"Error: address of variable this assigned to this with longer lifetime"

[Nathan S.]

What is this malarky?

https://run.dlang.io/is/S42EBb

"onlineapp.d(16): Error: address of variable this assigned to 
this with longer lifetime"

```d
import std.stdio;

struct SmallString
{
     char[24] small;
     char[] data;

     @disable this();

     this(scope const(char)[] s) @safe
     {
         if (s.length < small.length)
         {
             small[0 .. s.length] = s[];
             small[s.length] = 0;
             data = small[0 .. s.length];
         }
         else
         {
             assert(0, "Compilation failed before I wrote this.");
         }
     }
}

void main()
{
     writeln("Hello D");
}
```