1 use crate::consts::{constant_simple, Constant};
4 use crate::utils::span_help_and_lint;
6 /// **What it does:** Checks for `0.0 / 0.0`.
8 /// **Why is this bad?** It's less readable than `std::f32::NAN` or
11 /// **Known problems:** None.
17 declare_clippy_lint! {
18 pub ZERO_DIVIDED_BY_ZERO,
20 "usage of `0.0 / 0.0` to obtain NaN instead of std::f32::NaN or std::f64::NaN"
25 impl LintPass for Pass {
26 fn get_lints(&self) -> LintArray {
27 lint_array!(ZERO_DIVIDED_BY_ZERO)
31 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
32 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
33 // check for instances of 0.0/0.0
35 if let ExprBinary(ref op, ref left, ref right) = expr.node;
36 if let BinOp_::BiDiv = op.node;
37 // TODO - constant_simple does not fold many operations involving floats.
38 // That's probably fine for this lint - it's pretty unlikely that someone would
39 // do something like 0.0/(2.0 - 2.0), but it would be nice to warn on that case too.
40 if let Some(lhs_value) = constant_simple(cx, cx.tables, left);
41 if let Some(rhs_value) = constant_simple(cx, cx.tables, right);
42 if Constant::F32(0.0) == lhs_value || Constant::F64(0.0) == lhs_value;
43 if Constant::F32(0.0) == rhs_value || Constant::F64(0.0) == rhs_value;
45 // since we're about to suggest a use of std::f32::NaN or std::f64::NaN,
46 // match the precision of the literals that are given.
47 let float_type = match (lhs_value, rhs_value) {
49 | (_, Constant::F64(_)) => "f64",
56 "constant division of 0.0 with 0.0 will always result in NaN",
58 "Consider using `std::{}::NAN` if you would like a constant representing NaN",