enum Enum { Foo, Bar }
void test(Enum en)()
    if(0)
{ 
}

void main()
{
    test!(Enum.Bar)();
}

test.d(11): Error: template instance test!(cast(Enum)1) test!(cast(Enum)1) does not match template declaration test(Enum en) if (0)
test.d(11): Error: function expected before (), not test!(cast(Enum)1) of type void

This is really awful because when you have over a few dozen fields in an enum you end up having to count the fields to figure out which enum value was actually used when instantiating the template. (Either that or having to insert a to!string call just for debugging).

The above errors should be:

test.d(11): Error: template instance test!(Enum.Bar) test!(Enum.Bar) does not match template declaration test(Enum en) if (0)
test.d(11): Error: function expected before (), not test!(Enum.Bar) of type void