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);
23 /// let x = 3f32 / 2f32;
24 /// println!("{}", x);
28 "integer division may cause loss of precision"
31 declare_lint_pass!(IntegerDivision => [INTEGER_DIVISION]);
33 impl<'tcx> LateLintPass<'tcx> for IntegerDivision {
34 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
35 if is_integer_division(cx, expr) {
42 "division of integers may cause loss of precision. consider using floats.",
48 fn is_integer_division<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) -> bool {
50 if let hir::ExprKind::Binary(binop, left, right) = &expr.kind;
51 if let hir::BinOpKind::Div = &binop.node;
53 let (left_ty, right_ty) = (cx.typeck_results().expr_ty(left), cx.typeck_results().expr_ty(right));
54 return left_ty.is_integral() && right_ty.is_integral();