struct Vector(int size, T)
{
    T[size] array;

    auto ref opBinary(string op)(T rhs) const
    if (op == "+" || op == "-" || op == "*" || op == "/")
    {
        Vector vector = this;
        mixin("return vector" ~ op ~ "= rhs;");
    }

    auto ref opOpAssign(string op)(T rhs)
    if (op == "+" || op == "-" || op == "*" || op == "/")
    {
        mixin("array[] " ~ op ~ "= rhs;");
        return this;
    }

    auto opOpAssign(string op)(const ref Vector rhs)
    // auto opOpAssign(string op)(const Vector rhs) // witouth ref everything works
    if (op == "+" || op == "-")
    {
        mixin("array[] " ~ op ~ "= rhs.array[];");
        return this;
    }
}
alias Vector!(3, float) Vec3f;

import std.stdio;

void main()
{
    auto a = Vec3f([0, 0, 0]);
    a += a * 0;
    writeln(a.array); // prints random values like [-1.13483, 4.2039e-45, -1.13482]
    assert(a == Vec3f([0, 0, 0])); // fails
}