Customize: Introduce a fix for themes that pass a stringable object through the template_include filter despite it being documented as only accepting a string.

This has historically worked until [61892] increased the strictness of the template file validation which dismissed any value of a type other than a string, which a stringable object is not.

Merges r61913 to the 6.4 branch.
Props dmsnell, westonruter.


git-svn-id: https://develop.svn.wordpress.org/branches/6.4@61926 602fd350-edb4-49c9-b593-d223f7449a82

Author: peterwilsoncc

src/wp-includes/template-loader.php

@@ -101,8 +101,9 @@
 	 *
 	 * @param string $template The path of the template to include.
 	 */
-	$template = apply_filters( 'template_include', $template );
-	$template = is_string( $template ) ? realpath( $template ) : null;
+	$template   = apply_filters( 'template_include', $template );
+	$is_stringy = is_string( $template ) || ( is_object( $template ) && method_exists( $template, '__toString' ) );
+	$template   = $is_stringy ? realpath( (string) $template ) : null;
 	if (
 		is_string( $template ) &&
 		( str_ends_with( $template, '.php' ) || str_ends_with( $template, '.html' ) ) &&