73 lines
3.0 KiB
Rust
73 lines
3.0 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:** This lint finds 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 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:** `a + b < a`
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declare_lint!(pub OVERFLOW_CHECK_CONDITIONAL, Warn,
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"Using overflow checks which are likely to panic");
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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 LateLintPass 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, expr: &Expr) {
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if_let_chain! {[
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let Expr_::ExprBinary(ref op, ref first, ref second) = expr.node,
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let Expr_::ExprBinary(ref op2, ref ident1, ref ident2) = first.node,
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let Expr_::ExprPath(_,ref path1) = ident1.node,
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let Expr_::ExprPath(_, ref path2) = ident2.node,
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let Expr_::ExprPath(_, ref path3) = second.node,
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&path1.segments[0] == &path3.segments[0] || &path2.segments[0] == &path3.segments[0],
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cx.tcx.expr_ty(ident1).is_integral(),
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cx.tcx.expr_ty(ident2).is_integral()
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], {
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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, "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, "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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if_let_chain! {[
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let Expr_::ExprBinary(ref op, ref first, ref second) = expr.node,
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let Expr_::ExprBinary(ref op2, ref ident1, ref ident2) = second.node,
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let Expr_::ExprPath(_,ref path1) = ident1.node,
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let Expr_::ExprPath(_, ref path2) = ident2.node,
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let Expr_::ExprPath(_, ref path3) = first.node,
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&path1.segments[0] == &path3.segments[0] || &path2.segments[0] == &path3.segments[0],
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cx.tcx.expr_ty(ident1).is_integral(),
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cx.tcx.expr_ty(ident2).is_integral()
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], {
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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, "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, "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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