Re: Wired constant expression syntax and bug

I'll add some tests later (Please remind me if I didn't add them until tomorrow evening). Bob Am 30.6.2014 um 21:32 schrieb Dmitry Stogov <dmitry@zend.com>: > OK. I'll commit the patch. > > According to the wired syntax, note that your example code will make PHP at first construct an > array and then destroy it. > > why not to write $var = DO ? "value1" : "value2"; > > it must be more clear and efficient. > > In case you like to keep this new syntax in PHP-5.6 at least please cover it with tests. > I'm not a big fun of it, but won't object if it can't make real harm. > > Thanks. Dmitry. > > > On Mon, Jun 30, 2014 at 11:21 PM, Bob Weinand <bobwei9@hotmail.com> wrote: > That syntax wasn't part of the RFC because it wasn't yet possible (existence of > IS_CONSTANT_ARRAY at that time). > Also the use case for that one is mainly: > > class Foo { > public $var = ["value1", "value2"][DO]; > } > > And then just write > const DO = 0; (or 1) > > I don't exactly know at which point that conflicts with opcache. Or if that really fixes > the bug. > The copying itself in your patch looks fine, but please take the responsibility for it and > apply it yourself. > > Thanks, > Bob > > Am 30.6.2014 um 21:06 schrieb Dmitry Stogov <dmitry@zend.com>: > > Hi Bob, > > > > I'm wondered why you introduced this wired syntax in PHP-5.6. > > > > class FooBar { > > const bar = ["bar" => 3]["bar"]; > > } > > > > It wasn't a part of RFC, it wasn't covered by tests, and it actually > > doesn't make a lot of sense. May be it's better to remove it? > > > > Also I found a constant expression related bug, that leads to unpredictable > > crashes from time to time. Previously we had IS_CONSTANT_ARRAY that was > > handled in a special way. When you replaced it with IS_ARRAY, you missed > > this handling, and I missed it as well when reviewed your patch. Now > > IS_ARRAY constants might be incompletely copied from OPCache shared memory > > and modified (incremented/decremented reference counter) directly in SHM. > > Such modifications occur in simultaneously running processes and this > > finally leads to crash on some race condition. > > > > It's possible to emulate the problem running the following script with > > opcache.protect_memory=1 > > > > <?php > > function foo($query = NULL, array $exclude = array('q')) {} > > foo(); > > ?> > > > > I propose a simple fix: > > https://gist.github.com/dstogov/b73884e252b376957ebc > > Please review and apply if agree. > > > > Thanks. Dmitry.