Doc #62756 [Opn]: 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 User updated by: marco at greenlightsolutions dot nl Reported by: marco at greenlightsolutions dot nl Summary: preg documentation should mention '=' should not be first in character class Status: Open Type: Documentation Problem Package: Documentation problem PHP Version: Irrelevant Block user comment: N Private report: N New Comment: 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. Previous Comments: ------------------------------------------------------------------------ [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