[Issue 23164] New: [REG 2.097] Infinite loop on assertion failure + DMD moves struct with copy constructor

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=23164

          Issue ID: 23164
           Summary: [REG 2.097] Infinite loop on assertion failure + DMD
                    moves struct with copy constructor
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: regression
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: pro.mathias.lang at gmail.com

The following code shows 2 assertions failures in v2.096.1, an infinite loop on
v2.097.0:
```
struct std_string
{
    std_string* ptr;
    ulong[3] data;

    this (ulong data)
    {
        this.data[] = data;
        this.ptr = &this;
    }

    this(const scope ref std_string from)
    {
        assert(&from is from.ptr);
        assert(this.ptr is null);
        this.ptr = &this;
        this.data = from.data;
    }

    ~this ()
    {
        assert(this.ptr is &this);
    }

    alias opAssign = assign;

    ref std_string assign () (const auto ref std_string rhs)
    {
        return this.assign2(rhs);
    }

    ref std_string assign2 (const ref std_string rhs) return
    {
        assert(rhs.ptr is &rhs);
        assert(this.ptr is null || this.ptr is &this);
        this.data = rhs.data;
        return this;
    }
}

void main ()
{
    std_string tmp = 42;
    assert(tmp.ptr is &tmp);
    tmp = std_string(42);
    assert(tmp.ptr is &tmp);
}
```

The original test was to see whether or not DMD would move a struct with a copy
constructor. The above code compiles and runs fine with LDC & GDC, but asserts
with DMD.

--