1 use crate::utils::span_lint_and_help;
2 use if_chain::if_chain;
4 use rustc_lint::{LateContext, LateLintPass};
5 use rustc_session::{declare_lint_pass, declare_tool_lint};
8 /// **What it does:** Checks for division of integers
10 /// **Why is this bad?** When outside of some very specific algorithms,
11 /// integer division is very often a mistake because it discards the
14 /// **Known problems:** None.
20 /// println!("{}", x);
25 "integer division may cause loss of precision"
28 declare_lint_pass!(IntegerDivision => [INTEGER_DIVISION]);
30 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IntegerDivision {
31 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'_>) {
32 if is_integer_division(cx, expr) {
39 "division of integers may cause loss of precision. consider using floats.",
45 fn is_integer_division<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx hir::Expr<'_>) -> bool {
47 if let hir::ExprKind::Binary(binop, left, right) = &expr.kind;
48 if let hir::BinOpKind::Div = &binop.node;
50 let (left_ty, right_ty) = (cx.tables.expr_ty(left), cx.tables.expr_ty(right));
51 return left_ty.is_integral() && right_ty.is_integral();