The WordPress coreCoreCore is the set of software required to run WordPress. The Core Development Team builds WordPress. development team builds WordPress! Follow this site for general updates, status reports, and the occasional code debate. There’s lots of ways to contribute:
Found a bugbugA bug is an error or unexpected result. Performance improvements, code optimization, and are considered enhancements, not defects. After feature freeze, only bugs are dealt with, with regressions (adverse changes from the previous version) being the highest priority.?Create a ticket in the bug tracker.
This is an important release which makes significant changes to improve the accuracy, performance, stability and maintainability of all sniffssniffA module for PHP Code Sniffer that analyzes code for a specific problem. Multiple stiffs are combined to create a PHPCS standard. The term is named because it detects code smells, similar to how a dog would "sniff" out food., as well as makes WordPressCS much better at handling modern PHPPHPThe web scripting language in which WordPress is primarily architected. WordPress requires PHP 5.6.20 or higher.
Most rules which were proposed in the Make post from March 2020 have been added to the Coding standards guidelines. Proposed rules which yielded a lot of discussion or to which objections were raised, have not been added. The intention is to publish separate Make posts for each of these over time, to discuss these more controversial proposals further.
For a large number of the new rules, sniffs have been added to WordPressCS to enforce these rules. More sniffs may be added in future WordPressCS releases to comprehensively cover the new and updated rules.
WordPressCS previously had only one runtime dependency, which was PHP_CodeSniffer and end-users would need to manually register WordPressCS with PHP_CodeSniffer (or use a Composer pluginPluginA plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party to do so).
As of WordPressCS 3.0.0, WordPressCS will have four run-time dependencies and because of this, Composer will be the only supported way to install WordPressCS.
Mind: it is still perfectly possible to install WordPressCS and its dependencies without using Composer. It is just not an installation method for which support will be provided.
PHPCSUtils is a set of utility functions for use with PHP_CodeSniffer. PHPCSExtra is an additional set of sniffs. Composer Installer is a Composer plugin which will make sure that WordPressCS, PHPCSUtils as well as PHPCSExtra will be registered correctly with PHP_CodeSniffer.
New, non-WordPress-specific, sniffs will now be added to PHPCSExtra, while all WordPress-specific sniffs continue to be maintained in WordPressCS. Some of the pre-existing WordPressCS sniffs, which could benefit the wider PHP community, have been removed and replaced by similar (and improved!) sniffs which were added to PHPCSExtra.
Upgrading to WordPressCS 3.0.0
WordPressCS 3.0.0 contains breaking changes, both for people using ignore annotations, people maintaining custom rulesets, as well as for sniffsniffA module for PHP Code Sniffer that analyzes code for a specific problem. Multiple stiffs are combined to create a PHPCS standard. The term is named because it detects code smells, similar to how a dog would "sniff" out food. developers who maintain a custom PHPCSPHP Code SnifferPHP Code Sniffer, a popular tool for analyzing code quality. The WordPress Coding Standards rely on PHPCS. standard based on WordPressCS.
Please read the provided documentation carefully before you upgrade.
WordPress CoreCoreCore is the set of software required to run WordPress. The Core Development Team builds WordPress. will upgrade to WordPressCS 3.0.0 in the near future as well. Follow TracTracAn open source project by Edgewall Software that serves as a bug tracker and project management tool for WordPress.ticketticketCreated for both bug reports and feature development on the bug tracker.#59161 if you want to stay informed and be sure to run composer update --with-all-dependencies once the patchpatchA special text file that describes changes to code, by identifying the files and lines which are added, removed, and altered. It may also be referred to as a diff. A patch can be applied to a codebase for testing. has been committed to benefit from the latest & greatest sniff goodies.
Why did it take so long for this release to be “ready” ?
This release is basically the result of four big projects combined. It wasn’t necessarily the intention when work on WordPressCS 3.0.0 started that these projects would be combined into one release, but internal and external influences had an impact on timing, which made it so.
Also, please keep in mind that this project is basically maintained by a very, very small group of unpaid volunteers, who also have real jobs to do.
The four big projects we are talking about are:
A big refactor.
Adding new rules based on the Make post from March 2020.
Making the sniffs compatible with PHP 7.4, 8.0, 8.1 and 8.2 (* 8.2 in so far currently possible as PHP_CodeSniffer doesn’t fully support all 8.2 syntaxes yet).
Improving the available documentation.
