gh-96385: Correctly raise error on `[*T, *V]` substitution (GH-96386)
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index ca7bd8e..7eea019 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -596,6 +596,7 @@ class GenericAliasSubstitutionTests(BaseTestCase):
def test_one_parameter(self):
T = TypeVar('T')
Ts = TypeVarTuple('Ts')
+ Ts2 = TypeVarTuple('Ts2')
class C(Generic[T]): pass
@@ -621,6 +622,8 @@ class C(Generic[T]): pass
# Should definitely raise TypeError: list only takes one argument.
('list[T, *tuple_type[int, ...]]', '[int]', 'list[int, *tuple_type[int, ...]]'),
('List[T, *tuple_type[int, ...]]', '[int]', 'TypeError'),
+ # Should raise, because more than one `TypeVarTuple` is not supported.
+ ('generic[*Ts, *Ts2]', '[int]', 'TypeError'),
]
for alias_template, args_template, expected_template in tests:
diff --git a/Lib/typing.py b/Lib/typing.py
index 43ef07e..596744e 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -1074,7 +1074,7 @@ def __typing_subst__(self, arg):
def __typing_prepare_subst__(self, alias, args):
params = alias.__parameters__
typevartuple_index = params.index(self)
- for param in enumerate(params[typevartuple_index + 1:]):
+ for param in params[typevartuple_index + 1:]:
if isinstance(param, TypeVarTuple):
raise TypeError(f"More than one TypeVarTuple parameter in {alias}")
diff --git a/Misc/NEWS.d/next/Library/2022-08-29-15-28-39.gh-issue-96385.uLRTsf.rst b/Misc/NEWS.d/next/Library/2022-08-29-15-28-39.gh-issue-96385.uLRTsf.rst
new file mode 100644
index 0000000..5735482
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-08-29-15-28-39.gh-issue-96385.uLRTsf.rst
@@ -0,0 +1,3 @@
+Fix ``TypeVarTuple.__typing_prepare_subst__``. ``TypeError`` was not raised
+when using more than one ``TypeVarTuple``, like ``[*T, *V]`` in type alias
+substitutions.
