Mixin a constructor ?

[language_fan]

>> template C ()
>> {
>> this (int i)
>> {
>> }
>> }
>> class A
>> {
>> mixin C;
>> this ()
>> {
>> }
>> }
>> void main ()
>> {
>> auto a = new A(3);
>> }

Since the constructor has no meaning outside classes, should it be 
interpreted as a free function if mixed in a non-class context? I really 
wonder how this could be valid code. Does the grammar even support the 
3rd line?