restore python3.7 support

Author: RonnyPfannschmidt

pyproject.toml

@@ -2,6 +2,8 @@
 requires = [
     "setuptools>=45",
     "tomli>=1.0",
-    "packaging>=20.0"
+    "packaging>=20.0",
+    "typing_extensions",
+    "importlib_metadata",
 ]
 build-backend = "setuptools.build_meta"

setup.cfg

@@ -30,6 +30,7 @@ install_requires =
     packaging>=20.0
     setuptools
     tomli>=1.0.0 # keep in sync
+    typing-extensions
 python_requires = >=3.7
 package_dir =
     =src

src/setuptools_scm/_entrypoints.py

@@ -4,9 +4,10 @@
 from typing import Any
 from typing import Iterator
 from typing import overload
-from typing import Protocol
 from typing import TYPE_CHECKING
 
+from typing_extensions import Protocol
+
 from . import _types as _t
 from .utils import function_has_arg
 from .utils import trace

src/setuptools_scm/_types.py

@@ -1,24 +1,19 @@
 from __future__ import annotations
 
-import os
-import sys
 from typing import Any
 from typing import Callable
 from typing import List
 from typing import NamedTuple
-from typing import Protocol
 from typing import TYPE_CHECKING
 from typing import TypeVar
 from typing import Union
 
 
 if TYPE_CHECKING:
     from setuptools_scm import version
+    import os
 
-if sys.version_info >= (3, 9):
-    from typing import ParamSpec, TypeAlias
-else:
-    from typing_extensions import ParamSpec, TypeAlias
+from typing_extensions import ParamSpec, TypeAlias, Protocol
 
 PathT = Union["os.PathLike[str]", str]
 

tox.ini

@@ -29,6 +29,7 @@ deps=
     setuptools >= 45
     tomli
     virtualenv>20
+    typing_extensions
 commands=
     test: pytest []
     selfcheck: python setup.py --version