gh-122688: Fix support of var-positional parameter in Argument Clinic (GH-122689)

* Parameters after the var-positional parameter are now keyword-only
  instead of positional-or-keyword.
* Correctly calculate min_kw_only.
* Raise errors for invalid combinations of the var-positional parameter
  with "*", "/" and deprecation markers.

Author: serhiy-storchaka

Lib/test/clinic.test.c

@@ -4134,8 +4134,8 @@ test_vararg_and_posonly
 
 
     a: object
-    *args: object
     /
+    *args: object
 
 [clinic start generated code]*/
 
@@ -4177,7 +4177,7 @@ test_vararg_and_posonly(PyObject *module, PyObject *const *args, Py_ssize_t narg
 
 static PyObject *
 test_vararg_and_posonly_impl(PyObject *module, PyObject *a, PyObject *args)
-/*[clinic end generated code: output=79b75dc07decc8d6 input=08dc2bf7afbf1613]*/
+/*[clinic end generated code: output=79b75dc07decc8d6 input=9cfa748bbff09877]*/
 
 /*[clinic input]
 test_vararg
@@ -4920,7 +4920,7 @@ Test_an_metho_arg_named_arg_impl(TestObj *self, int arg)
 /*[clinic input]
 Test.__init__
     *args: object
-    /
+
 Varargs init method. For example, nargs is translated to PyTuple_GET_SIZE.
 [clinic start generated code]*/
 
@@ -4958,14 +4958,14 @@ Test___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 
 static int
 Test___init___impl(TestObj *self, PyObject *args)
-/*[clinic end generated code: output=0ed1009fe0dcf98d input=96c3ddc0cd38fc0c]*/
+/*[clinic end generated code: output=0ed1009fe0dcf98d input=2a8bd0033c9ac772]*/
 
 
 /*[clinic input]
 @classmethod
 Test.__new__
     *args: object
-    /
+
 Varargs new method. For example, nargs is translated to PyTuple_GET_SIZE.
 [clinic start generated code]*/
 
@@ -5002,7 +5002,7 @@ Test(PyTypeObject *type, PyObject *args, PyObject *kwargs)
 
 static PyObject *
 Test_impl(PyTypeObject *type, PyObject *args)
-/*[clinic end generated code: output=8b219f6633e2a2e9 input=26a672e2e9750120]*/
+/*[clinic end generated code: output=8b219f6633e2a2e9 input=70ad829df3dd9b84]*/
 
 
 /*[clinic input]

Lib/test/test_clinic.py

@@ -322,7 +322,7 @@ def __init__(self):
         """
         self.expect_failure(block, err, lineno=8)
 
-    def test_multiple_star_in_args(self):
+    def test_star_after_vararg(self):
         err = "'my_test_func' uses '*' more than once."
         block = """
             /*[clinic input]
@@ -336,6 +336,20 @@ def test_multiple_star_in_args(self):
         """
         self.expect_failure(block, err, lineno=6)
 
+    def test_vararg_after_star(self):
+        err = "'my_test_func' uses '*' more than once."
+        block = """
+            /*[clinic input]
+            my_test_func
+
+                pos_arg: object
+                *
+                *args: object
+                kw_arg: object
+            [clinic start generated code]*/
+        """
+        self.expect_failure(block, err, lineno=6)
+
     def test_module_already_got_one(self):
         err = "Already defined module 'm'!"
         block = """
@@ -1787,13 +1801,43 @@ def test_parameters_required_after_depr_star2(self):
         )
         self.expect_failure(block, err, lineno=4)
 
+    def test_parameters_required_after_depr_star3(self):
+        block = """
+            module foo
+            foo.bar
+                a: int
+                * [from 3.14]
+                *args: object
+                b: int
+            Docstring.
+        """
+        err = (
+            "Function 'bar' specifies '* [from ...]' without "
+            "following parameters."
+        )
+        self.expect_failure(block, err, lineno=4)
+
     def test_depr_star_must_come_before_star(self):
         block = """
             module foo
             foo.bar
-                this: int
+                a: int
                 *
                 * [from 3.14]
+                b: int
+            Docstring.
+        """
+        err = "Function 'bar': '* [from ...]' must precede '*'"
+        self.expect_failure(block, err, lineno=4)
+
+    def test_depr_star_must_come_before_vararg(self):
+        block = """
+            module foo
+            foo.bar
+                a: int
+                *args: object
+                * [from 3.14]
+                b: int
             Docstring.
         """
         err = "Function 'bar': '* [from ...]' must precede '*'"
@@ -1908,7 +1952,7 @@ def test_double_slash(self):
         err = "Function 'bar' uses '/' more than once."
         self.expect_failure(block, err)
 
-    def test_mix_star_and_slash(self):
+    def test_slash_after_star(self):
         block = """
             module foo
             foo.bar
@@ -1921,6 +1965,19 @@ def test_mix_star_and_slash(self):
         err = "Function 'bar': '/' must precede '*'"
         self.expect_failure(block, err)
 
+    def test_slash_after_vararg(self):
+        block = """
+            module foo
+            foo.bar
+               x: int
+               y: int
+               *args: object
+               z: int
+               /
+        """
+        err = "Function 'bar': '/' must precede '*'"
+        self.expect_failure(block, err)
+
     def test_depr_star_must_come_after_slash(self):
         block = """
             module foo
@@ -1960,6 +2017,19 @@ def test_star_must_come_after_depr_slash(self):
         err = "Function 'bar': '/ [from ...]' must precede '*'"
         self.expect_failure(block, err, lineno=4)
 
