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Keep sign in int-to-float casts

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This commit is contained in:
Geoffrey Copin 2020-10-23 23:40:57 +02:00
parent 30f80c3b8c
commit d46edd9966
4 changed files with 48 additions and 12 deletions
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16
clippy_lints/src/types.rs
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@ -1236,6 +1236,13 @@ declare_clippy_lint! {
/// let _ = 2i32 as i32;
/// let _ = 0.5 as f32;
/// ```
///
/// Better:
///
/// ```rust
/// let _ = 2_i32;
/// let _ = 0.5_f32;
/// ```
pub UNNECESSARY_CAST,
complexity,
"cast to the same type, e.g., `x as i32` where `x: i32`"
@ -1612,7 +1619,8 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
let to_nbits = fp_ty_mantissa_nbits(cast_to);
if from_nbits != 0 && to_nbits != 0 && from_nbits <= to_nbits && num_lit.is_decimal();
then {
show_unnecessary_cast(cx, expr, num_lit.integer, cast_from, cast_to);
let literal_str = if is_unary_neg(ex) { format!("-{}", num_lit.integer) } else { num_lit.integer.into() };
show_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
return;
}
}
@ -1624,7 +1632,7 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
LitKind::Float(_, LitFloatType::Unsuffixed) if cast_to.is_floating_point() => {
show_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
},
LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed) => (),
LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed) => {},
_ => {
if cast_from.kind() == cast_to.kind() && !in_external_macro(cx.sess(), expr.span) {
span_lint(
@ -1649,6 +1657,10 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
}
}
fn is_unary_neg(expr: &Expr<'_>) -> bool {
matches!(expr.kind, ExprKind::Unary(UnOp::UnNeg, _))
}
fn get_numeric_literal<'e>(expr: &'e Expr<'e>) -> Option<&'e Lit> {
match expr.kind {
ExprKind::Lit(ref lit) => Some(lit),