Doc #62756 [Opn->Csd]: preg documentation should mention '=' should not be first in character class

Edit report at https://bugs.php.net/bug.php?id=62756&edit=1 ID: 62756 Updated by: daverandom@php.net Reported by: marco at greenlightsolutions dot nl Summary: preg documentation should mention '=' should not be first in character class -Status: Open +Status: Closed Type: Documentation Problem Package: Documentation problem PHP Version: Irrelevant -Assigned To: +Assigned To: daverandom Block user comment: N Private report: N New Comment: This bug has been fixed in the documentation's XML sources. Since the online and downloadable versions of the documentation need some time to get updated, we would like to ask you to be a bit patient. Thank you for the report, and for helping us make our documentation better. Documented at http://php.net/reference.pcre.pattern.posix Previous Comments: ------------------------------------------------------------------------ [2013-10-23 08:40:48] daverandom@php.net Automatic comment from SVN on behalf of daverandom Revision: http://svn.php.net/viewvc/?view=revision&amp;revision=331924 Log: Document difference between PCRE and POSIX character classes. Fixes bug #62756. ------------------------------------------------------------------------ [2012-08-06 12:58:51] marco at greenlightsolutions dot nl You are right. It actually was part of a compound expression, and I'd overlooked that the other parts were also relevant. The following line generates the error message: $x=preg_match("%[=~]|<[>=]%", "test"); (PHP 5.3.8, PCRE 8.13.2011-08-16). Regardless, the documentation does not mention the '[=..=]' POSIX collating-element construct. It does not mention the '=' symbol at all. This should be fixed in the documentation. Ideally, the documentation should also contain the phrase 'POSIX collating element', so that it appears as a search result when people search for the text of the error message. ------------------------------------------------------------------------ [2012-08-06 12:32:59] salathe@php.net [=~] should not be causing the warning, however [=abc=] and [.abc.] will. ------------------------------------------------------------------------ [2012-08-06 11:32:58] marco at greenlightsolutions dot nl Description: ------------ --- From manual page: http://www.php.net/regexp.reference.character-classes --- Briefly: The documentation for character classes should state that '=' after '[' is a reserved construct and should be avoided. In detail: If you put a '=' first in a character class in a perl regular expression, such as '[=~]', in certain versions of PHP (including PHP 5.3.8) this will fail to compile, with a warning "Compilation failed: POSIX collating elements are not supported". Rewriting it as '[~=]' prevents the error message. This is because the combination "[=" is seen as indicative of a "POSIX collating element", a reserved, not-yet-implemented syntactical construct. A full description of the cause was written up by Tom Christiansen at http://stackoverflow.com/questions/7173787/compilation-failed-posix-collating-elements-are-not-supported#7175589. The 'preg character classes' documentation page should include the information that '=' in the beginning of a character class is treated special, but it doesn't mention the '=' sign at all. ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=62756&edit=1