Make _TemporaryFileWrapper generic on AnyStr, use it (#5456)

* Make _TemporaryFileWrapper generic on AnyStr, use it

Previously it was not used on NamedTemoraryFile and thus the file
field was missing from the types for the return value of
NamedTemoraryFile.

stdlib/tempfile.pyi

@@ -28,7 +28,7 @@ if sys.version_info >= (3, 8):
         delete: bool = ...,
         *,
         errors: Optional[str] = ...,
-    ) -> IO[str]: ...
+    ) -> _TemporaryFileWrapper[str]: ...
     @overload
     def NamedTemporaryFile(
         mode: Literal["rb", "wb", "ab", "xb", "r+b", "w+b", "a+b", "x+b"] = ...,
@@ -41,7 +41,7 @@ if sys.version_info >= (3, 8):
         delete: bool = ...,
         *,
         errors: Optional[str] = ...,
-    ) -> IO[bytes]: ...
+    ) -> _TemporaryFileWrapper[bytes]: ...
     @overload
     def NamedTemporaryFile(
         mode: str = ...,
@@ -54,7 +54,7 @@ if sys.version_info >= (3, 8):
         delete: bool = ...,
         *,
         errors: Optional[str] = ...,
-    ) -> IO[Any]: ...
+    ) -> _TemporaryFileWrapper[Any]: ...
 
 else:
     @overload
@@ -67,7 +67,7 @@ else:
         prefix: Optional[AnyStr] = ...,
         dir: Optional[_DirT[AnyStr]] = ...,
         delete: bool = ...,
-    ) -> IO[str]: ...
+    ) -> _TemporaryFileWrapper[str]: ...
     @overload
     def NamedTemporaryFile(
         mode: Literal["rb", "wb", "ab", "xb", "r+b", "w+b", "a+b", "x+b"] = ...,
@@ -78,7 +78,7 @@ else:
         prefix: Optional[AnyStr] = ...,
         dir: Optional[_DirT[AnyStr]] = ...,
         delete: bool = ...,
-    ) -> IO[bytes]: ...
+    ) -> _TemporaryFileWrapper[bytes]: ...
     @overload
     def NamedTemporaryFile(
         mode: str = ...,
@@ -89,7 +89,7 @@ else:
         prefix: Optional[AnyStr] = ...,
         dir: Optional[_DirT[AnyStr]] = ...,
         delete: bool = ...,
-    ) -> IO[Any]: ...
+    ) -> _TemporaryFileWrapper[Any]: ...
 
 if sys.platform == "win32":
     TemporaryFile = NamedTemporaryFile
@@ -163,12 +163,12 @@ else:
             dir: Optional[_DirT[AnyStr]] = ...,
         ) -> IO[Any]: ...
 
-class _TemporaryFileWrapper(IO[str]):
-    file: IO[str]
+class _TemporaryFileWrapper(Generic[AnyStr], IO[AnyStr]):
+    file: IO[AnyStr]
     name: Any
     delete: bool
-    def __init__(self, file: IO[str], name: Any, delete: bool = ...) -> None: ...
-    def __enter__(self) -> _TemporaryFileWrapper: ...
+    def __init__(self, file: IO[AnyStr], name: Any, delete: bool = ...) -> None: ...
+    def __enter__(self) -> _TemporaryFileWrapper[AnyStr]: ...
     def __exit__(
         self, exc: Optional[Type[BaseException]], value: Optional[BaseException], tb: Optional[TracebackType]
     ) -> Optional[bool]: ...
@@ -178,23 +178,30 @@ class _TemporaryFileWrapper(IO[str]):
     # These methods don't exist directly on this object, but
     # are delegated to the underlying IO object through __getattr__.
     # We need to add them here so that this class is concrete.
-    def __iter__(self) -> Iterator[str]: ...
-    def __next__(self) -> str: ...
+    def __iter__(self) -> Iterator[AnyStr]: ...
+    # FIXME: __next__ doesn't actually exist on this class and should be removed:
+    #        see also https://github.com/python/typeshed/pull/5456#discussion_r633068648
+    # >>> import tempfile
+    # >>> ntf=tempfile.NamedTemporaryFile()
+    # >>> next(ntf)
+    # Traceback (most recent call last):
+    #   File "<stdin>", line 1, in <module>
+    # TypeError: '_TemporaryFileWrapper' object is not an iterator
+    def __next__(self) -> AnyStr: ...
     def fileno(self) -> int: ...
     def flush(self) -> None: ...
     def isatty(self) -> bool: ...
-    def next(self) -> str: ...
-    def read(self, n: int = ...) -> str: ...
+    def read(self, n: int = ...) -> AnyStr: ...
     def readable(self) -> bool: ...
-    def readline(self, limit: int = ...) -> str: ...
-    def readlines(self, hint: int = ...) -> List[str]: ...
+    def readline(self, limit: int = ...) -> AnyStr: ...
+    def readlines(self, hint: int = ...) -> list[AnyStr]: ...
     def seek(self, offset: int, whence: int = ...) -> int: ...
     def seekable(self) -> bool: ...
     def tell(self) -> int: ...
     def truncate(self, size: Optional[int] = ...) -> int: ...
     def writable(self) -> bool: ...
-    def write(self, s: str) -> int: ...
-    def writelines(self, lines: Iterable[str]) -> None: ...
+    def write(self, s: AnyStr) -> int: ...
+    def writelines(self, lines: Iterable[AnyStr]) -> None: ...
 
 # It does not actually derive from IO[AnyStr], but it does implement the
 # protocol.