import std.stdio;

import std.range : iota;

import std.array : join;

import std.algorithm : map;

import std.conv : to;

​

enum qwerty(alias mapper, alias delimiter, size_t count) = iota(0, count).map!(mapper).join(delimiter);

​

void exec() // test function

{

    enum count = 2; // value is calculated somewhere

    //... some code

    static if(count > 0)

    {       

        auto arg0 = "?qaz"; // calculated somewhere

        auto arg1 = "wsx"; // calculated somewhere

        if(mixin(qwerty!(i => "arg" ~ i.to!string ~ "[0] == '?'", "||", count))) // Error

        //if(iota(0, count).map!(i => "arg" ~ i.to!string ~ "[0] == '?'").join("||")) // Works...

        {

            //...

            writeln("Qwerty!");

        }

    }

}

​

void main()

{   

    exec();

}