Now let’s talk a little about each of these.
WordPressCS previously had only one runtime dependency, which was PHP_CodeSniffer and end-users would need to manually register WordPressCS with PHP_CodeSniffer (or use a Composer plugin to do so). PHP_CodeSniffer offers some limited “utility” functions for sniffs and some basic abstracts.
But… WordPressCS – and other external standards, like PHPCompatibility – wanted more utility functions and better abstracts to be available, so these projects added their own and these utilities then had to be maintained in each of those projects.
Moving this work to a separate project was a setback and meant having to rework a lot. This separate project was published as PHPCSUtils in January 2020.
By that time, PHP 8.0 also started to come into play and it was becoming very clear that this would involve lots of changes for Coding Standards projects and both PHP_CodeSniffer, as well as the utilities, would have to be made compatible with PHP 8.0 before a new version of WordPressCS could be released.
In practical terms, most non-WordPress-specific utility functions are now available via PHPCSUtils. The remaining utility functions, i.e. the few exceptions + the WordPress-specific utilities, have all been moved to separate “helper” classes and traits to make the code more re-usable for sniffs not based on the WordPressCS specific base Sniff class.
The Make post from March 2020 proposed a lot of new rules, which resulted in a healthy discussion on the post and save for a few rules, most of the new rules met with approval.
This meant two things:
Research needed to be done whether there were any pre-existing sniffs that could be used to implement the approved rules.
For anything for which no sniff existed, a new sniff would need to be written.
A whopping 35 new sniffs were written for this release, 32 of these were added to PHPCSExtra, and 3 to WordPressCS itself.
To see a list of all the rules included in a particular standard, use:
vendor/bin/phpcs -e --standard=WordPress
(you can replace WordPress with, for instance, WordPress-Core or Universal or PSR12 to see the sniffs included in a particular standard)
Making sniffs compatible with PHP 7.4, 8.0, 8.1 (and 8.2)
Making a PHP project compatible with a new PHP version is one thing, doing so for a static analysis tool is something else altogether.
Making sniffs compatible with a new PHP version, basically involves three things:
Making sure the existing code will run on the new PHP version without errors or notices.
Making sure that sniffs do not throw a false positive/negative when confronted with a new syntax. Example: if a sniff looks for function calls to analyse and excludes method calls – function calls preceded by a -> or :: -, for PHP 8.0, these sniffs needed to be adjusted to also exclude function calls preceded by the nullsafe object operator ?->.
Add explicit support for new PHP features. Example: if a sniff would examine the name of a class-like structure, like a class, interface, or trait, the sniff would probably benefit from new code to also examine the names of PHP 8.1 enum structures.
Now, aside from 1, for 2 and 3, WordPressCS has a BIG dependency on PHP_CodeSniffer itself as PHP_CodeSniffer needs to support the new syntaxes first before an individual sniff can start to support them.
At the time work started for WordPressCS 3.0.0, PHP_CodeSniffer didn’t fully support PHP 7.4 yet, which added quite some new syntaxes and then PHP 8.0, 8.1 and 8.2 came along adding yet even more.
PHP 7.4, 8.0, 8.1, 8.2 added more new syntaxes to PHP than all of the PHP 5 and 7 releases before it combined.
Now you may ask yourself: “Why should the sniffs take all those new PHP syntaxes into account ?” After all, WordPress still supports PHP 7.0 (PHP 5.6 prior to WP 6.3), so those syntaxes cannot be used in code written for WordPress Core…
May also refer to The collection of PHP_CodeSniffer rules (sniffs) used to format and validate PHP code developed for WordPress according to the PHP coding standards. are a community standard and WordPressCS codifies this into automated checks and as such, WordPressCS is not only used by WordPress Core, but also by the wider WordPress community, including agencies, plugin and theme authors etc. And plugins and themes may have a higher minimum supported PHP version, especially when we’re talking in-company/closed source plugins and themes.
Aside from that, sooner or later, WP will raise the minimum supported PHP version to a version including these new syntaxes, so the work would need to be done anyway and it’s easier to do this when what’s changed in PHP is still fresh in our minds.
So, a new waiting game started, where PHPCS needed to be updated first, then PHPCSUtils and only then could support for the new syntaxes be added to WordPressCS.
Safe for the PHP 8.2 Disjunctive Normal Form Types, which isn’t supported yet by PHP_CodeSniffer itself, all new syntaxes which were introduced in recent PHP versions are now taken into account in all sniffs in as far as our (my) imagination reached.
