Revisions: Add a way to filter the revisions considered for deletion.

This changeset introduces a new filter for `wp_save_post_revision()`. `wp_save_post_revision_revisions_before_deletion` passes the revisions to be considered for deletion, and the new revision's post ID.

This allows extenders to exclude specific revisions from being considered for deletion.

Props jhned, costdev, audrasjb, adamsilverstein, mukesh27.
Fixes #57320.

Built from https://develop.svn.wordpress.org/trunk@55254


git-svn-id: http://core.svn.wordpress.org/trunk@54787 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/revision.php

@@ -200,6 +200,35 @@ function wp_save_post_revision( $post_id ) {
 
 	$revisions = wp_get_post_revisions( $post_id, array( 'order' => 'ASC' ) );
 
+	/**
+	 * Filters the revisions to be considered for deletion.
+	 *
+	 * @since 6.2.0
+	 *
+	 * @param WP_Post[]|int[] $revisions Array of revision objects or IDs,
+	 *                                   or an empty array if none.
+	 * @param int             $post_id   The ID of the post to save as a revision.
+	 */
+	$filtered_revisions = apply_filters(
+		'wp_save_post_revision_revisions_before_deletion',
+		$revisions,
+		$post_id
+	);
+
+	if ( is_array( $filtered_revisions ) ) {
+		$revisions = $filtered_revisions;
+	} else {
+		_doing_it_wrong(
+			__FUNCTION__,
+			sprintf(
+				/* translators: %s: The filter name. */
+				__( 'The "%s" filter should return an array.' ),
+				'wp_save_post_revision_revisions_before_deletion'
+			),
+			'6.2.0'
+		);
+	}
+
 	$delete = count( $revisions ) - $revisions_to_keep;
 
 	if ( $delete < 1 ) {

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-alpha-55253';
+$wp_version = '6.2-alpha-55254';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.