gh-127610: Added validation for more than one var positional and var keyword parameters in inspect.Signature

Lib/inspect.py

@@ -2943,6 +2943,8 @@ def __init__(self, parameters=None, *, return_annotation=_empty,
                 params = OrderedDict()
                 top_kind = _POSITIONAL_ONLY
                 seen_default = False
+                var_positional_count = 0
+                var_keyword_count = 0
 
                 for param in parameters:
                     kind = param.kind
@@ -2971,6 +2973,18 @@ def __init__(self, parameters=None, *, return_annotation=_empty,
                             # There is a default for this parameter.
                             seen_default = True
 
+                    if kind == _VAR_POSITIONAL:
+                        var_positional_count += 1
+                        if var_positional_count > 1:
+                            msg = 'more than one var positional parameter'
+                            raise ValueError(msg)
+
+                    if kind == _VAR_KEYWORD:
+                        var_keyword_count += 1
+                        if var_keyword_count > 1:
+                            msg = 'more than one var keyword parameter'
+                            raise ValueError(msg)
+
                     if name in params:
                         msg = 'duplicate parameter name: {!r}'.format(name)
                         raise ValueError(msg)

Lib/test/test_inspect/test_inspect.py

@@ -2992,6 +2992,14 @@ def test2(pod=42, /):
         with self.assertRaisesRegex(ValueError, 'follows default argument'):
             S((pkd, pk))
 
+        second_args = args.replace(name="second_args")
+        with self.assertRaisesRegex(ValueError, 'more than one var positional parameter'):
+            S((args, second_args))
+
+        second_kwargs = kwargs.replace(name="second_kwargs")
+        with self.assertRaisesRegex(ValueError, 'more than one var keyword parameter'):
+            S((kwargs, second_kwargs))
+
     def test_signature_object_pickle(self):
         def foo(a, b, *, c:1={}, **kw) -> {42:'ham'}: pass
         foo_partial = functools.partial(foo, a=1)

Misc/ACKS

@@ -24,6 +24,7 @@ Eitan Adler
 Anton Afanasyev
 Ali Afshar
 Nitika Agarwal
+Maxim Ageev
 Anjani Agrawal
 Pablo S. Blum de Aguiar
 Jim Ahlstrom