| use clippy_utils::diagnostics::span_lint_and_sugg; |
| use clippy_utils::source::snippet_with_applicability; |
| use clippy_utils::{match_def_path, path_def_id}; |
| use if_chain::if_chain; |
| use rustc_ast::ast; |
| use rustc_errors::Applicability; |
| use rustc_hir as hir; |
| use rustc_lint::LateContext; |
| use rustc_middle::ty::layout::LayoutOf; |
| |
| pub fn check( |
| cx: &LateContext<'_>, |
| expr: &hir::Expr<'_>, |
| arith_lhs: &hir::Expr<'_>, |
| arith_rhs: &hir::Expr<'_>, |
| unwrap_arg: &hir::Expr<'_>, |
| arith: &str, |
| ) { |
| let ty = cx.typeck_results().expr_ty(arith_lhs); |
| if !ty.is_integral() { |
| return; |
| } |
| |
| let Some(mm) = is_min_or_max(cx, unwrap_arg) else { |
| return; |
| }; |
| |
| if ty.is_signed() { |
| use self::MinMax::{Max, Min}; |
| use self::Sign::{Neg, Pos}; |
| |
| let Some(sign) = lit_sign(arith_rhs) else { |
| return; |
| }; |
| |
| match (arith, sign, mm) { |
| ("add", Pos, Max) | ("add", Neg, Min) | ("sub", Neg, Max) | ("sub", Pos, Min) => (), |
| // "mul" is omitted because lhs can be negative. |
| _ => return, |
| } |
| } else { |
| match (mm, arith) { |
| (MinMax::Max, "add" | "mul") | (MinMax::Min, "sub") => (), |
| _ => return, |
| } |
| } |
| |
| let mut applicability = Applicability::MachineApplicable; |
| span_lint_and_sugg( |
| cx, |
| super::MANUAL_SATURATING_ARITHMETIC, |
| expr.span, |
| "manual saturating arithmetic", |
| &format!("try using `saturating_{arith}`"), |
| format!( |
| "{}.saturating_{arith}({})", |
| snippet_with_applicability(cx, arith_lhs.span, "..", &mut applicability), |
| snippet_with_applicability(cx, arith_rhs.span, "..", &mut applicability), |
| ), |
| applicability, |
| ); |
| } |
| |
| #[derive(PartialEq, Eq)] |
| enum MinMax { |
| Min, |
| Max, |
| } |
| |
| fn is_min_or_max(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<MinMax> { |
| // `T::max_value()` `T::min_value()` inherent methods |
| if_chain! { |
| if let hir::ExprKind::Call(func, args) = &expr.kind; |
| if args.is_empty(); |
| if let hir::ExprKind::Path(hir::QPath::TypeRelative(_, segment)) = &func.kind; |
| then { |
| match segment.ident.as_str() { |
| "max_value" => return Some(MinMax::Max), |
| "min_value" => return Some(MinMax::Min), |
| _ => {} |
| } |
| } |
| } |
| |
| let ty = cx.typeck_results().expr_ty(expr); |
| let ty_str = ty.to_string(); |
| |
| // `std::T::MAX` `std::T::MIN` constants |
| if let Some(id) = path_def_id(cx, expr) { |
| if match_def_path(cx, id, &["core", &ty_str, "MAX"]) { |
| return Some(MinMax::Max); |
| } |
| |
| if match_def_path(cx, id, &["core", &ty_str, "MIN"]) { |
| return Some(MinMax::Min); |
| } |
| } |
| |
| // Literals |
| let bits = cx.layout_of(ty).unwrap().size.bits(); |
| let (minval, maxval): (u128, u128) = if ty.is_signed() { |
| let minval = 1 << (bits - 1); |
| let mut maxval = !(1 << (bits - 1)); |
| if bits != 128 { |
| maxval &= (1 << bits) - 1; |
| } |
| (minval, maxval) |
| } else { |
| (0, if bits == 128 { !0 } else { (1 << bits) - 1 }) |
| }; |
| |
| let check_lit = |expr: &hir::Expr<'_>, check_min: bool| { |
| if let hir::ExprKind::Lit(lit) = &expr.kind { |
| if let ast::LitKind::Int(value, _) = lit.node { |
| if value == maxval { |
| return Some(MinMax::Max); |
| } |
| |
| if check_min && value == minval { |
| return Some(MinMax::Min); |
| } |
| } |
| } |
| |
| None |
| }; |
| |
| if let r @ Some(_) = check_lit(expr, !ty.is_signed()) { |
| return r; |
| } |
| |
| if ty.is_signed() { |
| if let hir::ExprKind::Unary(hir::UnOp::Neg, val) = &expr.kind { |
| return check_lit(val, true); |
| } |
| } |
| |
| None |
| } |
| |
| #[derive(PartialEq, Eq)] |
| enum Sign { |
| Pos, |
| Neg, |
| } |
| |
| fn lit_sign(expr: &hir::Expr<'_>) -> Option<Sign> { |
| if let hir::ExprKind::Unary(hir::UnOp::Neg, inner) = &expr.kind { |
| if let hir::ExprKind::Lit(..) = &inner.kind { |
| return Some(Sign::Neg); |
| } |
| } else if let hir::ExprKind::Lit(..) = &expr.kind { |
| return Some(Sign::Pos); |
| } |
| |
| None |
| } |