diff -r c7c34916027a -r 177826044cd9 wp/wp-includes/blocks/latest-comments.php
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/wp/wp-includes/blocks/latest-comments.php	Mon Oct 14 18:28:13 2019 +0200
@@ -0,0 +1,185 @@
+<?php
+/**
+ * Server-side rendering of the `core/latest-comments` block.
+ *
+ * @package WordPress
+ */
+
+/**
+ * Get the post title.
+ *
+ * The post title is fetched and if it is blank then a default string is
+ * returned.
+ *
+ * Copied from `wp-admin/includes/template.php`, but we can't include that
+ * file because:
+ *
+ * 1. It causes bugs with test fixture generation and strange Docker 255 error
+ *    codes.
+ * 2. It's in the admin; ideally we *shouldn't* be including files from the
+ *    admin for a block's output. It's a very small/simple function as well,
+ *    so duplicating it isn't too terrible.
+ *
+ * @since 3.3.0
+ *
+ * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global $post.
+ * @return string The post title if set; "(no title)" if no title is set.
+ */
+function wp_latest_comments_draft_or_post_title( $post = 0 ) {
+	$title = get_the_title( $post );
+	if ( empty( $title ) ) {
+		$title = __( '(no title)' );
+	}
+	return esc_html( $title );
+}
+
+/**
+ * Renders the `core/latest-comments` block on server.
+ *
+ * @param array $attributes The block attributes.
+ *
+ * @return string Returns the post content with latest comments added.
+ */
+function render_block_core_latest_comments( $attributes = array() ) {
+	// This filter is documented in wp-includes/widgets/class-wp-widget-recent-comments.php.
+	$comments = get_comments(
+		apply_filters(
+			'widget_comments_args',
+			array(
+				'number'      => $attributes['commentsToShow'],
+				'status'      => 'approve',
+				'post_status' => 'publish',
+			)
+		)
+	);
+
+	$list_items_markup = '';
+	if ( ! empty( $comments ) ) {
+		// Prime the cache for associated posts. This is copied from \WP_Widget_Recent_Comments::widget().
+		$post_ids = array_unique( wp_list_pluck( $comments, 'comment_post_ID' ) );
+		_prime_post_caches( $post_ids, strpos( get_option( 'permalink_structure' ), '%category%' ), false );
+
+		foreach ( $comments as $comment ) {
+			$list_items_markup .= '<li class="wp-block-latest-comments__comment">';
+			if ( $attributes['displayAvatar'] ) {
+				$avatar = get_avatar(
+					$comment,
+					48,
+					'',
+					'',
+					array(
+						'class' => 'wp-block-latest-comments__comment-avatar',
+					)
+				);
+				if ( $avatar ) {
+					$list_items_markup .= $avatar;
+				}
+			}
+
+			$list_items_markup .= '<article>';
+			$list_items_markup .= '<footer class="wp-block-latest-comments__comment-meta">';
+			$author_url         = get_comment_author_url( $comment );
+			if ( empty( $author_url ) && ! empty( $comment->user_id ) ) {
+				$author_url = get_author_posts_url( $comment->user_id );
+			}
+
+			$author_markup = '';
+			if ( $author_url ) {
+				$author_markup .= '<a class="wp-block-latest-comments__comment-author" href="' . esc_url( $author_url ) . '">' . get_comment_author( $comment ) . '</a>';
+			} else {
+				$author_markup .= '<span class="wp-block-latest-comments__comment-author">' . get_comment_author( $comment ) . '</span>';
+			}
+
+			// `_draft_or_post_title` calls `esc_html()` so we don't need to wrap that call in
+			// `esc_html`.
+			$post_title = '<a class="wp-block-latest-comments__comment-link" href="' . esc_url( get_comment_link( $comment ) ) . '">' . wp_latest_comments_draft_or_post_title( $comment->comment_post_ID ) . '</a>';
+
+			$list_items_markup .= sprintf(
+				/* translators: 1: author name (inside <a> or <span> tag, based on if they have a URL), 2: post title related to this comment */
+				__( '%1$s on %2$s' ),
+				$author_markup,
+				$post_title
+			);
+
+			if ( $attributes['displayDate'] ) {
+				$list_items_markup .= sprintf(
+					'<time datetime="%1$s" class="wp-block-latest-comments__comment-date">%2$s</time>',
+					esc_attr( get_comment_date( 'c', $comment ) ),
+					date_i18n( get_option( 'date_format' ), get_comment_date( 'U', $comment ) )
+				);
+			}
+			$list_items_markup .= '</footer>';
+			if ( $attributes['displayExcerpt'] ) {
+				$list_items_markup .= '<div class="wp-block-latest-comments__comment-excerpt">' . wpautop( get_comment_excerpt( $comment ) ) . '</div>';
+			}
+			$list_items_markup .= '</article></li>';
+		}
+	}
+
+	$class = 'wp-block-latest-comments';
+	if ( ! empty( $attributes['className'] ) ) {
+		$class .= ' ' . $attributes['className'];
+	}
+	if ( isset( $attributes['align'] ) ) {
+		$class .= " align{$attributes['align']}";
+	}
+	if ( $attributes['displayAvatar'] ) {
+		$class .= ' has-avatars';
+	}
+	if ( $attributes['displayDate'] ) {
+		$class .= ' has-dates';
+	}
+	if ( $attributes['displayExcerpt'] ) {
+		$class .= ' has-excerpts';
+	}
+	if ( empty( $comments ) ) {
+		$class .= ' no-comments';
+	}
+	$classnames = esc_attr( $class );
+
+	$block_content = ! empty( $comments ) ? sprintf(
+		'<ol class="%1$s">%2$s</ol>',
+		$classnames,
+		$list_items_markup
+	) : sprintf(
+		'<div class="%1$s">%2$s</div>',
+		$classnames,
+		__( 'No comments to show.' )
+	);
+
+	return $block_content;
+}
+
+register_block_type(
+	'core/latest-comments',
+	array(
+		'attributes'      => array(
+			'align'          => array(
+				'type' => 'string',
+				'enum' => array( 'left', 'center', 'right', 'wide', 'full' ),
+			),
+			'className'      => array(
+				'type' => 'string',
+			),
+			'commentsToShow' => array(
+				'type'    => 'number',
+				'default' => 5,
+				'minimum' => 1,
+				'maximum' => 100,
+			),
+			'displayAvatar'  => array(
+				'type'    => 'boolean',
+				'default' => true,
+			),
+			'displayDate'    => array(
+				'type'    => 'boolean',
+				'default' => true,
+			),
+			'displayExcerpt' => array(
+				'type'    => 'boolean',
+				'default' => true,
+			),
+		),
+		'render_callback' => 'render_block_core_latest_comments',
+	)
+);