[3.9] gh-91583: AC: Fix regression for functions with defining_class (GH-91739) (GH-92080)

Argument Clinic now generates the same efficient code as before
adding the defining_class parameter.
(cherry picked from commit a055dac0b45031878a8196a8735522de018491e3)

4 files changed, 120 insertions, 57 deletions

diff --git a/Misc/NEWS.d/next/Tools-Demos/2022-04-20-14-26-14.gh-issue-91583.200qI0.rst b/Misc/NEWS.d/next/Tools-Demos/2022-04-20-14-26-14.gh-issue-91583.200qI0.rst
new file mode 100644
index 0000000..bdfa711
--- /dev/null
+++ b/Misc/NEWS.d/next/Tools-Demos/2022-04-20-14-26-14.gh-issue-91583.200qI0.rst
@@ -0,0 +1,2 @@
+Fix regression in the code generated by Argument Clinic for functions with
+the ``defining_class`` parameter.
diff --git a/Modules/clinic/_testmultiphase.c.h b/Modules/clinic/_testmultiphase.c.h
index 0d38c23..23180d0 100644
--- a/Modules/clinic/_testmultiphase.c.h
+++ b/Modules/clinic/_testmultiphase.c.h
@@ -18,18 +18,11 @@ _testmultiphase_StateAccessType_get_defining_module_impl(StateAccessTypeObject *
 static PyObject *
 _testmultiphase_StateAccessType_get_defining_module(StateAccessTypeObject *self, PyTypeObject *cls, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
-    PyObject *return_value = NULL;
-    static const char * const _keywords[] = { NULL};
-    static _PyArg_Parser _parser = {":get_defining_module", _keywords, 0};
-
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser
-        )) {
-        goto exit;
+    if (nargs) {
+        PyErr_SetString(PyExc_TypeError, "get_defining_module() takes no arguments");
+        return NULL;
     }
-    return_value = _testmultiphase_StateAccessType_get_defining_module_impl(self, cls);
-
-exit:
-    return return_value;
+    return _testmultiphase_StateAccessType_get_defining_module_impl(self, cls);
 }
 
 PyDoc_STRVAR(_testmultiphase_StateAccessType_increment_count_clinic__doc__,
@@ -55,14 +48,42 @@ _testmultiphase_StateAccessType_increment_count_clinic(StateAccessTypeObject *se
 {
     PyObject *return_value = NULL;
     static const char * const _keywords[] = {"n", "twice", NULL};
-    static _PyArg_Parser _parser = {"|i$p:increment_count_clinic", _keywords, 0};
+    static _PyArg_Parser _parser = {NULL, _keywords, "increment_count_clinic", 0};
+    PyObject *argsbuf[2];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
     int n = 1;
     int twice = 0;
 
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
-        &n, &twice)) {
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 1, 0, argsbuf);
+    if (!args) {
         goto exit;
     }
+    if (!noptargs) {
+        goto skip_optional_pos;
+    }
+    if (args[0]) {
+        if (PyFloat_Check(args[0])) {
+            PyErr_SetString(PyExc_TypeError,
+                            "integer argument expected, got float" );
+            goto exit;
+        }
+        n = _PyLong_AsInt(args[0]);
+        if (n == -1 && PyErr_Occurred()) {
+            goto exit;
+        }
+        if (!--noptargs) {
+            goto skip_optional_pos;
+        }
+    }
+skip_optional_pos:
+    if (!noptargs) {
+        goto skip_optional_kwonly;
+    }
+    twice = PyObject_IsTrue(args[1]);
+    if (twice < 0) {
+        goto exit;
+    }
+skip_optional_kwonly:
     return_value = _testmultiphase_StateAccessType_increment_count_clinic_impl(self, cls, n, twice);
 
