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Suggest manual_div_ceil even when right operand is a constant (#13951)

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changelog: [`manual_div_ceil`]: lint constants as well

Fix #13950
This commit is contained in:
Alejandra González 2025-01-14 19:06:32 +00:00 • committed by GitHub
commit 7e83ec57c6
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7 changed files with 124 additions and 2 deletions
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36
clippy_lints/src/manual_div_ceil.rs
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@ -102,12 +102,48 @@ impl<'tcx> LateLintPass<'tcx> for ManualDivCeil {
{
build_suggestion(cx, expr, add_lhs, div_rhs, &mut applicability);
}
// (x + (Y - 1)) / Y
if inner_op.node == BinOpKind::Add && differ_by_one(inner_rhs, div_rhs) {
build_suggestion(cx, expr, inner_lhs, div_rhs, &mut applicability);
}
// ((Y - 1) + x) / Y
if inner_op.node == BinOpKind::Add && differ_by_one(inner_lhs, div_rhs) {
build_suggestion(cx, expr, inner_rhs, div_rhs, &mut applicability);
}
// (x - (-Y - 1)) / Y
if inner_op.node == BinOpKind::Sub
&& let ExprKind::Unary(UnOp::Neg, abs_div_rhs) = div_rhs.kind
&& differ_by_one(abs_div_rhs, inner_rhs)
{
build_suggestion(cx, expr, inner_lhs, div_rhs, &mut applicability);
}
}
}
extract_msrv_attr!(LateContext);
}
/// Checks if two expressions represent non-zero integer literals such that `small_expr + 1 ==
/// large_expr`.
fn differ_by_one(small_expr: &Expr<'_>, large_expr: &Expr<'_>) -> bool {
if let ExprKind::Lit(small) = small_expr.kind
&& let ExprKind::Lit(large) = large_expr.kind
&& let LitKind::Int(s, _) = small.node
&& let LitKind::Int(l, _) = large.node
{
Some(l.get()) == s.get().checked_add(1)
} else if let ExprKind::Unary(UnOp::Neg, small_inner_expr) = small_expr.kind
&& let ExprKind::Unary(UnOp::Neg, large_inner_expr) = large_expr.kind
{
differ_by_one(large_inner_expr, small_inner_expr)
} else {
false
}
}
fn check_int_ty_and_feature(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
let expr_ty = cx.typeck_results().expr_ty(expr);
match expr_ty.peel_refs().kind() {