Address PR comments

newsfragments/4505.feature.rst

@@ -1 +1 @@
-Changed the order of type checks in ``setuptools.command.easy_install.CommandSpec.from_param`` to support any `collections.abc.Iterable` of `str` param and to always fallback to the environment if the param type is unsupported -- by :user:`Avasam`
+Changed the order of type checks in ``setuptools.command.easy_install.CommandSpec.from_param`` to support any `collections.abc.Iterable` of `str` param -- by :user:`Avasam`

setuptools/command/easy_install.py

@@ -2070,7 +2070,10 @@ def from_param(cls, param: Self | str | Iterable[str] | None) -> Self:
             return cls.from_string(param)
         if isinstance(param, Iterable):
             return cls(param)
-        return cls.from_environment()
+        if param is None:
+            return cls.from_environment()
+        # AttributeError to keep backwards compatibility, this should really be a TypeError though
+        raise AttributeError(f"Argument has an unsupported type {type(param)}")
 
     @classmethod
     def from_environment(cls):

setuptools/extension.py

@@ -128,7 +128,7 @@ class Extension(_Extension):
     """
 
     def __init__(
-        self, name: str, sources: list[str], *args, py_limited_api: bool = False, **kw
+        self, name: str, sources, *args, py_limited_api: bool = False, **kw
     ):
         # The *args is needed for compatibility as calls may use positional
         # arguments. py_limited_api may be set only via keyword.