+    def test_vararg_must_come_after_depr_slash(self):
+        block = """
+            module foo
+            foo.bar
+                a: int
+                *args: object
+                / [from 3.14]
+                b: int
+            Docstring.
+        """
+        err = "Function 'bar': '/ [from ...]' must precede '*'"
+        self.expect_failure(block, err, lineno=4)
+
     def test_depr_slash_must_come_after_slash(self):
         block = """
             module foo
@@ -1987,7 +2057,7 @@ def test_parameters_not_permitted_after_slash_for_now(self):
         self.expect_failure(block, err)
 
     def test_parameters_no_more_than_one_vararg(self):
-        err = "Too many var args"
+        err = "Function 'bar' uses '*' more than once."
         block = """
             module foo
             foo.bar
@@ -3319,13 +3389,6 @@ def test_posonly_vararg(self):
         with self.assertRaises(TypeError):
             ac_tester.posonly_vararg(1, 2, 3, b=4)
 
-    def test_vararg_and_posonly(self):
-        with self.assertRaises(TypeError):
-            ac_tester.vararg_and_posonly()
-        with self.assertRaises(TypeError):
-            ac_tester.vararg_and_posonly(1, b=2)
-        self.assertEqual(ac_tester.vararg_and_posonly(1, 2, 3, 4), (1, (2, 3, 4)))
-
     def test_vararg(self):
         with self.assertRaises(TypeError):
             ac_tester.vararg()
@@ -3363,6 +3426,17 @@ def test_vararg_with_only_defaults(self):
         self.assertEqual(ac_tester.vararg_with_only_defaults(1, 2, 3, 4), ((1, 2, 3, 4), None))
         self.assertEqual(ac_tester.vararg_with_only_defaults(1, 2, 3, 4, b=5), ((1, 2, 3, 4), 5))
 
+    def test_vararg_kwonly_req_opt(self):
+        fn = ac_tester.vararg_kwonly_req_opt
+        self.assertRaises(TypeError, fn)
+        self.assertEqual(fn(a=1), ((), 1, None, None))
+        self.assertEqual(fn(a=1, b=2), ((), 1, 2, None))
+        self.assertEqual(fn(a=1, b=2, c=3), ((), 1, 2, 3))
+        self.assertRaises(TypeError, fn, 1)
+        self.assertEqual(fn(1, a=2), ((1,), 2, None, None))
+        self.assertEqual(fn(1, a=2, b=3), ((1,), 2, 3, None))
+        self.assertEqual(fn(1, a=2, b=3, c=4), ((1,), 2, 3, 4))
+
     def test_gh_32092_oob(self):
         ac_tester.gh_32092_oob(1, 2, 3, 4, kw1=5, kw2=6)
 

Modules/_testclinic.c

@@ -981,23 +981,6 @@ posonly_vararg_impl(PyObject *module, PyObject *a, PyObject *b,
 }
 
 
-/*[clinic input]
-vararg_and_posonly
-
-    a: object
-    *args: object
-    /
-
-[clinic start generated code]*/
-
-static PyObject *
-vararg_and_posonly_impl(PyObject *module, PyObject *a, PyObject *args)
-/*[clinic end generated code: output=42792f799465a14d input=defe017b19ba52e8]*/
-{
-    return pack_arguments_newref(2, a, args);
-}
-
-
 /*[clinic input]
 vararg
 
@@ -1068,6 +1051,25 @@ vararg_with_only_defaults_impl(PyObject *module, PyObject *args, PyObject *b)
 }
 
 
+/*[clinic input]
+vararg_kwonly_req_opt
+
+    *args: object
+    a: object
+    b: object = None
+    c: object = None
+
+[clinic start generated code]*/
+
+static PyObject *
+vararg_kwonly_req_opt_impl(PyObject *module, PyObject *args, PyObject *a,
+                           PyObject *b, PyObject *c)
+/*[clinic end generated code: output=54694a99c3da370a input=b0d8bf09e540d400]*/
+{
+    return pack_arguments_newref(4, args, a, b, c);
+}
+
+
 
 /*[clinic input]
 gh_32092_oob
@@ -1115,15 +1117,14 @@ gh_32092_kw_pass_impl(PyObject *module, PyObject *pos, PyObject *args,
 gh_99233_refcount
 
     *args: object
-    /
 
 Proof-of-concept of GH-99233 refcount error bug.
 
 [clinic start generated code]*/
 
 static PyObject *
 gh_99233_refcount_impl(PyObject *module, PyObject *args)
-/*[clinic end generated code: output=585855abfbca9a7f input=85f5fb47ac91a626]*/
+/*[clinic end generated code: output=585855abfbca9a7f input=eecfdc2092d90dc3]*/
 {
     Py_RETURN_NONE;
 }
@@ -1923,11 +1924,11 @@ static PyMethodDef tester_methods[] = {
     POSONLY_OPT_KEYWORDS_OPT_KWONLY_OPT_METHODDEF
     KEYWORD_ONLY_PARAMETER_METHODDEF
     POSONLY_VARARG_METHODDEF
-    VARARG_AND_POSONLY_METHODDEF
     VARARG_METHODDEF
     VARARG_WITH_DEFAULT_METHODDEF
     VARARG_WITH_DEFAULT2_METHODDEF
     VARARG_WITH_ONLY_DEFAULTS_METHODDEF
+    VARARG_KWONLY_REQ_OPT_METHODDEF
     GH_32092_OOB_METHODDEF
     GH_32092_KW_PASS_METHODDEF
     GH_99233_REFCOUNT_METHODDEF