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Date: Tue, 03 Feb 2026 15:18:14 +0100
To: Ben Ramsey <ramsey@php.net>
Cc: internals@lists.php.net
Subject: Re: [PHP-DEV] [Vote] Add form feed as a whitespace character in trim,
 ltrim and rtrim
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From: tim@bastelstu.be (=?UTF-8?Q?Tim_D=C3=BCsterhus?=)

Hi

Am 2026-01-30 01:37, schrieb Ben Ramsey:
> I've voted "no" on this RFC since the RFC says the proposed PHP version 
> is PHP 8.5, which I interpret as meaning PHP 8.6, since 8.5 was 
> released in November.
> 
> Even if PHP 8.6 is the proposed version, I still think the target 
> version should be PHP 9.0, since this is a BC break. I mentioned my 
> concern about this being a BC break in the discussion thread.
> 
> The RFC is also clear this is a BC break. It says:
> 
>> This is a **backward incompatible change**. Scripts that rely on
>> `trim()` *preserving* leading or trailing Form Feed characters will
>> be affected.
> 
> I'm a little surprised by the number of folks who voted "yes" on this, 
> despite it being very clear this is a BC break and PHP "Next" is the 
> implied proposed version.

I however disagree that the target version of this RFC should be 9.0.

It technically is a BC break, but so is almost anything else, including 
any bugfix. Our policy explicitly allows BC breaks in minor version, but 
gives some recommendations as to what BC breaks are acceptable: 
https://github.com/php/policies/blob/6ff3612f7f60e9d91188d986cfb4ca84d0722732/release-process.rst#minor-version-number

While the proposed BC break would be a “silent” BC break, I believe it 
qualifies for the “case by case” exception, since:

- It is unifying the behavior with other programming languages, 
including standards defining what “whitespace” means.
- trim is well-understood in the community as “removing whitespace”.
- Thus it not removing something that clearly is whitespace could be 
interpreted as a bug.
- If users for some reason rely on form feed characters being preserved, 
I expect them to be well aware of their special requirement.
- For those users, mitigating the break is possible with basic tooling, 
by simply searching the codebase for all occurences of `trim(` and then 
adjusting the calls to explicitly specify a list of characters to trim 
(or to replace them with a wrapper).

For these reasons I don't think we should wait several years until PHP 9 
to make the change. We're shipping more impactful breaking changes and 
bugfixes with every minor version.

Best regards
Tim Düsterhus