Playing with ranges and ufcs

[bearophile]

> auto opSlice(size_t i, size_t j)
> in {
>     assert(i <= j, "some message here");
> } body {
>     auto retval = this.save;
>     retval._index += i;
>     return takeExactly(retval, j - i);
> }


This is the bug opened by Andrea Fontana for this thread:
http://d.puremagic.com/issues/show_bug.cgi?id=9612


At its start I show this code, that contains a but that the D 
compiler is able to catch at compile-time:

void main() {
     auto a = [0,1,2,3,4,5,6,7,8,9][5 .. 2];
}


To do the same with user-defined structures time ago I have 
suggested this, that is currently closed waiting for a better 
solution:
http://d.puremagic.com/issues/show_bug.cgi?id=5906

Bye,
bearophile