Re: Fix for issue #72320 - compatibility breakage in 7.0.11

On 22.12.2016 at 16:13, Zeev Suraski wrote: > All, > > In 7.0.11, the behavior of iconv_substr() was changed so that if the length argument is equal > to the length of the string - an empty string is returned, as opposed to FALSE. > > While I think there's a case to be made that this makes sense - what worries me is that > we've introduced a behavioral change for a function in a bugfix release - one that has bitten > us in Zend Framework - and I think it's safe to assume that it will affect plenty of other > codebases. > > Personally, I think we should be *much* more selective about introducing behavioral changes in > maintenance releases, even if they can be considered bugfixes. Depending on their scope and impact, > they should either go into the next mini version (this one probably falls in that category) or the > next major version. Of course - there are plenty of bugfixes where the existing behavior is a > crash, or undefined/unpredictable - those are obviously fine to fix without further discussion. > I'm talking about the cases where the current behavior is very much defined and has been that > way for a long time, but for whatever reason, people think it should change. > > We've worked hard to establish trust that people can upgrade into the next maintenance > version with minimal testing - which greatly helps people keep current with the latest and greatest > fixes incl. security, and even the next minor version with relatively limited testing, when we > ensured downwards compatibility within these versions. It does mean that our finger needs to be a > lot more hesitant on the trigger when we evaluate behavioral changes such as these. > > It's arguably too late to revert this patch now, but I think it's a good opportunity > to discuss the guidelines for dealing with such issues. > > Thoughts? What about bug #73817? (I'm omitting a proper link due to the current mailing list issues regarding "spammy URLs" from php dot net.) Some related code[1] is obviously wrong, but it is wrong since at least PHP 5.4.x[2]. Fixing this may very well introduce a BC break, as any user relying on the current behavior might already have introduced some fix in userland. So, should the fix be postponed to PHP 7.2.0? :-) [1] <https://github.com/php/php-src/blob/PHP-7.1.0/ext/standard/html.c#L1600-L1601> [2] <https://github.com/php/php-src/blob/PHP-5.4/ext/standard/html.c#L1583-L1584> -- Christoph M. Becker