import std.stdio;

​

void main()

{

    auto writer = buildWriter();

    // Tester tester = writerFor(writer);           // It's OK 

    // Tester tester = new Tester(writer);          // It's OK

    // Tester tester = new Tester(buildWriter());   // can't compile

    Tester tester = writerFor(buildWriter());       // Here is a bug

    tester.run("for test");

}

​

struct StringWriter

{

    void put(string s)

    {

        writeln(s, ` `, a);

    }

    int a = 123;

}

​

auto writerFor(OutRange)(auto ref OutRange outRange)

{

    auto res = new Tester(outRange);

    return res;

}

​

StringWriter buildWriter()

{

    return StringWriter();

}

​

class Tester

{

    private StringWriter* writer;

​

    this(ref StringWriter output)

    {

        writer =  &output;

        writeln("in setSink: ", this.writer);

    }

    void run(string m)

    {

        writer.put(m);

    }

}