From 76b9992384e972acbd5d853dfb490c91345413ee Mon Sep 17 00:00:00 2001
From: Takeshi KOMIYA <i.tkomiya@gmail.com>
Date: Tue, 7 Jun 2016 11:02:07 +0900
Subject: [PATCH] Fix #2633: Sphinx crashes with old styled indices

---
 CHANGES              |  1 +
 sphinx/io.py         |  4 ++--
 sphinx/transforms.py | 18 ++++++++++++++++++
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/CHANGES b/CHANGES
index 1e5295cb1..f28b98652 100644
--- a/CHANGES
+++ b/CHANGES
@@ -6,6 +6,7 @@ Bugs fixed
 
 * #2630: Latex sphinx.sty Notice Enviroment formatting problem
 * #2632: Warning directives fail in quote environment latex build
+* #2633: Sphinx crashes with old styled indices
 
 
 Release 1.4.3 (released Jun 5, 2016)
diff --git a/sphinx/io.py b/sphinx/io.py
index 8d9970e80..56d133641 100644
--- a/sphinx/io.py
+++ b/sphinx/io.py
@@ -15,7 +15,7 @@ from six import string_types, text_type
 
 from sphinx.transforms import ApplySourceWorkaround, ExtraTranslatableNodes, Locale, \
     CitationReferences, DefaultSubstitutions, MoveModuleTargets, HandleCodeBlocks, \
-    AutoNumbering, SortIds, RemoveTranslatableInline
+    AutoNumbering, AutoIndexUpgrader, SortIds, RemoveTranslatableInline
 from sphinx.util import import_object, split_docinfo
 
 
@@ -59,7 +59,7 @@ class SphinxStandaloneReader(SphinxBaseReader):
     """
     transforms = [ApplySourceWorkaround, ExtraTranslatableNodes, Locale, CitationReferences,
                   DefaultSubstitutions, MoveModuleTargets, HandleCodeBlocks,
-                  AutoNumbering, SortIds, RemoveTranslatableInline]
+                  AutoNumbering, AutoIndexUpgrader, SortIds, RemoveTranslatableInline]
 
 
 class SphinxI18nReader(SphinxBaseReader):
diff --git a/sphinx/transforms.py b/sphinx/transforms.py
index abeab7dab..cb4a5779b 100644
--- a/sphinx/transforms.py
+++ b/sphinx/transforms.py
@@ -170,6 +170,24 @@ class ApplySourceWorkaround(Transform):
                 apply_source_workaround(n)
 
 
+class AutoIndexUpgrader(Transform):
+    """
+    Detect old style; 4 column based indices and automatically upgrade to new style.
+    """
+    default_priority = 210
+
+    def apply(self):
+        env = self.document.settings.env
+        for node in self.document.traverse(addnodes.index):
+            if 'entries' in node and any(len(entry) == 4 for entry in node['entries']):
+                msg = ('4 column based index found. '
+                       'It might be a bug of extensions you use: %r' % node['entries'])
+                env.warn_node(msg, node)
+                for i, entry in enumerate(node['entries']):
+                    if len(entry) == 4:
+                        node['entries'][i] = entry + (None,)
+
+
 class ExtraTranslatableNodes(Transform):
     """
     make nodes translatable