Don't suggest unstable and doc(hidden) variants.

clippy_lints/src/matches.rs

@@ -992,9 +992,9 @@ fn with_prefix(&mut self, path: &'a [PathSegment<'a>]) {
     }
 }
 
-fn is_doc_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
+fn is_hidden(cx: &LateContext<'_>, variant_def: &VariantDef) -> bool {
     let attrs = cx.tcx.get_attrs(variant_def.def_id);
-    clippy_utils::attrs::is_doc_hidden(attrs)
+    clippy_utils::attrs::is_doc_hidden(attrs) || clippy_utils::attrs::is_unstable(attrs)
 }
 
 #[allow(clippy::too_many_lines)]
@@ -1033,7 +1033,7 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])
 
     // Accumulate the variants which should be put in place of the wildcard because they're not
     // already covered.
-    let mut missing_variants: Vec<_> = adt_def.variants.iter().collect();
+    let mut missing_variants: Vec<_> = adt_def.variants.iter().filter(|x| !is_hidden(cx, x)).collect();
 
     let mut path_prefix = CommonPrefixSearcher::None;
     for arm in arms {
@@ -1118,7 +1118,7 @@ fn check_wild_enum_match(cx: &LateContext<'_>, ex: &Expr<'_>, arms: &[Arm<'_>])
 
     match missing_variants.as_slice() {
         [] => (),
-        [x] if !adt_def.is_variant_list_non_exhaustive() && !is_doc_hidden(cx, x) => span_lint_and_sugg(
+        [x] if !adt_def.is_variant_list_non_exhaustive() => span_lint_and_sugg(
             cx,
             MATCH_WILDCARD_FOR_SINGLE_VARIANTS,
             wildcard_span,

clippy_utils/src/attrs.rs

@@ -157,3 +157,8 @@ pub fn is_doc_hidden(attrs: &[ast::Attribute]) -> bool {
         .filter_map(ast::Attribute::meta_item_list)
         .any(|l| attr::list_contains_name(&l, sym::hidden))
 }
+
+/// Return true if the attributes contain `#[unstable]`
+pub fn is_unstable(attrs: &[ast::Attribute]) -> bool {
+    attrs.iter().any(|attr| attr.has_name(sym::unstable))
+}

tests/ui/auxiliary/non-exhaustive-enum.rs

@@ -20,4 +20,6 @@ pub enum ErrorKind {
     UnexpectedEof,
     Unsupported,
     OutOfMemory,
+    #[doc(hidden)]
+    Uncategorized,
 }