[GSoC] Strange struct destructor-postblit-writeln interaction bug.

[dsimcha]

== Quote from Cristi Cobzarenco (cristi.cobzarenco at gmail.com)'s article
> --bcaec520ef999f971804a64e04e4
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> While working on my project, I ran into a very hard to trace bug that I
> finally managed to isolate and reproduce on a small scale.
> The code:
> import std.stdio;
> import std.conv;
> struct Test {
> int x;
>  this( int m )     { x = m; }
>  this( this )      { writeln( "Postblit: ", x ); }
>  ~this()           { x = 42; }
>  string toString() { return to!string( x ); }
> }
> int main(string[] argv) {
>  auto a = Test(3);
> writeln( a );
> return 0;
> }
> Prints 42 on my computer, instead of 3. The writeln in the postblit
> constructor shows that the object is copied 6 times, and only on the last
> copy x becomes 42 instead of 3. Somehow the destructor gets called on an
> object before it is copied. The copying that causes the problem is in
> format.d at 1599 as far as I can tell with my debugger.
> I don't know if it's high priority for everyone, but it certainly is for me.

This is definitely a pretty severe bug and I can reproduce it.  Please file a bug
report in Bugzilla.  (http://d.puremagic.com/issues/)  It's ok to occasionally
bring up very high priority bugs on this newsgroup, but they should **always** be
filed in Bugzilla as well because otherwise they get forgotten.