If you run into a situation where a sniff appears to not be fully compatible with modern PHP syntaxes yet, please open a bug report.
Improving the documentation
PHPCS has a built-in sniff documentation feature. Until recently, WordPressCS didn’t really support this feature and WordPress sniffs didn’t provide the documentation needed.
(you can replace WordPress with, for instance, WordPress-Core or Universal or PSR12 to see the documentation for other standards)
The future of WordPressCS
While WordPressCS is currently in a good place with this release, this won’t last long with the pace at which PHP is going.
WordPressCS 3.0.0 has costs thousands of hours of work and the vast majority of work has been done by one, mostly unpaid, contributor, with code review support from two fellow maintainers.
If we are being realistic, the bus factor of WordPressCS is 1, which is the most dangerous situation for any project to be in.
A large part of the WordPress community, including WordPress Core, relies heavily on the WordPress Coding Standards for code quality and security checks and while the community has been pretty vocal with copious complaints about the delayed release, barely anyone has stepped up and actually contributed.
The majority of the work for WordPressCS requires specialized knowledge. Knowledge which can be learned with enough time investment, but in recent years nobody has stepped up to do so.
This is an unsustainable situation and it ends now.
Unless funding is found to continue maintaining WordPressCS and its dependencies, the future is bleak and maintenance will be halted.
Let this be a call to action for the corporate/agency users of WordPressCS to come together and figure out a way to fund the continued maintenance and development of WordPressCS as that one person on which the whole project, including all dependencies, leans, is done with the current status quo.
Support for PHPPHPThe web scripting language in which WordPress is primarily architected. WordPress requires PHP 5.6.20 or higher 5 will be dropped in WordPress 6.3, scheduled for release on August 8th 2023. The new minimum supported version of PHP will be 7.0.0. The recommended version of PHP remains at 7.4 or greater.
WordPress currently supports PHP version 5.6.20 or greater. The minimum supported version was last adjusted in WordPress 5.2 in 2019, and since then usage of PHP 5.6 has dropped to 3.9% of monitored WordPress installations as of July 2023.
There’s no concrete usage percentage that a PHP version must fall below before support in WordPress is dropped, but historically the project maintainers have used 5% as the baseline. Now that usage of PHP 5.6 is well below that at 3.9% and dropping by around 0.1% every few weeks, plans to increase the minimum supported PHP version can move forward.
The benefits to increasing the minimum supported PHP version manifest over time and in multiple places, including within the pluginPluginA plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party and theme ecosystem, within the long term perception of the WordPress project, within developer relations, and over time within the WordPress codebase and its developer tooling.
Sites that are running PHP 5.6 will remain on the 6.2 branchbranchA directory in Subversion. WordPress uses branches to store the latest development code for each major release (3.9, 4.0, etc.). Branches are then updated with code for any minor releases of that branch. Sometimes, a major version of WordPress and its minor versions are collectively referred to as a "branch", such as "the 4.0 branch". of WordPress which will continue receiving security updates as it does currently. The current security policy is to support WordPress versions 4.1 and greater.
What about the GutenbergGutenbergThe Gutenberg project is the new Editor Interface for WordPress. The editor improves the process and experience of creating new content, making writing rich content much simpler. It uses ‘blocks’ to add richness rather than shortcodes, custom HTML etc. https://wordpress.org/gutenberg/ plugin?
The Gutenberg plugin, which is used for development of the blockBlockBlock is the abstract term used to describe units of markup that, composed together, form the content or layout of a webpage using the WordPress editor. The idea combines concepts of what in the past may have achieved with shortcodes, custom HTML, and embed discovery into a single consistent API and user experience. editor, has a separate release schedule from WordPress core and officially supports the two most recent releases of WordPress. This means that the Gutenberg plugin will continue to support PHP 5.6 for the time being, most likely until WordPress 6.4 is released. See this issue on the Gutenberg repo for further information.
There are no plans to bump the minimum supported PHP version on a schedule. The core team will continue to monitor usage of PHP versions and work with the hosting team to encourage users and hosting companies to upgrade their versions of PHP as swiftly as possible. The 5% usage baseline will continue to be used for the foreseeable future.
Update on August 1, 2023: Added requirement to publish Make/CoreCoreCore is the set of software required to run WordPress. The Core Development Team builds WordPress. post that details the compatibility change for the release (added to the “Beta Support” removal process section). Props @chanthaboune.
