Always use the first version of a class that's loaded twice until the merging code is a bit better tested.

GNUmakefile

@@ -46,6 +46,7 @@ libobjcxx_LDFLAGS = -lstdc++ -lobjc
 
 ifneq ($(enable_legacy), no)
 libobjc_C_FILES += legacy_malloc.c
+libobjc_CPPFLAGS += -DNO_LEGACY
 endif
 
 libobjc_HEADER_FILES_DIR = objc

class_table.c

@@ -375,6 +375,7 @@ void objc_load_class(struct objc_class *class)
 			fprintf(stderr,
 				"Loading two versions of %s.  The class that will be used is undefined\n",
 				class->name);
+			return;
 		}
 		reload_class(class, existingClass);
 		return;