Re: Add form feed as a whitespace character in trim, ltrim and rtrim

On Sat, Dec 27, 2025 at 04:40 LamentXU <lamentxu@163.com> wrote: > Hi Internals, > > I have opened a Pull Request to add \f (form feed) to the list of > characters stripped by default in trim(), ltrim(), and rtrim(). > > Currently, the default behavior of trim() strips the following characters: > \n, \r, \t, \v, \0, and space. The form feed character \f is notably > missing, despite being widely recognized as a whitespace character (in > python, rust...). > Although I think this change aligns trim() with standard whitespace > definitions, it is technically a backward compatibility break. I am writing > to check if there are any strong objections to this change or if it > requires further discussion. > > References*:* > > - > > Issue: *https://github.com/php/php-src/issues/20783 > <https://github.com/php/php-src/issues/20783>* > - > > Pull Request: *https://github.com/php/php-src/pull/20788 > > <https://www.google.com/search?q=https://github.com/php/php-src/pull/20788>* > > Thanks, > Weilin Du > Notably, mb_trim(), introduced in 8.4, includes \f in the list of characters it trims. https://www.php.net/mb_trim I’m not opposed to this change, but the BC break could lead to really difficult and tricky bugs in applications that rely on the form feed to be retained. I can’t think of any use cases that would expect form feed to remain after trimming, but there might be some. On the other hand, many users might consider it a bug that form feed isn’t trimmed, so this might be argued as a bug fix, especially since other languages consider form feed as a whitespace character to remove in similar situations. I’m for this change, but on the fence about the BC break. Cheers, Ben