Issue 7461 - Include source page into warning text for unresolved links

cms/sources.py

 # This file is part of the Adblock Plus web scripts,
 # Copyright (C) 2006-present eyeo GmbH
 #
 # Adblock Plus is free software: you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 3 as
 # published by the Free Software Foundation.
 #
 # Adblock Plus is distributed in the hope that it will be useful,
 # but WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 # GNU General Public License for more details.
 #
 # You should have received a copy of the GNU General Public License
 # along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
 
 import io
 import collections
 import ConfigParser
 import json
 import os
 from StringIO import StringIO
 from random import randint
 import urlparse
 import logging
 
 from cms import utils
 
 
 class Source:
-    def resolve_link(self, url, locale):
+    def resolve_link(self, url, locale, source_page=None):
         parsed = urlparse.urlparse(url)
         page = parsed.path
         if parsed.scheme != '' or page.startswith('/') or page.startswith('.'):
             # Not a page link
             return None, None
 
         if url.startswith('tel:'):
             # Workaround for 'tel' scheme not recognized in Python <=2.7.3.
             return None, None
 
@@ skipping 11 matching lines @@
                 locale = default_locale
         elif self.has_page(page):
             if not self.has_locale(locale, page):
                 locale = default_locale
         elif self.has_page(alternative_page):
             if not self.has_locale(locale, alternative_page):
                 locale = default_locale
         elif self.has_static(page):
             locale = None
         else:
-            logging.warning('Link to %s cannot be resolved', page)
+            logging.warning('Link to "%s" (from "%s") cannot be resolved',
+                            page, source_page)
 
         parts = page.split('/')
         if parts[-1] == default_page:
             page = '/'.join(parts[:-1])
         if locale:
             path = '/{}/{}'.format(locale, page)
             return locale, urlparse.urlunparse(parsed[0:2] + (path,) + parsed[3:])
         return locale, '/' + page
 
     def read_config(self):
@@ skipping 326 matching lines @@
             'read_config',
             'read_template',
             'read_locale',
             'read_file',
             'read_include',
             'exec_file',
         ]:
             setattr(source, fname, utils.memoize(getattr(source, fname)))
 
     return source