From 6dab53e93bb948a59e48b5856208946d9ee83e74 Mon Sep 17 00:00:00 2001
From: Tonya Mork <hellofromtonya@git.wordpress.org>
Date: Tue, 3 May 2022 14:31:12 +0000
Subject: [PATCH] Editor: Sets 'paged' query arg only when there are comments:
 `build_comment_query_vars_from_block()`.

A SQL syntax error happened when a post has no comments and "Break comments into pages" is checked in Settings > Discussion. The fix sets the `'paged'` query arg only when there are comments. When there are no comments, `WP_Comment_Query` sets the default `'paged'` value to `1`.

Props bernhard-reiter, luisherranz, czapla, cbravobernal, davidbaumwald, hellofromTonya.

Follow-up to [53142], [53138].
Fixes #55658.

git-svn-id: https://develop.svn.wordpress.org/trunk@53336 602fd350-edb4-49c9-b593-d223f7449a82
---
 src/wp-includes/blocks.php                    |  5 +-
 .../tests/blocks/renderCommentTemplate.php    | 56 +++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/blocks.php b/src/wp-includes/blocks.php
index adaf1ae255..9df70abaf4 100644
--- a/src/wp-includes/blocks.php
+++ b/src/wp-includes/blocks.php
@@ -1325,7 +1325,10 @@ function build_comment_query_vars_from_block( $block ) {
 			} elseif ( 'oldest' === $default_page ) {
 				$comment_args['paged'] = 1;
 			} elseif ( 'newest' === $default_page ) {
-				$comment_args['paged'] = (int) ( new WP_Comment_Query( $comment_args ) )->max_num_pages;
+				$max_num_pages = (int) ( new WP_Comment_Query( $comment_args ) )->max_num_pages;
+				if ( 0 !== $max_num_pages ) {
+					$comment_args['paged'] = $max_num_pages;
+				}
 			}
 			// Set the `cpage` query var to ensure the previous and next pagination links are correct
 			// when inheriting the Discussion Settings.
diff --git a/tests/phpunit/tests/blocks/renderCommentTemplate.php b/tests/phpunit/tests/blocks/renderCommentTemplate.php
index 8f70fff000..4199537f0c 100644
--- a/tests/phpunit/tests/blocks/renderCommentTemplate.php
+++ b/tests/phpunit/tests/blocks/renderCommentTemplate.php
@@ -137,6 +137,62 @@ class Tests_Blocks_RenderReusableCommentTemplate extends WP_UnitTestCase {
 		);
 	}
 
+	/**
+	 * Test that if pagination is set to display the last page by default (i.e. newest comments),
+	 * the query is set to look for page 1 (rather than page 0, which would cause an error).
+	 *
+	 * Regression: https://github.com/WordPress/gutenberg/issues/40758.
+	 *
+	 * @ticket 55658
+	 * @covers ::build_comment_query_vars_from_block
+	 */
+	function test_build_comment_query_vars_from_block_pagination_with_no_comments() {
+		$comments_per_page     = get_option( 'comments_per_page' );
+		$default_comments_page = get_option( 'default_comments_page' );
+
+		update_option( 'comments_per_page', 50 );
+		update_option( 'previous_default_page', 'newest' );
+
+		$post_without_comments = self::factory()->post->create_and_get(
+			array(
+				'post_type'    => 'post',
+				'post_status'  => 'publish',
+				'post_name'    => 'fluffycat',
+				'post_title'   => 'Fluffy Cat',
+				'post_content' => 'Fluffy Cat content',
+				'post_excerpt' => 'Fluffy Cat',
+			)
+		);
+
+		$parsed_blocks = parse_blocks(
+			'<!-- wp:comment-template --><!-- wp:comment-author-name /--><!-- wp:comment-content /--><!-- /wp:comment-template -->'
+		);
+
+		$block = new WP_Block(
+			$parsed_blocks[0],
+			array(
+				'postId' => $post_without_comments->ID,
+			)
+		);
+
+		$this->assertSameSetsWithIndex(
+			array(
+				'orderby'       => 'comment_date_gmt',
+				'order'         => 'ASC',
+				'status'        => 'approve',
+				'no_found_rows' => false,
+				'post_id'       => $post_without_comments->ID,
+				'hierarchical'  => 'threaded',
+				'number'        => 50,
+			),
+			build_comment_query_vars_from_block( $block )
+		);
+
+		update_option( 'comments_per_page', $comments_per_page );
+		update_option( 'default_comments_page', $default_comments_page );
+	}
+
+
 	/**
 	 * Test that both "Older Comments" and "Newer Comments" are displayed in the correct order
 	 * inside the Comment Query Loop when we enable pagination on Discussion Settings.