Issue #20226: Major improvements to Argument Clinic.

* You may now specify an expression as the default value for a
  parameter!  Example: "sys.maxsize - 1".  This support is
  intentionally quite limited; you may only use values that
  can be represented as static C values.
* Removed "doc_default", simplified support for "c_default"
  and "py_default".  (I'm not sure we still even need
  "py_default", but I'm leaving it in for now in case a
  use presents itself.)
* Parameter lines support a trailing '\\' as a line
  continuation character, allowing you to break up long lines.
* The argument parsing code generated when supporting optional
  groups now uses PyTuple_GET_SIZE instead of PyTuple_GetSize,
  leading to a 850% speedup in parsing.  (Just kidding, this
  is an unmeasurable difference.)
* A bugfix for the recent regression where the generated
  prototype from pydoc for builtins would be littered with
  unreadable "=<object ...>"" default values for parameters
  that had no default value.
* Converted some asserts into proper failure messages.
* Many doc improvements and fixes.

6 files changed, 14 insertions, 12 deletions

diff --git a/Modules/_cursesmodule.c b/Modules/_cursesmodule.c
index 2a70337..9eaf09c 100644
--- a/Modules/_cursesmodule.c
+++ b/Modules/_cursesmodule.c
@@ -618,7 +618,7 @@ curses_window_addch(PyObject *self, PyObject *args)
     int group_right_1 = 0;
     long attr = 0;
 
-    switch (PyTuple_Size(args)) {
+    switch (PyTuple_GET_SIZE(args)) {
         case 1:
             if (!PyArg_ParseTuple(args, "O:addch", &ch))
                 return NULL;
@@ -650,7 +650,7 @@ curses_window_addch(PyObject *self, PyObject *args)
 
 static PyObject *
 curses_window_addch_impl(PyObject *self, int group_left_1, int x, int y, PyObject *ch, int group_right_1, long attr)
-/*[clinic end generated code: checksum=44ed958b891cde91205e584c766e048f3999714f]*/
+/*[clinic end generated code: checksum=b073327add8197b6ba7fb96c87062422c8312954]*/
 {
     PyCursesWindowObject *cwself = (PyCursesWindowObject *)self;
     int coordinates_group = group_left_1;
diff --git a/Modules/_dbmmodule.c b/Modules/_dbmmodule.c
index c9e16e3..d027e1c 100644
--- a/Modules/_dbmmodule.c
+++ b/Modules/_dbmmodule.c
@@ -297,7 +297,7 @@ dbm_dbm_get(PyObject *self, PyObject *args)
     int group_right_1 = 0;
     PyObject *default_value = NULL;
 
-    switch (PyTuple_Size(args)) {
+    switch (PyTuple_GET_SIZE(args)) {
         case 1:
             if (!PyArg_ParseTuple(args, "s#:get", &key, &key_length))
                 return NULL;
@@ -318,7 +318,7 @@ dbm_dbm_get(PyObject *self, PyObject *args)
 
 static PyObject *
 dbm_dbm_get_impl(dbmobject *dp, const char *key, Py_ssize_clean_t key_length, int group_right_1, PyObject *default_value)
-/*[clinic end generated code: checksum=28cf8928811bde51e535d67ae98ea039d79df717]*/
+/*[clinic end generated code: checksum=2c3209571267017f1b9abbd19e1b521849fd5d4a]*/
 {
     datum dbm_key, val;
 
@@ -450,7 +450,7 @@ dbm.open as dbmopen
     flags: str="r"
         How to open the file.  "r" for reading, "w" for writing, etc.
 
-    mode: int(doc_default="0o666") = 0o666
+    mode: int(py_default="0o666") = 0o666
         If creating a new file, the mode bits for the new file
         (e.g. os.O_RDWR).
 
diff --git a/Modules/_opcode.c b/Modules/_opcode.c
index fe7f8ab..2e84699 100644
--- a/Modules/_opcode.c
+++ b/Modules/_opcode.c
@@ -39,7 +39,7 @@ _opcode_stack_effect(PyModuleDef *module, PyObject *args)
     int oparg = 0;
     int _return_value;
 
-    switch (PyTuple_Size(args)) {
+    switch (PyTuple_GET_SIZE(args)) {
         case 1:
             if (!PyArg_ParseTuple(args, "i:stack_effect", &opcode))
                 return NULL;
@@ -64,7 +64,7 @@ exit:
 
 static int
 _opcode_stack_effect_impl(PyModuleDef *module, int opcode, int group_right_1, int oparg)
-/*[clinic end generated code: checksum=e880e62dc7b0de73403026eaf4f8074aa106358b]*/
+/*[clinic end generated code: checksum=47e76ec27523da4ab192713642d32482cd743aa4]*/
 {
     int effect;
     if (HAS_ARG(opcode)) {
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index b8fe8d5..4f4c69e 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -2870,7 +2870,7 @@ PyDoc_STRVAR(docstring_with_signature_and_extra_newlines,
 );
 
 PyDoc_STRVAR(docstring_with_signature_with_defaults,
-"docstring_with_signature_with_defaults(s='avocado', d=3.14, i=35, c=sys.maxsize, n=None, t=True, f=False)\n"
+"docstring_with_signature_with_defaults(s='avocado', b=b'bytes', d=3.14, i=35, n=None, t=True, f=False, local=the_number_three, sys=sys.maxsize, exp=sys.maxsize - 1)\n"
 "\n"
 "\n"
 "\n"
@@ -3317,6 +3317,8 @@ PyInit__testcapi(void)
     Py_INCREF(&PyInstanceMethod_Type);
     PyModule_AddObject(m, "instancemethod", (PyObject *)&PyInstanceMethod_Type);
 
+    PyModule_AddIntConstant(m, "the_number_three", 3);
+
     TestError = PyErr_NewException("_testcapi.error", NULL, NULL);
     Py_INCREF(TestError);
     PyModule_AddObject(m, "error", TestError);
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index f9dc735..0a3b250 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -2401,7 +2401,7 @@ class dir_fd_converter(CConverter):
 
 /*[clinic input]
 
-os.stat -> object(doc_default='stat_result')
+os.stat
 
     path : path_t(allow_fd=True)
         Path to be examined; can be string, bytes, or open-file-descriptor int.
@@ -2523,7 +2523,7 @@ posix_lstat(PyObject *self, PyObject *args, PyObject *kwargs)
     #define OS_ACCESS_DIR_FD_CONVERTER dir_fd_unavailable
 #endif
 /*[clinic input]
-os.access -> object(doc_default='True if granted, False otherwise')
+os.access
 
     path: path_t(allow_fd=True)
         Path to be tested; can be string, bytes, or open-file-descriptor int.
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index 575dbd2..59fc620 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -202,7 +202,7 @@ zlib_compress(PyModuleDef *module, PyObject *args)
     int group_right_1 = 0;
     int level = 0;
 
-    switch (PyTuple_Size(args)) {
+    switch (PyTuple_GET_SIZE(args)) {
         case 1:
             if (!PyArg_ParseTuple(args, "y*:compress", &bytes))
                 return NULL;
@@ -227,7 +227,7 @@ zlib_compress(PyModuleDef *module, PyObject *args)
 
 static PyObject *
 zlib_compress_impl(PyModuleDef *module, Py_buffer *bytes, int group_right_1, int level)
-/*[clinic end generated code: checksum=2c59af563a4595c5ecea4011701f482ae350aa5f]*/
+/*[clinic end generated code: checksum=66c4d16d0b8b9dd423648d9ef00d6a89d3363665]*/
 {
     PyObject *ReturnVal = NULL;
     Byte *input, *output = NULL;