Options, Meta APIs: Check setting group exists before search in unreg…

…ister_setting().

Checks if the given `$option_group` exists before searching for the `$option_name`. Sets the `$pos` to `false`, as `array_search()` returns `false` if the option name (needle) does not exist.

This changeset fixes 2 different PHP Warning|Notice scenarios:
1. When the global `$new_allowed_options` is `null`, fixes raising `Trying to access array offset on value of type null` PHP Notice (PHP 7.4) | Warning (on PHP 8).

2. When the global `$new_allowed_options` is an `array` and the setting group key does not exist, fixes raising "Undefined index: unknown_setting_group" PHP Notice (PHP 7) | Warning (on PHP 8).

For both scenarios, the `array_search()` is skipped and the `$pos` is set to a default of `false`, i.e. which is the value returned when `array_search()` is unsuccessful.

Props xknown, hellofromTonya, nicolefurlan, oglekler, SergeyBiryukov, shailu25.
Fixes #57674.

git-svn-id: https://develop.svn.wordpress.org/trunk@56817 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/option.php

@@ -2903,7 +2903,10 @@ function unregister_setting( $option_group, $option_name, $deprecated = '' ) {
 		$option_group = 'reading';
 	}
 
-	$pos = array_search( $option_name, (array) $new_allowed_options[ $option_group ], true );
+	$pos = false;
+	if ( isset( $new_allowed_options[ $option_group ] ) ) {
+		$pos = array_search( $option_name, (array) $new_allowed_options[ $option_group ], true );
+	}
 
 	if ( false !== $pos ) {
 		unset( $new_allowed_options[ $option_group ][ $pos ] );

tests/phpunit/tests/option/registration.php

@@ -149,4 +149,18 @@ public function test_unregister_setting_removes_default() {
 
 		$this->assertFalse( has_filter( 'default_option_test_default', 'filter_default_option' ) );
 	}
+
+	/**
+	 * The test passes if a Notice | Warning | Error is not raised. Thus. the absence of a Notice | Warning | Error
+	 * is an indicator the fix in the ticket resolves the issue.
+	 *
+	 * @ticket 57674
+	 *
+	 * @covers ::unregister_setting
+	 */
+	public function test_unregister_invalid_setting_does_not_raise_php_notice_warning_or_error() {
+		$setting = uniqid();
+		unregister_setting( $setting, $setting );
+		$this->assertFalse( has_filter( 'default_option_' . $setting, 'filter_default_option' ) );
+	}
 }