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