[torchgen] Refactor torchgen.utils.FileManager to accept pathlib.Path (#150726)

This PR allows `FileManager` to accept `pathlib.Path` as arguments while keeping the original `str` path support.

This allows us to simplify the code such as:

1. `os.path.join(..., ...)` with `Path.__floordiv__(..., ...)`.

95a5958db4/torchgen/utils.py (L155)

95a5958db4/torchgen/utils.py (L176)

2. `os.path.basename(...)` with `Path(...).name`.
 95a5958db4/torchgen/utils.py (L161)

3. Manual file extension split with `Path(...).with_stem(new_stem)`

95a5958db4/torchgen/utils.py (L241-L256)

------

Pull Request resolved: https://github.com/pytorch/pytorch/pull/150726
Approved by: https://github.com/aorenste

torchgen/api/cpp.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
+from typing_extensions import assert_never
 
 from torchgen import local
 from torchgen.api.types import (
@@ -48,7 +49,6 @@ from torchgen.model import (
     TensorOptionsArguments,
     Type,
 )
-from torchgen.utils import assert_never
 
 
 if TYPE_CHECKING:

torchgen/api/dispatcher.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import itertools
 from typing import TYPE_CHECKING
+from typing_extensions import assert_never
 
 from torchgen.api import cpp
 from torchgen.api.types import ArgName, Binding, CType, NamedCType
@@ -13,7 +14,7 @@ from torchgen.model import (
     TensorOptionsArguments,
     Type,
 )
-from torchgen.utils import assert_never, concatMap
+from torchgen.utils import concatMap
 
 
 if TYPE_CHECKING:

torchgen/api/native.py

@@ -1,6 +1,7 @@
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
+from typing_extensions import assert_never
 
 from torchgen import local
 from torchgen.api import cpp
@@ -29,7 +30,6 @@ from torchgen.model import (
     TensorOptionsArguments,
     Type,
 )
-from torchgen.utils import assert_never
 
 
 if TYPE_CHECKING:

torchgen/api/structured.py

@@ -1,5 +1,7 @@
 from __future__ import annotations
 
+from typing_extensions import assert_never
+
 from torchgen.api import cpp
 from torchgen.api.types import (
     ArgName,
@@ -30,7 +32,6 @@ from torchgen.model import (
     TensorOptionsArguments,
     Type,
 )
-from torchgen.utils import assert_never
 
 
 # This file describes the translation of JIT schema to the structured functions API.