From a825106c2c5f2599643e1ad6d4caa1bfc6e1e999 Mon Sep 17 00:00:00 2001
From: Eric Jolibois <em.jolibois@gmail.com>
Date: Thu, 29 Dec 2022 11:18:00 +0100
Subject: [PATCH] fix: avoid multiple calls of `__post_init__` when dataclasses
 are inherited (#4493)

---
 changes/4487-PrettyWood.md |  1 +
 pydantic/dataclasses.py    |  5 ++++-
 tests/test_dataclasses.py  | 25 +++++++++++++++++++++++++
 3 files changed, 30 insertions(+), 1 deletion(-)
 create mode 100644 changes/4487-PrettyWood.md

diff --git a/changes/4487-PrettyWood.md b/changes/4487-PrettyWood.md
new file mode 100644
index 0000000000..8f18dd0c50
--- /dev/null
+++ b/changes/4487-PrettyWood.md
@@ -0,0 +1 @@
+fix: avoid multiple calls of `__post_init__` when dataclasses are inherited
diff --git a/pydantic/dataclasses.py b/pydantic/dataclasses.py
index 00e413a666..1856a1203c 100644
--- a/pydantic/dataclasses.py
+++ b/pydantic/dataclasses.py
@@ -288,7 +288,10 @@ def handle_extra_init(self: 'Dataclass', *args: Any, **kwargs: Any) -> None:
             init(self, *args, **kwargs)
 
     if hasattr(dc_cls, '__post_init__'):
-        post_init = dc_cls.__post_init__
+        try:
+            post_init = dc_cls.__post_init__.__wrapped__  # type: ignore[attr-defined]
+        except AttributeError:
+            post_init = dc_cls.__post_init__
 
         @wraps(post_init)
         def new_post_init(self: 'Dataclass', *args: Any, **kwargs: Any) -> None:
diff --git a/tests/test_dataclasses.py b/tests/test_dataclasses.py
index 9d7d55595a..65151801cc 100644
--- a/tests/test_dataclasses.py
+++ b/tests/test_dataclasses.py
@@ -1474,6 +1474,31 @@ def __post_init__(self):
     assert C().a == 6  # 1 * 3 + 3
 
 
+def test_inheritance_post_init_2():
+    post_init_calls = 0
+    post_init_post_parse_calls = 0
+
+    @pydantic.dataclasses.dataclass
+    class BaseClass:
+        def __post_init__(self):
+            nonlocal post_init_calls
+            post_init_calls += 1
+
+    @pydantic.dataclasses.dataclass
+    class AbstractClass(BaseClass):
+        pass
+
+    @pydantic.dataclasses.dataclass
+    class ConcreteClass(AbstractClass):
+        def __post_init_post_parse__(self):
+            nonlocal post_init_post_parse_calls
+            post_init_post_parse_calls += 1
+
+    ConcreteClass()
+    assert post_init_calls == 1
+    assert post_init_post_parse_calls == 1
+
+
 def test_dataclass_setattr():
     class Foo:
         bar: str = 'cat'