Officially WordPress Core currently provides “betaBetaA pre-release of software that is given out to a large group of users to trial under real conditions. Beta versions have gone through alpha testing in-house and are generally fairly close in look, feel and function to the final product; however, design changes often occur as part of the process. support” (or “beta compatibility”) for PHPPHPThe web scripting language in which WordPress is primarily architected. WordPress requires PHP 5.6.20 or higher 8.0, 8.1, and 8.2, as per the compatibility table in the handbook. The term “beta support” was first used in 2020 for WordPress 5.6 and PHP 8.0, though no criteria were set for determining when it could be removed. When should WordPress Core be considered compatible with a specific PHP version? Could it be compatible even with known and documented incompatible exceptions? This proposal is being set forth by a group of trusted contributors (see the props list below) who have consistently focused on the overall forward and backward compatibility of WordPress in the context of PHP as a way to outline any criteria, data, or roadmap needed to answer these questions.
The scope and goals of this proposal are:
Set the criteria for determining when WordPress Core has reached compatibility with a specific PHP version that WordPress supports.
Once the criteria are met, then the “beta support” classification can be removed for that WordPress version and beyond.
Set a phased approach for moving from “beta support” → to compatible with exceptions (optional) → to fully compatible.
The proposal starts with an understanding of what “compatibility” means, then dissects the meaning to identify indicators, and finally uses the indicators to build decision-making criteria.
What is outside the scope of this proposal?
Theme or pluginPluginA plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party compatibility. There is no guarantee that any theme or plugin a site owner uses is compatible with or safe to upgrade to a PHP version. Rather, this proposal is for WordPress Core itself.
List of supported PHP versions. It is not for determining which PHP versions WordPress should support, e.g. PHP EOL (End of Life), raising the minimum supported PHP version, etc.
Because of the nature of WordPress usage and the commitment to our user base, compatibility is to be considered in the eyes of those users. The goal is to elevate the broader ecosystem to a state that is compatible with PHP 8. That requires that the Core software not just be compatible on its own, but also provides defenses against common problems seen in the transition to PHP 8, while continuing to function on older versions of PHP.
Building upon the above quote, compatibility means:
WordPress Core’s compatibility with a specific PHP version happens when enough sites run without issues (a) in the ways users configure and use their sites (b) while also continuing to function on all older PHP versions WordPress supports.
Notice this description intentionally focuses on users with emphasis on the ways users use WordPress. WordPress is committed to being user-first. Technical decisions (including compatibility) should first focus on users and thus usage.
Is full 100% compatibility required before removing “beta support”?
No. This proposal does not require a full 100% compatibility requirement for removing “beta support”. Instead, it takes a more pragmatic phased approach.
Some PHP version features or changes are breaking changes that (a) may require more effort and time to fully resolve or (b) may not be fully resolvable due to various reasons such as external dependencies, backward compatibility, etc.
Imagine the scenario where the bulk of WordPress Core is compatible with a specific PHP version but there are one or more incompatibilities yet to be resolved. Should those incompatibilities blockBlockBlock is the abstract term used to describe units of markup that, composed together, form the content or layout of a webpage using the WordPress editor. The idea combines concepts of what in the past may have achieved with shortcodes, custom HTML, and embed discovery into a single consistent API and user experience. removing “beta support”? Or could those be accepted and documented as exceptions?
This proposal proposes the following phases:
compatible with documented exceptions
Reaching full 100% compatibility may not always be possible or it may take extensive amount of time. This should not block the removal of the “beta support” label. If one version is blocked, then all versions after that version are also blocked. By taking a phased approach, the project retains flexibility to take decisions that are best for users and the broader ecosystem.
2. Identifying indicators
In dissecting the above meaning, the keys to achieve compatibility reside in:
Enough sites: enough sites running on a given PHP version over enough time.
Issues: all known compatibility issues resolved or accepted as incompatible.
BC: compatibility changes are backward compatible with all earlier PHP versions WordPress supports.
Enough sites: What does a minimum threshold of sites signify?
Enough sites should indicate a variety of different usages. Usages are important.
It can indicate WordPress itself runs with different technical stacks of themes, plugins, configurations, and hosted environments.
