+#[derive(Clone, Copy)]
+enum Item {
+ Lang(LangItem),
+ Diag(Symbol, Symbol),
+}
+
+fn is_pat_variant(cx: &LateContext<'_>, pat: &Pat<'_>, path: &QPath<'_>, expected_item: Item) -> bool {
+ let Some(id) = cx.typeck_results().qpath_res(path, pat.hir_id).opt_def_id() else { return false };
+
+ match expected_item {
+ Item::Lang(expected_lang_item) => {
+ let expected_id = cx.tcx.lang_items().require(expected_lang_item).unwrap();
+ cx.tcx.parent(id) == expected_id
+ },
+ Item::Diag(expected_ty, expected_variant) => {
+ let ty = cx.typeck_results().pat_ty(pat);
+
+ if is_type_diagnostic_item(cx, ty, expected_ty) {
+ let variant = ty
+ .ty_adt_def()
+ .expect("struct pattern type is not an ADT")
+ .variant_of_res(cx.qpath_res(path, pat.hir_id));
+
+ return variant.name == expected_variant;
+ }
+
+ false
+ },
+ }
+}
+