typing: minor changes (#3933)

* typing: fix argument names of cast
* typing: use private _Alias class

For py37 and above, this is _GenericAlias, for py36 and below it's
_TypeAlias. I don't think we need to make typing.pyi definitions
correspond more precisely, but we should avoid leaking a
typing.TypeAlias class

tests/stubtest_whitelists/py35.txt

@@ -71,10 +71,8 @@ typing.MutableSequence.remove
 typing.MutableSet.add
 typing.MutableSet.discard
 typing.MutableSet.remove
-typing.Protocol
 typing.Sequence.count
 typing.Sequence.index
-typing.Type
 typing.runtime_checkable
 unittest.async_case
 uuid.UUID.int

tests/stubtest_whitelists/py36.txt

@@ -71,10 +71,8 @@ typing.MutableSequence.remove
 typing.MutableSet.add
 typing.MutableSet.discard
 typing.MutableSet.remove
-typing.Protocol
 typing.Sequence.count
 typing.Sequence.index
-typing.Type
 typing.runtime_checkable
 unittest.async_case
 urllib.parse.parse_qs

tests/stubtest_whitelists/py37.txt

@@ -66,36 +66,6 @@ tracemalloc.Traceback.format
 types.ClassMethodDescriptorType.__get__
 types.MethodDescriptorType.__get__
 types.WrapperDescriptorType.__get__
-typing.AbstractSet
-typing.AsyncContextManager
-typing.AsyncGenerator
-typing.AsyncIterable
-typing.AsyncIterator
-typing.Awaitable
-typing.ByteString
-typing.Collection
-typing.Container
-typing.ContextManager
-typing.Coroutine
-typing.Generator
-typing.GenericMeta
-typing.Hashable
-typing.ItemsView
-typing.Iterable
-typing.Iterator
-typing.KeysView
-typing.Mapping
-typing.MappingView
-typing.MutableMapping
-typing.MutableSequence
-typing.MutableSet
-typing.Optional
-typing.Protocol
-typing.Reversible
-typing.Sequence
-typing.Sized
-typing.Union
-typing.ValuesView
 typing.runtime_checkable
 unittest.async_case
 urllib.parse.parse_qs

tests/stubtest_whitelists/py38.txt

@@ -148,35 +148,6 @@ types.ClassMethodDescriptorType.__get__
 types.CodeType.replace
 types.MethodDescriptorType.__get__
 types.WrapperDescriptorType.__get__
-typing.AbstractSet
-typing.AsyncContextManager
-typing.AsyncGenerator
-typing.AsyncIterable
-typing.AsyncIterator
-typing.Awaitable
-typing.ByteString
-typing.Collection
-typing.Container
-typing.ContextManager
-typing.Coroutine
-typing.Generator
-typing.GenericMeta
-typing.Hashable
-typing.ItemsView
-typing.Iterable
-typing.Iterator
-typing.KeysView
-typing.Mapping
-typing.MappingView
-typing.MutableMapping
-typing.MutableSequence
-typing.MutableSet
-typing.Optional
-typing.Reversible
-typing.Sequence
-typing.Sized
-typing.Union
-typing.ValuesView
 unittest.TestCase.addCleanup
 unittest.case.TestCase.addCleanup
 unittest.doModuleCleanups

tests/stubtest_whitelists/py3_common.txt

@@ -510,17 +510,12 @@ types.coroutine
 types.new_class
 types.prepare_class
 typing.AwaitableGenerator
-typing.Generic
 typing.IO.__iter__
 typing.IO.__next__
 typing.IO.closed
-typing.Match
 typing.NamedTuple._asdict
 typing.NamedTuple._make
 typing.NamedTuple._replace
-typing.Pattern
-typing.TypeAlias
-typing.cast
 typing.type_check_only
 unittest.TestCase.assertAlmostEqual
 unittest.TestCase.assertDictContainsSubset
@@ -592,6 +587,8 @@ builtins.quit
 # Builtins that mypy pretends exist
 builtins.reveal_locals
 builtins.reveal_type
+# Various classes in typing aren't types at runtime. In addition, mypy thinks some special forms are tautologically defined.
+typing.[A-Z]\w+
 # We can't distinguish not having a default value from having a default value of inspect.Parameter.empty
 inspect.Parameter.__init__
 inspect.Signature.__init__