bpo-45325: Add a new 'p' parameter to Py_BuildValue to convert an integer into a Python bool

Author: pablogsal

Doc/c-api/arg.rst

@@ -616,6 +616,11 @@ Building values
    ``n`` (:class:`int`) [Py_ssize_t]
       Convert a C :c:type:`Py_ssize_t` to a Python integer.
 
+   ``p`` (:class:`int`) [int]
+      Convert a C :c:type:`int` to a Python :class:`bool` object.
+
+      .. versionadded:: 3.11
+
    ``c`` (:class:`bytes` of length 1) [char]
       Convert a C :c:type:`int` representing a byte to a Python :class:`bytes` object of
       length 1.

Doc/whatsnew/3.11.rst

@@ -455,6 +455,10 @@ New Features
 * Add a new :c:func:`PyType_GetQualName` function to get type's qualified name.
   (Contributed by Hai Shi in :issue:`42035`.)
 
+* Add a new ``p`` format parameter to :c:func:`Py_BuildValue` that allows to
+  take a C integer and produce a Python :class:`bool` object. (Contributed by
+  Pablo Galindo in :issue:`45325`.)
+
 Porting to Python 3.11
 ----------------------
 

Lib/test/test_capi.py

@@ -295,6 +295,9 @@ def test_getitem_with_error(self):
     def test_buildvalue_N(self):
         _testcapi.test_buildvalue_N()
 
+    def test_buildvalue_P(self):
+        _testcapi.test_buildvalue_p()
+
     def test_set_nomemory(self):
         code = """if 1:
             import _testcapi

Misc/NEWS.d/next/C API/2021-09-29-19-20-07.bpo-45325.Cwif9z.rst

@@ -0,0 +1,3 @@
+Add a new ``p`` format parameter to :c:func:`Py_BuildValue` that allows to
+take a C integer and produce a Python :class:`bool` object. Patch by Pablo
+Galindo.

Modules/_testcapimodule.c

@@ -1039,6 +1039,32 @@ test_buildvalue_N_error(const char *fmt)
     return 0;
 }
 
+static PyObject *
+test_buildvalue_p(PyObject *self, PyObject *Py_UNUSED(ignored))
+{
+    PyObject *res = Py_BuildValue("p",  3);
+    if (res == NULL) {
+        return NULL;
+    }
+    if (!Py_IsTrue(res)) {
+        Py_DECREF(res);
+        return raiseTestError("test_buildvalue_p", "Py_BuildValue(\"p\", 3) returned wrong result");
+    }
+    Py_DECREF(res);
+
+    res = Py_BuildValue("p",  0);
+    if (res == NULL) {
+        return NULL;
+    }
+    if (!Py_IsFalse(res)) {
+        Py_DECREF(res);
+        return raiseTestError("test_buildvalue_p", "Py_BuildValue(\"p\", 0) returned wrong result");
+    }
+    Py_DECREF(res);
+
+    Py_RETURN_NONE;
+} 
+
 static PyObject *
 test_buildvalue_N(PyObject *self, PyObject *Py_UNUSED(ignored))
 {
@@ -5717,6 +5743,7 @@ static PyMethodDef TestMethods[] = {
 #endif
     {"getbuffer_with_null_view", getbuffer_with_null_view, METH_O},
     {"PyBuffer_SizeFromFormat",  test_PyBuffer_SizeFromFormat, METH_VARARGS},
+    {"test_buildvalue_p",       test_buildvalue_p,               METH_NOARGS},
     {"test_buildvalue_N",       test_buildvalue_N,               METH_NOARGS},
     {"test_buildvalue_issue38913", test_buildvalue_issue38913,   METH_NOARGS},
     {"get_args",                get_args,                        METH_VARARGS},

Python/modsupport.c

@@ -389,7 +389,11 @@ do_mkvalue(const char **p_format, va_list *p_va, int flags)
             int i = va_arg(*p_va, int);
             return PyUnicode_FromOrdinal(i);
         }
-
+        case 'p':
+        {
+            int i = va_arg(*p_va, int);
+            return PyBool_FromLong(i);
+        }
         case 's':
         case 'z':
         case 'U':   /* XXX deprecated alias */