https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89629
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think we should just use size_t for the len_aligned variable:
--- a/libstdc++-v3/libsupc++/hash_bytes.cc
+++ b/libstdc++-v3/libsupc++/hash_bytes.cc
@@ -139,7 +139,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Remove the bytes not divisible by the sizeof(size_t). This
// allows the main loop to process the data as 64-bit integers.
- const int len_aligned = len & ~0x7;
+ const size_t len_aligned = len & ~0x7;
const char* const end = buf + len_aligned;
size_t hash = seed ^ (len * mul);
for (const char* p = buf; p != end; p += 8)
