Fix #72918: negative offset inside a quoted string leads to parse error

[cmb69]

We allow negative numeric offsets for the simple syntax inside
double-quoted and heredoc strings.

[cmb69]

I'm not sure whether https://bugs.php.net/72918 qualifies as bug, or should be regarded as feature request. The documentation states:

Similarly, an array index or an object property can be parsed. With array indices, the closing square bracket (]) marks the end of the index.

According to this, negative offsets would have to be supported.

Anyhow, supporting negative offsets seems to be particularly appealing since negative offsets are supported for strings as of PHP-7.1, so even if we don't consider this issue to be a bug, the patch might be considered to be applied to PHP-7.1, too.

[cmb69]

@flaupretre As you've authored the Generalize support of negative string offsets RFC, what do you think about this PR?

[hikari-no-yume]

Not supporting this on arrays seems like an oversight, given array keys can be negative numbers, and it's additionally useful now given PHP 7.1's negative string offset support. Targeting 7.1 makes sense to me.

[nikic]

Yeah, agree. I'd like to see this land in PHP 7.1.

Please fix the indent in zend_language_parser.y and adjust the comment in https://github.com/cmb69/php-src/blob/8d2ef27608a69817ad3ad282cea9d925913ff4e5/Zend/zend_language_scanner.l#L1878 to say '[' or '-'.

[cmb69]

@nikic Thanks!

@dshafik Okay to target PHP 7.1?

[dshafik]

@cmb69 yes

[cmb69]

Thanks! Applied with commit 2cc3aeb.