WordPress is never used in isolation (without any theme or plugins), so WordPress itself being able to run on PHP 8 does not indicate “full” compatibility…
The state of PHP 8 support within the broader ecosystem (plugins, themes, etc.) is impossible to know.
Usages can also indicate a variety of the WordPress functionality is being used by users. Why is this important? It can indicate how much of the WordPress Core’s source code is being run on a specific PHP version with the different technical stacks.
Issues: What does “issues” signify?
If the number of sites running on a specific PHP version continues to grow over time, then an inference could be made that the sites run without issue. How so? The thinking is: why would the usage grow over time if there are compatibility issues blocking sites from running on the version? Using that logic, the growth of “enough sites” over time can indicate there are no known compatibility “issues”.
Historically, WordPress relies on users to provide feedback and report issues. Thus, the “issues” indicator also means all known compatibility issues are resolved or excluded. (Note: In TracTracAn open source project by Edgewall Software that serves as a bug tracker and project management tool for WordPress., the phpNN keyword convention (e.g. php80, php81, and php82) identifies a PHP compatibility issue or task. A new php-compatibility focus is also proposed for further help with identifying compatibility tickets.)
Thus, “issues” can be considered as a combination of the growth of enough sites over time and all reported and known compatibility issues are resolved or accepted as incompatible.
What is resolved?
A known issue is resolved by various actions including fixed, closed, accepted as not impacting compatibility, or documenting as being incompatible.
Backward compatibility: How does backward compatibility relate to PHP versions?
Users and user confidence. WordPress has a long history of prioritizing backward compatibility (also known as BC and back compatback compatBackward compatibility - a desire to ensure that plugins and themes do not break under new releases - is a driving philosophy of WordPress. While it is a commonly accepted software development practice to break compatibility in major releases, WordPress strives to avoid this at all costs. Any backward incompatible change is carefully considered by the entire core development team and announced, with affected plugins often contacted. It should be noted that external libraries, such as jQuery, do have backward incompatible changes between major releases, which is often going to be a greater concern for developers.) to ensure WordPress runs for users regardless of which PHP version they are using. In this way, users can upgrade to a newer PHP version with the confidence their site will continue to function.
PHP 8 introduces many breaking changes, meaning the changes in the language do not work on versions older than PHP 8. To make WordPress compatible with PHP 8, changes must also stay compatible with all PHP versions it supports.
How can backward compatibility be determined?
Each change must not change the previously intended behavior or code usage (e.g. function names or signatures, input types or data structures, return types or data structures, etc.) and must work on all WordPress supported PHP versions.
The adopted approach is to add automated tests prior to the compatibility change and then ensure the change does not alter the behavior or code usage.
3. Proposed compatibility criteria
Using the above indicators, let’s build criteria for determining when a WordPress version is compatible with a specific PHP version.
All of these indicators must be true for a specific PHP version:
Possible Incompatibilities for acceptance consideration:
Named parameters: Should WordPress be fully-compatible with named parameters? There are backward compatibility (BC) considerations to consider. Once WordPress is compatible with a specific PHP version, the names of function/method parameters can never change as any changes would be a BC break (See Trac 57838).
Explicitly setting default value of the flags parameter for htmlentities() et all (See Trac 53465).
BC: there are no known unresolved backward compatibility issues, though there is not a specific keyword available for tracking.
PHP 8.0 and 8.1 meet the minimum “enough sites” criteria, but have open tickets that need to be resolved to pass the “issues” criteria. Once each is resolved or accepted as incompatible, then it is possible for WordPress 6.3 to be declared compatible (possibly with incompatibility exceptions) with PHP 8.0 and 8.1.
Why not use the automated test suites as the compatibility indicator?
Automated tests are an important part of the testing and feedback loopLoopThe Loop is PHP code used by WordPress to display posts. Using The Loop, WordPress processes each post to be displayed on the current page, and formats it according to how it matches specified criteria within The Loop tags. Any HTML or PHP code in the Loop will be processed on each post. https://codex.wordpress.org/The_Loop. strategy in software development. A good set of tests can identify problems before the code ships to users.
But as previously noted, users are not running WordPress by itself, but rather as part of a stack of technologies. Knowing the majority of possible usage scenarios (such as an array of different themes and plugins) to use as test data is difficult. Thus, automated testing is part of an overall strategy when combined with the other indicators previously noted.
The automated tests are not included as part of the indicators. Currently the WordPress automated test suites are not yet significant or good enough to indicate with confidence that the source code is fully compatible and meets all of the above criteria.
