Fix "unsafe narrowing" warnings in absl, 2/n.

Addresses failures with the following, in some files:
-Wshorten-64-to-32
-Wimplicit-int-conversion
-Wsign-compare
-Wsign-conversion
-Wtautological-unsigned-zero-compare

(This specific CL focuses on .cc files in dirs a-h.)

Bug: chromium:1292951
PiperOrigin-RevId: 464541951
Change-Id: If23b63ccea8e9b730159ff1c7288e9300a40b6bd

2 files changed, 12 insertions, 11 deletions

diff --git a/absl/hash/internal/city.cc b/absl/hash/internal/city.cc
index 5460134e..f0d31964 100644
--- a/absl/hash/internal/city.cc
+++ b/absl/hash/internal/city.cc
@@ -97,7 +97,7 @@ static uint32_t Hash32Len13to24(const char *s, size_t len) {
   uint32_t d = Fetch32(s + (len >> 1));
   uint32_t e = Fetch32(s);
   uint32_t f = Fetch32(s + len - 4);
-  uint32_t h = len;
+  uint32_t h = static_cast<uint32_t>(len);
 
   return fmix(Mur(f, Mur(e, Mur(d, Mur(c, Mur(b, Mur(a, h)))))));
 }
@@ -106,15 +106,15 @@ static uint32_t Hash32Len0to4(const char *s, size_t len) {
   uint32_t b = 0;
   uint32_t c = 9;
   for (size_t i = 0; i < len; i++) {
-    signed char v = s[i];
-    b = b * c1 + v;
+    signed char v = static_cast<signed char>(s[i]);
+    b = b * c1 + static_cast<uint32_t>(v);
     c ^= b;
   }
-  return fmix(Mur(b, Mur(len, c)));
+  return fmix(Mur(b, Mur(static_cast<uint32_t>(len), c)));
 }
 
 static uint32_t Hash32Len5to12(const char *s, size_t len) {
-  uint32_t a = len, b = len * 5, c = 9, d = b;
+  uint32_t a = static_cast<uint32_t>(len), b = a * 5, c = 9, d = b;
   a += Fetch32(s);
   b += Fetch32(s + len - 4);
   c += Fetch32(s + ((len >> 1) & 4));
@@ -129,7 +129,7 @@ uint32_t CityHash32(const char *s, size_t len) {
   }
 
   // len > 24
-  uint32_t h = len, g = c1 * len, f = g;
+  uint32_t h = static_cast<uint32_t>(len), g = c1 * h, f = g;
 
   uint32_t a0 = Rotate32(Fetch32(s + len - 4) * c1, 17) * c2;
   uint32_t a1 = Rotate32(Fetch32(s + len - 8) * c1, 17) * c2;
@@ -230,11 +230,11 @@ static uint64_t HashLen0to16(const char *s, size_t len) {
     return HashLen16(len + (a << 3), Fetch32(s + len - 4), mul);
   }
   if (len > 0) {
-    uint8_t a = s[0];
-    uint8_t b = s[len >> 1];
-    uint8_t c = s[len - 1];
+    uint8_t a = static_cast<uint8_t>(s[0]);
+    uint8_t b = static_cast<uint8_t>(s[len >> 1]);
+    uint8_t c = static_cast<uint8_t>(s[len - 1]);
     uint32_t y = static_cast<uint32_t>(a) + (static_cast<uint32_t>(b) << 8);
-    uint32_t z = len + (static_cast<uint32_t>(c) << 2);
+    uint32_t z = static_cast<uint32_t>(len) + (static_cast<uint32_t>(c) << 2);
     return ShiftMix(y * k2 ^ z * k0) * k2;
   }
   return k2;
diff --git a/absl/hash/internal/low_level_hash.cc b/absl/hash/internal/low_level_hash.cc
index d288f3ec..e05e7885 100644
--- a/absl/hash/internal/low_level_hash.cc
+++ b/absl/hash/internal/low_level_hash.cc
@@ -106,7 +106,8 @@ uint64_t LowLevelHash(const void* data, size_t len, uint64_t seed,
   } else if (len > 0) {
     // If we have at least 1 and at most 3 bytes, read all of the provided
     // bits into A, with some adjustments.
-    a = ((ptr[0] << 16) | (ptr[len >> 1] << 8) | ptr[len - 1]);
+    a = static_cast<uint64_t>((ptr[0] << 16) | (ptr[len >> 1] << 8) |
+                              ptr[len - 1]);
     b = 0;
   } else {
     a = 0;