From b9158b96d261eb6126dbd035aa72c621ddea91e8 Mon Sep 17 00:00:00 2001
From: Takeshi KOMIYA <i.tkomiya@gmail.com>
Date: Mon, 21 Jun 2021 02:43:55 +0900
Subject: [PATCH] Fix #9364: autodoc: 1-element tuple on the defarg is wrongly
 rendered

---
 CHANGES                  | 2 ++
 sphinx/pycode/ast.py     | 8 +++++---
 tests/test_pycode_ast.py | 3 ++-
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/CHANGES b/CHANGES
index a0f1bab262..e48dcace95 100644
--- a/CHANGES
+++ b/CHANGES
@@ -65,6 +65,8 @@ Bugs fixed
 * #9250: autodoc: The inherited method not having docstring is wrongly parsed
 * #9283: autodoc: autoattribute directive failed to generate document for an
   attribute not having any comment
+* #9364: autodoc: single element tuple on the default argument value is wrongly
+  rendered
 * #9317: html: Pushing left key causes visiting the next page at the first page
 * #9270: html theme : pyramid theme generates incorrect logo links
 * #9217: manpage: The name of manpage directory that is generated by
diff --git a/sphinx/pycode/ast.py b/sphinx/pycode/ast.py
index f541ec0a90..23da575bde 100644
--- a/sphinx/pycode/ast.py
+++ b/sphinx/pycode/ast.py
@@ -213,10 +213,12 @@ def visit_UnaryOp(self, node: ast.UnaryOp) -> str:
         return "%s %s" % (self.visit(node.op), self.visit(node.operand))
 
     def visit_Tuple(self, node: ast.Tuple) -> str:
-        if node.elts:
-            return "(" + ", ".join(self.visit(e) for e in node.elts) + ")"
-        else:
+        if len(node.elts) == 0:
             return "()"
+        elif len(node.elts) == 1:
+            return "(%s,)" % self.visit(node.elts[0])
+        else:
+            return "(" + ", ".join(self.visit(e) for e in node.elts) + ")"
 
     if sys.version_info < (3, 8):
         # these ast nodes were deprecated in python 3.8
diff --git a/tests/test_pycode_ast.py b/tests/test_pycode_ast.py
index e800623517..6ae7050da3 100644
--- a/tests/test_pycode_ast.py
+++ b/tests/test_pycode_ast.py
@@ -53,8 +53,9 @@
     ("+ a", "+ a"),                             # UAdd
     ("- 1", "- 1"),                             # UnaryOp
     ("- a", "- a"),                             # USub
-    ("(1, 2, 3)", "(1, 2, 3)"),                   # Tuple
+    ("(1, 2, 3)", "(1, 2, 3)"),                 # Tuple
     ("()", "()"),                               # Tuple (empty)
+    ("(1,)", "(1,)"),                           # Tuple (single item)
 ])
 def test_unparse(source, expected):
     module = ast.parse(source)