 exit:
@@ -85,17 +106,10 @@ _testmultiphase_StateAccessType_get_count_impl(StateAccessTypeObject *self,
 static PyObject *
 _testmultiphase_StateAccessType_get_count(StateAccessTypeObject *self, PyTypeObject *cls, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
-    PyObject *return_value = NULL;
-    static const char * const _keywords[] = { NULL};
-    static _PyArg_Parser _parser = {":get_count", _keywords, 0};
-
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser
-        )) {
-        goto exit;
+    if (nargs) {
+        PyErr_SetString(PyExc_TypeError, "get_count() takes no arguments");
+        return NULL;
     }
-    return_value = _testmultiphase_StateAccessType_get_count_impl(self, cls);
-
-exit:
-    return return_value;
+    return _testmultiphase_StateAccessType_get_count_impl(self, cls);
 }
-/*[clinic end generated code: output=39eea487e94e7f5d input=a9049054013a1b77]*/
+/*[clinic end generated code: output=60d68e2336064f96 input=a9049054013a1b77]*/
diff --git a/Modules/clinic/posixmodule.c.h b/Modules/clinic/posixmodule.c.h
index 28798ab..f5df5c3 100644
--- a/Modules/clinic/posixmodule.c.h
+++ b/Modules/clinic/posixmodule.c.h
@@ -8438,12 +8438,10 @@ static PyObject *
 os_DirEntry_is_symlink(DirEntry *self, PyTypeObject *defining_class, PyObject *const *args, Py_ssize_t nargs, PyObject *kwnames)
 {
     PyObject *return_value = NULL;
-    static const char * const _keywords[] = { NULL};
-    static _PyArg_Parser _parser = {":is_symlink", _keywords, 0};
     int _return_value;
 
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser
-        )) {
+    if (nargs) {
+        PyErr_SetString(PyExc_TypeError, "is_symlink() takes no arguments");
         goto exit;
     }
     _return_value = os_DirEntry_is_symlink_impl(self, defining_class);
@@ -8474,13 +8472,23 @@ os_DirEntry_stat(DirEntry *self, PyTypeObject *defining_class, PyObject *const *
 {
     PyObject *return_value = NULL;
     static const char * const _keywords[] = {"follow_symlinks", NULL};
-    static _PyArg_Parser _parser = {"|$p:stat", _keywords, 0};
+    static _PyArg_Parser _parser = {NULL, _keywords, "stat", 0};
+    PyObject *argsbuf[1];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
     int follow_symlinks = 1;
 
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
-        &follow_symlinks)) {
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 0, 0, argsbuf);
+    if (!args) {
         goto exit;
     }
+    if (!noptargs) {
+        goto skip_optional_kwonly;
+    }
+    follow_symlinks = PyObject_IsTrue(args[0]);
+    if (follow_symlinks < 0) {
+        goto exit;
+    }
+skip_optional_kwonly:
     return_value = os_DirEntry_stat_impl(self, defining_class, follow_symlinks);
 
 exit:
@@ -8505,14 +8513,24 @@ os_DirEntry_is_dir(DirEntry *self, PyTypeObject *defining_class, PyObject *const
 {
     PyObject *return_value = NULL;
     static const char * const _keywords[] = {"follow_symlinks", NULL};
-    static _PyArg_Parser _parser = {"|$p:is_dir", _keywords, 0};
+    static _PyArg_Parser _parser = {NULL, _keywords, "is_dir", 0};
+    PyObject *argsbuf[1];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
     int follow_symlinks = 1;
     int _return_value;
 
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
-        &follow_symlinks)) {
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 0, 0, argsbuf);
+    if (!args) {
         goto exit;
     }
+    if (!noptargs) {
+        goto skip_optional_kwonly;
+    }
+    follow_symlinks = PyObject_IsTrue(args[0]);
+    if (follow_symlinks < 0) {
+        goto exit;
+    }
+skip_optional_kwonly:
     _return_value = os_DirEntry_is_dir_impl(self, defining_class, follow_symlinks);
     if ((_return_value == -1) && PyErr_Occurred()) {
         goto exit;
@@ -8541,14 +8559,24 @@ os_DirEntry_is_file(DirEntry *self, PyTypeObject *defining_class, PyObject *cons
 {
     PyObject *return_value = NULL;
     static const char * const _keywords[] = {"follow_symlinks", NULL};
-    static _PyArg_Parser _parser = {"|$p:is_file", _keywords, 0};
+    static _PyArg_Parser _parser = {NULL, _keywords, "is_file", 0};
+    PyObject *argsbuf[1];
+    Py_ssize_t noptargs = nargs + (kwnames ? PyTuple_GET_SIZE(kwnames) : 0) - 0;
     int follow_symlinks = 1;
     int _return_value;
 
