Make sure path link in footers work correctly (#1508)

Fixes #1498

Author: st0012

lib/rdoc/generator/aliki.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'uri'
+
 ##
 # Aliki theme for RDoc documentation
 #
@@ -115,6 +117,21 @@ def write_search_index
     File.write search_index_path, "var search_data = #{JSON.generate(data)};"
   end
 
+  ##
+  # Resolves a URL for use in templates. Absolute URLs are returned unchanged.
+  # Relative URLs are prefixed with rel_prefix to ensure they resolve correctly from any page.
+
+  def resolve_url(rel_prefix, url)
+    uri = URI.parse(url)
+    if uri.absolute?
+      url
+    else
+      "#{rel_prefix}/#{url}"
+    end
+  rescue URI::InvalidURIError
+    "#{rel_prefix}/#{url}"
+  end
+
   private
 
   def build_class_module_entry(klass)

lib/rdoc/generator/template/aliki/_footer.rhtml

@@ -6,7 +6,7 @@
       <h3><%= h column_title %></h3>
       <ul>
         <% links.each do |text, url| %>
-        <li><a href="<%= h url %>"><%= h text %></a></li>
+        <li><a href="<%= h resolve_url(rel_prefix, url) %>"><%= h text %></a></li>
         <% end %>
       </ul>
     </div>