simplified dict.get to not require overloads

Author: randolf-scholz

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

@@ -71,34 +71,33 @@ def test_iterable_tuple_overload(x: Iterable[tuple[int, str]]) -> dict[int, str]
 int_value = 1
 
 assert_type(d_any["key"], Any)
-assert_type(d_any.get("key"), Union[Any, None])
-assert_type(d_any.get("key", None), Union[Any, None])
+assert_type(d_any.get("key"), Any | None)
+assert_type(d_any.get("key", None), 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)
+assert_type(d_any.get("key", str_value), Any | str)
+assert_type(d_any.get("key", int_value), Any | int)
 
 assert_type(d_str["key"], str)
-assert_type(d_str.get("key"), Union[str, None])
-assert_type(d_str.get("key", None), Union[str, None])
+assert_type(d_str.get("key"), str | None)
+assert_type(d_str.get("key", None), str | None)
 # Pyright has str instead of Any here
-assert_type(d_str.get("key", any_value), Any)  # pyright: ignore[reportAssertTypeFailure]
+assert_type(d_str.get("key", any_value), str | Any)
 assert_type(d_str.get("key", str_value), str)
-assert_type(d_str.get("key", int_value), Union[str, int])
+assert_type(d_str.get("key", int_value), str | int)
 
 # Now with context!
 result: str
 result = d_any["key"]
 result = d_any.get("key")  # type: ignore[assignment]
 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_any.get("key", any_value)  # OK
+result = d_any.get("key", str_value)  # OK
+result = d_any.get("key", int_value)  # type: ignore[assignment]
 
 result = d_str["key"]
 result = d_str.get("key")  # type: ignore[assignment]
 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", any_value)
 result = d_str.get("key", str_value)
 result = d_str.get("key", int_value)  # type: ignore[arg-type]
 
@@ -143,8 +142,10 @@ def test9() -> str:
     return d_str.get("key", None)  # type: ignore[return-value]
 
 
-def test10() -> str:
-    return d_str.get("key", any_value)  # type: ignore[no-any-return]
+# Pyright doesn't have a version of no-any-return,
+# and mypy doesn't have a type: ignore that pyright will ignore.
+# def test10() -> str:
+#     return d_str.get("key", any_value)  # mypy: ignore[no-any-return]
 
 
 def test11() -> str:

stdlib/builtins.pyi

@@ -96,6 +96,7 @@ _SupportsAnextT_co = TypeVar("_SupportsAnextT_co", bound=SupportsAnext[Any], cov
 _AwaitableT = TypeVar("_AwaitableT", bound=Awaitable[Any])
 _AwaitableT_co = TypeVar("_AwaitableT_co", bound=Awaitable[Any], covariant=True)
 _P = ParamSpec("_P")
+_NoneDefaultT = TypeVar("_NoneDefaultT", default=None)
 
 # Type variables for slice
 _StartT_co = TypeVar("_StartT_co", covariant=True, default=Any)  # slice -> slice[Any, Any, Any]
@@ -1218,13 +1219,7 @@ class dict(MutableMapping[_KT, _VT]):
     @classmethod
     @overload
     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, default: None = None, /) -> _VT | None: ...
-    @overload
-    def get(self, key: _KT, default: _VT, /) -> _VT: ...
-    @overload
-    def get(self, key: _KT, default: _T, /) -> _VT | _T: ...
+    def get(self, key: _KT, default: _NoneDefaultT = None, /) -> _VT | _NoneDefaultT: ...  # type: ignore[assignment]
     @overload
     def pop(self, key: _KT, /) -> _VT: ...
     @overload