[RFC] Always enable JSON support in php 8.0

Currently, it's possible to disable the json extension with
`./configure --disable-json` (for historical reasons that no longer apply).
However, JSON is widely used in 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 I'd personally find it useful if it was always enabled.

Examples of where this would be useful:

- For internal classes to be able to implement `JsonSerializable`
  which currently requires a hard dependency on the JSON extension.
- For 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)
- So that php-src's own modules, tools and test cases can start using JSON
  if it's a good choice for encoding a value. (same for PECLs)

https://wiki.php.net/rfc/jsond mentions that in PHP 5,

> The current Json Parser 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.

Changes:

- Remove all flags related to JSON such as `configure --disable-json`
- Require that JSON be compiled statically instead of as a shared library

Examples of uses of JSON in various distros
(backwards incompatible changes such as changing packaging are typically
reserved for major versions, and 8.0 is a major version)

- JSON is required by `php-cli` or `php` in ubuntu:
  https://packages.ubuntu.com/focal/php/
- The php-json package has to be installed separately
  from the PHP binary in Fedora repos.

Closes GH-5495

1 files changed, 4 insertions, 0 deletions

diff --git a/UPGRADING b/UPGRADING
index 81b945d204..cca70bcfee 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -698,6 +698,10 @@ PHP 8.0 UPGRADE NOTES
   . The function imagegetinterpolation() to get the current interpolation method
     has been added.
 
+- JSON:
+  . The JSON extension cannot be disabled anymore and is always an integral part
+    of any PHP build, similar to the date extension.
+
 - MBString:
   . The Unicode data tables have been updated to version 13.0.0.