From eb9c18b1bc6d7b870d05f92355f9c7b8218254a0 Mon Sep 17 00:00:00 2001
From: Daniel Pizetta <daniel.pizetta@usp.br>
Date: Mon, 4 Sep 2017 16:14:30 -0300
Subject: [PATCH] Fix #4019: exception treatment for NoneType group attibute.

---
 sphinx/ext/inheritance_diagram.py | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/sphinx/ext/inheritance_diagram.py b/sphinx/ext/inheritance_diagram.py
index f5b0228a5ff..f7cf3411104 100644
--- a/sphinx/ext/inheritance_diagram.py
+++ b/sphinx/ext/inheritance_diagram.py
@@ -80,14 +80,18 @@ def try_import(objname):
         __import__(objname)
         return sys.modules.get(objname)  # type: ignore
     except ImportError:
-        modname, attrname = module_sig_re.match(objname).groups()  # type: ignore
-        if modname is None:
-            return None
         try:
-            __import__(modname)
-            return getattr(sys.modules.get(modname), attrname, None)
-        except ImportError:
+            modname, attrname = module_sig_re.match(objname).groups()  # type: ignore
+        except AttributeError:
             return None
+        else:
+            if modname is None:
+                return None
+            try:
+                __import__(modname)
+                return getattr(sys.modules.get(modname), attrname, None)
+            except ImportError:
+                return None
 
 
 def import_classes(name, currmodule):