c++: ICE with anonymous union [PR97974]

While working on the GCC 11 patch, it occurred to me that we could move
the errors about invalid members from finish_struct_anon_r to here, so we
properly get a diagnostic in g++.law/union4.C.

gcc/cp/ChangeLog:

	PR c++/97974
	* class.c (finish_struct_anon_r): Drop complain parm.
	Remove non-field diagnostic.
	(finish_struct_anon): Adjust.
	* decl.c (fixup_anonymous_aggr): Move non-field diagnostic here.

gcc/testsuite/ChangeLog:

	PR c++/97974
	* g++.old-deja/g++.law/union4.C: Add expected diagnostic.

3 files changed, 44 insertions, 37 deletions

diff --git a/gcc/cp/class.c b/gcc/cp/class.c
index 2cf527e..d693b43 100644
--- a/gcc/cp/class.c
+++ b/gcc/cp/class.c
@@ -3023,7 +3023,7 @@ warn_hidden (tree t)
 /* Recursive helper for finish_struct_anon.  */
 
 static void
-finish_struct_anon_r (tree field, bool complain)
+finish_struct_anon_r (tree field)
 {
   for (tree elt = TYPE_FIELDS (TREE_TYPE (field)); elt; elt = DECL_CHAIN (elt))
     {
@@ -3039,34 +3039,6 @@ finish_struct_anon_r (tree field, bool complain)
 	      || TYPE_UNNAMED_P (TREE_TYPE (elt))))
 	continue;
 
-      if (complain
-	  && (TREE_CODE (elt) != FIELD_DECL
-	      || (TREE_PRIVATE (elt) || TREE_PROTECTED (elt))))
-	{
-	  /* We already complained about static data members in
-	     finish_static_data_member_decl.  */
-	  if (!VAR_P (elt))
-	    {
-	      auto_diagnostic_group d;
-	      if (permerror (DECL_SOURCE_LOCATION (elt),
-			     TREE_CODE (TREE_TYPE (field)) == UNION_TYPE
-			     ? "%q#D invalid; an anonymous union may "
-			     "only have public non-static data members"
-			     : "%q#D invalid; an anonymous struct may "
-			     "only have public non-static data members", elt))
-		{
-		  static bool hint;
-		  if (flag_permissive && !hint)
-		    {
-		      hint = true;
-		      inform (DECL_SOURCE_LOCATION (elt),
-			      "this flexibility is deprecated and will be "
-			      "removed");
-		    }
-		}
-	    }
-	}
-
       TREE_PRIVATE (elt) = TREE_PRIVATE (field);
       TREE_PROTECTED (elt) = TREE_PROTECTED (field);
 
@@ -3084,7 +3056,7 @@ finish_struct_anon_r (tree field, bool complain)
 	 int j=A().i;  */
       if (DECL_NAME (elt) == NULL_TREE
 	  && ANON_AGGR_TYPE_P (TREE_TYPE (elt)))
-	finish_struct_anon_r (elt, /*complain=*/false);
+	finish_struct_anon_r (elt);
     }
 }
 
@@ -3103,7 +3075,7 @@ finish_struct_anon (tree t)
 
       if (DECL_NAME (field) == NULL_TREE
 	  && ANON_AGGR_TYPE_P (TREE_TYPE (field)))
-	finish_struct_anon_r (field, /*complain=*/true);
+	finish_struct_anon_r (field);
     }
 }
 
diff --git a/gcc/cp/decl.c b/gcc/cp/decl.c
index 60dc2bf..e51c1b0 100644
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -5005,12 +5005,47 @@ fixup_anonymous_aggr (tree t)
   TYPE_HAS_COPY_ASSIGN (t) = 0;
   TYPE_HAS_CONST_COPY_ASSIGN (t) = 0;
 
-  /* Splice the implicitly generated functions out of TYPE_FIELDS.  */
+  /* Splice the implicitly generated functions out of TYPE_FIELDS and diagnose
+     invalid members.  */
   for (tree probe, *prev_p = &TYPE_FIELDS (t); (probe = *prev_p);)
-    if (TREE_CODE (probe) == FUNCTION_DECL && DECL_ARTIFICIAL (probe))
-      *prev_p = DECL_CHAIN (probe);
-    else
-      prev_p = &DECL_CHAIN (probe);
+    {
+      if (TREE_CODE (probe) == FUNCTION_DECL && DECL_ARTIFICIAL (probe))
+	*prev_p = DECL_CHAIN (probe);
+      else
+	prev_p = &DECL_CHAIN (probe);
+
+      if (DECL_ARTIFICIAL (probe)
+	  && (!DECL_IMPLICIT_TYPEDEF_P (probe)
+	      || TYPE_ANON_P (TREE_TYPE (probe))))
+	continue;
+
+      if (TREE_CODE (probe) != FIELD_DECL
+	  || (TREE_PRIVATE (probe) || TREE_PROTECTED (probe)))
+	{
+	  /* We already complained about static data members in
+	     finish_static_data_member_decl.  */
+	  if (!VAR_P (probe))
+	    {
+	      auto_diagnostic_group d;
+	      if (permerror (DECL_SOURCE_LOCATION (probe),
+			     TREE_CODE (t) == UNION_TYPE
+			     ? "%q#D invalid; an anonymous union may "
+			     "only have public non-static data members"
+			     : "%q#D invalid; an anonymous struct may "
+			     "only have public non-static data members", probe))
+		{
+		  static bool hint;
+		  if (flag_permissive && !hint)
+		    {
+		      hint = true;
+		      inform (DECL_SOURCE_LOCATION (probe),
+			      "this flexibility is deprecated and will be "
+			      "removed");
+		    }
+		}
+	    }
+	}
+      }
 
   /* Splice all functions out of CLASSTYPE_MEMBER_VEC.  */
   vec<tree,va_gc>* vec = CLASSTYPE_MEMBER_VEC (t);
diff --git a/gcc/testsuite/g++.old-deja/g++.law/union4.C b/gcc/testsuite/g++.old-deja/g++.law/union4.C
index 958ff0a..ec30d1e 100644
--- a/gcc/testsuite/g++.old-deja/g++.law/union4.C
+++ b/gcc/testsuite/g++.old-deja/g++.law/union4.C
@@ -7,7 +7,7 @@
 // Message-ID: <m0pA49A-0000LdC@piano.veritas.com>
 
 static union {
-        struct SS {
+        struct SS {		// { dg-error "anonymous union" }
                 int ss;
         };
 };// { dg-error "no members" }