//file1 testA.d
module testa;
import testb;

enum TestEnum {
	A,
}

class CCC{
	int a;
}

struct SSS{
	int a;
}

------------------------------

//file2 testB.d
module testb;
import testa;

TestEnum te;
CCC ccc;
SSS sss;




Compile the testA.d, class and struct are ok, but to enum,dmd say "enum TestEnum is forward referenced"

This question is divided into these kinds of situations specifically:
1.Compiling two files of above alone separately,DMD and GDC all fail when compiling testA.d.
   dmd testA.d -c
   
2.DMD and GDC all fail to Compile two files of above in once,and testA.d in before testB.d in back.
   dmd testA.d testB.d -c
   
3.DMD is OK GDC is fail when testB.d in before testA.d in back.
   dmd testB.d testA.d -c