow conditions that will fail in Rust."); |
| } |
| } |
| }} |
| |
| if_let_chain! {[ |
| let Expr_::ExprBinary(ref op, ref first, ref second) = expr.node, |
| let Expr_::ExprBinary(ref op2, ref ident1, ref ident2) = second.node, |
| let Expr_::ExprPath(_,ref path1) = ident1.node, |
| let Expr_::ExprPath(_, ref path2) = ident2.node, |
| let Expr_::ExprPath(_, ref path3) = first.node, |
| (&path1.segments[0]).identifier == (&path3.segments[0]).identifier || (&path2.segments[0]).identifier == (&path3.segments[0]).identifier, |
| cx.tcx.expr_ty(ident1).is_integral(), |
| cx.tcx.expr_ty(ident2).is_integral() |
| ], { |
| if let BinOp_::BiGt = op.node { |
| if let BinOp_::BiAdd = op2.node { |
| span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span, "You are trying to use classic C overflow conditions that will fail in Rust."); |
| } |
| } |
| if let BinOp_::BiLt = op.node { |
| if let BinOp_::BiSub = op2.node { |
| span_lint(cx, OVERFLOW_CHECK_CONDITIONAL, expr.span, "You are trying to use classic C underflow conditions that will fail in Rust."); |
| } |
| } |
| }} |
| } |
| } |