A range analysis question

[bearophile]

Ali Çehreli:

> I don't think we are there yet. :)

Thinking some more about this topic I have created a small test 
example:


uint i = 100;
void main(in string[] args) {
     auto j = args.length;
     ubyte x1 = (i ^^ 2) % 256; // OK
     ubyte x2 = (i ^^ 3) % 256; // OK
     ubyte[] arr = [(i ^^ 2) % 256, (i ^^ 3) % 256]; // OK!
     ubyte y = [(i ^^ 2) % 256, (i ^^ 3) % 256][j]; // Error
}


The lines with x1 and x2 are accepted, because the range analysis 
is able to infer those are in-range assignments. While the 
assignment of y is refused, despite all the contents of the array 
can be inferred as castable to ubyte, as shown in assignment of 
arr.

I think this (the line with y) is worth an enhancement request.

Bye,
bearophile