bpo-39489: Remove COUNT_ALLOCS special build (GH-18259)

Remove:

* COUNT_ALLOCS macro
* sys.getcounts() function
* SHOW_ALLOC_COUNT code in listobject.c
* SHOW_TRACK_COUNT code in tupleobject.c
* PyConfig.show_alloc_count field
* -X showalloccount command line option
* @test.support.requires_type_collecting decorator

4 files changed, 15 insertions, 45 deletions

diff --git a/Doc/c-api/init_config.rst b/Doc/c-api/init_config.rst
index 108bd2c..c589a6f 100644
--- a/Doc/c-api/init_config.rst
+++ b/Doc/c-api/init_config.rst
@@ -627,14 +627,6 @@ PyConfig
 
       ``python3 -m MODULE`` argument. Used by :c:func:`Py_RunMain`.
 
-   .. c:member:: int show_alloc_count
-
-      Show allocation counts at exit?
-
-      Set to 1 by :option:`-X showalloccount <-X>` command line option.
-
-      Need a special Python build with ``COUNT_ALLOCS`` macro defined.
-
    .. c:member:: int show_ref_count
 
       Show total reference count at exit?
@@ -702,6 +694,10 @@ arguments are stripped from ``argv``: see :ref:`Command Line Arguments
 The ``xoptions`` options are parsed to set other options: see :option:`-X`
 option.
 
+.. versionchanged:: 3.9
+
+   The ``show_alloc_count`` field has been removed.
+
 
 Initialization with PyConfig
 ----------------------------
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
index 7b205c0..a8a779e 100644
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -148,15 +148,6 @@ Quick Reference
    | :c:member:`~PyTypeObject.tp_vectorcall`        | :c:type:`vectorcallfunc`          |                   |   |   |   |   |
    +------------------------------------------------+-----------------------------------+-------------------+---+---+---+---+
 
-If :const:`COUNT_ALLOCS` is defined then the following (internal-only)
-fields exist as well:
-
-* :c:member:`~PyTypeObject.tp_allocs`
-* :c:member:`~PyTypeObject.tp_frees`
-* :c:member:`~PyTypeObject.tp_maxalloc`
-* :c:member:`~PyTypeObject.tp_prev`
-* :c:member:`~PyTypeObject.tp_next`
-
 .. [#slots]
    A slot name in parentheses indicates it is (effectively) deprecated.
    Names in angle brackets should be treated as read-only.
@@ -1904,31 +1895,6 @@ and :c:type:`PyType_Type` effectively act as defaults.)
    .. versionadded:: 3.9 (the field exists since 3.8 but it's only used since 3.9)
 
 
-The remaining fields are only defined if the feature test macro
-:const:`COUNT_ALLOCS` is defined, and are for internal use only. They are
-documented here for completeness.  None of these fields are inherited by
-subtypes.
-
-.. c:member:: Py_ssize_t PyTypeObject.tp_allocs
-
-   Number of allocations.
-
-.. c:member:: Py_ssize_t PyTypeObject.tp_frees
-
-   Number of frees.
-
-.. c:member:: Py_ssize_t PyTypeObject.tp_maxalloc
-
-   Maximum simultaneously allocated objects.
-
-.. c:member:: PyTypeObject* PyTypeObject.tp_prev
-
-   Pointer to the previous type object with a non-zero :c:member:`~PyTypeObject.tp_allocs` field.
-
-.. c:member:: PyTypeObject* PyTypeObject.tp_next
-
-   Pointer to the next type object with a non-zero :c:member:`~PyTypeObject.tp_allocs` field.
-
 Also, note that, in a garbage collected Python, :c:member:`~PyTypeObject.tp_dealloc` may be called from
 any Python thread, not just the thread which created the object (if the object
 becomes part of a refcount cycle, that cycle might be collected by a garbage
diff --git a/Doc/using/cmdline.rst b/Doc/using/cmdline.rst
index fb88673..2206e50 100644
--- a/Doc/using/cmdline.rst
+++ b/Doc/using/cmdline.rst
@@ -434,9 +434,6 @@ Miscellaneous options
      stored in a traceback of a trace. Use ``-X tracemalloc=NFRAME`` to start
      tracing with a traceback limit of *NFRAME* frames. See the
      :func:`tracemalloc.start` for more information.
-   * ``-X showalloccount`` to output the total count of allocated objects for
-     each type when the program finishes. This only works when Python was built with
-     ``COUNT_ALLOCS`` defined.
    * ``-X importtime`` to show how long each import takes. It shows module
      name, cumulative time (including nested imports) and self time (excluding
      nested imports).  Note that its output may be broken in multi-threaded
@@ -479,6 +476,8 @@ Miscellaneous options
       Using ``-X dev`` option, check *encoding* and *errors* arguments on
       string encoding and decoding operations.
 
+      The ``-X showalloccount`` option has been removed.
+
 
 Options you shouldn't use
 ~~~~~~~~~~~~~~~~~~~~~~~~~
diff --git a/Doc/whatsnew/3.9.rst b/Doc/whatsnew/3.9.rst
index 931f8bf..3b7a9d1 100644
--- a/Doc/whatsnew/3.9.rst
+++ b/Doc/whatsnew/3.9.rst
@@ -348,6 +348,9 @@ Build and C API Changes
   functions are now required to build Python.
   (Contributed by Victor Stinner in :issue:`39395`.)
 
+* The ``COUNT_ALLOCS`` special build macro has been removed.
+  (Contributed by Victor Stinner in :issue:`39489`.)
+
 
 Deprecated
 ==========
@@ -484,6 +487,12 @@ Removed
   ``asyncio.Condition`` and ``asyncio.Semaphore``.
   (Contributed by Andrew Svetlov in :issue:`34793`.)
 
+* The :func:`sys.getcounts` function, the ``-X showalloccount`` command line
+  option and the ``show_alloc_count`` field of the C structure
+  :c:type:`PyConfig` have been removed. They required a special Python build by
+  defining ``COUNT_ALLOCS`` macro.
+  (Contributed by Victor Stinner in :issue:`39489`.)
+
 
 Porting to Python 3.9
 =====================