gh-158077: Remove deprecated PySlice_GetIndicesEx() function

Only remove the function implementation. PySlice_GetIndicesEx()
remains available as a static inline function, so the API does not
change.

Convert PySlice_GetIndicesEx() macro to a static inline functions.
Arguments are now only evaluated once.

The function is no longer supported on limited C API older than
3.6.1.

Author: vstinner

Doc/c-api/slice.rst

@@ -68,9 +68,11 @@ Slice Objects
       is replaced by ::
 
          if (PySlice_Unpack(slice, &start, &stop, &step) < 0) {
-             // return error
+            slicelength = 0;
+            return -1;
          }
          slicelength = PySlice_AdjustIndices(length, &start, &stop, step);
+         return 0;
 
    .. versionchanged:: 3.2
       The parameter type for the *slice* parameter was ``PySliceObject*``
@@ -83,10 +85,9 @@ Slice Objects
       :c:func:`!PySlice_Unpack` and :c:func:`!PySlice_AdjustIndices`.
       Arguments *start*, *stop* and *step* are evaluated more than once.
 
-   .. deprecated:: 3.6.1
-      If ``Py_LIMITED_API`` is set to the value less than ``0x03050400`` or
-      between ``0x03060000`` and ``0x03060100`` (not including)
-      :c:func:`!PySlice_GetIndicesEx` is a deprecated function.
+   .. versionchanged:: next
+      :c:func:`!PySlice_GetIndicesEx` is now implemented as a static inline
+      function. Arguments are only evaluated once.
 
 
 .. c:function:: int PySlice_Unpack(PyObject *slice, Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step)

Doc/data/stable_abi.dat

@@ -16,8 +16,6 @@ although there is currently no date scheduled for their removal.
   Use :c:func:`PyModule_GetFilenameObject` instead.
 * :c:func:`PyOS_AfterFork`:
   Use :c:func:`PyOS_AfterFork_Child` instead.
-* :c:func:`PySlice_GetIndicesEx`:
-  Use :c:func:`PySlice_Unpack` and :c:func:`PySlice_AdjustIndices` instead.
 * :c:func:`PyUnicode_READY`:
   Unneeded since Python 3.12
 * :c:func:`!PyErr_Display`:

Doc/deprecations/c-api-pending-removal-in-future.rst

@@ -1128,6 +1128,11 @@ Deprecated C APIs
   and :c:func:`PyAsyncGen_New` are deprecated.
   They are scheduled for removal in 3.18.
 
+* Remove :c:func:`PySlice_GetIndicesEx` function, deprecated since Python 3.7.
+  Only remove the function implementation: :c:func:`PySlice_GetIndicesEx`
+  remains available as a static inline function, so the API does not change.
+  (Contributed by Victor Stinner in :gh:`158077`.)
+
 .. Add C API deprecations above alphabetically, not here at the end.
 
 .. include:: ../deprecations/c-api-pending-removal-in-3.18.rst

Doc/whatsnew/3.16.rst

@@ -25,23 +25,28 @@ PyAPI_FUNC(PyObject *) PySlice_New(PyObject* start, PyObject* stop,
                                   PyObject* step);
 PyAPI_FUNC(int) PySlice_GetIndices(PyObject *r, Py_ssize_t length,
                                   Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step);
-Py_DEPRECATED(3.7)
-PyAPI_FUNC(int) PySlice_GetIndicesEx(PyObject *r, Py_ssize_t length,
-                                     Py_ssize_t *start, Py_ssize_t *stop,
-                                     Py_ssize_t *step,
-                                     Py_ssize_t *slicelength);
-
-#if !defined(Py_LIMITED_API) || (Py_LIMITED_API+0 >= 0x03050400 && Py_LIMITED_API+0 < 0x03060000) || Py_LIMITED_API+0 >= 0x03060100
-#define PySlice_GetIndicesEx(slice, length, start, stop, step, slicelen) (  \
-    PySlice_Unpack((slice), (start), (stop), (step)) < 0 ?                  \
-    ((*(slicelen) = 0), -1) :                                               \
-    ((*(slicelen) = PySlice_AdjustIndices((length), (start), (stop), *(step))), \
-     0))
+
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x03060100
 PyAPI_FUNC(int) PySlice_Unpack(PyObject *slice,
                                Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step);
 PyAPI_FUNC(Py_ssize_t) PySlice_AdjustIndices(Py_ssize_t length,
                                              Py_ssize_t *start, Py_ssize_t *stop,
                                              Py_ssize_t step);
+
+static inline int
+_PySlice_GetIndicesEx(PyObject *slice, Py_ssize_t length,
+                      Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step,
+                      Py_ssize_t *slicelen)
+{
+    if (PySlice_Unpack(slice, start, stop, step) < 0) {
+        *slicelen = 0;
+        return -1;
+    }
+
+    *slicelen = PySlice_AdjustIndices(length, start, stop, *step);
+    return 0;
+}
+#define PySlice_GetIndicesEx _PySlice_GetIndicesEx
 #endif
 
 #ifndef Py_LIMITED_API

Include/sliceobject.h

@@ -0,0 +1,4 @@
+Remove :c:func:`PySlice_GetIndicesEx` function, deprecated since Python 3.7.
+Only remove the function implementation: :c:func:`PySlice_GetIndicesEx`
+remains available as a static inline function, so the API does not change.
+Patch by Victor Stinner.

Misc/NEWS.d/next/C_API/2026-09-24-16-05-50.gh-issue-158077.DEaM49.rst

@@ -1314,6 +1314,7 @@
     added = '3.2'
 [function.PySlice_GetIndicesEx]
     added = '3.2'
+    abi_only = true
 [function.PySlice_New]
     added = '3.2'
 [data.PySlice_Type]

Misc/stable_abi.toml

@@ -297,13 +297,17 @@ PySlice_AdjustIndices(Py_ssize_t length,
 
 #undef PySlice_GetIndicesEx
 
-int
+// Function removed from Python 3.16 C API, but kept in the stable ABI
+PyAPI_FUNC(int)
 PySlice_GetIndicesEx(PyObject *_r, Py_ssize_t length,
                      Py_ssize_t *start, Py_ssize_t *stop, Py_ssize_t *step,
                      Py_ssize_t *slicelength)
 {
-    if (PySlice_Unpack(_r, start, stop, step) < 0)
+    if (PySlice_Unpack(_r, start, stop, step) < 0) {
+        *slicelength = 0;
         return -1;
+    }
+
     *slicelength = PySlice_AdjustIndices(length, start, stop, *step);
     return 0;
 }