Add _Py_HashSecret_t.expat.hashsalt16 instead

Author: StanFromIreland

Include/internal/pycore_pyhash.h

@@ -27,14 +27,14 @@ _Py_HashPointerRaw(const void *ptr)
  *   pppppppp ssssssss ........  fnv -- two Py_hash_t
  *   k0k0k0k0 k1k1k1k1 ........  siphash -- two uint64_t
  *   ........ ........ ssssssss  djbx33a -- 16 bytes padding + one Py_hash_t
- *   ........ ........ eeeeeeee  pyexpat XML hash salt
+ *   eeeeeeee eeeeeeee eeeeeeee  pyexpat XML hash salt
  *
  * memory layout on 32 bit systems
  *   cccccccc cccccccc cccccccc  uc
  *   ppppssss ........ ........  fnv -- two Py_hash_t
  *   k0k0k0k0 k1k1k1k1 ........  siphash -- two uint64_t (*)
  *   ........ ........ ssss....  djbx33a -- 16 bytes padding + one Py_hash_t
- *   ........ ........ eeee....  pyexpat XML hash salt
+ *   eeeeeeee eeeeeeee eeee....  pyexpat XML hash salt
  *
  * (*) The siphash member may not be available on 32 bit platforms without
  *     an unsigned int64 data type.
@@ -58,7 +58,9 @@ typedef union {
         Py_hash_t suffix;
     } djbx33a;
     struct {
-        unsigned char padding[16];
+        /* 16 bytes for XML_SetHashSalt16Bytes */
+        uint8_t hashsalt16[16];
+        /* 4/8 bytes for legacy XML_SetHashSalt */
         Py_hash_t hashsalt;
     } expat;
 } _Py_HashSecret_t;

Modules/_elementtree.c

@@ -3738,7 +3738,7 @@ _elementtree_XMLParser___init___impl(XMLParserObject *self, PyObject *target,
     // Prefer 16-byte entropy, only expat >= 2.8.0. See gh-149018
     if (EXPAT(st, SetHashSalt16Bytes) != NULL) {
         EXPAT(st, SetHashSalt16Bytes)(self->parser,
-                                      (const uint8_t *)_Py_HashSecret.uc);
+                                      _Py_HashSecret.expat.hashsalt16);
     }
     else if (EXPAT(st, SetHashSalt) != NULL) {
         EXPAT(st, SetHashSalt)(self->parser,

Modules/pyexpat.c

@@ -1535,8 +1535,7 @@ newxmlparseobject(pyexpat_state *state, const char *encoding,
     }
 #if XML_COMBINED_VERSION >= 20800
     /* This feature was added upstream in libexpat 2.8.0. */
-    XML_SetHashSalt16Bytes(self->itself,
-                           (const uint8_t *)_Py_HashSecret.uc);
+    XML_SetHashSalt16Bytes(self->itself, _Py_HashSecret.expat.hashsalt16);
 #elif XML_COMBINED_VERSION >= 20100
     /* This feature was added upstream in libexpat 2.1.0. */
     XML_SetHashSalt(self->itself,