====== 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 ''real'' type
  * Magic quotes legacy
  * ''array_key_exists()'' with objects
  * ''FILTER_SANITIZE_MAGIC_QUOTES'' filter
  * Reflection ''export()'' methods
  * ''mb_strrpos()'' with encoding as 3rd argument
  * ''implode()'' parameter order mix
  * Unbinding ''$this'' from non-static closures
  * ''hebrevc()'' function
  * ''convert_cyr_string()'' function
  * ''money_format()'' function
  * ''ezmlm_hash()'' function
  * ''restore_include_path()'' function
  * ''allow_url_include'' ini 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.

<doodle title="Deprecate (real) cast and is_real() function?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate get_magic_quotes_gpc() and get_magic_quotes_runtime()?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== array_key_exists() with objects ====

The documentation already marks the use of array_key_exists() with objects as legacy behavior:

<blockquote>
For backward compatibility reasons, array_key_exists() will also return TRUE if ''key'' is a property defined within an object given as ''array''. This behaviour should not be relied upon, and care should be taken to ensure that ''array'' is an array. To check whether a property exists in an object, use ''property_exists()''. 
</blockquote>

''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()''.

<doodle title="Deprecate array_key_exists() with objects?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate FILTER_SANITIZE_MAGIC_QUOTES?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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:

<code php>
ReflectionFunction::export('foo');
// same as
echo new ReflectionFunction('foo'), "\n";

$str = ReflectionFunction::export('foo', true);
// same as
$str = (string) new ReflectionFunction('foo');
</code>

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.

<doodle title="Deprecate Reflection export() methods?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== mb_strrpos() with encoding as 3rd argument ====

The documentation for ''mb_strrpos()'' states:

<blockquote>
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.
</blockquote>

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.

<doodle title="Deprecate mb_strrpos() with encoding as 3rd argument?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate implode() with inverted parameter order?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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''.

<doodle title="Deprecate unbinding of $this from non-static closures?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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 [[https://www.w3.org/International/questions/qa-visual-vs-logical|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.

<doodle title="Deprecate hebrevc() function?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate convert_cyr_string() function?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate money_format() function?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate ezmlm_hash() function?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate restore_include_path() function?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>

==== 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.

<doodle title="Deprecate allow_url_include ini option?" auth="nikic" voteType="single" closed="true">
   * Yes
   * No
</doodle>


===== 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 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_SESSION'' and ''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_request_headers()'' and ''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.