From: http://forum.dlang.org/thread/jbxscocwxabfwoatjsxa@forum.dlang.org

Following code should work, but doesn't.

struct CborConfig(a, b) {}

struct NonSerialized {}

alias defaultCborConfig = CborConfig!(NonSerialized, NonSerialized);

void accepter(Config : CborConfig!(T) = defaultCborConfig, T...)()
{
    pragma(msg, T);
}

void main()
{
    //accepter!()();  // ok
    accepter();       // Line 15
}

output:

test.d(15): Error: template test.accepter cannot deduce function from argument types !()(), candidates are:
test.d(7):        test.accepter(Config : CborConfig!T = defaultCborConfig, T...)()