What is required for the test suites to be considered significant and good enough?
The vast majority of the code would need to be exercised by the tests.
A broad set of scenarios for what should (happy path) and shouldn’t (unhappy path) happen in the ways users configure and use WordPress.
Currently, the WordPress Core’s automated test suites do not meet this criteria. For example, using the published code coverage report, less than half of the code is being exercised by tests. (Note: the published code coverage report is misleading as it represents “unclean” code coverage. The actual percentage is significantly lower. Work is ongoing to improve the reporting .) In addition, the test suites need to grow their testing scenarios to include the different ways users use WordPress.
4. “Beta Support” removal process
Once the above criteria are met, then the “beta support” classification can be removed for the next major WordPress release. Since only the most recent major branchbranchA directory in Subversion. WordPress uses branches to store the latest development code for each major release (3.9, 4.0, etc.). Branches are then updated with code for any minor releases of that branch. Sometimes, a major version of WordPress and its minor versions are collectively referred to as a "branch", such as "the 4.0 branch". of WP is supported, previous versions of WP with “beta support” for a PHP version will remain, even if security updates are pushed to older branches after the fact.
TriagetriageThe act of evaluating and sorting bug reports, in order to decide priority, severity, and other factors. all php-compatibility tickets for the PHP version (phpNN keyword) to ensure all tickets are resolved.
Verify backward compatibility.
Gather the list of accepted incompatibilities.
Identify and resolve dependency needs, such as a MetaMetaMeta is a term that refers to the inside workings of a group. For us, this is the team that works on internal WordPress sites like WordCamp Central and Make WordPress. change for Site Health to get the “recommended PHP” version via an APIAPIAn API or Application Programming Interface is a software intermediary that allows programs to interact with each other and share data in limited, clearly defined ways. call.
When adding the next major releasemajor releaseA release, identified by the first two numbers (3.6), which is the focus of a full release cycle and feature development. WordPress uses decimaling count for major release versions, so 2.8, 2.9, 3.0, and 3.1 are sequential and comparable in scope. to to the PHP Compatibility and WordPress Versions handbook page, do not add the * next to that specific PHP version. If there are incompatibilities, add ** next to the PHP version and list each incompatibility below the table.
Publish a Make/Core post that details what the compatibility change means for users and extenders.
This post presents a thoroughly referred recommendation for when to remove “beta support” from PHP 8 and newer versions. The criteria were a result of the feedback from several contributors listed below. However, it is only a proposal and is not concrete. Adjustments can be made to this proposal based on feedback from contributors in the comments below. If you have any thoughts, please do leave them below!
Unless there is a need to republish a modified version of this proposal for further feedback, after a consensus is reached and any needed approval from leadership to implement this proposal is received, the following action items would need to be addressed:
The Make WordPress Core handbook should be updated in the appropriate places to:
outline the criteria and process for reviewing each “beta support” PHP version with each WordPress major release.
Add php-compatibility focus, which will be listed in “Contributor Focuses”. (Status: Done on Aug 1, 2023 ✅)
Contributors should scrub all tickets for PHP compatibility to (Status: Done as of Aug 8, 2023 ✅)
Add the php-compatibility focus with a description of “Relating to PHP forward and backwards compatibility. A phpNN keyword identifies the PHP version that introduced the incompatibility”.
Update the PHP version phpNN keyword, if necessary.
Determine the ticketticketCreated for both bug reports and feature development on the bug tracker. status and next step toward resolution, including: close with a message why, complete, or get consensus on ones to be accepted as incompatible.
Any other action items identified while discussing this proposal.
After discussion with several coreCoreCore is the set of software required to run WordPress. The Core Development Team builds WordPress. committers and WordPress leads, the title and the contents of the text were changed to clarify that this is a proposal and not a decision set in stone.
Yoda conditions (or Yoda notation) is the programming style where the parts of an expression in the condition are reversed from the ‘typical’ order.
In a large part of the world, the natural reading order is left to right (LTR). This is what most programming languages adhere to. That means the variable assignments or echo/print statements are written with the variable first:
$post_type = 'post';
With the same idea in mind, conditions can also be written left to right, like:
While seemingly helpful at first glance, the obvious problem with them is the decreased readability of code, especially for people with reading disabilities such as dyslexia.