-    if (!_PyArg_ParseStackAndKeywords(args, nargs, kwnames, &_parser,
-        &follow_symlinks)) {
+    args = _PyArg_UnpackKeywords(args, nargs, NULL, kwnames, &_parser, 0, 0, 0, argsbuf);
+    if (!args) {
         goto exit;
     }
+    if (!noptargs) {
+        goto skip_optional_kwonly;
+    }
+    follow_symlinks = PyObject_IsTrue(args[0]);
+    if (follow_symlinks < 0) {
+        goto exit;
+    }
+skip_optional_kwonly:
     _return_value = os_DirEntry_is_file_impl(self, defining_class, follow_symlinks);
     if ((_return_value == -1) && PyErr_Occurred()) {
         goto exit;
@@ -9441,4 +9469,4 @@ exit:
 #ifndef OS_WAITSTATUS_TO_EXITCODE_METHODDEF
     #define OS_WAITSTATUS_TO_EXITCODE_METHODDEF
 #endif /* !defined(OS_WAITSTATUS_TO_EXITCODE_METHODDEF) */
-/*[clinic end generated code: output=c7c8796918b09139 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=08879489d9e259a1 input=a9049054013a1b77]*/
diff --git a/Tools/clinic/clinic.py b/Tools/clinic/clinic.py
index 61d30b0..655e386 100755
--- a/Tools/clinic/clinic.py
+++ b/Tools/clinic/clinic.py
@@ -636,6 +636,10 @@ class CLanguage(Language):
         assert parameters
         assert isinstance(parameters[0].converter, self_converter)
         del parameters[0]
+        requires_defining_class = False
+        if parameters and isinstance(parameters[0].converter, defining_class_converter):
+            requires_defining_class = True
+            del parameters[0]
         converters = [p.converter for p in parameters]
 
         has_option_groups = parameters and (parameters[0].group or parameters[-1].group)
@@ -657,10 +661,6 @@ class CLanguage(Language):
                 if not p.is_optional():
                     min_pos = i
 
-        requires_defining_class = any(
-            isinstance(p.converter, defining_class_converter)
-            for p in parameters)
-
         meth_o = (len(parameters) == 1 and
               parameters[0].is_positional_only() and
               not converters[0].is_optional() and
@@ -763,24 +763,40 @@ class CLanguage(Language):
             return linear_format(output(), parser_declarations=declarations)
 
         if not parameters:
-            # no parameters, METH_NOARGS
+            if not requires_defining_class:
+                # no parameters, METH_NOARGS
+                flags = "METH_NOARGS"
 
-            flags = "METH_NOARGS"
+                parser_prototype = normalize_snippet("""
+                    static PyObject *
+                    {c_basename}({self_type}{self_name}, PyObject *Py_UNUSED(ignored))
+                    """)
+                parser_code = []
 
-            parser_prototype = normalize_snippet("""
-                static PyObject *
-                {c_basename}({self_type}{self_name}, PyObject *Py_UNUSED(ignored))
-                """)
-            parser_definition = parser_prototype
+            else:
+                assert not new_or_init
 
-            if default_return_converter:
-                parser_definition = parser_prototype + '\n' + normalize_snippet("""
-                    {{
-                        return {c_basename}_impl({impl_arguments});
+                flags = "METH_METHOD|METH_FASTCALL|METH_KEYWORDS"
+
+                parser_prototype = parser_prototype_def_class
+                return_error = ('return NULL;' if default_return_converter
+                                else 'goto exit;')
+                parser_code = [normalize_snippet("""
+                    if (nargs) {{
+                        PyErr_SetString(PyExc_TypeError, "{name}() takes no arguments");
+                        %s
                     }}
-                    """)
+                    """ % return_error, indent=4)]
+
+            if default_return_converter:
+                parser_definition = '\n'.join([
+                    parser_prototype,
+                    '{{',
+                    *parser_code,
+                    '    return {c_basename}_impl({impl_arguments});',
+                    '}}'])
             else:
-                parser_definition = parser_body(parser_prototype)
+                parser_definition = parser_body(parser_prototype, *parser_code)
 
         elif meth_o:
             flags = "METH_O"
@@ -939,6 +955,9 @@ class CLanguage(Language):
 
             add_label = None
             for i, p in enumerate(parameters):
+                if isinstance(p.converter, defining_class_converter):
+                    raise ValueError("defining_class should be the first "
+                                     "parameter (after self)")
                 displayname = p.get_displayname(i+1)
                 parsearg = p.converter.parse_arg(argname_fmt % i, displayname)
                 if parsearg is None: