PHP RFC: Deprecations for PHP 7.4
- Date: 26th June, 2018
- Authors: Kalle Sommer Nielsen firstname.lastname@example.org, Nikita Popov email@example.com
- Status: Implemented
- Targets: PHP 7.4
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:
- Magic quotes legacy
mb_strrpos()with encoding as 3rd argument
implode()parameter order mix
$thisfrom non-static closures
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:
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
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.
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 as
array. This behaviour should not be relied upon, and care should be taken to ensure that
arrayis an array. To check whether a property exists in an object, use
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
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
FILTER_SANITIZE_ADD_SLASHES) was added as a new alias for this filter, to allow us to move away from the
Proposed action: Emit a deprecation notice each time the
FILTER_SANITIZE_MAGIC_QUOTES filter is used and advise users to use the
FILTER_SANITIZE_ADD_SLASHES) filter instead.
Reflection export() methods
Reflector interface, which is implemented by all reflection classes, specifies two methods:
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.
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
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
$pieces parameters in reverse order from the documented order of arguments. This is inconsistent and makes the argument handling non-standard (for example, strict types are not respected). This also affects the alias
Proposal: Emit a deprecation warning when calling
implode($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
$this binding can be avoided in the first place by marking the closure as
hebrevc() function is equivalent to calling
nl2br() on the result of
hebrev(), which is a function to convert Hebrew text from logical to visual ordering. While
nl2br(hebrev($str)) is already preferable over
hebrevc($str) for readability reasons, use of visual ordering is only relevant in contexts that do not have proper Unicode bidi support, such as certain terminals. As detailed in W3C Visual vs. logical ordering of text, visual ordering should never be used for HTML. The
hebrevc() function is an explicit violation of this principle.
hebrevc() as deprecated.
convert_cyr_string() function allows conversion between Cyrillic character sets. The character sets are specified using obscure single character names, such as
convert_cyr_string($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
UConverter may be used for this purpose.
convert_cyr_string() as deprecated.
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
strfmon() implementation seems to have an internal buffer overrun on macos, which indicates that this functionality is not well tested.
money_format() as deprecated.
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.
ezmlm_hash() as deprecated.
This function is essentially an “alias” of doing
ini_restore('include_path'). Unlike other functions like
restore_exception_handler(), this function does not operate on a stack and always resets to the original/initial value. While you can use
restore_error_handler() as a pair, doing the same with
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.
restore_include_path() as deprecated.
allow_url_include ini directive (disabled by default) allows the
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.
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 assumptions
dl()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 if
dl()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_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 also
apache_response_headers()defined by non-Apache SAPIs, which does not have a SAPI-agnostic alias. There are also more SAPI-specific functions like
litespeed_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.