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Remove an outdated comment on _Py_tracemalloc_config.

Include/cpython/objimpl.h

@@ -37,8 +37,9 @@
        PyObject *op;
 
        op = (PyObject *) Your_Allocator(_PyObject_SIZE(YourTypeStruct));
-       if (op == NULL)
-       return PyErr_NoMemory();
+       if (op == NULL) {
+           return PyErr_NoMemory();
+       }
 
        PyObject_Init(op, &YourTypeStruct);
 
@@ -51,40 +52,6 @@
    the 1st step is performed automatically for you, so in a C++ class
    constructor you would start directly with PyObject_Init/InitVar. */
 
-
-/* Inline functions trading binary compatibility for speed:
-   PyObject_INIT() is the fast version of PyObject_Init(), and
-   PyObject_INIT_VAR() is the fast version of PyObject_InitVar().
-
-   These inline functions must not be called with op=NULL. */
-static inline PyObject*
-_PyObject_INIT(PyObject *op, PyTypeObject *typeobj)
-{
-    assert(op != NULL);
-    Py_SET_TYPE(op, typeobj);
-    if (PyType_GetFlags(typeobj) & Py_TPFLAGS_HEAPTYPE) {
-        Py_INCREF(typeobj);
-    }
-    _Py_NewReference(op);
-    return op;
-}
-
-#define PyObject_INIT(op, typeobj) \
-    _PyObject_INIT(_PyObject_CAST(op), (typeobj))
-
-static inline PyVarObject*
-_PyObject_INIT_VAR(PyVarObject *op, PyTypeObject *typeobj, Py_ssize_t size)
-{
-    assert(op != NULL);
-    Py_SET_SIZE(op, size);
-    PyObject_INIT((PyObject *)op, typeobj);
-    return op;
-}
-
-#define PyObject_INIT_VAR(op, typeobj, size) \
-    _PyObject_INIT_VAR(_PyVarObject_CAST(op), (typeobj), (size))
-
-
 /* This function returns the number of allocated memory blocks, regardless of size */
 PyAPI_FUNC(Py_ssize_t) _Py_GetAllocatedBlocks(void);
 

Include/internal/pycore_object.h

@@ -15,6 +15,37 @@ extern "C" {
 PyAPI_FUNC(int) _PyType_CheckConsistency(PyTypeObject *type);
 PyAPI_FUNC(int) _PyDict_CheckConsistency(PyObject *mp, int check_content);
 
+// Fast inlined version of PyType_HasFeature()
+static inline int
+_PyType_HasFeature(PyTypeObject *type, unsigned long feature) {
+    return ((type->tp_flags & feature) != 0);
+}
+
+/* Inline functions trading binary compatibility for speed:
+   _PyObject_Init() is the fast version of PyObject_Init(), and
+   _PyObject_InitVar() is the fast version of PyObject_InitVar().
+
+   These inline functions must not be called with op=NULL. */
+static inline void
+_PyObject_Init(PyObject *op, PyTypeObject *typeobj)
+{
+    assert(op != NULL);
+    Py_SET_TYPE(op, typeobj);
+    if (_PyType_HasFeature(typeobj, Py_TPFLAGS_HEAPTYPE)) {
+        Py_INCREF(typeobj);
+    }
+    _Py_NewReference(op);
+}
+
+static inline void
+_PyObject_InitVar(PyVarObject *op, PyTypeObject *typeobj, Py_ssize_t size)
+{
+    assert(op != NULL);
+    Py_SET_SIZE(op, size);
+    _PyObject_Init((PyObject *)op, typeobj);
+}
+
+
 /* Tell the GC to track this object.
  *
  * NB: While the object is tracked by the collector, it must be safe to call the
@@ -96,12 +127,6 @@ _PyObject_GET_WEAKREFS_LISTPTR(PyObject *op)
     return (PyObject **)((char *)op + offset);
 }
 
-// Fast inlined version of PyType_HasFeature()
-static inline int
-_PyType_HasFeature(PyTypeObject *type, unsigned long feature) {
-    return ((type->tp_flags & feature) != 0);
-}
-
 // Fast inlined version of PyObject_IS_GC()
 static inline int
 _PyObject_IS_GC(PyObject *obj)

Include/internal/pycore_pymem.h

@@ -69,9 +69,6 @@ PyAPI_FUNC(int) _PyMem_GetAllocatorName(
    PYMEM_ALLOCATOR_NOT_SET does nothing. */
 PyAPI_FUNC(int) _PyMem_SetupAllocators(PyMemAllocatorName allocator);
 
-/* bpo-35053: Expose _Py_tracemalloc_config for _Py_NewReference()
-   which access directly _Py_tracemalloc_config.tracing for best
-   performances. */
 struct _PyTraceMalloc_Config {
     /* Module initialized?
        Variable protected by the GIL */

Include/objimpl.h

@@ -118,7 +118,14 @@ PyAPI_FUNC(void) PyObject_Free(void *ptr);
 /* Functions */
 PyAPI_FUNC(PyObject *) PyObject_Init(PyObject *, PyTypeObject *);
 PyAPI_FUNC(PyVarObject *) PyObject_InitVar(PyVarObject *,
-                                                 PyTypeObject *, Py_ssize_t);
+                                           PyTypeObject *, Py_ssize_t);
+
+#define PyObject_INIT(op, typeobj) \
+    PyObject_Init(_PyObject_CAST(op), (typeobj))
+#define PyObject_INIT_VAR(op, typeobj, size) \
+    PyObject_InitVar(_PyVarObject_CAST(op), (typeobj), (size))
+
+
 PyAPI_FUNC(PyObject *) _PyObject_New(PyTypeObject *);
 PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t);
 
@@ -136,19 +143,6 @@ PyAPI_FUNC(PyVarObject *) _PyObject_NewVar(PyTypeObject *, Py_ssize_t);
 #define PyObject_NEW_VAR(type, typeobj, n) PyObject_NewVar(type, typeobj, n)
 
 
-#ifdef Py_LIMITED_API
-/* Define PyObject_INIT() and PyObject_INIT_VAR() as aliases to PyObject_Init()
-   and PyObject_InitVar() in the limited C API for compatibility with the
-   CPython C API. */
-#  define PyObject_INIT(op, typeobj) \
-        PyObject_Init(_PyObject_CAST(op), (typeobj))
-#  define PyObject_INIT_VAR(op, typeobj, size) \
-        PyObject_InitVar(_PyVarObject_CAST(op), (typeobj), (size))
-#else
-/* PyObject_INIT() and PyObject_INIT_VAR() are defined in cpython/objimpl.h */
-#endif
-
-
 /*
  * Garbage Collection Support
  * ==========================