Revert "Revert "Comment template: Call comment_class() before recur…

…sing into child comments (#40455)""

This reverts commit 922abd3.

packages/block-library/src/comment-template/index.php

@@ -8,6 +8,8 @@
 /**
  * Function that recursively renders a list of nested comments.
  *
+ * @global int $comment_depth
+ *
  * @param WP_Comment[] $comments The array of comments.
  * @param WP_Block $block Block instance.
  * @return string
@@ -31,6 +33,17 @@ function block_core_comment_template_render_comments( $comments, $block ) {
 
  $children = $comment->get_children();
 
+ /*
+ * We need to create the CSS classes BEFORE recursing into the children.
+ * This is because comment_class() uses globals like `$comment_alt`
+ * and `$comment_thread_alt` which are order-sensitive.
+ *
+ * The `false` parameter at the end means that we do NOT want the function
+ * to `echo` the output but to return a string.
+ * See https://developer.wordpress.org/reference/functions/comment_class/#parameters.
+ */
+ $comment_classes = comment_class( '', $comment->comment_ID, $comment->comment_post_ID, false );
+
  // If the comment has children, recurse to create the HTML for the nested
  // comments.
  if ( ! empty( $children ) ) {
@@ -43,10 +56,6 @@ function block_core_comment_template_render_comments( $comments, $block ) {
  $comment_depth -= 1;
  }
 
- // The `false` parameter at the end means that we do NOT want the function to `echo` the output but to return a string.
- // See https://developer.wordpress.org/reference/functions/comment_class/#parameters.
- $comment_classes = comment_class( '', $comment->comment_ID, $comment->comment_post_ID, false );
-
  $content .= sprintf( '<li id="comment-%1$s" %2$s>%3$s</li>', $comment->comment_ID, $comment_classes, $block_content );
  }