Following code should compile.

void foo(){}

struct X(alias a) {}

//template Y(T : A!f, alias A, alias f) {}  //OK
template Y(T : A!foo, alias A) {}           //NG

void main()
{
    alias Y!(X!foo) y;
    // Error: template instance Y!(X!(foo)) Y!(X!(foo)) 
    // does not match template declaration Y(T : A!(foo),alias A)
}