gh-143869: Add PEP 757 functions to the limited API (#143906)

Co-authored-by: Petr Viktorin <encukou@gmail.com>

Author: skirpichev

Doc/c-api/long.rst

@@ -687,7 +687,7 @@ Export API
 
 .. versionadded:: 3.14
 
-.. c:struct:: PyLongLayout
+.. c:type:: PyLongLayout
 
    Layout of an array of "digits" ("limbs" in the GMP terminology), used to
    represent absolute value for arbitrary precision integers.
@@ -727,15 +727,15 @@ Export API
 
    Get the native layout of Python :class:`int` objects.
 
-   See the :c:struct:`PyLongLayout` structure.
+   See the :c:type:`PyLongLayout` structure.
 
    The function must not be called before Python initialization nor after
    Python finalization. The returned layout is valid until Python is
    finalized. The layout is the same for all Python sub-interpreters
    in a process, and so it can be cached.
 
 
-.. c:struct:: PyLongExport
+.. c:type:: PyLongExport
 
    Export of a Python :class:`int` object.
 
@@ -769,7 +769,7 @@ Export API
 
    Export a Python :class:`int` object.
 
-   *export_long* must point to a :c:struct:`PyLongExport` structure allocated
+   *export_long* must point to a :c:type:`PyLongExport` structure allocated
    by the caller. It must not be ``NULL``.
 
    On success, fill in *\*export_long* and return ``0``.
@@ -799,7 +799,7 @@ The :c:type:`PyLongWriter` API can be used to import an integer.
 
 .. versionadded:: 3.14
 
-.. c:struct:: PyLongWriter
+.. c:type:: PyLongWriter
 
    A Python :class:`int` writer instance.
 
@@ -827,7 +827,7 @@ The :c:type:`PyLongWriter` API can be used to import an integer.
    The layout of *digits* is described by :c:func:`PyLong_GetNativeLayout`.
 
    Digits must be in the range [``0``; ``(1 << bits_per_digit) - 1``]
-   (where the :c:struct:`~PyLongLayout.bits_per_digit` is the number of bits
+   (where the :c:type:`~PyLongLayout.bits_per_digit` is the number of bits
    per digit).
    Any unused most significant digits must be set to ``0``.
 

Doc/data/stable_abi.dat

@@ -138,45 +138,6 @@ _PyLong_CompactValue(const PyLongObject *op)
 
 #define PyUnstable_Long_CompactValue _PyLong_CompactValue
 
-
-/* --- Import/Export API -------------------------------------------------- */
-
-typedef struct PyLongLayout {
-    uint8_t bits_per_digit;
-    uint8_t digit_size;
-    int8_t digits_order;
-    int8_t digit_endianness;
-} PyLongLayout;
-
-PyAPI_FUNC(const PyLongLayout*) PyLong_GetNativeLayout(void);
-
-typedef struct PyLongExport {
-    int64_t value;
-    uint8_t negative;
-    Py_ssize_t ndigits;
-    const void *digits;
-    // Member used internally, must not be used for other purpose.
-    Py_uintptr_t _reserved;
-} PyLongExport;
-
-PyAPI_FUNC(int) PyLong_Export(
-    PyObject *obj,
-    PyLongExport *export_long);
-PyAPI_FUNC(void) PyLong_FreeExport(
-    PyLongExport *export_long);
-
-
-/* --- PyLongWriter API --------------------------------------------------- */
-
-typedef struct PyLongWriter PyLongWriter;
-
-PyAPI_FUNC(PyLongWriter*) PyLongWriter_Create(
-    int negative,
-    Py_ssize_t ndigits,
-    void **digits);
-PyAPI_FUNC(PyObject*) PyLongWriter_Finish(PyLongWriter *writer);
-PyAPI_FUNC(void) PyLongWriter_Discard(PyLongWriter *writer);
-
 #ifdef __cplusplus
 }
 #endif

