stubgen: Use PEP 604 instead of Optional (#10624)

mypy/stubgen.py

@@ -1159,10 +1159,8 @@ def get_str_type_of_node(self, rvalue: Expression,
             return 'bool'
         if can_infer_optional and \
                 isinstance(rvalue, NameExpr) and rvalue.name == 'None':
-            self.add_typing_import('Optional')
             self.add_typing_import('Any')
-            return '{}[{}]'.format(self.typing_name('Optional'),
-                                   self.typing_name('Any'))
+            return '{} | None'.format(self.typing_name('Any'))
         self.add_typing_import('Any')
         return self.typing_name('Any')
 

test-data/unit/stubgen.test

@@ -32,9 +32,9 @@ def g(b: int = ..., c: int = ...) -> None: ...
 [case testDefaultArgNone]
 def f(x=None): ...
 [out]
-from typing import Any, Optional
+from typing import Any
 
-def f(x: Optional[Any] = ...) -> None: ...
+def f(x: Any | None = ...) -> None: ...
 
 [case testDefaultArgBool]
 def f(x=True, y=False): ...
@@ -772,12 +772,12 @@ class A:
     def method(self, a=None):
         self.x = []
 [out]
-from typing import Any, Optional
+from typing import Any
 
 class A:
     x: Any = ...
-    def __init__(self, a: Optional[Any] = ...) -> None: ...
-    def method(self, a: Optional[Any] = ...) -> None: ...
+    def __init__(self, a: Any | None = ...) -> None: ...
+    def method(self, a: Any | None = ...) -> None: ...
 
 [case testAnnotationImportsFrom]
 import foo
@@ -1700,10 +1700,10 @@ def Optional():
     return 0
 
 [out]
-from typing import Any as _Any, Optional as _Optional
+from typing import Any as _Any
 
 def f(x: _Any = ...): ...
-def g(x: _Optional[_Any] = ...) -> None: ...
+def g(x: _Any | None = ...) -> None: ...
 
 x: _Any