PHP 8.5 for WordPress developers: pipes, clone with, and when to upgrade

PHP 8.5 was released on 20 November 2025. For its first months, the short answer to “should I move the site to 8.5?” was “not yet”. Then in May 2026 the WordPress core team announced that WordPress 6.9 and 7.0 fully support PHP 8.5, and retired the “beta support” label for good.

So core is ready. The real question now is whether your plugins and your own code are, and which parts of 8.5 are worth using.

01The pipe operator: more readable, not magic#

The most visible change in 8.5 is the |> operator. It passes the value on the left to the callable on the right, so you can build chains. The classic example builds a slug from a title:

$slug = $title
	|> trim(...)
	|> ( fn( $s ) => str_replace( ' ', '-', $s ) )
	|> strtolower(...);

In WordPress code it shines in sanitising and transformation chains, for example cleaning an input before saving it:

$clean_tags = $raw_tags
	|> ( fn( $s ) => explode( ',', $s ) )
	|> ( fn( $a ) => array_map( 'sanitize_text_field', $a ) )
	|> ( fn( $a ) => array_filter( $a ) )
	|> array_values(...);

It has three important limits:

• One required parameter: every callable in the chain must take exactly one required parameter, and the value always goes in as the first argument.
• No by-reference parameters: functions such as array_pop cannot be used in a chain.
• No backward compatibility: code containing |> does not even parse on PHP 8.4 or older. In a plugin you publish for everyone, its time has not come yet: WordPress’s minimum is PHP 7.4 and your users run every kind of server. In a bespoke project where you control the server, go ahead.

02clone with: the end of hand-written with-methods#

If you use readonly objects, such as value objects in a payment plugin, clone can now change several properties at once:

final readonly class Money {
	public function __construct(
		public int $amount,
		public string $currency,
	) {}

	public function withAmount( int $amount ): self {
		return clone( $this, array( 'amount' => $amount ) );
	}
}

Before this you had to call the constructor again with every argument, or reach for Reflection.

03Small things you will use every day#

• **array_first() and array_last():** they return the first and last value of an array, or null for an empty one, so they pair nicely with ??. No more reset() and end() moving the array’s internal pointer.
• **#[\NoDiscard]:** PHP warns when the return value of a function marked with it is ignored. That is ideal for functions that return a modified copy when everyone assumes they modify the original.
• The URI extension: Uri\Rfc3986\Uri parses addresses according to RFC 3986 and the WHATWG URL standard. It is more reliable than parse_url for validating redirects and webhooks.
• Backtraces for fatal errors: errors such as an exceeded execution time now include a full backtrace. For debugging heavy WooCommerce cron jobs, that alone is worth the upgrade.

04What was deprecated#

You will see these often in old plugins, especially code that has passed through several hands:

• Non-canonical cast names: (boolean), (integer), (double) and (binary) are deprecated. Write (bool), (int), (float) and (string) instead.
• The backtick operator: using it as an alias for shell_exec() is deprecated. If you find one in a plugin, there is probably a bigger security problem nearby.
• **null as an array key:** using null as an array offset, or in array_key_exists(), is deprecated.
• **case ending in a semicolon:** ending a case with ; instead of : is deprecated.
• **__sleep() and __wakeup():** both are soft-deprecated in favour of __serialize() and __unserialize().
• New warnings: casting a float to int when it cannot be represented, and destructuring a non-array value, now emit warnings.

None of these takes a site down, but they fill the log. A full log means you see the next real error late.

05The upgrade order I recommend#

1. Know where you stand. Check the PHP version under Tools › Site Health › Info. WordPress’s minimum recommended version is still 8.3; if you are below it, move to 8.3 or 8.4 first.
2. Test on staging with full warnings. Turn on WP_DEBUG and WP_DEBUG_LOG, walk through the sensitive paths end to end (checkout, registration, cron jobs and webhooks), then read the log.
3. Run an automated compatibility scan. PHPCompatibility on PHPCS, with 8.5 as the target, catches most deprecations before anything runs.
4. Check commercial plugins separately. Encoded plugins in particular are usually the last to support a new PHP version.
5. Upgrade PHP on its own. Do it separately from WordPress and plugin updates. When three things change at once and something breaks, you cannot tell which one did it.

PHP 8.5 is not a revolution, but it is full of small things that make code cleaner and debugging easier. If your project is bespoke and you control the server, now is a good time to try it on staging. If you write a public plugin, use the new features only in branches whose Requires PHP really says 8.5.

06Sources#

• PHP 8.5 release announcement, php.net
• PHP support clarification, spring 2026, Make WordPress Core
• PHP 8.5: Pipe operator, PHP.Watch
• PHP 8.5 and WordPress – When to Upgrade?, Seravo