diff options
Diffstat (limited to 'src/tools/clippy/clippy_lints/src/casts/cast_nan_to_int.rs')
-rw-r--r-- | src/tools/clippy/clippy_lints/src/casts/cast_nan_to_int.rs | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/casts/cast_nan_to_int.rs b/src/tools/clippy/clippy_lints/src/casts/cast_nan_to_int.rs new file mode 100644 index 000000000..322dc41b3 --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/casts/cast_nan_to_int.rs @@ -0,0 +1,28 @@ +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, + } +} |