struct X;
struct F
{
void Foo( X x= X() );
float f;
};
int main(){}
Standard input is empty
prog.cpp:5:20: error: invalid use of incomplete type ‘struct X’
   void Foo( X x= X() );
                    ^
prog.cpp:1:8: note: forward declaration of ‘struct X’
 struct X;
        ^
		
		
	
	Standard output is empty