ftest1: 
ftest2: pointer_type ptr0, 
ftest3: pointer_type ptr0, 
func1: pointer_type ptr1, 
test24.c: In function 'func1':
test24.c:32:5: warning: Using parameter 'ptr1' without checking for null pointer
     ptr1();
     ^
func2: pointer_type ptr1, 
func3: pointer_type ptr1, 
func4: pointer_type ptr1,