[Issue 14078] Call DTor for stack allocated objects

[via Digitalmars-d-bugs]

https://issues.dlang.org/show_bug.cgi?id=14078

--- Comment #4 from rswhite4 at gmail.com ---
(In reply to Ketmar Dark from comment #3)
> (In reply to rswhite4 from comment #2)
> > (In reply to Ketmar Dark from comment #1)
> > > `emplace` is not a built-in. one can write alot of emplace-like functions
> > > that allocates any memory for the object. even the function named `emplace`,
> > > that will sometimes allocates on stack and sometimes uses `malloc()`.
> > > 
> > > what you actually asking is compiler that is able to use some AI to see what
> > > programmer *means* by writing the code. this is not possible.
> > 
> > No. The compiler should be able to detect that a2 is stack allocated (the
> > compiler should be able to see the type of a2 -> A and also that the memory
> > is on the stack).
> compiler doesn't know what `emplace` does. to determine that it have to
> switch on secret AI button somehow. can you please show a sample code that
> is able to determine such things in all cases? 'cause if some cases are
> missed, then there will be no way for programmer to determine when
> destructor will be called and when not.
> 
I'm not talking about emplace. That is completely irrelevant. My thought was
that the compiler should recognize that a2 is stack allocated and therefore
call the dtor. Therefore the label "enhancement".

> > But your example with malloc could be true, but I'm sure that the DTor of a2
> > should be called at least at the end of the programm. The compiler should be
> > able to do that, even without any AI. ;)
> class dtors are not guaranteed to be called at all. if someone will change
> GC so it will stop calling dtors, it will break nothing by the specs. and
> this is not an oversight.
That is new to me. Ok, then it is probably impossible.
I thought at least it would be helpful to call all remaining dtors at the end
of the program.
If that is not desired I will close this issue.

> > > if you want stack-allocated classes with automatic dtors, why don't use
> > > `std.typecons.scoped`?
> > 
> > It is IMO not well implemented.
> please, can you show the cases where it's not working, so we can fill
> bugreports and somebody will fix it?
Look at the code. One thing is that the buffer is overproportional. But that is
not the topic.

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