[WIP] DIP63 : operator overloading for raw templates

[mihails-strasuns]

http://wiki.dlang.org/DIP63

After countless trial & error cycles I got most basic version that works for opIndex + opDollar. However my DMD hacking skills are horrible and before cleaning everything and adding more operator support I'd love to read some feedback if the way it is implemented is acceptable.

Please do not pay attention to all the debug stuff, just how it fits DMD architecture in general.
@9rnsr your feedback is most appreciated.

@WalterBright this DIP still needs your approval / rejection

template Pack(T...)
{
    alias opIndex(size_t index) = T[index];
    enum opDollar = T.length;
}

alias element1 = Pack!(int, double)[1]; 
alias element2 = Pack!(int, double)[$-1];

pragma(msg, element1);
pragma(msg, element2);

[mihails-strasuns]

What I am concerned most about is that this DIP introduces new interpretation of template instances and I don't know if this needs to be represented as new distinct AST type.

[mihails-strasuns]

While initial experiments proved promising I have not found any way to implement opSlice support without major changes to internal AST structure. Going to close this for now as I only can pay attention to low hanging fruits.