From 7897678777982e942aa6c22b823aced7ffd07095 Mon Sep 17 00:00:00 2001
From: Takeshi KOMIYA <i.tkomiya@gmail.com>
Date: Tue, 11 Apr 2017 23:44:17 +0900
Subject: [PATCH] Fix #3618: autodoc crashes with tupled arguments

---
 CHANGES               |  1 +
 sphinx/ext/autodoc.py | 17 +++++++++++++----
 2 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/CHANGES b/CHANGES
index e192bf5b7..4035a50ce 100644
--- a/CHANGES
+++ b/CHANGES
@@ -14,6 +14,7 @@ Bugs fixed
 ----------
 
 * #3614: Sphinx crashes with requests-2.5.0
+* #3618: autodoc crashes with tupled arguments
 
 Testing
 --------
diff --git a/sphinx/ext/autodoc.py b/sphinx/ext/autodoc.py
index 9e513276f..9203e673b 100644
--- a/sphinx/ext/autodoc.py
+++ b/sphinx/ext/autodoc.py
@@ -380,10 +380,19 @@ def formatargspec(function, args, varargs=None, varkw=None, defaults=None,
 
     for i, arg in enumerate(args):
         arg_fd = StringIO()
-        arg_fd.write(format_arg_with_annotation(arg))
-        if defaults and i >= defaults_start:
-            arg_fd.write(' = ' if arg in annotations else '=')
-            arg_fd.write(object_description(defaults[i - defaults_start]))
+        if isinstance(arg, list):
+            # support tupled arguments list (only for py2): def foo((x, y))
+            arg_fd.write('(')
+            arg_fd.write(format_arg_with_annotation(arg[0]))
+            for param in arg[1:]:
+                arg_fd.write(', ')
+                arg_fd.write(format_arg_with_annotation(param))
+            arg_fd.write(')')
+        else:
+            arg_fd.write(format_arg_with_annotation(arg))
+            if defaults and i >= defaults_start:
+                arg_fd.write(' = ' if arg in annotations else '=')
+                arg_fd.write(object_description(defaults[i - defaults_start]))
         formatted.append(arg_fd.getvalue())
 
     if varargs: