Re: Deprecated partially supported callables: should is_callable() throwa deprecation notice ?

On 18-3-2022 14:37, Christoph M. Becker wrote:

On 16.03.2022 at 06:52, Juliette Reinders Folmer wrote:

I've just been looking in detail at the Partially Supported Callables deprecation RFC: https://wiki.php.net/rfc/deprecate_partially_supported_callables The RFC explicitly excludes the is_callable() function and the callable type from throwing deprecation notices.

The |is_callable()| function and |callable| type remain side-effect free and do not throw a deprecation warning. They will continue to accept these callables until support is removed entirely.

While I can fully support this for the callable type, I wonder if the decision to not throw a deprecation on use in is_callable() is the right one (though I understand the desire to keep it side-effect free). Consider these code samples: function foo(callable $callback) {} foo('static::method'); This function call not throwing a deprecation is not problematic as in PHP 9.0 the function will start throwing a TypeError. if (is_callable('static::method')) {

       static::method();

} The second code sample, however, is problematic, as in PHP 9.0, the behaviour of this code will be silently reversed for those callbacks which would previously result in is_callable() returning true, which makes this a potentially dangerous change without deprecation notice. Would anyone care to enlighten me as to whether this was given due consideration ?

Frankly, I don't know. Apparently, there was almost no discussion about that RFC. Part of the reasoning to not raise E_DEPRECATED when calling is_callable() was likely the typical use case $callable = …; if (is_callable($callable)) {

       call_user_func($callable);

} what would report the deprecation when actually calling the callable. Not sure what to do regarding your given use case(s). -- Christoph M. Becker

Unfortunately, those aren't the only places I see this happening and my example is not a stand-alone case either. I came across the above code sample ( is_callable('static::method') / is_callable(['parent', __FUNCTION__]) with variable method calls) in a number of different packages when testing a (PHPCompatibility) sniff I am writing to detect the deprecation, so this code pattern looks to be relatively common. Some examples: * https://github.com/symfony/service-contracts/blob/bc0a2247c72d29241b5a06fb60dc1c9d9acf2a3a/ServiceSubscriberTrait.php#L39 * https://github.com/mockery/mockery/blob/c10a5f6e06fc2470ab1822fa13fa2a7380f8fbac/library/Mockery/Mock.php#L960 * https://github.com/simplepie/simplepie/blob/dacf0ed495d2e8fb306e526ca3f2a846af78a7c9/tests/oldtests/absolutize/RFC3986.5.4/base.php#L13