gdb/

Fix modification of cplus_struct_default.
	* dwarf2read.c (dwarf2_add_member_fn) <no DW_AT_vtable_elem_location>:
	Call ALLOCATE_CPLUS_STRUCT_TYPE.
	* gdbtypes.c (cplus_struct_default): New empty initializer, comment it.

gdb/testsuite/
	* gdb.cp/virtbase.cc (class RTTI_base, class RTTI_data)
	(main) <rtti_data>: New.
	* gdb.cp/virtbase.exp (print rtti_data): New.

gdb/dwarf2read.c

@@ -4954,6 +4954,7 @@ dwarf2_add_member_fn (struct field_info *fip, struct die_info *die,
 	  complaint (&symfile_complaints,
 		     _("Member function \"%s\" (offset %d) is virtual but the vtable offset is not specified"),
 		     fieldname, die->offset);
+	  ALLOCATE_CPLUS_STRUCT_TYPE (type);
 	  TYPE_CPLUS_DYNAMIC (type) = 1;
 	}
     }