Struct constructor, opCall mess.

[Remo]

Hi,

right now I am truing to figure out how the constructors behave 
in D2.

Question 1: why it is not possible to create custom ctor for 
struct?
I know this is not really necessary because you can initialize 
fields like this.
struct S{ int i = 1; }

But this is a big problem if one tries to port C++ code to D2 and 
default ctor call some important initialization code.

Question 2: is there a way to mimic compiler generated ctor (that 
work in CTFE)?

Question 3: why it is possible to call static opCall like this?
VectorC v5 = v4(1.0);

Right now opCall seems to be better as this(...) because it work 
in CTFE but because of unwanted calls this is not well at all.

Question 4: why this(...) does not work in CTFE mode?

Here is highly simplified test code.
http://melpon.org/wandbox/permlink/ofvNby99mKqOBQBf

I am asking this because I am learning D2 now by porting and 
warping/connecting some big C++ (C++11) project to D2.