How we got here
When the handbook rule about Yoda conditions was introduced there was barely any static analysis tooling available in the PHPPHPThe web scripting language in which WordPress is primarily architected. WordPress requires PHP 5.6.20 or higher world. The only ‘foolproof’ way to prevent accidental assignment in conditions was to invert the order of the value being checked and the variable.
Automated checking for assignments in conditions via PHP_CodeSniffer (PHPCSPHP Code SnifferPHP Code Sniffer, a popular tool for analyzing code quality. The WordPress Coding Standards rely on PHPCS.), the underlying tooling for WPCSWPCSThe collection of PHP_CodeSniffer rules (sniffs) used to format and validate PHP code developed for WordPress according to the WordPress Coding Standards.
Today there is tooling in place that can help with identifying assignments in conditions, making the Yoda rules obsolete.
Keep in mind that strict comparisons (===) are already strongly encouraged and a part of the WordPress-Core ruleset (warning), making accidental assignments even less likely.
A thorough analysis was made by Lucas Bustamante in the WPCS ticketticketCreated for both bug reports and feature development on the bug tracker. on the impact this could have on the plugins in the WordPress directory. The analysis showed that Yoda conditions are used in 18.02% of the plugins, so the majority of pluginPluginA plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party developers are using non-Yoda conditions.
What to do next?
The discussion in the WPCS ticket is long and opinionated, but comes down to these points:
Disallow Yoda condition
Drop the handbook rule that requires Yoda conditions and instead explicitly disallow using them.
Remove Yoda condition as a requirement
Discourage, but don’t disallow Yoda conditions. Just don’t report if the code is or is not using Yoda conditions. The rule would also be dropped from the handbook.
In both cases, assignments in conditions will still be checked for and forbidden.
Impact on the Core code
Disallowing Yoda conditions for WordPress Core would mean that all existing patches on open tickets for Core would need to be revisited and fixed accordingly, which could burden the contributors.
Running the same analysis as Lucas did for plugins, over the WordPress Core, there were 5427 Yoda conditions, and 312 non-Yoda conditions.
Luckily, these are violations that can be automatically fixed using phpcbf tool, but care should be taken to check if all the violations were correctly fixed.
If Yoda conditions are discouraged (option 2), and the existing Yoda conditions in the Core code remain, that would mean less work for the Core contributorsCore ContributorsCore contributors are those who have worked on a release of WordPress, by creating the functions or finding and patching bugs. These contributions are done through Trac. https://core.trac.wordpress.org., but also would add lots of inconsistencies in the Core code (mixed Yoda and non-Yoda conditions).
The chosen way forward is to remove the Yoda condition as a requirement (remove it from the handbook) but not disallow it for the time being.
For WPCS, that would mean the removal of the Yoda conditions requirement (and sniff) in WPCS 3.0, with a notice that non-Yoda conditions will start to be required in WPCS 4.0 version.
Work is currently actively ongoing to prepare for the WPCS 3.0.0 release. There will be a minimum of six months between the 3.0.0 and the 4.0.0 release to allow time for Core and other projects to adjust.
Once WPCS 4.0.0 version is released, a one-time-only auto-fix of all the remaining Yoda conditions in Core will be made, and any patches to the Core which go in after that will have to use non-Yoda.
How to enforce the non-Yoda conditions in your code
If you are a WordPress plugin or theme developer, and you’d like to enforce non-Yoda conditions in your code, you can use the Generic.ControlStructures.DisallowYodaConditions sniff. In your phpcs.xml.dist file you should add the following sniff:
<ruleset xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" name="Example Project" xsi:noNamespaceSchemaLocation="https://raw.githubusercontent.com/squizlabs/PHP_CodeSniffer/master/phpcs.xsd">
<!-- Your custom rules. -->
<!-- Disallow Yoda conditions in your codebase. -->
If you want to change the Yoda conditions to non-Yoda conditions, use the phpcbf tool (part of PHPCS) with the Slevomat coding standards. Specifically, the SlevomatCodingStandard.ControlStructures.DisallowYodaComparison sniff that has the fixer for the Yoda conditions.
A long-standing goal of the WordPress project is to be compatible with new versions of PHP on their release day. The next major version of PHP (version 8.0) is currently scheduled for release on November 26, 2020. WordPress Core contributorsCore ContributorsCore contributors are those who have worked on a release of WordPress, by creating the functions or finding and patching bugs. These contributions are done through Trac. https://core.trac.wordpress.org. are working to ensure PHPPHPThe web scripting language in which WordPress is primarily architected. WordPress requires PHP 5.6.20 or higher 8.0 is supported in the next major version of WordPress (version 5.6), which is currently scheduled to be released on December 8, 2020.
