Include stubs for mypy_extensions in bundled typeshed (#10507)

JukkaL · web-flow · commit 58aef054dccb · 2021-05-19T13:32:51.000+01:00
Also don't install a stub package for `mypy_extensions`.

There are two reasons why we're doing this:

* We make assumptions about what's defined in `mypy_extensions`, and
  if users are free to modify it, various things may break, and this
  could even cause mypy crashes.

* Older mypy versions complain about installed stubs for
  `mypy_extensions`. Updating to an earlier mypy versions in the same
  environment is broken if we use a stub package.
diff --git a/misc/sync-typeshed.py b/misc/sync-typeshed.py
@@ -42,6 +42,10 @@ def update_typeshed(typeshed_dir: str, commit: Optional[str]) -> str:
     shutil.rmtree(stub_dir)
     # Copy new stdlib stubs.
     shutil.copytree(os.path.join(typeshed_dir, 'stdlib'), stub_dir)
+    # Copy mypy_extensions stubs. We don't want to use a stub package, since it's
+    # treated specially by mypy and we make assumptions about what's there.
+    shutil.copy(os.path.join(typeshed_dir, 'stubs', 'mypy-extensions', 'mypy_extensions.pyi'),
+                stub_dir)
     return commit
 
 
diff --git a/mypy-requirements.txt b/mypy-requirements.txt
@@ -1,5 +1,4 @@
 typing_extensions>=3.7.4
 mypy_extensions>=0.4.3,<0.5.0
 typed_ast>=1.4.0,<1.5.0
-types-mypy-extensions>=0.4.0
 toml
diff --git a/mypy/stubinfo.py b/mypy/stubinfo.py
@@ -47,7 +47,6 @@
     'markupsafe': 'types-MarkupSafe',
     'maxminddb': 'types-maxminddb',
     'mock': 'types-mock',
-    'mypy_extensions': 'types-mypy-extensions',
     'OpenSSL': 'types-openssl-python',
     'orjson': 'types-orjson',
     'paramiko': 'types-paramiko',
diff --git a/mypy/test/teststubtest.py b/mypy/test/teststubtest.py
@@ -834,7 +834,6 @@ def test_get_typeshed_stdlib_modules(self) -> None:
         assert "builtins" in stdlib
         assert "os" in stdlib
         assert "os.path" in stdlib
-        assert "mypy_extensions" not in stdlib
         assert "asyncio" in stdlib
         assert ("dataclasses" in stdlib) == (sys.version_info >= (3, 7))
 
diff --git a/mypy/typeshed/stdlib/mypy_extensions.pyi b/mypy/typeshed/stdlib/mypy_extensions.pyi
@@ -0,0 +1,46 @@
+import abc
+import sys
+from typing import Any, Callable, Dict, Generic, ItemsView, KeysView, Mapping, Optional, Type, TypeVar, Union, ValuesView
+
+_T = TypeVar("_T")
+_U = TypeVar("_U")
+
+# Internal mypy fallback type for all typed dicts (does not exist at runtime)
+class _TypedDict(Mapping[str, object], metaclass=abc.ABCMeta):
+    def copy(self: _T) -> _T: ...
+    # Using NoReturn so that only calls using mypy plugin hook that specialize the signature
+    # can go through.
+    def setdefault(self, k: NoReturn, default: object) -> object: ...
+    # Mypy plugin hook for 'pop' expects that 'default' has a type variable type.
+    def pop(self, k: NoReturn, default: _T = ...) -> object: ...  # type: ignore
+    def update(self: _T, __m: _T) -> None: ...
+    if sys.version_info >= (3, 0):
+        def items(self) -> ItemsView[str, object]: ...
+        def keys(self) -> KeysView[str]: ...
+        def values(self) -> ValuesView[object]: ...
+    else:
+        def has_key(self, k: str) -> bool: ...
+        def viewitems(self) -> ItemsView[str, object]: ...
+        def viewkeys(self) -> KeysView[str]: ...
+        def viewvalues(self) -> ValuesView[object]: ...
+    def __delitem__(self, k: NoReturn) -> None: ...
+
+def TypedDict(typename: str, fields: Dict[str, Type[Any]], total: bool = ...) -> Type[Dict[str, Any]]: ...
+def Arg(type: _T = ..., name: Optional[str] = ...) -> _T: ...
+def DefaultArg(type: _T = ..., name: Optional[str] = ...) -> _T: ...
+def NamedArg(type: _T = ..., name: Optional[str] = ...) -> _T: ...
+def DefaultNamedArg(type: _T = ..., name: Optional[str] = ...) -> _T: ...
+def VarArg(type: _T = ...) -> _T: ...
+def KwArg(type: _T = ...) -> _T: ...
+
+# Return type that indicates a function does not return.
+# This type is equivalent to the None type, but the no-op Union is necessary to
+# distinguish the None type from the None value.
+NoReturn = Union[None]  # Deprecated: Use typing.NoReturn instead.
+
+# This is intended as a class decorator, but mypy rejects abstract classes
+# when a Type[_T] is expected, so we can't give it the type we want
+def trait(cls: Any) -> Any: ...
+def mypyc_attr(*attrs: str, **kwattrs: object) -> Callable[[_T], _T]: ...
+
+class FlexibleAlias(Generic[_T, _U]): ...
diff --git a/setup.py b/setup.py
@@ -194,7 +194,6 @@ def run(self):
       install_requires=["typed_ast >= 1.4.0, < 1.5.0; python_version<'3.8'",
                         'typing_extensions>=3.7.4',
                         'mypy_extensions >= 0.4.3, < 0.5.0',
-                        'types-mypy-extensions>=0.4.0',
                         'toml',
                         ],
       # Same here.
