Fix the internals of our hash functions to used unsigned values during hash

computation as the overflow behavior of signed integers is undefined.

In practice we require compiling everything with -fwrapv which forces overflow
to be defined as twos compliment but this keeps the code cleaner for checkers
or in the case where someone has compiled it without -fwrapv or their
compiler's equivalent.

Found by Clang trunk's Undefined Behavior Sanitizer (UBSan).

Cleanup only - no functionality or hash values change.

1 files changed, 5 insertions, 5 deletions

diff --git a/Objects/tupleobject.c b/Objects/tupleobject.c
index b3454600c9..c725227979 100644
--- a/Objects/tupleobject.c
+++ b/Objects/tupleobject.c
@@ -315,11 +315,11 @@ error:
 static Py_hash_t
 tuplehash(PyTupleObject *v)
 {
-    register Py_hash_t x, y;
+    register Py_uhash_t x, y;  /* Unsigned for defined overflow behavior. */
     register Py_ssize_t len = Py_SIZE(v);
     register PyObject **p;
-    Py_hash_t mult = _PyHASH_MULTIPLIER;
-    x = 0x345678L;
+    Py_uhash_t mult = _PyHASH_MULTIPLIER;
+    x = 0x345678UL;
     p = v->ob_item;
     while (--len >= 0) {
         y = PyObject_Hash(*p++);
@@ -327,9 +327,9 @@ tuplehash(PyTupleObject *v)
             return -1;
         x = (x ^ y) * mult;
         /* the cast might truncate len; that doesn't change hash stability */
-        mult += (Py_hash_t)(82520L + len + len);
+        mult += (Py_uhash_t)(82520UL + len + len);
     }
-    x += 97531L;
+    x += 97531UL;
     if (x == -1)
         x = -2;
     return x;