How to turn an inout(Object) into a string

[Meta via Digitalmars-d-learn]

The following code spits out pages of error messages, and it's 
driving me insane. I know that Object.toString only has a mutable 
variant, so how am I supposed to use writeln, toString, etc. with 
an inout, const, or immutable object?

void main(inout string[] args)
{
        import std.stdio;
        
        immutable(Object) o = new immutable Object();
        //Compile error: template instance
        //std.format.formatGeneric!(
        //        LockingTextWriter, immutable(Object),
        //        char)
        //error instantiating
        writeln(o);
}