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Date: Tue, 23 Feb 2021 17:12:30 +0100
Message-ID: <CAF+90c-n2Ep_MRvWHsHLtc=2okbOZ2Qx__v9Ww2sfNnnc78ygg@mail.gmail.com>
To: Guilliam Xavier <guilliam.xavier@gmail.com>
Cc: "G. P. B." <george.banyard@gmail.com>, PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Interaction between finally blocks and exit()
From: nikita.ppv@gmail.com (Nikita Popov)

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On Tue, Feb 23, 2021 at 4:52 PM Guilliam Xavier <guilliam.xavier@gmail.com>
wrote:

> On Fri, Feb 5, 2021 at 2:10 PM G. P. B. <george.banyard@gmail.com> wrote:
>
> > Greetings internals,
> >
> > While working on rewriting the PHP docs about errors and error handling
> [1]
> > I came across a change of behaviour in an edge case of an edge case.
> >
> > finally blocks are meant to be always executed regardless that an
> Exception
> > has been thrown or not, which it does, however a call to exit() (or die()
> > as they are aliases).
> > This can be seen with the following example: https://3v4l.org/6Tger
> >
> > However, there is one case where finally blocks are executed when exit()
> is
> > used, namely when a generator has a finally block and exit() is called
> > during its traversal, an example of this in action can be seen here:
> > https://3v4l.org/HGKHS
> >
> > The behaviour of this edge case of an edge case is highly dependent on
> the
> > version of PHP where this is run, PHP 5.5, 5.6, 7.0, early version of PHP
> > 7.1, PHP 7.2.0, PHP 7.2.1, and PHP 8.0 all run the finally block on
> exit().
> > Later versions of PHP 7.1, 7.2.2 and above and PHP 7.3 and 7.4 all skip
> the
> > finally block.
> >
> > Frankly this is already going to be a mess to document, but this begs the
> > question is there a "bug" in executing the finally blocks in generators
> > during a call to exit() or is the "bug" to not execute finally blocks
> when
> > exit() is called.
> >
> > I've CCed the PHP 8.0 RMs as if the consensus is that skipping finally
> > blocks after a call to exit() is performed it would be wise to change
> this
> > behaviour in PHP 8.0 only and land this ASAP, even though it's a BC
> break.
> >
> > Interested in hearing your thoughts.
> >
> > Best regards,
> >
> > George P. Banyard
> >
> > [1] https://github.com/php/doc-en/pull/320
> >
>
> Hello again,
>
> From my message from two weeks ago, my understanding is that finally blocks
> are *never* supposed to be executed on exit(), and that there is indeed a
> bug (regression) with generators.
>
> With PHP 8.0.3RC1 having been released without any reply here from the
> people CCed, maybe you should open a bug report?
>

Finally blocks are intended to be always executed when destructors are
executed. The fact that they are not yet executed for exit() outside
generators is a known bug. (For generators, finally is part of the
destructor, which is why the issue does not appear there.)

Regards,
Nikita

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