1 use consts
::{constant_simple, Constant}
;
4 use 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",