Fix "unsafe narrowing" warnings in absl, 12/12.

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 enables these warnings and fixes the remaining known issues.)

Bug: chromium:1292951
PiperOrigin-RevId: 480981210
Change-Id: I92d5023c6833e24d6aa29b10d433116329972f41

2 files changed, 3 insertions, 2 deletions

diff --git a/absl/random/internal/fast_uniform_bits.h b/absl/random/internal/fast_uniform_bits.h
index f3a5c00f..8d8ed045 100644
--- a/absl/random/internal/fast_uniform_bits.h
+++ b/absl/random/internal/fast_uniform_bits.h
@@ -151,7 +151,8 @@ FastUniformBits<UIntType>::Generate(URBG& g,  // NOLINT(runtime/references)
 
   result_type r = static_cast<result_type>(g() - kMin);
   for (size_t n = 1; n < kIters; ++n) {
-    r = (r << kShift) + static_cast<result_type>(g() - kMin);
+    r = static_cast<result_type>(r << kShift) +
+        static_cast<result_type>(g() - kMin);
   }
   return r;
 }
diff --git a/absl/random/internal/nonsecure_base.h b/absl/random/internal/nonsecure_base.h
index c7d7fa4b..c3b80335 100644
--- a/absl/random/internal/nonsecure_base.h
+++ b/absl/random/internal/nonsecure_base.h
@@ -44,7 +44,7 @@ class RandenPoolSeedSeq {
   // Generate random unsigned values directly into the buffer.
   template <typename Contiguous>
   void generate_impl(ContiguousTag, Contiguous begin, Contiguous end) {
-    const size_t n = std::distance(begin, end);
+    const size_t n = static_cast<size_t>(std::distance(begin, end));
     auto* a = &(*begin);
     RandenPool<uint8_t>::Fill(
         absl::MakeSpan(reinterpret_cast<uint8_t*>(a), sizeof(*a) * n));