This code

unittest
{   
    void foo(ref string bar)
    {   
        bar = bar[1 .. $];
    }
    
    foo("test");
}

segfaults with dmd v2.056 on Linux.
In my understanding the problem is that "test" is an rvalue and dmd should report an compile error. I have no complete understanding regarding lvalues vs. rvalues in D.