clean up lru_cache in compat

src/flake8/_compat.py

@@ -1,10 +1,9 @@
 """Expose backports in a single place."""
 import sys
-from functools import lru_cache
 
 if sys.version_info >= (3, 8):  # pragma: no cover (PY38+)
     import importlib.metadata as importlib_metadata
 else:  # pragma: no cover (<PY38)
     import importlib_metadata
 
-__all__ = ("lru_cache", "importlib_metadata")
+__all__ = ("importlib_metadata",)

src/flake8/style_guide.py

@@ -4,6 +4,7 @@ import collections
 import contextlib
 import copy
 import enum
+import functools
 import itertools
 import linecache
 import logging
@@ -20,7 +21,6 @@ from typing import Union
 from flake8 import defaults
 from flake8 import statistics
 from flake8 import utils
-from flake8._compat import lru_cache
 from flake8.formatting import base as base_formatter
 
 __all__ = ("StyleGuide",)
@@ -49,7 +49,7 @@ class Decision(enum.Enum):
     Selected = "selected error"
 
 
-@lru_cache(maxsize=512)
+@functools.lru_cache(maxsize=512)
 def find_noqa(physical_line):  # type: (str) -> Optional[Match[str]]
     return defaults.NOQA_INLINE_REGEXP.search(physical_line)
 
@@ -374,7 +374,7 @@ class StyleGuideManager:
                 filename=filename, extend_ignore_with=violations
             )
 
-    @lru_cache(maxsize=None)
+    @functools.lru_cache(maxsize=None)
     def style_guide_for(self, filename):  # type: (str) -> StyleGuide
         """Find the StyleGuide for the filename in particular."""
         guides = sorted(

src/flake8/utils.py

@@ -1,6 +1,7 @@
 """Utility methods for flake8."""
 import collections
 import fnmatch as _fnmatch
+import functools
 import inspect
 import io
 import logging
@@ -21,7 +22,6 @@ from typing import Tuple
 from typing import Union
 
 from flake8 import exceptions
-from flake8._compat import lru_cache
 
 if False:  # `typing.TYPE_CHECKING` was introduced in 3.5.2
     from flake8.plugins.manager import Plugin
@@ -209,7 +209,7 @@ def _stdin_get_value_py3():  # type: () -> str
         return stdin_value.decode("utf-8")
 
 
-@lru_cache(maxsize=1)
+@functools.lru_cache(maxsize=1)
 def stdin_get_value():  # type: () -> str
     """Get and cache it so plugins can use it."""
     return _stdin_get_value_py3()