Options, Meta APIs: Add a new pre-option filter.

Although a `pre_option_{$option}` filter already exists, this change adds a more general `pre_option` filter that will run on every `get_option` call.  This brings the control flow into similar flow as `update_option`.

Props flixos90, NathanAtmoz, desrosj, spacedmonkey, pbearne.
Fixes #37930.

git-svn-id: https://develop.svn.wordpress.org/trunk@54145 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-includes/option.php

@@ -131,6 +131,24 @@ function get_option( $option, $default = false ) {
 	 */
 	$pre = apply_filters( "pre_option_{$option}", false, $option, $default );
 
+	/**
+	 * Filters the value of all existing options before it is retrieved.
+	 *
+	 * Returning a truthy value from the filter will effectively short-circuit retrieval
+	 * and return the passed value instead.
+	 *
+	 * @since 6.1.0
+	 *
+	 * @param mixed  $pre_option  The value to return instead of the option value. This differs
+	 *                            from `$default`, which is used as the fallback value in the event
+	 *                            the option doesn't exist elsewhere in get_option().
+	 *                            Default false (to skip past the short-circuit).
+	 * @param string $option      Name of the option.
+	 * @param mixed  $default     The fallback value to return if the option does not exist.
+	 *                            Default false.
+	 */
+	$pre = apply_filters( 'pre_option', $pre, $option, $default );
+
 	if ( false !== $pre ) {
 		return $pre;
 	}

tests/phpunit/tests/option/option.php

@@ -297,4 +297,19 @@ class Tests_Option_Option extends WP_UnitTestCase {
 			array( 'autoload_false', false, 'no' ),
 		);
 	}
+
+	/**
+	 * @ticket 37930
+	 *
+	 * @covers ::get_option
+	 */
+	public function test_filter_pre_option_all_filter_is_called() {
+		$filter = new MockAction();
+
+		add_filter( 'pre_option', array( $filter, 'filter' ) );
+
+		get_option( 'ignored' );
+
+		$this->assertSame( 1, $filter->get_call_count() );
+	}
 }