remove warnings from google-benchmarks in libcxx

Differential Revision: https://reviews.llvm.org/D25522

Patch written by Aditya Kumar.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@284179 91177308-0d34-0410-b5e6-96231b3b80d8

benchmarks/ContainerBenchmarks.hpp

@@ -11,10 +11,11 @@ namespace ContainerBenchmarks {
 template <class Container, class GenInputs>
 void BM_ConstructIterIter(benchmark::State& st, Container, GenInputs gen) {
     auto in = gen(st.range(0));
+    const auto begin = in.begin();
     const auto end = in.end();
     benchmark::DoNotOptimize(&in);
     while (st.KeepRunning()) {
-        Container c(in.begin(), in.end());
+        Container c(begin, end);
         benchmark::DoNotOptimize(c.data());
     }
 }

benchmarks/GenerateInput.hpp

@@ -112,7 +112,7 @@ inline std::vector<std::string> getDuplicateStringInputs(size_t N) {
 
 inline std::vector<std::string> getRandomStringInputs(size_t N) {
     std::vector<std::string> inputs;
-    for (int i=0; i < N; ++i) {
+    for (size_t i=0; i < N; ++i) {
         inputs.push_back(getRandomString(1024));
     }
     return inputs;