wp_shortlink_wp_head should exit on non-singles and frontpage

[andrejcremoznik]

There is no need for shortlinks on archives and front page.

The default function which outputs shortlink markup should check if the displayed content is a single post or page but not a static front page before outputting anything.

This is what I use instead of the default wp_shortlink_wp_head.

function print_shortlink() {
    $shortlink = wp_get_shortlink(0, 'query');
    if (empty($shortlink) || is_front_page() || (!is_single() && !is_page()))
      return;
    echo "<link rel='shortlink' href='" . esc_url($shortlink) . "'>\n";
  }
}

[swissspidy]

The return value of wp_get_shortlink() can be filtered. It's possible that someone's creating a shortlink for archives and other areas. If not, that function returns an empty string, which wp_shortlink_wp_head() checks for. This behaviour shouldn't be changed, otherwise it would break BC.