Bug in RefCounted?

[Rene Zwanenburg]

On Monday, 28 October 2013 at 19:30:12 UTC, Maxim Fomin wrote:
> Here is my attempt:
>
> import std.stdio;
>
> struct S
> {
>    int i;
>    this(int i)   { writefln("ctor, %X", i); this.i = i; }
>    this(this)  { writefln("postblit, %X, %X", &this, i); }
>    ~this()     { writefln("dtor, %X, %X", &this, i); }
> }
>
> auto foo()
> {
>    S s = S(1);
>    return { s = S(2); } ;
> }
>
> void main()
> {
>    foo()();
> }
>
> ctor, 1
> dtor, 7FFFF7ED8FF8, 1
> ctor, 2
> dtor, 7FFFFFFFDB30, 1
>
> Inside foo() function object 's' is destroyed twice: first time 
> as a regular struct at the end of block scope, second time 
> before assigning S(2).
>
> There are other tools: union bug, control flow tricks, 
> __traits, __dtor but they are move obvious.

That's pretty nasty :). But I suspect this is a bug and not by 
design. __dtor and __traits are, IMHO, the proverbial escape 
hatch D should provide, so I think that's OK. I take it that by 
control flow trick you mean the try/catch example in your other 
post?

Anyway, thanks for pointing this out. Will probably save me some 
debugging in the future.