Check and fix unpacks early - normally does that, but semanal uses its own anal_type wrapper in a loop

Author: sterliakov

mypy/semanal.py

@@ -6071,6 +6071,9 @@ def analyze_type_application_args(self, expr: IndexExpr) -> list[Type] | None:
                 return None
             types.append(analyzed)
 
+        analyzer = self.type_analyzer()
+        types = analyzer.check_unpacks_in_list(types)
+
         if has_param_spec and num_args == 1 and types:
             first_arg = get_proper_type(types[0])
             single_any = len(types) == 1 and isinstance(first_arg, AnyType)

test-data/unit/check-python312.test

@@ -2029,3 +2029,13 @@ def foo() -> None:
 class Z: ...  # E: Name "Z" already defined on line 2
 [builtins fixtures/tuple.pyi]
 [typing fixtures/typing-full.pyi]
+
+[case testPEP695MultipleUnpacksInBareApplicationNoCrash]
+# https://github.com/python/mypy/issues/18856
+class A[*Ts]: ...
+
+A[*tuple[int, ...], *tuple[int, ...]]  # E: More than one Unpack in a type is not allowed
+
+b: tuple[*tuple[int, ...], *tuple[int, ...]]  # E: More than one Unpack in a type is not allowed
+[builtins fixtures/tuple.pyi]
+[typing fixtures/typing-full.pyi]