bpo-35582: Argument Clinic: Optimize the "all boring objects" case. (GH-11520)

Use _PyArg_CheckPositional() and inlined code instead of
PyArg_UnpackTuple() and _PyArg_UnpackStack() if all parameters
are positional and use the "object" converter.

Author: serhiy-storchaka

Lib/test/clinic.test

@@ -106,11 +106,15 @@ test_objects_converter(PyObject *module, PyObject *const *args, Py_ssize_t nargs
     PyObject *a;
     PyObject *b = NULL;
 
-    if (!_PyArg_UnpackStack(args, nargs, "test_objects_converter",
-        1, 2,
-        &a, &b)) {
+    if (!_PyArg_CheckPositional("test_objects_converter", nargs, 1, 2)) {
         goto exit;
     }
+    a = args[0];
+    if (nargs < 2) {
+        goto skip_optional;
+    }
+    b = args[1];
+skip_optional:
     return_value = test_objects_converter_impl(module, a, b);
 
 exit:
@@ -119,7 +123,7 @@ exit:
 
 static PyObject *
 test_objects_converter_impl(PyObject *module, PyObject *a, PyObject *b)
-/*[clinic end generated code: output=068c25d6ae8cd1ef input=4cbb3d9edd2a36f3]*/
+/*[clinic end generated code: output=58009c0e42b4834e input=4cbb3d9edd2a36f3]*/
 
 /*[clinic input]
 test_object_converter_subclass_of

Modules/_io/clinic/bufferedio.c.h

@@ -389,11 +389,14 @@ _io__Buffered_truncate(buffered *self, PyObject *const *args, Py_ssize_t nargs)
     PyObject *return_value = NULL;
     PyObject *pos = Py_None;
 
-    if (!_PyArg_UnpackStack(args, nargs, "truncate",
-        0, 1,
-        &pos)) {
+    if (!_PyArg_CheckPositional("truncate", nargs, 0, 1)) {
         goto exit;
     }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    pos = args[0];
+skip_optional:
     return_value = _io__Buffered_truncate_impl(self, pos);
 
 exit:
@@ -591,4 +594,4 @@ _io_BufferedRandom___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=a85f61f495feff5c input=a9049054013a1b77]*/
+/*[clinic end generated code: output=b7f51040defff318 input=a9049054013a1b77]*/

Modules/_io/clinic/bytesio.c.h

@@ -282,11 +282,14 @@ _io_BytesIO_readlines(bytesio *self, PyObject *const *args, Py_ssize_t nargs)
     PyObject *return_value = NULL;
     PyObject *arg = Py_None;
 
-    if (!_PyArg_UnpackStack(args, nargs, "readlines",
-        0, 1,
-        &arg)) {
+    if (!_PyArg_CheckPositional("readlines", nargs, 0, 1)) {
         goto exit;
     }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    arg = args[0];
+skip_optional:
     return_value = _io_BytesIO_readlines_impl(self, arg);
 
 exit:
@@ -503,4 +506,4 @@ _io_BytesIO___init__(PyObject *self, PyObject *args, PyObject *kwargs)
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=5c68eb481fa960bf input=a9049054013a1b77]*/
+/*[clinic end generated code: output=a6b47dd7921abfcd input=a9049054013a1b77]*/

Modules/_io/clinic/fileio.c.h

@@ -368,11 +368,14 @@ _io_FileIO_truncate(fileio *self, PyObject *const *args, Py_ssize_t nargs)
     PyObject *return_value = NULL;
     PyObject *posobj = NULL;
 
