[TorchGen] Remove unused variables and function imports (#164538)

This PR removes unused code in torchgen.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/164538
Approved by: https://github.com/Skylion007, https://github.com/albanD

torchgen/gen_functionalization_type.py

@@ -654,28 +654,6 @@ def emit_inplace_functionalization_body(
         for e in translate(unwrapped_args_ctx, functional_sig.arguments(), method=False)
     ]
 
-    if f.func.is_out_fn():
-        mutable_input_post_processing = "\n".join(
-            [
-                f"""
-      at::functionalization::impl::replace_(
-        {a.name}, {"std::get<" + str(i) + ">(tmp_output)" if len(f.func.returns) > 1 else "tmp_output"});
-      at::functionalization::impl::commit_update({a.name});"""
-                for (i, a) in enumerate(f.func.arguments.out)
-                if a.annotation and a.annotation.is_write and a.type.is_tensor_like()
-            ]
-        )
-    else:
-        mutable_input_post_processing = "\n".join(  # noqa: F841
-            [
-                f"""
-      at::functionalization::impl::replace_({a.name}, tmp_output);
-      at::functionalization::impl::commit_update({a.name});"""
-                for a in f.func.arguments.flat_all
-                if a.annotation and a.annotation.is_write and a.type.is_tensor_like()
-            ]
-        )
-
     meta_conversion_str, meta_call_ctx = convert_to_meta_tensors(dispatcher_sig)
     # We don't want to run the inplace meta func for ops like .set_(), because:
     # (1) they're unnecessary: inplace meta checks are only useful for ops like add_(),

torchgen/utils.py

@@ -11,8 +11,8 @@ from dataclasses import is_dataclass
 from enum import auto, Enum
 from pathlib import Path
 from pprint import pformat
-from typing import Any, Generic, NoReturn, TYPE_CHECKING, TypeVar
-from typing_extensions import assert_never, deprecated, Self
+from typing import Any, Generic, TYPE_CHECKING, TypeVar
+from typing_extensions import assert_never, Self
 
 from torchgen.code_template import CodeTemplate
 
@@ -98,15 +98,6 @@ def context(msg_fn: Callable[[], str]) -> Iterator[None]:
         raise
 
 
-if TYPE_CHECKING:
-    # A little trick from https://github.com/python/mypy/issues/6366
-    # for getting mypy to do exhaustiveness checking
-    # TODO: put this somewhere else, maybe
-    @deprecated("Use typing_extensions.assert_never instead")
-    def assert_never(x: NoReturn) -> NoReturn:  # type: ignore[misc] # noqa: F811
-        raise AssertionError(f"Unhandled type: {type(x).__name__}")
-
-
 @functools.cache
 def _read_template(template_fn: str) -> CodeTemplate:
     return CodeTemplate.from_file(template_fn)