re PR c++/50207 (G++ segv's on reduced test case)

	PR c++/50207
	* class.c (finish_struct_1): Complain if the first field is
	artificial.

Co-Authored-By: Jason Merrill <jason@redhat.com>

From-SVN: r178276

gcc/cp/ChangeLog

+2011-08-29  Jakub Jelinek  <jakub@redhat.com>
+	    Jason Merrill  <jason@redhat.com>
+
+	PR c++/50207
+	* class.c (finish_struct_1): Complain if the first field is
+	artificial.
+
 2011-08-29  Jason Merrill  <jason@redhat.com>
 
 	PR c++/50209

gcc/cp/class.c

@@ -5795,10 +5795,25 @@ finish_struct_1 (tree t)
   /* Finish debugging output for this type.  */
   rest_of_type_compilation (t, ! LOCAL_CLASS_P (t));
 
-  if (TYPE_TRANSPARENT_AGGR (t) && first_field (t) == NULL_TREE)
+  if (TYPE_TRANSPARENT_AGGR (t))
     {
-      error ("type transparent class %qT does not have any fields", t);
-      TYPE_TRANSPARENT_AGGR (t) = 0;
+      tree field = first_field (t);
+      if (field == NULL_TREE || error_operand_p (field))
+	{
+	  error ("type transparent class %qT does not have any fields", t);
+	  TYPE_TRANSPARENT_AGGR (t) = 0;
+	}
+      else if (DECL_ARTIFICIAL (field))
+	{
+	  if (DECL_FIELD_IS_BASE (field))
+	    error ("type transparent class %qT has base classes", t);
+	  else
+	    {
+	      gcc_checking_assert (DECL_VIRTUAL_P (field));
+	      error ("type transparent class %qT has virtual functions", t);
+	    }
+	  TYPE_TRANSPARENT_AGGR (t) = 0;
+	}
     }
 }
 

gcc/testsuite/ChangeLog

+2011-08-29  Jakub Jelinek  <jakub@redhat.com>
+	    Jason Merrill  <jason@redhat.com>
+
+	* g++.dg/dfp/base.C: New test.
+
 2011-08-29  Jason Merrill  <jason@redhat.com>
 
 	Core DR 994

gcc/testsuite/g++.dg/dfp/base.C

+// PR c++/50207
+// { dg-do compile }
+
+namespace std
+{
+  namespace decimal
+  {
+    template <class _Fmt> struct _FmtTraits;
+    class decimal32;
+    template <> struct _FmtTraits <decimal32>
+    {
+      static const long _NumBytes = 4UL;
+    };
+    template <class _Tr> class _DecBase
+    {
+      unsigned char _Bytes[_Tr::_NumBytes];
+    };
+    class decimal32 : public _DecBase <_FmtTraits <decimal32> >	// { dg-error "has base" }
+    {
+      decimal32 () { }
+    };
+  }
+}