PHP RFC: Deprecations for PHP 7.4
- Date: 26th June, 2018
- Authors: Kalle Sommer Nielsen kalle@php.net, Nikita Popov nikic@php.net
- Status: Implemented
- Targets: PHP 7.4
Introduction
The RFC proposes to deprecate the listed functionality in PHP 7.4 and remove it in PHP 8.
The following list provides a short overview of the functionality targeted for deprecation, while more detailed explanation is provided in the Proposal section:
- The
realtype - Magic quotes legacy
array_key_exists()with objectsFILTER_SANITIZE_MAGIC_QUOTESfilter- Reflection
export()methods mb_strrpos()with encoding as 3rd argumentimplode()parameter order mix- Unbinding
$thisfrom non-static closures hebrevc()functionconvert_cyr_string()functionmoney_format()functionezmlm_hash()functionrestore_include_path()functionallow_url_includeini directive
Proposal
Each feature proposed for deprecation is voted separately and requires a 2/3 majority. All votes refer to deprecation in PHP 7.4 and removal in PHP 8.0. Voting started 2019-07-08 and ends 2019-07-22.
The 'real' type
Currently PHP has a float data type, with two additional aliases: double and real. The latter is very rarely used and should be deprecated. This includes both the (real) type-cast and the is_real() function. Currently the settype() function does not support the “real” string, so it is not affected.
Upgrading is relatively easy and can be done by replacing all (real) type-casts with (float) and all is_real() calls with is_float().
Proposal: Emit a deprecation warning each time the (real) type-cast is used and mark is_real() as deprecated.
Magic quotes legacy
PHP's infamous magic_quotes configuration was removed in PHP 5.4 and the function implementations of checking whether or not these settings have been enabled have returned false since then. With PHP 7.0 not having magic_quotes at all, it is time to deprecate these functions and remove them entirely.
Proposal: Mark get_magic_quotes_gpc() and get_magic_quotes_runtime() as deprecated.
This should only impact legacy code bases prior to PHP 5.4, running non-supported versions of PHP.
array_key_exists() with objects
The documentation already marks the use of array_key_exists() with objects as legacy behavior:
For backward compatibility reasons, array_key_exists() will also return TRUE if
keyis a property defined within an object given asarray. This behaviour should not be relied upon, and care should be taken to ensure thatarrayis an array. To check whether a property exists in an object, useproperty_exists().
array_key_exists() on objects also has some technical issues: It operates directly on mangled property names and does not respect property visibility. Furthermore, it does not take into account differences in normalization between array and object keys, so incorrect results may be returned for properties with integral keys.
Additionally, the fact that array_key_exists() accepts objects may mistakenly lead users to believe that it can operate on ArrayAccess objects in a sensible manner. This is not the case: array_key_exists() has no support for ArrayAccess, it exclusively works on mangled object properties.
Proposal: Throw a deprecation warning if an object is passed to array_key_exists().
FILTER_SANITIZE_MAGIC_QUOTES
Magic quotes were deprecated all the way back in PHP 5.3 and later removed in PHP 5.4. The filter extension implements a sanitization filter that mimics this behavior of magic_quotes by calling addslashes() on the input in question.
In PHP 7.3 add_slashes (FILTER_SANITIZE_ADD_SLASHES) was added as a new alias for this filter, to allow us to move away from the magic_quotes terminology.
Proposed action: Emit a deprecation notice each time the FILTER_SANITIZE_MAGIC_QUOTES filter is used and advise users to use the add_slashes (FILTER_SANITIZE_ADD_SLASHES) filter instead.
Reflection export() methods
The Reflector interface, which is implemented by all reflection classes, specifies two methods: __toString() and export(). The latter is a static method which, ostensibly, does not accept arguments. In reality this static method is implemented with varying signatures in each subclass, something which would normally result in an incompatible signature error. However, the implementation uses an internal mechanism to suppress this error.
The export() methods are essentially equivalent to a combination of the class constructor and __toString(). For example:
ReflectionFunction::export('foo'); // same as echo new ReflectionFunction('foo'), "\n"; $str = ReflectionFunction::export('foo', true); // same as $str = (string) new ReflectionFunction('foo');
As such, the export() method is wholly unnecessary, confusing, and violates PHP's own inheritance rules.
Proposed action: In PHP 7.4 remove the method from the Reflector interface and deprecate all implementations of the method in reflection classes. In PHP 8 also remove the implementations.
mb_strrpos() with encoding as 3rd argument
The documentation for mb_strrpos() states:
The encoding parameter was moved from the third position to the fourth in PHP 5.2.0. For backward compatibility, encoding can be specified as the third parameter, but doing so is deprecated and will be removed in the future.
However, this deprecation has never been realized in the implementation. The need to support both signatures makes this parameter behave subtly different from other integer parameters (e.g. it is not subject to strict types). As little software is expected to support both PHP 7.4 and PHP 5.1, enforcing the new signature does not pose a significant backwards compatibility concern.
Proposed action: In PHP 7.4 throw a deprecation warning if an encoding is passed as the 3rd argument. In PHP 8 change the argument to accept an integer only.
implode() parameter order mix
For historical reasons, the implode() function supports passing the $glue and $pieces parameters in reverse order from the documented order of arguments. This is inconsistent and makes the argument handling non-standard (for example, strict types are not respected). This also affects the alias join().
