Fix #2050: Symbols sections are appeared twice in the index page

Multibyte symbols are categorized to independent symbols section
different to single byte symbols.  This integrate them to a single
section.

1 files changed, 9 insertions, 5 deletions

diff --git a/sphinx/environment/adapters/indexentries.py b/sphinx/environment/adapters/indexentries.py
index 5af213932..b13ac97c3 100644
--- a/sphinx/environment/adapters/indexentries.py
+++ b/sphinx/environment/adapters/indexentries.py
@@ -98,9 +98,8 @@ class IndexEntries:
             for subentry in indexentry[1].values():
                 subentry[0].sort(key=keyfunc0)  # type: ignore
 
-        # sort the index entries; put all symbols at the front, even those
-        # following the letters in ASCII, this is where the chr(127) comes from
-        def keyfunc(entry: Tuple[str, List]) -> Tuple[str, str]:
+        # sort the index entries
+        def keyfunc(entry: Tuple[str, List]) -> Tuple[Tuple[int, str], str]:
             key, (void, void, category_key) = entry
             if category_key:
                 # using specified category key to sort
@@ -108,11 +107,16 @@ class IndexEntries:
             lckey = unicodedata.normalize('NFD', key.lower())
             if lckey.startswith('\N{RIGHT-TO-LEFT MARK}'):
                 lckey = lckey[1:]
+
             if lckey[0:1].isalpha() or lckey.startswith('_'):
-                lckey = chr(127) + lckey
+                # put non-symbol characters at the folloing group (1)
+                sortkey = (1, lckey)
+            else:
+                # put symbols at the front of the index (0)
+                sortkey = (0, lckey)
             # ensure a determinstic order *within* letters by also sorting on
             # the entry itself
-            return (lckey, entry[0])
+            return (sortkey, entry[0])
         newlist = sorted(new.items(), key=keyfunc)
 
         if group_entries: