std.range.choose should use lazy arguments

[MrcSnm]

Given that example code:

auto getRangeA()
{
    import std.stdio;
    writeln("Range A");
    static struct RangeA
    {
        void popFront(){}
        bool front(){return true;}
        bool empty(){return true;}
    }
    return RangeA();
}
auto getRangeB()
{
    import std.stdio;
    writeln("Range B");
    static struct RangeB
    {
        void popFront(){}
        bool front(){return true;}
        bool empty(){return true;}
    }
    return RangeB();
}


void main() 
{
    import std.range;
    choose(true, getRangeA, getRangeB);
}

You can see that both ranges needs to be constructed, even though it is guaranteed only one of them will be used. And they don't even escape the scope. The problem is that one may need to build the range to use it and that may take a plenty of time.

[Gauravsh-24]

Hello @MrcSnm
I would like to work on this issue. can you please assign to me.

[thewilsonator]

Thos sounds like a phobos bug, not a dmd bug. Is it?