Deprecate wp_unregister_GLOBALS()

[desrosj]

register_globals was ​deprecated in PHP 5.3.0 and removed in 5.4.0. Since Core now supports PHP >= 5.6.20, this can probably be deprecated.

The first line of wp_unregister_GLOBALS() checks if ( ! ini_get( 'register_globals' ) ) and returns early. ini_get() returns false if the option is not set, so this function is probably dead code.

Follow up ticket to #46152, #49922.

[desrosj]

What's not clear to me is whether an .ini configuration will apply if PHP does not support the option. If it does, then deprecating will be more difficult. However, this is something that has not been supported for some time, and modifying Super globals should be discouraged.

[ayeshrajans]

If a user-land ini_set() call tries to set a PHP configuration value that's not recognized (which the case for register_globals), its value will not "stick".

For example:

var_dump(ini_set('register_globals', 'on'));
var_dump(ini_get('register_globals'));

Both of these will return false because register_globals is not registered as a value.

[ayeshrajans]

Attaching a atch that removes the call to this function, moves it the deprecated functions file, and emits a deprecation notice. It also removes the dead code that would never run in PHP versions beyond PHP 5.4.

Trac ticket: https://core.trac.wordpress.org/ticket/49938

[desrosj]

Thanks for confirming @ayeshrajans! You beat me to testing. I created a PR to ensure the build passes (which it does). I am also marking this early. While it does not appear there would be any consequences of deprecating this function, I'd rather land it early because it affects the loading process just in case.

[desrosj]

In 47612:

Bootstrap/Load: Deprecate wp_unregister_GLOBALS().

The register_globals directive in PHP was deprecated in version 5.3 and removed entirely in 5.4.

Now that WordPress only supports PHP 5.6.20 and newer, the wp_unregister_GLOBALS() function can be deprecated.

Props ayeshrajans, desrosj, SergeyBiryukov.
Fixes #49938.

This was merged into core in https://core.trac.wordpress.org/changeset/47612.

[desrosj]

Going to note this in a PHP improvements dev note.

[desrosj]

Referenced in the following dev note: ​https://make.wordpress.org/core/2020/07/14/php-related-improvements-changes-wordpress-5-5-edition/.