Proposal: Emit a deprecation warning when calling implode($pieces, $glue) or join($pieces, $glue). Calling the function with just an array continues to be allowed: implode($pieces) does not generate a deprecation warning.
Unbinding $this from non-static closures
Currently it is possible to unbind the $this variable from a closure that originally had one by using $closure->bindTo(null). Due to the removal of static calls to non-static methods in PHP 8, we now have a guarantee that $this always exists inside non-static methods. We would like to have a similar guarantee that $this always exists for non-static closures declared inside non-static methods. Otherwise, we will end up imposing an unnecessary performance penalty either on $this accesses in general, or $this accesses inside such closures.
Proposal: Deprecate unbinding $this from a closure that originally had a $this binding. In particular this applies to non-static closures declared inside non-static methods. A $this binding can be avoided in the first place by marking the closure as static.
hebrevc() function
The hebrevc() function is equivalent to calling nl2br() on the result of hebrev(), which is a function to convert Hebrew text from logical to visual ordering. While nl2br(hebrev($str)) is already preferable over hebrevc($str) for readability reasons, use of visual ordering is only relevant in contexts that do not have proper Unicode bidi support, such as certain terminals. As detailed in W3C Visual vs. logical ordering of text, visual ordering should never be used for HTML. The hebrevc() function is an explicit violation of this principle.
Proposal: Mark hebrevc() as deprecated.
convert_cyr_string()
The convert_cyr_string() function allows conversion between Cyrillic character sets. The character sets are specified using obscure single character names, such as convert_cyr_string($str, “k”, “i”). This is a legacy function from a time where PHP did not provide general functions for conversion between character sets. Nowadays one of mb_convert_encoding(), iconv() or UConverter may be used for this purpose.
Proposal: Mark convert_cyr_string() as deprecated.
money_format()
The money_format() function formats currency values using locale-specific settings. It is based on the strfmon() C function, which is not supported on all platforms. Most notably it is not available on Windows. Nowadays the NumberFormatter::formatCurrency() method provided by intl should be used instead, which is both platform-independent and does not rely on the system locale. Additionally, intl also provides the ability to parse currency values using NumberFormatter::parseCurrency().
Furthermore, the strfmon() implementation seems to have an internal buffer overrun on macos, which indicates that this functionality is not well tested.
Proposal: Mark money_format() as deprecated.
ezmlm_hash()
The ezmlm_hash() function creates hashes of email addresses which the EZMLM/QMail mailing list system understands. This function is of very limited usefulness for the average PHP developer as the EZMLM/QMail system is barely maintained and its last release was in 2007. The function was most likely originally added for use in the php.net mailing list infrastructure. It can be trivially reimplemented in userland code if needed.
Proposal: Mark ezmlm_hash() as deprecated.
restore_include_path() function
This function is essentially an “alias” of doing ini_restore('include_path'). Unlike other functions like restore_error_handler() or restore_exception_handler(), this function does not operate on a stack and always resets to the original/initial value. While you can use set_error_handler() and restore_error_handler() as a pair, doing the same with set_include_path() and restore_include_path() is not safe. As such, this function does not offer any benefit over ini_restore('include_path') and just causes wrong expectations.
Proposal: Mark restore_include_path() as deprecated.
allow_url_include
The allow_url_include ini directive (disabled by default) allows the require, require_once, include and include_once language constructs to use URL stream wrappers. To use this ini directive, the allow_url_fopen ini directive must also be enabled.
Enabling this option creates a potential security hazard if the path passed to one of the include constructs is crafted by external data. The ability to include a PHP file from a remote domain is questionable in the first place and has a huge potential security risk and therefore should be deprecated from PHP.
Proposal: Add a deprecation notice if allow_url_include=1 on startup.
Backward Incompatible Changes
For PHP 7.4 additional deprecation notices will appear. For PHP 8.0 the previously deprecated functionality will no longer be available.
Changelog
The following deprecations were originally part of this RFC, but have been removed:
get_called_class(), because the deprecation was not well motivated.enable_dl, because contrary to original assumptionsdl()is currently available on CGI by default, which is a server SAPI. This goes against the original premise that having this ini option does not make sense ifdl()is only available on CLI in the first place.enable_argc_argv, because it is technically hard to actually deprecate something here, we'll likely want to just make some changes in PHP 8.INPUT_SESSIONandINPUT_REQUEST. These were instead directly removed in PHP 8, as they have been generated a warning for a long time, so an additional deprecation is not necessary.is_writeable(), because this was very contentious. Some people consider this not just a valid spelling, but even preferable for searchability purposes.apache_request_headers(), because the problem here is much bigger and just removing a single function does not really help. In particular there is alsoapache_response_headers()defined by non-Apache SAPIs, which does not have a SAPI-agnostic alias. There are also more SAPI-specific functions likelitespeed_request_headers()andlitespeed_response_headers(). These should all be dealt with together.hebrev(), because it may still be useful in some terminal contexts. However,hebrevc()is still slated for deprecation, as it is only relevant for HTML contexts, where visual representation should not be used.