Index: wp-includes/post.php
===================================================================
--- wp-includes/post.php	(revision 41471)
+++ wp-includes/post.php	(working copy)
@@ -2596,6 +2596,19 @@
 		return false;
 
 	/**
+	 * Filters whether trashing a post should take place.
+	 *
+	 * @since 4.8.2
+	 *
+	 * @param bool    $trash        Whether to go forward with trashing.
+	 * @param WP_Post $post         Post object.
+	 */
+	$check = apply_filters( 'pre_trash_post', null, $post );
+	if ( null !== $check ) {
+		return $check;
+	}
+
+	/**
 	 * Fires before a post is sent to the trash.
 	 *
 	 * @since 3.3.0