From a17e8bebfe8fa22f284168aa07a6c667deae8c2a Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <raymond.hettinger@gmail.com>
Date: Sun, 29 Dec 2019 13:16:32 -0600
Subject: [PATCH 1/2] Support empty sets

---
 Lib/ast.py           | 3 +++
 Lib/test/test_ast.py | 1 +
 2 files changed, 4 insertions(+)

diff --git a/Lib/ast.py b/Lib/ast.py
index ee3f74358ee120b..db405a6adf12bec 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -82,6 +82,9 @@ def _convert(node):
             return list(map(_convert, node.elts))
         elif isinstance(node, Set):
             return set(map(_convert, node.elts))
+        elif (isinstance(node, Call) and isinstance(node.func, Name) and
+              node.func.id == 'set' and node.args == node.keywords == []):
+            return set()
         elif isinstance(node, Dict):
             return dict(zip(map(_convert, node.keys),
                             map(_convert, node.values)))
diff --git a/Lib/test/test_ast.py b/Lib/test/test_ast.py
index 51a7c1af1ffe702..55b91cfa23beca6 100644
--- a/Lib/test/test_ast.py
+++ b/Lib/test/test_ast.py
@@ -891,6 +891,7 @@ def test_literal_eval(self):
         self.assertEqual(ast.literal_eval('(True, False, None)'), (True, False, None))
         self.assertEqual(ast.literal_eval('{1, 2, 3}'), {1, 2, 3})
         self.assertEqual(ast.literal_eval('b"hi"'), b"hi")
+        self.assertEqual(ast.literal_eval('set()'), set())
         self.assertRaises(ValueError, ast.literal_eval, 'foo()')
         self.assertEqual(ast.literal_eval('6'), 6)
         self.assertEqual(ast.literal_eval('+6'), 6)

From 24384feac7b0cb4381b8fe64b270ed8adf0e167c Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <raymond.hettinger@gmail.com>
Date: Sun, 29 Dec 2019 15:47:05 -0600
Subject: [PATCH 2/2] Add docs and blurb

---
 Doc/library/ast.rst                                            | 3 +++
 .../next/Library/2019-12-29-15-44-38.bpo-39158.cxVoOR.rst      | 1 +
 2 files changed, 4 insertions(+)
 create mode 100644 Misc/NEWS.d/next/Library/2019-12-29-15-44-38.bpo-39158.cxVoOR.rst

diff --git a/Doc/library/ast.rst b/Doc/library/ast.rst
index baf563f5d7877e6..47544a40c49599a 100644
--- a/Doc/library/ast.rst
+++ b/Doc/library/ast.rst
@@ -194,6 +194,9 @@ and classes for traversing abstract syntax trees:
    .. versionchanged:: 3.2
       Now allows bytes and set literals.
 
+   .. versionchanged:: 3.9
+      Now supports creating empty sets with ``'set()'``.
+
 
 .. function:: get_docstring(node, clean=True)
 
diff --git a/Misc/NEWS.d/next/Library/2019-12-29-15-44-38.bpo-39158.cxVoOR.rst b/Misc/NEWS.d/next/Library/2019-12-29-15-44-38.bpo-39158.cxVoOR.rst
new file mode 100644
index 000000000000000..c41799bebaeb9b4
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-12-29-15-44-38.bpo-39158.cxVoOR.rst
@@ -0,0 +1 @@
+ast.literal_eval() now supports empty sets.