bpo-40989: PyObject_INIT() becomes an alias to PyObject_Init() (GH-20901)

The PyObject_INIT() and PyObject_INIT_VAR() macros become aliases to,
respectively, PyObject_Init() and PyObject_InitVar() functions.

Rename _PyObject_INIT() and _PyObject_INIT_VAR() static inline
functions to, respectively, _PyObject_Init() and _PyObject_InitVar(),
and move them to pycore_object.h. Remove their return value:
their return type becomes void.

The _datetime module is now built with the Py_BUILD_CORE_MODULE macro
defined.

Remove an outdated comment on _Py_tracemalloc_config.

Objects/bytesobject.c

@@ -79,9 +79,10 @@ _PyBytes_FromSize(Py_ssize_t size, int use_calloc)
         op = (PyBytesObject *)PyObject_Calloc(1, PyBytesObject_SIZE + size);
     else
         op = (PyBytesObject *)PyObject_Malloc(PyBytesObject_SIZE + size);
-    if (op == NULL)
+    if (op == NULL) {
         return PyErr_NoMemory();
-    (void)PyObject_INIT_VAR(op, &PyBytes_Type, size);
+    }
+    _PyObject_InitVar((PyVarObject*)op, &PyBytes_Type, size);
     op->ob_shash = -1;
     if (!use_calloc)
         op->ob_sval[size] = '\0';
@@ -148,9 +149,10 @@ PyBytes_FromString(const char *str)
 
     /* Inline PyObject_NewVar */
     op = (PyBytesObject *)PyObject_MALLOC(PyBytesObject_SIZE + size);
-    if (op == NULL)
+    if (op == NULL) {
         return PyErr_NoMemory();
-    (void)PyObject_INIT_VAR(op, &PyBytes_Type, size);
+    }
+    _PyObject_InitVar((PyVarObject*)op, &PyBytes_Type, size);
     op->ob_shash = -1;
     memcpy(op->ob_sval, str, size+1);
     /* share short strings */
@@ -1435,9 +1437,10 @@ bytes_repeat(PyBytesObject *a, Py_ssize_t n)
         return NULL;
     }
     op = (PyBytesObject *)PyObject_MALLOC(PyBytesObject_SIZE + nbytes);
-    if (op == NULL)
+    if (op == NULL) {
         return PyErr_NoMemory();
-    (void)PyObject_INIT_VAR(op, &PyBytes_Type, size);
+    }
+    _PyObject_InitVar((PyVarObject*)op, &PyBytes_Type, size);
     op->ob_shash = -1;
     op->ob_sval[size] = '\0';
     if (Py_SIZE(a) == 1 && n > 0) {

Objects/complexobject.c

@@ -6,8 +6,10 @@
 /* Submitted by Jim Hugunin */
 
 #include "Python.h"
+#include "pycore_object.h"        // _PyObject_Init()
 #include "structmember.h"         // PyMemberDef
 
+
 /*[clinic input]
 class complex "PyComplexObject *" "&PyComplex_Type"
 [clinic start generated code]*/
@@ -229,13 +231,12 @@ complex_subtype_from_c_complex(PyTypeObject *type, Py_complex cval)
 PyObject *
 PyComplex_FromCComplex(Py_complex cval)
 {
-    PyComplexObject *op;
-
     /* Inline PyObject_New */
-    op = (PyComplexObject *) PyObject_MALLOC(sizeof(PyComplexObject));
-    if (op == NULL)
+    PyComplexObject *op = PyObject_MALLOC(sizeof(PyComplexObject));
+    if (op == NULL) {
         return PyErr_NoMemory();
-    (void)PyObject_INIT(op, &PyComplex_Type);
+    }
+    _PyObject_Init((PyObject*)op, &PyComplex_Type);
     op->cval = cval;
     return (PyObject *) op;
 }

Objects/floatobject.c

@@ -4,8 +4,9 @@
    for any kind of float exception without losing portability. */
 
 #include "Python.h"
-#include "pycore_dtoa.h"
+#include "pycore_dtoa.h"          // _Py_dg_dtoa()
 #include "pycore_interp.h"        // _PyInterpreterState.float_state
+#include "pycore_object.h"        // _PyObject_Init()
 #include "pycore_pystate.h"       // _PyInterpreterState_GET()
 
 #include <ctype.h>
@@ -129,7 +130,7 @@ PyFloat_FromDouble(double fval)
             return PyErr_NoMemory();
         }
     }
-    (void)PyObject_INIT(op, &PyFloat_Type);
+    _PyObject_Init((PyObject*)op, &PyFloat_Type);
     op->ob_fval = fval;
     return (PyObject *) op;
 }

