From b18a4cd6744b4cd6177b9002bfed3f59863955cf Mon Sep 17 00:00:00 2001
From: Iurii Kemaev <y.kemaev@gmail.com>
Date: Tue, 9 Feb 2021 00:24:42 +0300
Subject: [PATCH 1/3] fix processing of empty dataclasses

---
 Lib/dataclasses.py           |  2 +-
 Lib/test/test_dataclasses.py | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index 0c4b47564b0605..97c961f1cf7915 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -851,7 +851,7 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen):
         # Only process classes that have been processed by our
         # decorator.  That is, they have a _FIELDS attribute.
         base_fields = getattr(b, _FIELDS, None)
-        if base_fields:
+        if base_fields is not None:
             has_dataclass_bases = True
             for f in base_fields.values():
                 fields[f.name] = f
diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index 8887eb6461bc34..e5c41883a161b8 100644
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -2594,6 +2594,30 @@ class D(C):
         self.assertEqual(d.i, 0)
         self.assertEqual(d.j, 10)
 
+    def test_inherit_nonfrozen_from_empty_frozen(self):
+        @dataclass(frozen=True)
+        class C:
+            pass
+
+        with self.assertRaisesRegex(TypeError,
+                                    'cannot inherit non-frozen dataclass from a frozen one'):
+            @dataclass
+            class D(C):
+                j: int
+
+    def test_inherit_nonfrozen_from_empty_(self):
+        @dataclass
+        class C:
+            pass
+
+        @dataclass
+        class D(C):
+            j: int
+
+        d = D(3)
+        self.assertEqual(d.j, 3)
+        self.assertIsInstance(d, C)
+
     # Test both ways: with an intermediate normal (non-dataclass)
     #  class and without an intermediate class.
     def test_inherit_nonfrozen_from_frozen(self):

From 940d27b541de452d40c13682d50eb72201062a9b Mon Sep 17 00:00:00 2001
From: "blurb-it[bot]" <43283697+blurb-it[bot]@users.noreply.github.com>
Date: Tue, 9 Feb 2021 07:24:30 +0000
Subject: [PATCH 2/3] =?UTF-8?q?=F0=9F=93=9C=F0=9F=A4=96=20Added=20by=20blu?=
 =?UTF-8?q?rb=5Fit.?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../NEWS.d/next/Library/2021-02-09-07-24-29.bpo-43176.bocNQn.rst | 1 +
 1 file changed, 1 insertion(+)
 create mode 100644 Misc/NEWS.d/next/Library/2021-02-09-07-24-29.bpo-43176.bocNQn.rst

diff --git a/Misc/NEWS.d/next/Library/2021-02-09-07-24-29.bpo-43176.bocNQn.rst b/Misc/NEWS.d/next/Library/2021-02-09-07-24-29.bpo-43176.bocNQn.rst
new file mode 100644
index 00000000000000..66a175d21255c2
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-02-09-07-24-29.bpo-43176.bocNQn.rst
@@ -0,0 +1 @@
+Fixed processing of empty dataclasses.
\ No newline at end of file

From a44e321a57cfa837e4fc4b485d5c7e5cd0377e75 Mon Sep 17 00:00:00 2001
From: Iurii Kemaev <y.kemaev@gmail.com>
Date: Wed, 10 Feb 2021 23:45:03 +0300
Subject: [PATCH 3/3] fix typo

---
 Lib/test/test_dataclasses.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Lib/test/test_dataclasses.py b/Lib/test/test_dataclasses.py
index e5c41883a161b8..b2b0b82557d2b6 100644
--- a/Lib/test/test_dataclasses.py
+++ b/Lib/test/test_dataclasses.py
@@ -2605,7 +2605,7 @@ class C:
             class D(C):
                 j: int
 
-    def test_inherit_nonfrozen_from_empty_(self):
+    def test_inherit_nonfrozen_from_empty(self):
         @dataclass
         class C:
             pass