PHP 8.0 has been in the making for some time and brings a lot of exciting features. But because PHP 8.0 is a major version release, it also includes some backward incompatible changes. Because of this, a great deal of both manual and automated testing is needed in order to ensure the WordPress CoreCoreCore is the set of software required to run WordPress. The Core Development Team builds WordPress. codebase is ready for PHP 8.0.
Even though WordPress 5.6 will add support for PHP 8.0, no changes will be made to the minimum required version of PHP at this time. Any changes made to provide support for PHP 8.0 will be done in a way that maintains backward compatibility for all versions of PHP supported by WordPress (currently to PHP 5.6.20).
Your help is needed to test WordPress on PHP 8.0! While contributors are working on addressing incompatibilities that can be identified by looking at the PHP release notes and upgrade guides, some issues will need to be found through manually testing.
Timeline for testing
Since changes for PHP 8.0 compatibility may be extensive, November 17, 2020 (the current planned date for 5.6 RCrelease candidateOne of the final stages in the version release cycle, this version signals the potential to be a final release to the public. Also see alpha (beta). 1) should be seen as the cut off date for the change to be included in WordPress 5.6. To ensure that changes receive proper testing, patches and pull requests should be submitted as soon as possible.
How to test WordPress on PHP 8.0
There are a few ways that you can test WordPress on PHP 8.0. Some more experienced developers may prefer to install PHP 8.0 manually on their own. But below are instructions for what is likely the quickest and easiest way for most contributors to get set up with PHP 8.
Local WordPress Core Docker environment
The WordPress development repository includes the tools needed to easily spin up a local Docker environment for developing WordPress. Here’s how to get started using this method.
Edit the .env file in the clone to change LOCAL_PHP=latest to LOCAL_PHP=8.0-fpm (or run export LOCAL_PHP=8.0-fpm in the command line window you are using). If you like to test locally using the build directory, also change LOCAL_DIR to build (or run export LOCAL_DIR=build).
Install NPM dependencies by running npm install.
Build WordPress using npm run build:dev (or npm run build if you prefer to test locally using the build directory)
Start the Docker environment by running npm run env:start.
Install WordPress in the Docker container by running npm run env:install.
You will then be able to access the site at localhost:8889 in your browser. As new development versions of PHP 8 are released (rc2, rc3, etc.), the containers will be updated. To ensure you are running the latest version of the PHP 8 container, you can run npm run env:pull. It is recommended that you do this before starting the container anytime you are testing WordPress on PHP 8.
Write new unit tests that confirm specific PHP 8.0 features or breaking changes work (or don’t) as expected.
Write new tests for areas of the codebase that does not have sufficient test coverage.
Test your favorite plugins and themes for issues.
If you discover something that you believe to be a PHP 8 compatibility issue, please create a bugbugA bug is an error or unexpected result. Performance improvements, code optimization, and are considered enhancements, not defects. After feature freeze, only bugs are dealt with, with regressions (adverse changes from the previous version) being the highest priority. report on the WordPress Core instance of Trac. Because this is an ongoing effort, it’s possible an issue you have found is already being tracked, is currently being worked on, or has already been fixed. To avoid duplicate reports, please look through pre-existing tickets. The best way to do this is by looking at tickets with the php8 keyword.
Please be sure to provide as many details as you can when creating a ticketticketCreated for both bug reports and feature development on the bug tracker. and provide steps that are as specific as possible so that other contributors can quickly and easily reproduce the problem.
Give feedback, write a patchpatchA special text file that describes changes to code, by identifying the files and lines which are added, removed, and altered. It may also be referred to as a diff. A patch can be applied to a codebase for testing., or test a patch!
Inform others that help is needed to test WordPress on PHP 8.0.
To ensure changes receive the necessary testing, it’s best to fix PHP 8.0 compatibility issues as early as possible during the WordPress development schedule. The 5.6 RC1 date (November 17th, 2020) should be considered the final cut off for changes. If additional critical PHP 8.0 issues are found during the RC period, they should receive tickets and patches and will be evaluated on a case by case basis. But, they will not be guaranteed to make the 5.6 release (usually, only regressions are addressed during the RC period).