PHP’s internal functions and (class-)constants can be marked as deprecated, making this information available to Reflection and emitting deprecation errors (E_DEPRECATED
), but there is no equivalent functionality for functions defined in userland.
While the functionality can be emulated using trigger_error()
to emit a E_USER_DEPRECATED
error when calling a deprecated function, combined with either parsing a doc comment for the /** @deprecated */
annotation or attaching a custom-defined attribute and reading it with Reflection, it requires special handling depending on whether the function in question is an internal or a userland function. ReflectionFunctionAbstract::isDeprecated()
always returns false
for userland functions - and doc comments / custom attributes are unavailable for internal functions. For class constants the deprecation behavior cannot be emulated at all.
A new attribute #[\Deprecated]
shall be added:
#[Attribute(Attribute::TARGET_METHOD|Attribute::TARGET_FUNCTION|Attribute::TARGET_CLASS_CONSTANT)] final class Deprecated { public readonly ?string $message; public function __construct(?string $message = null, ?string $since = null) {} }
Applying this attribute to a userland function, method, or class constant will add the internal ZEND_ACC_DEPRECATED
flag to the element, resulting in a behavior that is consistent with the existing deprecation functionality for internal functions and class constants. This means:
ReflectionFunctionAbstract::isDeprecated()
will return true
.ReflectionClassConstant::isDeprecated()
will return true
(this method is newly added in PHP 8.4).E_USER_DEPRECATED
error (internal functions emit E_DEPRECATED
, but this error code is reserved for internal functions).E_USER_DEPRECATED
error (likewise internal class constants use E_DEPRECATED
).
The $message
given within the attribute definition will be included in the error message when calling the function or accessing the class constant. It goes without saying that it will also be available to static analysis tools, just like the parameters of any other attribute.
The optional $since
argument is appended to the error message. It signals the version since the function/method is deprecated. This is included because due its pre-existing use in internals, php-doc, Symfony and others.
While internal, non-class constants can also be marked as deprecated, there is no support for attributes on them yet, and ReflectionConstant
has just been added in PHP 8.4. Adding attribute support for non-class constants is out of scope of this RFC/PR for now.
Enum cases are internally implemented as class constants. Adding the #[\Deprecated]
attribute to an enum case will behave as expected.
<?php #[\Deprecated] function test() { } #[\Deprecated("use test() instead")] function test2() { } #[\Deprecated("use test() instead", since: "2.4")] function test3() { } class Clazz { #[\Deprecated] public const OLD_WAY = 'foo'; #[\Deprecated] function test() { } #[\Deprecated("use test() instead")] function test2() { } } enum MyEnum { #[\Deprecated] case OldCase; } test(); // Deprecated: Function test() is deprecated in test.php on line 29 test2(); // Deprecated: Function test2() is deprecated, use test() instead in test.php on line 30 test3(); // Deprecated: Function test2() is deprecated since 2.4, use test() instead in test.php on line 30 call_user_func("test"); // Deprecated: Function test() is deprecated in test.php on line 31 $cls = new Clazz(); $cls->test(); // Deprecated: Method Clazz::test() is deprecated in test.php on line 34 $cls->test2(); // Deprecated: Method Clazz::test2() is deprecated, use test() instead in test.php on line 35 Clazz::OLD_WAY; // Deprecated: Constant Clazz::OLD_WAY is deprecated in test.php on line 36 MyEnum::OldCase; // Deprecated: Enum case MyEnum::OldCase is deprecated in test.php on line 38 call_user_func([$cls, "test"]); // Deprecated: Method Clazz::test() is deprecated in test.php on line 40 ?>
<?php #[\Deprecated] function test() { } $r = new ReflectionFunction('test'); var_dump($r->isDeprecated()); // bool(true) ?>
<?php class Clazz { #[\Deprecated] public const OLD_WAY = 'foo'; } $r = new ReflectionClassConstant(Clazz::class, 'OLD_WAY'); var_dump($r->isDeprecated()); // bool(true) ?>
<?php #[\Deprecated] function test1() { } #[\Deprecated()] function test2() { } #[\Deprecated("use test() instead")] function test3() { } $reflection = new ReflectionFunction('test1'); var_dump($reflection->getAttributes()[0]->newInstance()); /* object(Deprecated)#3 (1) { ["message"]=> NULL } */ $reflection = new ReflectionFunction('test2'); var_dump($reflection->getAttributes()[0]->newInstance()); /* object(Deprecated)#2 (1) { ["message"]=> NULL } */ $reflection = new ReflectionFunction('test3'); var_dump($reflection->getAttributes()[0]->newInstance()); /* object(Deprecated)#1 (1) { ["message"]=> string(18) "use test() instead" } */ ?>
Further examples are given by the newly added tests within the PR for this RFC.
Deprecated
can no longer be used as a class name in the global namespace. A GitHub search for “class Deprecated ” language:php symbol:deprecated
revealed a total of 173 matches in source code. The vast majority of them appear to be defined within a namespace.
Next minor (PHP 8.4).
None.
The #[\Deprecated]
attribute will also be available to internal functions and internal class constants. Within a stub file it will have the same effect as adding a /** @deprecated */
doc comment. The attribute will not be automatically applied to existing functions having the doc comment, but extension authors are encouraged to apply the attribute for consistency reasons.
For extensions that are part of php-src the attribute will replace the existing doc comment as part of this RFC.
None.
None.
None.
A few things tracked in https://github.com/php/php-src/pull/11293
#[\Deprecated]
on other targets of attributes that to not yet support deprecations for internally defined symbols.#[\Deprecated]
attribute beyond a custom message (e.g. hints for replacements that IDEs could use).n/a
E_DEPRECATED
error for internal functions).Deprecated
attribute class non-final: Child classes of attributes are not understood by the engine for technical reasons and the semantics of a child class would be less clear for static analysis tools.