1 use clippy_utils::diagnostics::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};
9 /// Checks for division of integers
11 /// ### Why is this bad?
12 /// When outside of some very specific algorithms,
13 /// integer division is very often a mistake because it discards the
20 /// println!("{}", x);
23 /// let x = 3f32 / 2f32;
24 /// println!("{}", x);
26 #[clippy::version = "1.37.0"]
29 "integer division may cause loss of precision"
32 declare_lint_pass!(IntegerDivision => [INTEGER_DIVISION]);
34 impl<'tcx> LateLintPass<'tcx> for IntegerDivision {
35 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
36 if is_integer_division(cx, expr) {
43 "division of integers may cause loss of precision. consider using floats",
49 fn is_integer_division<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) -> bool {
51 if let hir::ExprKind::Binary(binop, left, right) = &expr.kind;
52 if binop.node == hir::BinOpKind::Div;
54 let (left_ty, right_ty) = (cx.typeck_results().expr_ty(left), cx.typeck_results().expr_ty(right));
55 return left_ty.is_integral() && right_ty.is_integral();