src/tools/clippy/clippy_lints/src/operators/numeric_arithmetic.rs

   1 use clippy_utils::consts::constant_simple;
   2 use clippy_utils::diagnostics::span_lint;
   3 use rustc_hir as hir;
   4 use rustc_lint::LateContext;
   5 use rustc_span::source_map::Span;
   6
   7 use super::{FLOAT_ARITHMETIC, INTEGER_ARITHMETIC};
   8
   9 #[derive(Default)]
  10 pub struct Context {
  11     expr_id: Option<hir::HirId>,
  12     /// This field is used to check whether expressions are constants, such as in enum discriminants
  13     /// and consts
  14     const_span: Option<Span>,
  15 }
  16 impl Context {
  17     fn skip_expr(&mut self, e: &hir::Expr<'_>) -> bool {
  18         self.expr_id.is_some() || self.const_span.map_or(false, |span| span.contains(e.span))
  19     }
  20
  21     pub fn check_binary<'tcx>(
  22         &mut self,
  23         cx: &LateContext<'tcx>,
  24         expr: &'tcx hir::Expr<'_>,
  25         op: hir::BinOpKind,
  26         l: &'tcx hir::Expr<'_>,
  27         r: &'tcx hir::Expr<'_>,
  28     ) {
  29         if self.skip_expr(expr) {
  30             return;
  31         }
  32         match op {
  33             hir::BinOpKind::And
  34             | hir::BinOpKind::Or
  35             | hir::BinOpKind::BitAnd
  36             | hir::BinOpKind::BitOr
  37             | hir::BinOpKind::BitXor
  38             | hir::BinOpKind::Eq
  39             | hir::BinOpKind::Lt
  40             | hir::BinOpKind::Le
  41             | hir::BinOpKind::Ne
  42             | hir::BinOpKind::Ge
  43             | hir::BinOpKind::Gt => return,
  44             _ => (),
  45         }
  46
  47         let (l_ty, r_ty) = (cx.typeck_results().expr_ty(l), cx.typeck_results().expr_ty(r));
  48         if l_ty.peel_refs().is_integral() && r_ty.peel_refs().is_integral() {
  49             match op {
  50                 hir::BinOpKind::Div | hir::BinOpKind::Rem => match &r.kind {
  51                     hir::ExprKind::Lit(_lit) => (),
  52                     hir::ExprKind::Unary(hir::UnOp::Neg, expr) => {
  53                         if let hir::ExprKind::Lit(lit) = &expr.kind {
  54                             if let rustc_ast::ast::LitKind::Int(1, _) = lit.node {
  55                                 span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
  56                                 self.expr_id = Some(expr.hir_id);
  57                             }
  58                         }
  59                     },
  60                     _ => {
  61                         span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
  62                         self.expr_id = Some(expr.hir_id);
  63                     },
  64                 },
  65                 _ => {
  66                     span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
  67                     self.expr_id = Some(expr.hir_id);
  68                 },
  69             }
  70         } else if r_ty.peel_refs().is_floating_point() && r_ty.peel_refs().is_floating_point() {
  71             span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
  72             self.expr_id = Some(expr.hir_id);
  73         }
  74     }
  75
  76     pub fn check_negate<'tcx>(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>, arg: &'tcx hir::Expr<'_>) {
  77         if self.skip_expr(expr) {
  78             return;
  79         }
  80         let ty = cx.typeck_results().expr_ty(arg);
  81         if constant_simple(cx, cx.typeck_results(), expr).is_none() {
  82             if ty.is_integral() {
  83                 span_lint(cx, INTEGER_ARITHMETIC, expr.span, "integer arithmetic detected");
  84                 self.expr_id = Some(expr.hir_id);
  85             } else if ty.is_floating_point() {
  86                 span_lint(cx, FLOAT_ARITHMETIC, expr.span, "floating-point arithmetic detected");
  87                 self.expr_id = Some(expr.hir_id);
  88             }
  89         }
  90     }
  91
  92     pub fn expr_post(&mut self, id: hir::HirId) {
  93         if Some(id) == self.expr_id {
  94             self.expr_id = None;
  95         }
  96     }
  97
  98     pub fn enter_body(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) {
  99         let body_owner = cx.tcx.hir().body_owner(body.id());
 100         let body_owner_def_id = cx.tcx.hir().local_def_id(body_owner);
 101
 102         match cx.tcx.hir().body_owner_kind(body_owner_def_id) {
 103             hir::BodyOwnerKind::Static(_) | hir::BodyOwnerKind::Const => {
 104                 let body_span = cx.tcx.hir().span_with_body(body_owner);
 105
 106                 if let Some(span) = self.const_span {
 107                     if span.contains(body_span) {
 108                         return;
 109                     }
 110                 }
 111                 self.const_span = Some(body_span);
 112             },
 113             hir::BodyOwnerKind::Fn | hir::BodyOwnerKind::Closure => (),
 114         }
 115     }
 116
 117     pub fn body_post(&mut self, cx: &LateContext<'_>, body: &hir::Body<'_>) {
 118         let body_owner = cx.tcx.hir().body_owner(body.id());
 119         let body_span = cx.tcx.hir().span_with_body(body_owner);
 120
 121         if let Some(span) = self.const_span {
 122             if span.contains(body_span) {
 123                 return;
 124             }
 125         }
 126         self.const_span = None;
 127     }
 128 }