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