gh-127415: add PyMem_Raw{New,Resize} convenience macros

Doc/c-api/memory.rst

@@ -199,6 +199,31 @@ zero bytes.
    If *p* is ``NULL``, no operation is performed.
 
 
+The following type-oriented macros are provided for convenience.  Note  that
+*TYPE* refers to any C type.
+
+.. c:macro:: PyMem_RawNew(TYPE, n)
+
+   Same as :c:func:`PyMem_RawMalloc`, but allocates ``(n * sizeof(TYPE))``
+   bytes of memory.  Returns a pointer cast to ``TYPE*``.  The memory will
+   not have been initialized in any way.
+
+   .. versionadded:: next
+
+
+.. c:macro:: PyMem_RawResize(p, TYPE, n)
+
+   Same as :c:func:`PyMem_RawRealloc`, but the memory block is resized to
+   ``(n * sizeof(TYPE))`` bytes.  Returns a pointer cast to ``TYPE*``.
+   On return, *p* will be a pointer to the new memory area, or ``NULL`` in
+   the event of failure.
+
+   This is a C preprocessor macro; *p* is always reassigned.  Save the original
+   value of *p* to avoid losing memory when handling errors.
+
+   .. versionadded:: next
+
+
 .. _memoryinterface:
 
 Memory Interface

Doc/whatsnew/3.14.rst

@@ -988,13 +988,17 @@ New features
   test if two strings are equal.
   (Contributed by Victor Stinner in :gh:`124502`.)
 
-
 * Add :c:func:`PyType_Freeze` function to make a type immutable.
   (Contributed by Victor Stinner in :gh:`121654`.)
 
 * Add :c:func:`PyUnstable_Object_EnableDeferredRefcount` for enabling
   deferred reference counting, as outlined in :pep:`703`.
 
+* Add the :c:macro:`PyMem_RawNew` and :c:macro:`PyMem_RawResize` convenience
+  macros to the limited C API.
+  (Contributed by Bénédikt Tran in :gh:`127415`.)
+
+
 Porting to Python 3.14
 ----------------------
 

Include/pymem.h

@@ -60,20 +60,21 @@ PyAPI_FUNC(void) PyMem_Free(void *ptr);
  * overflow checking is always done.
  */
 
-#define PyMem_New(type, n) \
-  ( ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL :      \
-        ( (type *) PyMem_Malloc((n) * sizeof(type)) ) )
+#define PyMem_New(TYPE, N)                          \
+    (((size_t)(N) <= PY_SSIZE_T_MAX / sizeof(TYPE)) \
+        ? (TYPE *)PyMem_Malloc((N) * sizeof(TYPE))  \
+        : NULL)
 
 /*
- * The value of (p) is always clobbered by this macro regardless of success.
- * The caller MUST check if (p) is NULL afterwards and deal with the memory
- * error if so.  This means the original value of (p) MUST be saved for the
+ * The value of (PTR) is always clobbered by this macro regardless of success.
+ * The caller MUST check if (PTR) is NULL afterwards and deal with the memory
+ * error if so.  This means the original value of (PTR) MUST be saved for the
  * caller's memory error handler to not lose track of it.
  */
-#define PyMem_Resize(p, type, n) \
-  ( (p) = ((size_t)(n) > PY_SSIZE_T_MAX / sizeof(type)) ? NULL :        \
-        (type *) PyMem_Realloc((p), (n) * sizeof(type)) )
-
+#define PyMem_Resize(PTR, TYPE, N)                          \
+    ((PTR) = ((size_t)(N) <= PY_SSIZE_T_MAX / sizeof(TYPE)) \
+        ? (TYPE *)PyMem_Realloc((PTR), (N) * sizeof(TYPE)) \
+        : NULL)
 
 // Deprecated aliases only kept for backward compatibility.
 // PyMem_Del and PyMem_DEL are defined with no parameter to be able to use
@@ -86,7 +87,6 @@ PyAPI_FUNC(void) PyMem_Free(void *ptr);
 #define PyMem_Del(p)              PyMem_Free((p))
 #define PyMem_DEL(p)              PyMem_Free((p))
 
-
 #if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030d0000
 // Memory allocator which doesn't require the GIL to be held.
 // Usually, it's just a thin wrapper to functions of the standard C library:
@@ -98,6 +98,18 @@ PyAPI_FUNC(void *) PyMem_RawRealloc(void *ptr, size_t new_size);
 PyAPI_FUNC(void) PyMem_RawFree(void *ptr);
 #endif
 
+#if !defined(Py_LIMITED_API) || Py_LIMITED_API+0 >= 0x030e0000
+#define PyMem_RawNew(TYPE, N)                           \
+    (((size_t)(N) <= PY_SSIZE_T_MAX / sizeof(TYPE))     \
+        ? (TYPE *)PyMem_RawMalloc((N) * sizeof(TYPE))   \
+        : NULL)
+
+#define PyMem_RawResize(PTR, TYPE, N)                           \
+    ((PTR) = ((size_t)(N) <= PY_SSIZE_T_MAX / sizeof(TYPE))     \
+        ? (TYPE *)PyMem_RawRealloc((PTR), (N) * sizeof(TYPE))   \
+        : NULL)
+#endif
+
 #ifndef Py_LIMITED_API
 #  define Py_CPYTHON_PYMEM_H
 #  include "cpython/pymem.h"

Misc/NEWS.d/next/C_API/2024-11-29-14-54-07.gh-issue-127415.-ZmEdf.rst

@@ -0,0 +1,2 @@
+Add the :c:macro:`PyMem_RawNew` and :c:macro:`PyMem_RawResize` convenience
+macros to the limited C API. Patch by Bénédikt Tran.

Misc/stable_abi.toml

@@ -2540,3 +2540,7 @@
     added = '3.14'
 [function.PyType_Freeze]
     added = '3.14'
+[macro.PyMem_RawNew]
+    added = '3.14'
+[macro.PyMem_RawResize]
+    added = '3.14'