/// **What it does:** Checks for needlessly including a base struct on update
/// when all fields are changed anyway.
///
+ /// This lint is not applied to structs marked with
+ /// [non_exhaustive](https://doc.rust-lang.org/reference/attributes/type_system.html).
+ ///
/// **Why is this bad?** This will cost resources (because the base has to be
/// somewhere), and make the code less readable.
///
declare_lint_pass!(NeedlessUpdate => [NEEDLESS_UPDATE]);
-impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NeedlessUpdate {
- fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr<'_>) {
+impl<'tcx> LateLintPass<'tcx> for NeedlessUpdate {
+ fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
if let ExprKind::Struct(_, ref fields, Some(ref base)) = expr.kind {
- let ty = cx.tables.expr_ty(expr);
- if let ty::Adt(def, _) = ty.kind {
- if fields.len() == def.non_enum_variant().fields.len() {
+ let ty = cx.typeck_results().expr_ty(expr);
+ if let ty::Adt(def, _) = ty.kind() {
+ if fields.len() == def.non_enum_variant().fields.len()
+ && !def.variants[0_usize.into()].is_field_list_non_exhaustive()
+ {
span_lint(
cx,
NEEDLESS_UPDATE,