c++: Include anon enum types in namespace members_of [PR124831]

As the testcase shows, we have similar problem with namespace scope
anonymous enums like we have with namespace scope anonymous unions.
Because they are anonymous, in neither case we emit anything into the
namespace bindings but we should still list those.
Now, for anonymous union this is done by adding it (once only) when
seeing corresponding DECL_ANON_UNION_VAR_P (and it doesn't work when there
is anon union without any members but that is a pedwarn anyway).

The following patch handles it similarly for anon enums, namespace scope
enum {}; is still ignored (but that is a pedwarn as well, so not a big deal)
and when there is at least one enumerator in it, we add it when seeing
the CONST_DECL (but again, just once for the whole members_of call).

2026-04-10  Jakub Jelinek  <jakub@redhat.com>

	PR c++/124831
	* reflect.cc (namespace_members_of): Append reflection of anon unions
	when we see it first time as CP_DECL_CONTEXT of some CONST_DECL in
	the namespace.

	* g++.dg/reflect/members_of13.C: New test.

Reviewed-by: Jason Merrill <jason@redhat.com>

diff --git a/gcc/cp/reflect.cc b/gcc/cp/reflect.cc
index 8925bf49465d08e8bb730b4321bc8e0f481f5d80..06bfae2774832cc77a0eee7e6d74b48b93d843f8 100644 (file)
--- a/gcc/cp/reflect.cc
+++ b/gcc/cp/reflect.cc
@@ -6755,6 +6755,24 @@ namespace_members_of (location_t loc, tree ns)
          return;
        }
 
+      if (TREE_CODE (b) == CONST_DECL
+         && enum_with_enumerator_for_linkage_p (CP_DECL_CONTEXT (b))
+         && members_of_representable_p (data->ns, CP_DECL_CONTEXT (b)))
+       {
+         /* TODO: This doesn't handle namespace N { enum {}; }
+            but we pedwarn on that because it violates [dcl.pre]/6, so
+            perhaps it doesn't need to be handled.  */
+         tree type = CP_DECL_CONTEXT (b);
+         if (!data->seen)
+           data->seen = new hash_set<tree>;
+         if (!data->seen->add (type))
+           {
+             CONSTRUCTOR_APPEND_ELT (data->elts, NULL_TREE,
+                                     get_reflection_raw (data->loc, type));
+             return;
+           }
+       }
+
       if (TREE_CODE (b) == TYPE_DECL)
        m = TREE_TYPE (b);
 

diff --git a/gcc/testsuite/g++.dg/reflect/members_of13.C b/gcc/testsuite/g++.dg/reflect/members_of13.C
new file mode 100644 (file)
index 0000000..c9c0cc9
--- /dev/null
+++ b/gcc/testsuite/g++.dg/reflect/members_of13.C
@@ -0,0 +1,31 @@
+// PR c++/124831
+// { dg-do compile { target c++26 } }
+// { dg-additional-options "-freflection" }
+
+#include <meta>
+
+namespace N
+{
+  enum { A, B, C };
+  enum { D };
+  enum { E, F, G, H, I };
+}
+
+namespace O
+{
+  typedef enum { A, B, C } J;
+  typedef enum { D } K;
+  typedef enum { E, F, G, H, I } L;
+}
+
+static_assert (members_of (^^N, std::meta::access_context::current ()).size () == 3);
+static_assert (enumerators_of (members_of (^^N, std::meta::access_context::current ())[0])[0] == ^^N::A
+              || enumerators_of (members_of (^^N, std::meta::access_context::current ())[1])[0] == ^^N::A
+              || enumerators_of (members_of (^^N, std::meta::access_context::current ())[2])[0] == ^^N::A);
+static_assert (enumerators_of (members_of (^^N, std::meta::access_context::current ())[0])[0] == ^^N::D
+              || enumerators_of (members_of (^^N, std::meta::access_context::current ())[1])[0] == ^^N::D
+              || enumerators_of (members_of (^^N, std::meta::access_context::current ())[2])[0] == ^^N::D);
+static_assert (enumerators_of (members_of (^^N, std::meta::access_context::current ())[0])[0] == ^^N::E
+              || enumerators_of (members_of (^^N, std::meta::access_context::current ())[1])[0] == ^^N::E
+              || enumerators_of (members_of (^^N, std::meta::access_context::current ())[2])[0] == ^^N::E);
+static_assert (members_of (^^O, std::meta::access_context::current ()).size () == 6);