WL #13459: Optimize hash table in hash join

Post-push fix: Stop using the variable name “byte”, as it is a
named type in C++17, and causes problems in at least Clang 10.

Change-Id: I02f14f3b661c2a15d68fa086e8d36b331b706356

Author: Steinar H. Gunderson

sql/hash_join_buffer.cc

@@ -531,9 +531,9 @@ std::pair<const char *, uint64_t> VarintParseSlow64(const char *p,
                                                     uint32_t res32) {
   uint64_t res = res32;
   for (std::uint32_t i = 2; i < 10; i++) {
-    uint64_t byte = static_cast<uint8_t>(p[i]);
-    res += (byte - 1) << (7 * i);
-    if (likely(byte < 128)) {
+    uint64_t x = static_cast<uint8_t>(p[i]);
+    res += (x - 1) << (7 * i);
+    if (likely(x < 128)) {
       return {p + i + 1, res};
     }
   }

sql/immutable_string.h

@@ -118,9 +118,9 @@ inline const char *VarintParse64(const char *p, uint64_t *out) {
     *out = res;
     return p + 1;
   }
-  uint32_t byte = ptr[1];
-  res += (byte - 1) << 7;
-  if (!(byte & 0x80)) {
+  uint32_t x = ptr[1];
+  res += (x - 1) << 7;
+  if (!(x & 0x80)) {
     *out = res;
     return p + 2;
   }