From ca216ed3eddabdb10131ae8833311b46d70785f9 Mon Sep 17 00:00:00 2001
From: Michael Mitchell <michaelm@openai.com>
Date: Sat, 7 Mar 2026 01:44:45 -0800
Subject: [PATCH] [stubgen] Always generate ellipsis for class attr with
 initial value

---
 mypy/stubgen.py             | 17 ++++++++++++++---
 test-data/unit/stubgen.test | 26 +++++++++++++-------------
 2 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/mypy/stubgen.py b/mypy/stubgen.py
index ce6335e9e34f9..99336b377e89d 100755
--- a/mypy/stubgen.py
+++ b/mypy/stubgen.py
@@ -719,7 +719,7 @@ def visit_func_def(self, o: FuncDef) -> None:
                 if init in self.method_names:
                     # Can't have both an attribute and a method/property with the same name.
                     continue
-                init_code = self.get_init(init, value, annotation)
+                init_code = self.get_init(init, value, annotation, self_init=True)
                 if init_code:
                     self.add(init_code)
 
@@ -1288,7 +1288,11 @@ def visit_import(self, o: Import) -> None:
             self.record_name(target_name)
 
     def get_init(
-        self, lvalue: str, rvalue: Expression, annotation: Type | None = None
+        self,
+        lvalue: str,
+        rvalue: Expression,
+        annotation: Type | None = None,
+        self_init: bool = False,
     ) -> str | None:
         """Return initializer for a variable.
 
@@ -1320,7 +1324,10 @@ def get_init(
             return f"{self._indent}{lvalue} = ...\n"
         else:
             typename = self.get_str_type_of_node(rvalue)
-        initializer = self.get_assign_initializer(rvalue)
+        if self_init:
+            initializer = ""
+        else:
+            initializer = self.get_assign_initializer(rvalue)
         return f"{self._indent}{lvalue}: {typename}{initializer}\n"
 
     def get_assign_initializer(self, rvalue: Expression) -> str:
@@ -1344,6 +1351,10 @@ def get_assign_initializer(self, rvalue: Expression) -> str:
                     return f" = {rvalue.accept(p)}"
             if not (isinstance(rvalue, TempNode) and rvalue.no_rhs):
                 return " = ..."
+        if self.processing_enum:
+            return ""
+        if not (isinstance(rvalue, TempNode) and rvalue.no_rhs):
+            return " = ..."
         # TODO: support other possible cases, where initializer is important
 
         # By default, no initializer is required:
diff --git a/test-data/unit/stubgen.test b/test-data/unit/stubgen.test
index 161f14e8aea77..22bc7360be7f1 100644
--- a/test-data/unit/stubgen.test
+++ b/test-data/unit/stubgen.test
@@ -225,7 +225,7 @@ class C:
     x = 1
 [out]
 class C:
-    x: int
+    x: int = ...
 
 [case testInitTypeAnnotationPreserved]
 class C:
@@ -267,7 +267,7 @@ class C:
 x: int
 
 class C:
-    x: int
+    x: int = ...
     def __init__(self) -> None: ...
 
 [case testEmptyClass]
@@ -319,7 +319,7 @@ class A:
 _x: int
 
 class A:
-    _y: int
+    _y: int = ...
 
 [case testSpecialInternalVar]
 __all__ = []
@@ -706,7 +706,7 @@ class A:
 __all__ = ['A']
 
 class A:
-    x: int
+    x: int = ...
     def f(self) -> None: ...
 
 [case testSkipMultiplePrivateDefs]
@@ -972,16 +972,16 @@ class A(NamedTuple):
 
 class B(A):
     z1: str
-    z2: int
-    z3: str
+    z2: int = ...
+    z3: str = ...
 
 class RegularClass:
     x: int
-    y: str
+    y: str = ...
     class NestedNamedTuple(NamedTuple):
         x: int
         y: str = ...
-    z: str
+    z: str = ...
 
 
 [case testNestedClassInNamedTuple_semanal-xfail]
@@ -1337,7 +1337,7 @@ class A:
 [out]
 class A:
     class B:
-        x: int
+        x: int = ...
         def f(self) -> None: ...
     def g(self) -> None: ...
 
@@ -1388,7 +1388,7 @@ class A:
 from _typeshed import Incomplete
 
 class A:
-    x: Incomplete
+    x: Incomplete = ...
     def __init__(self, a=None) -> None: ...
     def method(self, a=None) -> None: ...
 
@@ -4342,21 +4342,21 @@ def create_model(cls): ...
 
 class X:
     a: int
-    b: str
+    b: str = ...
 
 @typing_extensions.dataclass_transform(kw_only_default=True)
 class ModelBase: ...
 
 class Y(ModelBase):
     a: int
-    b: str
+    b: str = ...
 
 @typing_extensions.dataclass_transform(kw_only_default=True)
 class DCMeta(type): ...
 
 class Z(metaclass=DCMeta):
     a: int
-    b: str
+    b: str = ...
 
 [case testDataclassTransformDecorator_semanal]
 import typing_extensions