Disable combining vectorcall and option groups

Author: cmaloney

Lib/test/test_clinic.py

@@ -2981,6 +2981,20 @@ class Foo "FooObject *" "Foo_Type"
         """
         self.expect_failure(block, err, lineno=6)
 
+    def test_vectorcall_with_option_groups(self):
+        err = "@vectorcall does not support optional groups"
+        block = """
+            module m
+            class Foo "FooObject *" "Foo_Type"
+            @vectorcall
+            Foo.__init__
+                [
+                a: object
+                ]
+                /
+        """
+        self.expect_failure(block, err, lineno=7)
+
     def test_unused_param(self):
         block = self.parse("""
             module foo

Tools/clinic/libclinic/dsl_parser.py

@@ -1549,6 +1549,9 @@ def check_vectorcall_parameters(self, lineno: int) -> None:
         if not self.function.vectorcall:
             return
         for i, p in enumerate(self.function.parameters.values()):
+            if p.group:
+                fail("@vectorcall does not support optional groups",
+                     line_number=lineno)
             if p.is_vararg() or p.is_var_keyword():
                 continue
             if isinstance(p.converter, (self_converter,

Tools/clinic/libclinic/parse_args.py

@@ -1602,6 +1602,8 @@ def parse_vectorcall(self) -> None:
 
         Dispatch to specific parser-code builders based on parameter shape.
         """
+        # The DSL parser rejects @vectorcall with optional groups.
+        assert not self.has_option_groups()
         if not self.parameters and not self.varpos and not self.var_keyword:
             self.parse_vectorcall_no_args()
         elif (self.pos_only == len(self.parameters)