Fix default of dict.get (#13222)

Author: tungol

stdlib/@tests/stubtest_allowlists/common.txt

@@ -4,7 +4,6 @@
 
 # Please keep sorted alphabetically
 
-builtins.dict.get
 collections\.ChainMap\.fromkeys  # https://github.com/python/mypy/issues/17023
 http.client.HTTPConnection.response_class  # the actual type at runtime is abc.ABCMeta
 importlib.abc.Loader.exec_module  # See Lib/importlib/_abc.py. Might be defined for backwards compatibility

stdlib/@tests/test_cases/builtins/check_dict.py

@@ -67,7 +67,7 @@ def test_iterable_tuple_overload(x: Iterable[tuple[int, str]]) -> dict[int, str]
 
 assert_type(d_any["key"], Any)
 assert_type(d_any.get("key"), Union[Any, None])
-assert_type(d_any.get("key", None), Any)
+assert_type(d_any.get("key", None), Union[Any, None])
 assert_type(d_any.get("key", any_value), Any)
 assert_type(d_any.get("key", str_value), Any)
 assert_type(d_any.get("key", int_value), Any)
@@ -84,15 +84,16 @@ def test_iterable_tuple_overload(x: Iterable[tuple[int, str]]) -> dict[int, str]
 result: str
 result = d_any["key"]
 result = d_any.get("key")  # type: ignore[assignment]
-result = d_any.get("key", None)
+result = d_any.get("key", None)  # type: ignore[assignment]
 result = d_any.get("key", any_value)
 result = d_any.get("key", str_value)
 result = d_any.get("key", int_value)
 
 result = d_str["key"]
 result = d_str.get("key")  # type: ignore[assignment]
-result = d_str.get("key", None)  # type: ignore[arg-type]
-result = d_str.get("key", any_value)
+result = d_str.get("key", None)  # type: ignore[assignment]
+# Pyright has str | None here, see https://github.com/microsoft/pyright/discussions/9570
+result = d_str.get("key", any_value)  # pyright: ignore[reportAssignmentType]
 result = d_str.get("key", str_value)
 result = d_str.get("key", int_value)  # type: ignore[arg-type]
 
@@ -134,11 +135,11 @@ def test8() -> str:
 
 
 def test9() -> str:
-    return d_str.get("key", None)  # type: ignore[arg-type]
+    return d_str.get("key", None)  # type: ignore[return-value]
 
 
 def test10() -> str:
-    return d_str.get("key", any_value)
+    return d_str.get("key", any_value)  # type: ignore[no-any-return]
 
 
 def test11() -> str:

stdlib/builtins.pyi

@@ -1143,7 +1143,7 @@ class dict(MutableMapping[_KT, _VT]):
     def fromkeys(cls, iterable: Iterable[_T], value: _S, /) -> dict[_T, _S]: ...
     # Positional-only in dict, but not in MutableMapping
     @overload  # type: ignore[override]
-    def get(self, key: _KT, /) -> _VT | None: ...
+    def get(self, key: _KT, default: None = None, /) -> _VT | None: ...
     @overload
     def get(self, key: _KT, default: _VT, /) -> _VT: ...
     @overload

stdlib/importlib/metadata/__init__.pyi

@@ -139,7 +139,7 @@ if sys.version_info >= (3, 10) and sys.version_info < (3, 12):
     class Deprecated(Generic[_KT, _VT]):
         def __getitem__(self, name: _KT) -> _VT: ...
         @overload
-        def get(self, name: _KT) -> _VT | None: ...
+        def get(self, name: _KT, default: None = None) -> _VT | None: ...
         @overload
         def get(self, name: _KT, default: _T) -> _VT | _T: ...
         def __iter__(self) -> Iterator[_KT]: ...