-    if (!_PyArg_UnpackStack(args, nargs, "truncate",
-        0, 1,
-        &posobj)) {
+    if (!_PyArg_CheckPositional("truncate", nargs, 0, 1)) {
         goto exit;
     }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    posobj = args[0];
+skip_optional:
     return_value = _io_FileIO_truncate_impl(self, posobj);
 
 exit:
@@ -402,4 +405,4 @@ _io_FileIO_isatty(fileio *self, PyObject *Py_UNUSED(ignored))
 #ifndef _IO_FILEIO_TRUNCATE_METHODDEF
     #define _IO_FILEIO_TRUNCATE_METHODDEF
 #endif /* !defined(_IO_FILEIO_TRUNCATE_METHODDEF) */
-/*[clinic end generated code: output=4cf4e5f0cd656b11 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=b6f327457938d4dd input=a9049054013a1b77]*/

Modules/_io/clinic/textio.c.h

@@ -419,11 +419,14 @@ _io_TextIOWrapper_truncate(textio *self, PyObject *const *args, Py_ssize_t nargs
     PyObject *return_value = NULL;
     PyObject *pos = Py_None;
 
-    if (!_PyArg_UnpackStack(args, nargs, "truncate",
-        0, 1,
-        &pos)) {
+    if (!_PyArg_CheckPositional("truncate", nargs, 0, 1)) {
         goto exit;
     }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    pos = args[0];
+skip_optional:
     return_value = _io_TextIOWrapper_truncate_impl(self, pos);
 
 exit:
@@ -548,4 +551,4 @@ _io_TextIOWrapper_close(textio *self, PyObject *Py_UNUSED(ignored))
 {
     return _io_TextIOWrapper_close_impl(self);
 }
-/*[clinic end generated code: output=8bdd1035bf878d6f input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c3d1b2a5d2d2d429 input=a9049054013a1b77]*/

Modules/cjkcodecs/clinic/multibytecodec.c.h

@@ -296,11 +296,14 @@ _multibytecodec_MultibyteStreamReader_read(MultibyteStreamReaderObject *self, Py
     PyObject *return_value = NULL;
     PyObject *sizeobj = Py_None;
 
-    if (!_PyArg_UnpackStack(args, nargs, "read",
-        0, 1,
-        &sizeobj)) {
+    if (!_PyArg_CheckPositional("read", nargs, 0, 1)) {
         goto exit;
     }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    sizeobj = args[0];
+skip_optional:
     return_value = _multibytecodec_MultibyteStreamReader_read_impl(self, sizeobj);
 
 exit:
@@ -325,11 +328,14 @@ _multibytecodec_MultibyteStreamReader_readline(MultibyteStreamReaderObject *self
     PyObject *return_value = NULL;
     PyObject *sizeobj = Py_None;
 
-    if (!_PyArg_UnpackStack(args, nargs, "readline",
-        0, 1,
-        &sizeobj)) {
+    if (!_PyArg_CheckPositional("readline", nargs, 0, 1)) {
         goto exit;
     }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    sizeobj = args[0];
+skip_optional:
     return_value = _multibytecodec_MultibyteStreamReader_readline_impl(self, sizeobj);
 
 exit:
@@ -354,11 +360,14 @@ _multibytecodec_MultibyteStreamReader_readlines(MultibyteStreamReaderObject *sel
     PyObject *return_value = NULL;
     PyObject *sizehintobj = Py_None;
 
-    if (!_PyArg_UnpackStack(args, nargs, "readlines",
-        0, 1,
-        &sizehintobj)) {
+    if (!_PyArg_CheckPositional("readlines", nargs, 0, 1)) {
         goto exit;
     }
+    if (nargs < 1) {
+        goto skip_optional;
+    }
+    sizehintobj = args[0];
+skip_optional:
     return_value = _multibytecodec_MultibyteStreamReader_readlines_impl(self, sizehintobj);
 
 exit:
@@ -422,4 +431,4 @@ PyDoc_STRVAR(_multibytecodec___create_codec__doc__,
 
 #define _MULTIBYTECODEC___CREATE_CODEC_METHODDEF    \
     {"__create_codec", (PyCFunction)_multibytecodec___create_codec, METH_O, _multibytecodec___create_codec__doc__},
-/*[clinic end generated code: output=2ed7030b28a79029 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=bcd6311010557faf input=a9049054013a1b77]*/