67 lines
2.5 KiB
Rust
67 lines
2.5 KiB
Rust
use clippy_utils::consts::{constant_simple, Constant};
|
|
use clippy_utils::diagnostics::span_lint_and_help;
|
|
use if_chain::if_chain;
|
|
use rustc_hir::{BinOpKind, Expr, ExprKind};
|
|
use rustc_lint::{LateContext, LateLintPass};
|
|
use rustc_session::{declare_lint_pass, declare_tool_lint};
|
|
|
|
declare_clippy_lint! {
|
|
/// ### What it does
|
|
/// Checks for `0.0 / 0.0`.
|
|
///
|
|
/// ### Why is this bad?
|
|
/// It's less readable than `f32::NAN` or `f64::NAN`.
|
|
///
|
|
/// ### Example
|
|
/// ```rust
|
|
/// let nan = 0.0f32 / 0.0;
|
|
/// ```
|
|
///
|
|
/// Use instead:
|
|
/// ```rust
|
|
/// let nan = f32::NAN;
|
|
/// ```
|
|
#[clippy::version = "pre 1.29.0"]
|
|
pub ZERO_DIVIDED_BY_ZERO,
|
|
complexity,
|
|
"usage of `0.0 / 0.0` to obtain NaN instead of `f32::NAN` or `f64::NAN`"
|
|
}
|
|
|
|
declare_lint_pass!(ZeroDiv => [ZERO_DIVIDED_BY_ZERO]);
|
|
|
|
impl<'tcx> LateLintPass<'tcx> for ZeroDiv {
|
|
fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
|
|
// check for instances of 0.0/0.0
|
|
if_chain! {
|
|
if let ExprKind::Binary(ref op, left, right) = expr.kind;
|
|
if op.node == BinOpKind::Div;
|
|
// TODO - constant_simple does not fold many operations involving floats.
|
|
// That's probably fine for this lint - it's pretty unlikely that someone would
|
|
// do something like 0.0/(2.0 - 2.0), but it would be nice to warn on that case too.
|
|
if let Some(lhs_value) = constant_simple(cx, cx.typeck_results(), left);
|
|
if let Some(rhs_value) = constant_simple(cx, cx.typeck_results(), right);
|
|
if Constant::F32(0.0) == lhs_value || Constant::F64(0.0) == lhs_value;
|
|
if Constant::F32(0.0) == rhs_value || Constant::F64(0.0) == rhs_value;
|
|
then {
|
|
// since we're about to suggest a use of f32::NAN or f64::NAN,
|
|
// match the precision of the literals that are given.
|
|
let float_type = match (lhs_value, rhs_value) {
|
|
(Constant::F64(_), _)
|
|
| (_, Constant::F64(_)) => "f64",
|
|
_ => "f32"
|
|
};
|
|
span_lint_and_help(
|
|
cx,
|
|
ZERO_DIVIDED_BY_ZERO,
|
|
expr.span,
|
|
"constant division of `0.0` with `0.0` will always result in NaN",
|
|
None,
|
|
&format!(
|
|
"consider using `{float_type}::NAN` if you would like a constant representing NaN",
|
|
),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|