From: et-repositories <142979605+et-repositories@users.noreply.github.com>
Date: Tue, 19 Mar 2024 14:58:40 +0000 (+0800)
Subject: gh-116647: Fix recursive child in dataclasses (#116790)
X-Git-Tag: v3.13.0a6~233
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=75935746be0cbd32b9d710b93db9bd49c8d634ba;p=thirdparty%2FPython%2Fcpython.git

gh-116647: Fix recursive child in dataclasses (#116790)
---

diff --git a/Lib/dataclasses.py b/Lib/dataclasses.py
index e511eff41250..7db8a4233df8 100644
--- a/Lib/dataclasses.py
+++ b/Lib/dataclasses.py
@@ -1075,7 +1075,9 @@ def _process_class(cls, init, repr, eq, order, unsafe_hash, frozen,
         cmp_fields = (field for field in field_list if field.compare)
         terms = [f'self.{field.name}==other.{field.name}' for field in cmp_fields]
         field_comparisons = ' and '.join(terms) or 'True'
-        body =  [f'if other.__class__ is self.__class__:',
+        body =  [f'if self is other:',
+                 f' return True',
+                 f'if other.__class__ is self.__class__:',
                  f' return {field_comparisons}',
                  f'return NotImplemented']
         func = _create_fn('__eq__',
diff --git a/Lib/test/test_dataclasses/__init__.py b/Lib/test/test_dataclasses/__init__.py
index e27abac51113..832e5672c77d 100644
--- a/Lib/test/test_dataclasses/__init__.py
+++ b/Lib/test/test_dataclasses/__init__.py
@@ -2471,6 +2471,15 @@ class TestRepr(unittest.TestCase):
 
 
 class TestEq(unittest.TestCase):
+    def test_recursive_eq(self):
+        # Test a class with recursive child
+        @dataclass
+        class C:
+            recursive: object = ...
+        c = C()
+        c.recursive = c
+        self.assertEqual(c, c)
+
     def test_no_eq(self):
         # Test a class with no __eq__ and eq=False.
         @dataclass(eq=False)
diff --git a/Misc/NEWS.d/next/Library/2024-03-14-09-38-51.gh-issue-116647.h0d_zj.rst b/Misc/NEWS.d/next/Library/2024-03-14-09-38-51.gh-issue-116647.h0d_zj.rst
new file mode 100644
index 000000000000..081f36bff916
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2024-03-14-09-38-51.gh-issue-116647.h0d_zj.rst
@@ -0,0 +1 @@
+Fix recursive child in dataclasses