Include/cpython/longintrepr.h

@@ -166,6 +166,44 @@ PyAPI_FUNC(PyObject *) PyLong_FromString(const char *, char **, int);
 PyAPI_FUNC(unsigned long) PyOS_strtoul(const char *, char **, int);
 PyAPI_FUNC(long) PyOS_strtol(const char *, char **, int);
 
+/* --- Import/Export API -------------------------------------------------- */
+
+typedef struct PyLongLayout {
+    uint8_t bits_per_digit;
+    uint8_t digit_size;
+    int8_t digits_order;
+    int8_t digit_endianness;
+} PyLongLayout;
+
+PyAPI_FUNC(const PyLongLayout*) PyLong_GetNativeLayout(void);
+
+typedef struct PyLongExport {
+    int64_t value;
+    uint8_t negative;
+    Py_ssize_t ndigits;
+    const void *digits;
+    // Member used internally, must not be used for other purpose.
+    Py_uintptr_t _reserved;
+} PyLongExport;
+
+PyAPI_FUNC(int) PyLong_Export(
+    PyObject *obj,
+    PyLongExport *export_long);
+PyAPI_FUNC(void) PyLong_FreeExport(
+    PyLongExport *export_long);
+
+
+/* --- PyLongWriter API --------------------------------------------------- */
+
+typedef struct PyLongWriter PyLongWriter;
+
+PyAPI_FUNC(PyLongWriter*) PyLongWriter_Create(
+    int negative,
+    Py_ssize_t ndigits,
+    void **digits);
+PyAPI_FUNC(PyObject*) PyLongWriter_Finish(PyLongWriter *writer);
+PyAPI_FUNC(void) PyLongWriter_Discard(PyLongWriter *writer);
+
 #ifndef Py_LIMITED_API
 #  define Py_CPYTHON_LONGOBJECT_H
 #  include "cpython/longobject.h"

Include/longobject.h

@@ -0,0 +1,5 @@
+Added :c:func:`PyLong_GetNativeLayout`, :c:struct:`PyLongLayout`,
+:c:struct:`PyLongExport`, :c:func:`PyLong_Export`,
+:c:func:`PyLong_FreeExport`, :c:struct:`PyLongWriter`,
+:c:func:`PyLongWriter_Create`, :c:func:`PyLongWriter_Finish` and
+:c:func:`PyLongWriter_Discard` to the limited API.

Lib/test/test_stable_abi_ctypes.py

@@ -41,6 +41,8 @@
 #   - 'full-abi': All of the struct is part of the ABI, including the size
 #     (users may define arrays of these structs).
 #     Typically used for initialization, rather than at runtime.
+#     Any members whose names start with an underscore are not part of the
+#     limited API; they're for CPython's use only.
 #   - 'opaque': No members are part of the ABI, nor is the size. The Limited
 #     API only handles these via pointers. The C definition should be
 #     incomplete (opaque).
@@ -2664,3 +2666,29 @@
 [function.Py_SET_SIZE]
     # Before 3.15, this was a macro that accessed the PyObject member
     added = '3.15'
+
+# PEP 757 import/export API.
+
+[function.PyLong_GetNativeLayout]
+    added = '3.15'
+[function.PyLong_Export]
+    added = '3.15'
+[function.PyLong_FreeExport]
+    added = '3.15'
+[function.PyLongWriter_Create]
+    added = '3.15'
+[function.PyLongWriter_Finish]
+    added = '3.15'
+[function.PyLongWriter_Discard]
+    added = '3.15'
+[struct.PyLongWriter]
+    added = '3.15'
+    struct_abi_kind = 'opaque'
+[struct.PyLongLayout]
+    added = '3.15'
+    struct_abi_kind = 'full-abi'
+[struct.PyLongExport]
+    added = '3.15'
+    # Note: The `_reserved` member of this struct is for interal use only.
+    # (The definition of 'full-abi' was clarified when this entry was added.)
+    struct_abi_kind = 'full-abi'