The first one is a little program that if correct shows that phobos dyna array reverse may enjoy a specialization for performance purposes:


import std.stdio: writefln;
import std.c.time;


double myclock() {
    return clock()/cast(double)CLOCKS_PER_SEC;
}



void main() {
    alias int Ty;
    auto a = new Ty[10000];
    const uint NLOOP = 1000;


    auto t = myclock();
    for (uint i; i < NLOOP; ++i)
        a.reverse;
    writefln("reverse method: ", myclock() - t, " s");


    t = myclock();
    for (uint i; i < NLOOP; ++i) {
        if (a.length > 1) {
            Ty tmp;
            size_t lo = 0;
            size_t hi = a.length - 1;


            for (; lo < hi; lo++, hi--) {
                tmp = a[lo];
                a[lo] = a[hi];
                a[hi] = tmp;
            }
        }
    }
    writefln("reverse: ", myclock() - t, " s");
}

------------------------------------------------------------------

This other little program crashes at the line I have marked with: Internal error: ..\ztc\blockopt.c 609


template Tuple(T...) { alias T Tuple; }


template Interval(int n) {
    static if (n < 1)
        alias Tuple!() Interval;
    else
        alias Tuple!(Interval!(n-1), n) Interval;
}



int[] foo(int N)() {
    int[N] a;
    return a.dup;
}



void main() {
    foreach(n; Interval!(198)) // error here
        auto a = foo!(n);
}


Bye,
bearophile