Objects/longobject.c

@@ -5,6 +5,7 @@
 #include "Python.h"
 #include "pycore_bitutils.h"      // _Py_popcount32()
 #include "pycore_interp.h"        // _PY_NSMALLPOSINTS
+#include "pycore_object.h"        // _PyObject_InitVar()
 #include "pycore_pystate.h"       // _Py_IsMainInterpreter()
 #include "longintrepr.h"
 
@@ -146,7 +147,8 @@ _PyLong_New(Py_ssize_t size)
         PyErr_NoMemory();
         return NULL;
     }
-    return (PyLongObject*)PyObject_INIT_VAR(result, &PyLong_Type, size);
+    _PyObject_InitVar((PyVarObject*)result, &PyLong_Type, size);
+    return result;
 }
 
 PyObject *

Objects/object.c

@@ -139,23 +139,23 @@ Py_DecRef(PyObject *o)
 PyObject *
 PyObject_Init(PyObject *op, PyTypeObject *tp)
 {
-    /* Any changes should be reflected in PyObject_INIT() macro */
     if (op == NULL) {
         return PyErr_NoMemory();
     }
 
-    return PyObject_INIT(op, tp);
+    _PyObject_Init(op, tp);
+    return op;
 }
 
 PyVarObject *
 PyObject_InitVar(PyVarObject *op, PyTypeObject *tp, Py_ssize_t size)
 {
-    /* Any changes should be reflected in PyObject_INIT_VAR() macro */
     if (op == NULL) {
         return (PyVarObject *) PyErr_NoMemory();
     }
 
-    return PyObject_INIT_VAR(op, tp, size);
+    _PyObject_InitVar(op, tp, size);
+    return op;
 }
 
 PyObject *
@@ -165,7 +165,7 @@ _PyObject_New(PyTypeObject *tp)
     if (op == NULL) {
         return PyErr_NoMemory();
     }
-    PyObject_INIT(op, tp);
+    _PyObject_Init(op, tp);
     return op;
 }
 
@@ -175,9 +175,11 @@ _PyObject_NewVar(PyTypeObject *tp, Py_ssize_t nitems)
     PyVarObject *op;
     const size_t size = _PyObject_VAR_SIZE(tp, nitems);
     op = (PyVarObject *) PyObject_MALLOC(size);
-    if (op == NULL)
+    if (op == NULL) {
         return (PyVarObject *)PyErr_NoMemory();
-    return PyObject_INIT_VAR(op, tp, nitems);
+    }
+    _PyObject_InitVar(op, tp, nitems);
+    return op;
 }
 
 void

Objects/tupleobject.c

@@ -62,7 +62,7 @@ tuple_alloc(struct _Py_tuple_state *state, Py_ssize_t size)
         assert(size != 0);
         state->free_list[size] = (PyTupleObject *) op->ob_item[0];
         state->numfree[size]--;
-        /* Inline PyObject_InitVar */
+        /* Inlined _PyObject_InitVar() without _PyType_HasFeature() test */
 #ifdef Py_TRACE_REFS
         Py_SET_SIZE(op, size);
         Py_SET_TYPE(op, &PyTuple_Type);

Objects/typeobject.c

@@ -1060,10 +1060,10 @@ PyType_GenericAlloc(PyTypeObject *type, Py_ssize_t nitems)
     memset(obj, '\0', size);
 
     if (type->tp_itemsize == 0) {
-        (void)PyObject_INIT(obj, type);
+        _PyObject_Init(obj, type);
     }
     else {
-        (void) PyObject_INIT_VAR((PyVarObject *)obj, type, nitems);
+        _PyObject_InitVar((PyVarObject *)obj, type, nitems);
     }
 
     if (_PyType_IS_GC(type)) {

Objects/unicodeobject.c

@@ -1435,11 +1435,10 @@ PyUnicode_New(Py_ssize_t size, Py_UCS4 maxchar)
      * it's data buffer.
      */
     obj = (PyObject *) PyObject_MALLOC(struct_size + (size + 1) * char_size);
-    if (obj == NULL)
+    if (obj == NULL) {
         return PyErr_NoMemory();
-    obj = PyObject_INIT(obj, &PyUnicode_Type);
-    if (obj == NULL)
-        return NULL;
+    }
+    _PyObject_Init(obj, &PyUnicode_Type);
 
     unicode = (PyCompactUnicodeObject *)obj;
     if (is_ascii)
@@ -8392,9 +8391,11 @@ PyUnicode_BuildEncodingMap(PyObject* string)
     /* Create a three-level trie */
     result = PyObject_MALLOC(sizeof(struct encoding_map) +
                              16*count2 + 128*count3 - 1);
-    if (!result)
+    if (!result) {
         return PyErr_NoMemory();
-    PyObject_Init(result, &EncodingMapType);
+    }
+
+    _PyObject_Init(result, &EncodingMapType);
     mresult = (struct encoding_map*)result;
     mresult->count2 = count2;
     mresult->count3 = count3;