dataclasses: various fixes

Author: hauntsaninja

stdlib/3.7/dataclasses.pyi

@@ -18,9 +18,9 @@ def astuple(obj: Any) -> Tuple[Any, ...]: ...
 @overload
 def astuple(obj: Any, *, tuple_factory: Callable[[List[Any]], _T]) -> _T: ...
 @overload
-def dataclass(_cls: Type[_T]) -> Type[_T]: ...
+def dataclass(__cls: Type[_T]) -> Type[_T]: ...
 @overload
-def dataclass(_cls: None) -> Callable[[Type[_T]], Type[_T]]: ...
+def dataclass(__cls: None) -> Callable[[Type[_T]], Type[_T]]: ...
 @overload
 def dataclass(
     *, init: bool = ..., repr: bool = ..., eq: bool = ..., order: bool = ..., unsafe_hash: bool = ..., frozen: bool = ...
@@ -36,6 +36,16 @@ class Field(Generic[_T]):
     init: bool
     compare: bool
     metadata: Mapping[str, Any]
+    def __init__(
+        self,
+        default: _T,
+        default_factory: Callable[[], _T],
+        init: bool,
+        repr: bool,
+        hash: Optional[bool],
+        compare: bool,
+        metadata: Mapping[str, Any],
+    ) -> None: ...
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, item: Any) -> GenericAlias: ...
 
@@ -76,6 +86,8 @@ def is_dataclass(obj: Any) -> bool: ...
 class FrozenInstanceError(AttributeError): ...
 
 class InitVar(Generic[_T]):
+    type: Type
+    def __init__(self, type: Type) -> None: ...
     if sys.version_info >= (3, 9):
         def __class_getitem__(cls, type: Any) -> GenericAlias: ...
 
@@ -92,4 +104,4 @@ def make_dataclass(
     unsafe_hash: bool = ...,
     frozen: bool = ...,
 ) -> type: ...
-def replace(obj: _T, **changes: Any) -> _T: ...
+def replace(__obj: _T, **changes: Any) -> _T: ...