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Diffstat (limited to 'clippy_lints/src/numeric_arithmetic.rs')
| -rw-r--r-- | clippy_lints/src/numeric_arithmetic.rs | 170 |
1 files changed, 170 insertions, 0 deletions
diff --git a/clippy_lints/src/numeric_arithmetic.rs b/clippy_lints/src/numeric_arithmetic.rs new file mode 100644 index 00000000000..5c4de338149 --- /dev/null +++ b/clippy_lints/src/numeric_arithmetic.rs @@ -0,0 +1,170 @@ +use clippy_utils::consts::constant_simple; +use clippy_utils::diagnostics::span_lint; +use rustc_hir as hir; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_session::{declare_tool_lint, impl_lint_pass}; +use rustc_span::source_map::Span; + +declare_clippy_lint! { + /// ### What it does + /// Checks for integer arithmetic operations which could overflow or panic. + /// + /// Specifically, checks for any operators (`+`, `-`, `*`, `<<`, etc) which are capable + /// of overflowing according to the [Rust + /// Reference](https://doc.rust-lang.org/reference/expressions/operator-expr.html#overflow), + /// or which can panic (`/`, `%`). No bounds analysis or sophisticated reasoning is + /// attempted. + /// + /// ### Why is this bad? + /// Integer overflow will trigger a panic in debug builds or will wrap in + /// release mode. Division by zero will cause a panic in either mode. In some applications one + /// wants explicitly checked, wrapping or saturating arithmetic. + /// + /// ### Example + /// ```rust + /// # let a = 0; + /// a + 1; + /// ``` + #[clippy::version = "pre 1.29.0"] + pub INTEGER_ARITHMETIC, + restriction, + "any integer arithmetic expression which could overflow or panic" +} + +declare_clippy_lint! { + /// ### What it does + /// Checks for float arithmetic. + /// + /// ### Why is this bad? + /// For some embedded systems or kernel development, it + /// can be useful to rule out floating-point numbers. + /// + /// ### Example + /// ```rust + /// # let a = 0.0; + /// a + 1.0; + /// ``` + #[clippy::version = "pre 1.29.0"] + pub FLOAT_ARITHMETIC, + restriction, + "any floating-point arithmetic statement" +} + +#[derive(Copy, Clone, Default)] +pub struct NumericArithmetic { + expr_span: Option<Span>, + /// This field is used to check whether expressions are constants, such as in enum discriminants + /// and consts + const_span: Option<Span>, +} + +impl_lint_pass!(NumericArithmetic => [INTEGER_ARITHMETIC, FLOAT_ARITHMETIC]); + +impl<'tcx> LateLintPass<'tcx> for NumericArithmetic { + fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) { + if self.expr_span.is_some() { + return; + } + + if let Some(span) = self.const_span { + if span.contains(expr.span) { + return; + } + } + match &expr.kind { + hir::ExprKind::Binary(op, l, r) | hir::ExprKind::AssignOp(op, l, r) => { + match op.node { + hir::BinOpKind::And + | hir::BinOpKind::Or + | hir::BinOpKind::BitAnd + | hir::BinOpKind::BitOr + | hir::BinOpKind::BitXor + | hir::BinOpKind::Eq + | hir::BinOpKind::Lt + | hir::BinOpKind::Le + | hir::BinOpKind::Ne + | hir::BinOpKind::Ge + | hir::BinOpKind::Gt => return, + _ => (), + } + + let (l_ty, r_ty) = (cx.typeck_results().expr_ty(l), cx.typeck_results().expr_ty(r)); + if l_ty.peel_refs().is_integral() && r_ty.peel_refs().is_integral() { + match op.node { + hir::BinOpKind::Div | hir::BinOpKind::Rem => match &r.kind { + hir::ExprKind::Lit(_lit) => (), + hir::ExprKind::Unary(hir::UnOp::Neg, expr) => { + if let hir::ExprKind::Lit(lit) = &expr.kind { + if let rustc_ast::ast::LitKind::Int(1, _) = lit.node { + span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected"); + self.expr_span = Some(expr.span); + } + } + }, + _ => { + span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected"); + self.expr_span = Some(expr.span); + }, + }, + _ => { + span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected"); + self.expr_span = Some(expr.span); + }, + } + } else if r_ty.peel_refs().is_floating_point() && r_ty.peel_refs().is_floating_point() { + span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected"); + self.expr_span = Some(expr.span); + } + }, + hir::ExprKind::Unary(hir::UnOp::Neg, arg) => { + let ty = cx.typeck_results().expr_ty(arg); + if constant_simple(cx, cx.typeck_results(), expr).is_none() { + if ty.is_integral() { + span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected"); + self.expr_span = Some(expr.span); + } else if ty.is_floating_point() { + span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected"); + self.expr_span = Some(expr.span); + } + } + }, + _ => (), + } + } + + fn check_expr_post(&mut self, _: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) { + if Some(expr.span) == self.expr_span { + self.expr_span = None; + } + } + + fn check_body(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) { + let body_owner = cx.tcx.hir().body_owner_def_id(body.id()); + + match cx.tcx.hir().body_owner_kind(body_owner) { + hir::BodyOwnerKind::Static(_) | hir::BodyOwnerKind::Const => { + let body_span = cx.tcx.def_span(body_owner); + + if let Some(span) = self.const_span { + if span.contains(body_span) { + return; + } + } + self.const_span = Some(body_span); + }, + hir::BodyOwnerKind::Fn | hir::BodyOwnerKind::Closure => (), + } + } + + fn check_body_post(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) { + let body_owner = cx.tcx.hir().body_owner(body.id()); + let body_span = cx.tcx.hir().span(body_owner); + + if let Some(span) = self.const_span { + if span.contains(body_span) { + return; + } + } + self.const_span = None; + } +} |