gh-92062: inspect.Parameter checks whether name is a keyword (GH-92065)

Fixes #92062.

Lib/inspect.py

@@ -149,6 +149,7 @@ import token
 import types
 import functools
 import builtins
+from keyword import iskeyword
 from operator import attrgetter
 from collections import namedtuple, OrderedDict
 
@@ -2707,7 +2708,10 @@ class Parameter:
             self._kind = _POSITIONAL_ONLY
             name = 'implicit{}'.format(name[1:])
 
-        if not name.isidentifier():
+        # It's possible for C functions to have a positional-only parameter
+        # where the name is a keyword, so for compatibility we'll allow it.
+        is_keyword = iskeyword(name) and self._kind is not _POSITIONAL_ONLY
+        if is_keyword or not name.isidentifier():
             raise ValueError('{!r} is not a valid parameter name'.format(name))
 
         self._name = name

Lib/test/test_inspect.py

@@ -3604,6 +3604,9 @@ class TestParameterObject(unittest.TestCase):
         with self.assertRaisesRegex(ValueError, 'not a valid parameter name'):
             inspect.Parameter('1', kind=inspect.Parameter.VAR_KEYWORD)
 
+        with self.assertRaisesRegex(ValueError, 'not a valid parameter name'):
+            inspect.Parameter('from', kind=inspect.Parameter.VAR_KEYWORD)
+
         with self.assertRaisesRegex(TypeError, 'name must be a str'):
             inspect.Parameter(None, kind=inspect.Parameter.VAR_KEYWORD)
 

Misc/NEWS.d/next/Library/2022-04-29-18-15-23.gh-issue-92062.X2c_Rj.rst

@@ -0,0 +1,2 @@
+:class:`inspect.Parameter` now raises :exc:`ValueError` if ``name`` is
+a keyword, in addition to the existing check that it is an identifier.