====== PHP RFC: Always available JSON extension ======
  * Version: 0.3
  * Date: 2020-04-29
  * Author: Tyson Andre <tandre@php.net>
  * Status: Implemented
  * Target version: PHP 8.0
  * Implementation: https://github.com/php/php-src/pull/5495
  * First Published at: https://wiki.php.net/rfc/always_enable_json

===== Introduction =====

Currently, it's possible to disable the json extension with ''./configure %%--%%disable-json''.
However, JSON is extremely useful to have because it's widely used for many use cases (web sites, logging output,
and as a data format that can be used to share data with many applications
and programming languages), so it would be useful for PHP maintainers and users to guarantee that ''json'' is always enabled.


Examples of where this would be useful:

  * Allowing internal classes to implement ''JsonSerializable'', which currently requires a hard dependency on the JSON extension. \\ (e.g. ''DateTime'' already has custom JSON serialization behavior, but is unable to implement ''JsonSerializable'' because that interface doesn't always exist.)

  * Allowing PHP users to publish single-file scripts that use json_encode and json_decode and don't require polyfills or less readable var_export output. \\   (polyfills are less efficient and may have issues with recursive data structures)

  * Letting php-src's own modules, tools and ''.phpt'' test cases start using JSON if it's a good choice for representing a value. (same for PECLs)

The reasons for allowing JSON to be disabled appear to be historical, and no longer apply. https://wiki.php.net/rfc/jsond mentions that:

> The current Json Parser (for PHP 5) in the json extension does not have a free license
> which is a problem for many Linux distros.
> This has been referenced at Bug #63520.
> That results in not packaging json extension in the many Linux distributions.

Starting in php 7.0 with the switch to jsond, it looks like licensing is no longer an issue.

Extensions have been made always-on by default. For example, e.g. https://wiki.php.net/rfc/permanent_hash_ext did this for the ''hash'' extension.

===== Proposal =====

Make it impossible to disable the JSON extension through configuration or build options. Require that JSON be built statically instead of as a shared library.

===== Backward Incompatible Changes =====

Build configurations that contain ''%%--%%enable-json'' or ''%%--%%disable-json'' will have to be updated, as the argument will cease to exist.

Because JSON would always be built statically to guarantee it can be used, package maintainers for OSes such as Fedora would need to create stub packages for the ''php-json'' package, or to remove the package in php 8 (or mark it as provided by the core ''php'' package).

Some other installations already use JSON statically by default (e.g. the zips published on windows.php.net, or the default when building php from source)

===== Proposed PHP Version(s) =====

8.0

===== RFC Impact =====
==== To SAPIs and Existing Extensions ====

PECL extensions can now always rely on the ''json'' extension to be available and use its API and PHP interfaces such as ''JsonSerializable''.

Minimal builds of PHP will slightly grow in size.

===== Unaffected PHP Functionality =====

Any already existing userland code will continue to work as before. Userland code may remove calls to ''extension_loaded('json')'' as they will now always return ''true''.

The ''json'' extension does not have any external dependencies, so this will not add any more dependencies for a minimal build of PHP.

===== Future Scope =====

  * Make internal classes that already have custom JSON serialization behavior (''ZEND_PROP_PURPOSE_JSON'' in property array getters) start implementing ''JsonSerializable'', and add implementations of jsonSerialize() returning arrays (e.g. for ''DateTime'', ''DateTimeZone'', ''DateTimeImmutable'', ''DateTimeZone''. (Changing ''ArrayObject'' wouldn't make sense, because php users rely on php serializing those with object syntax (e.g. ''{}'' instead of ''[]'')))

  * Start using JSON in more places within PHP's own functions. For example, adding additional conversion specifiers for ''printf()'' such as ''%j'' or ''%v'' to PHP to call JSON with the default options.

  * Add alternative options to use JSON to dump debug output in an easily machine-readable form. (e.g. ''opcache.opt_debug_level'' debug output is plaintext right now)

===== Vote =====

Voting started 2020-05-13 and ends 2020-05-27.

<doodle title="Make the JSON extension impossible to disable" auth="tandre" voteType="single" closed="true">
   * Yes
   * No
</doodle>

===== Changelog =====

0.3: Keep the HAVE_JSON constant in config.m4, to avoid a backwards compatibility break.

===== References =====

https://externals.io/message/109783 "Moving json extension to core?"

https://wiki.php.net/rfc/jsond

https://wiki.php.net/rfc/permanent_hash_ext