29 lines
884 B
Rust
29 lines
884 B
Rust
|
use super::CAST_NAN_TO_INT;
|
||
|
|
|
||
|
|
use clippy_utils::consts::{constant, Constant};
|
||
|
|
use clippy_utils::diagnostics::span_lint_and_note;
|
||
|
|
use rustc_hir::Expr;
|
||
|
|
use rustc_lint::LateContext;
|
||
|
|
use rustc_middle::ty::Ty;
|
||
|
|
|
||
|
|
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, from_ty: Ty<'_>, to_ty: Ty<'_>) {
|
||
|
|
if from_ty.is_floating_point() && to_ty.is_integral() && is_known_nan(cx, cast_expr) {
|
||
|
|
span_lint_and_note(
|
||
|
|
cx,
|
||
|
|
CAST_NAN_TO_INT,
|
||
|
|
expr.span,
|
||
|
|
&format!("casting a known NaN to {to_ty}"),
|
||
|
|
None,
|
||
|
|
"this always evaluates to 0",
|
||
|
|
);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
fn is_known_nan(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
|
||
|
|
match constant(cx, cx.typeck_results(), e) {
|
||
|
|
Some((Constant::F64(n), _)) => n.is_nan(),
|
||
|
|
Some((Constant::F32(n), _)) => n.is_nan(),
|
||
|
|
_ => false,
|
||
|
|
}
|
||
|
|
}
|