Ticket #5985: 5985.diff.1

Index: sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg-photos/template-parts/photo-single.php
===================================================================
--- sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg-photos/template-parts/photo-single.php    (revision 11597)
+++ sites/trunk/wordpress.org/public_html/wp-content/themes/pub/wporg-photos/template-parts/photo-single.php    (working copy)
@@ -55,13 +55,16 @@
        </header><!-- .entry-header -->
 
        <div class="entry-content">
+               <?php
+               $caption = get_the_content();
+               $image_alt = ( $caption ? wp_strip_all_tags( $caption, true ) : __( 'No image caption provided', 'wporg-photos' ) );
+               ?>
                <figure>
                        <a href="<?php echo wp_get_attachment_url( get_post_thumbnail_id() ); ?>">
-                               <img class="grid-photo" src="<?php echo get_the_post_thumbnail_url( get_the_ID(), 'medium'); ?>" srcset="<?php echo esc_attr( wp_get_attachment_image_srcset( get_post_thumbnail_id() ) ); ?>">
+                               <img class="grid-photo" src="<?php echo get_the_post_thumbnail_url( get_the_ID(), 'medium'); ?>" srcset="<?php echo esc_attr( wp_get_attachment_image_srcset( get_post_thumbnail_id() ) ); ?>" alt="<?php echo esc_attr( $image_alt ); ?>">
                        </a>
 
                        <?php
-                       $caption = get_the_content();
                        if ( $caption ) {
                        ?>