gh-119740: Remove deprecated trunc delegation (#119743)

Remove the delegation of `int` to the `__trunc__` special method: `int` will now only delegate to `__int__` and `__index__` (in that order). `__trunc__` continues to exist, but its sole purpose is to support `math.trunc`.

---------

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

3 files changed, 12 insertions, 11 deletions

diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index 7291461..4617767 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1004,9 +1004,8 @@ are always available.  They are listed here in alphabetical order.
       115
 
    If the argument defines :meth:`~object.__int__`,
-   ``int(x)`` returns ``x.__int__()``.  If the argument defines :meth:`~object.__index__`,
-   it returns ``x.__index__()``.  If the argument defines :meth:`~object.__trunc__`,
-   it returns ``x.__trunc__()``.
+   ``int(x)`` returns ``x.__int__()``.  If the argument defines
+   :meth:`~object.__index__`, it returns ``x.__index__()``.
    For floating point numbers, this truncates towards zero.
 
    If the argument is not a number or if *base* is given, then it must be a string,
@@ -1045,9 +1044,6 @@ are always available.  They are listed here in alphabetical order.
       Falls back to :meth:`~object.__index__` if :meth:`~object.__int__` is not defined.
 
    .. versionchanged:: 3.11
-      The delegation to :meth:`~object.__trunc__` is deprecated.
-
-   .. versionchanged:: 3.11
       :class:`int` string inputs and string representations can be limited to
       help avoid denial of service attacks. A :exc:`ValueError` is raised when
       the limit is exceeded while converting a string to an :class:`int` or
@@ -1055,6 +1051,9 @@ are always available.  They are listed here in alphabetical order.
       See the :ref:`integer string conversion length limitation
       <int_max_str_digits>` documentation.
 
+   .. versionchanged:: 3.14
+      :func:`int` no longer delegates to the :meth:`~object.__trunc__` method.
+
 .. function:: isinstance(object, classinfo)
 
    Return ``True`` if the *object* argument is an instance of the *classinfo*
diff --git a/Doc/reference/datamodel.rst b/Doc/reference/datamodel.rst
index 9110060..af4c585 100644
--- a/Doc/reference/datamodel.rst
+++ b/Doc/reference/datamodel.rst
@@ -3127,11 +3127,8 @@ left undefined.
    return the value of the object truncated to an :class:`~numbers.Integral`
    (typically an :class:`int`).
 
-   The built-in function :func:`int` falls back to :meth:`__trunc__` if neither
-   :meth:`__int__` nor :meth:`__index__` is defined.
-
-   .. versionchanged:: 3.11
-      The delegation of :func:`int` to :meth:`__trunc__` is deprecated.
+   .. versionchanged:: 3.14
+      :func:`int` no longer delegates to the :meth:`~object.__trunc__` method.
 
 
 .. _context-managers:
diff --git a/Doc/whatsnew/3.14.rst b/Doc/whatsnew/3.14.rst
index 45ffb28..9f471d2 100644
--- a/Doc/whatsnew/3.14.rst
+++ b/Doc/whatsnew/3.14.rst
@@ -225,6 +225,11 @@ Others
   It had previously raised a :exc:`DeprecationWarning` since Python 3.9. (Contributed
   by Jelle Zijlstra in :gh:`118767`.)
 
+* The :func:`int` built-in no longer delegates to
+  :meth:`~object.__trunc__`. Classes that want to support conversion to
+  integer must implement either :meth:`~object.__int__` or
+  :meth:`~object.__index__`. (Contributed by Mark Dickinson in :gh:`119743`.)
+
 
 Porting to Python 3.14
 ======================