Visual Studio compiler warnings clean-up (#315)

api/include/opentelemetry/context/context.h

@@ -1,5 +1,6 @@
 #pragma once
 
+#include <cstring>
 #include "opentelemetry/context/context_value.h"
 #include "opentelemetry/nostd/shared_ptr.h"
 #include "opentelemetry/nostd/string_view.h"
@@ -65,7 +66,7 @@ class Context
     {
       if (key.size() == data->key_length_)
       {
-        if (memcmp(key.data(), data->key_, data->key_length_) == 0)
+        if (std::memcmp(key.data(), data->key_, data->key_length_) == 0)
         {
           return data->value_;
         }
@@ -81,7 +82,7 @@ class Context
     {
       if (key.size() == data->key_length_)
       {
-        if (memcmp(key.data(), data->key_, data->key_length_) == 0)
+        if (std::memcmp(key.data(), data->key_, data->key_length_) == 0)
         {
           return true;
         }

api/include/opentelemetry/nostd/string_view.h

@@ -118,7 +118,12 @@ class string_view
 inline bool operator==(string_view lhs, string_view rhs) noexcept
 {
   return lhs.length() == rhs.length() &&
+#if _MSC_VER == 1900
+         // Avoid SCL error in Visual Studio 2015
+         (std::memcmp(lhs.data(), rhs.data(), lhs.length()) == 0);
+#else
          std::equal(lhs.data(), lhs.data() + lhs.length(), rhs.data());
+#endif
 }
 
 inline bool operator==(string_view lhs, const std::string &rhs) noexcept
@@ -172,3 +177,18 @@ inline std::ostream &operator<<(std::ostream &os, string_view s)
 }
 }  // namespace nostd
 OPENTELEMETRY_END_NAMESPACE
+
+namespace std
+{
+template <>
+struct hash<OPENTELEMETRY_NAMESPACE::nostd::string_view>
+{
+  std::size_t operator()(const OPENTELEMETRY_NAMESPACE::nostd::string_view &k) const
+  {
+    // TODO: for C++17 that has native support for std::basic_string_view it would
+    // be more performance-efficient to provide a zero-copy hash.
+    auto s = std::string(k.data(), k.size());
+    return std::hash<std::string>{}(s);
+  }
+};
+}  // namespace std

api/include/opentelemetry/version.h

@@ -12,4 +12,7 @@
 
 #define OPENTELEMETRY_END_NAMESPACE \
   }}
+
+#define OPENTELEMETRY_NAMESPACE opentelemetry :: OPENTELEMETRY_CONCAT(v, OPENTELEMETRY_ABI_VERSION_NO)
+
 // clang-format on

api/test/metrics/noop_metrics_test.cc

@@ -4,6 +4,7 @@
 #include "opentelemetry/metrics/observer_result.h"
 #include "opentelemetry/metrics/sync_instruments.h"
 
+#include <array>
 #include <memory>
 
 OPENTELEMETRY_BEGIN_NAMESPACE

api/test/nostd/utility_test.cc

@@ -1,5 +1,6 @@
 #include "opentelemetry/nostd/utility.h"
 
+#include <tuple>
 #include <type_traits>
 #include <vector>
 
@@ -20,7 +21,8 @@ TEST(UtilityTest, Data)
   std::vector<int> v = {1, 2, 3};
   int array[3]       = {1, 2, 3};
   std::initializer_list<int> list{1, 2, 3};
-  int x;
+  int x       = 0;
+  std::ignore = x;
 
   EXPECT_EQ(opentelemetry::nostd::data(v), v.data());
   EXPECT_EQ(opentelemetry::nostd::data(array), array);
@@ -32,7 +34,8 @@ TEST(UtilityTest, Size)
 {
   std::vector<int> v = {1, 2, 3};
   int array[3]       = {1, 2, 3};
-  int x;
+  int x              = 0;
+  std::ignore        = x;
 
   EXPECT_EQ(opentelemetry::nostd::size(v), v.size());
   EXPECT_EQ(opentelemetry::nostd::size(array), 3);

api/test/trace/key_value_iterable_view_test.cc

@@ -1,8 +1,8 @@
 #include "opentelemetry/trace/key_value_iterable_view.h"
 
-#include <map>
-
 #include <gtest/gtest.h>
+#include <map>
+#include "opentelemetry/nostd/type_traits.h"
 
 using namespace opentelemetry;
 

exporters/ostream/include/opentelemetry/exporters/ostream/metrics_exporter.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <iostream>
+#include <string>
 #include "opentelemetry/sdk/metrics/aggregator/exact_aggregator.h"
 #include "opentelemetry/sdk/metrics/aggregator/gauge_aggregator.h"
 #include "opentelemetry/sdk/metrics/aggregator/histogram_aggregator.h"
@@ -82,9 +83,9 @@ class OStreamMetricsExporter final : public sdkmetrics::MetricsExporter
         }
         else
         {
-          auto vec = agg->get_checkpoint();
-          int size = vec.size();
-          int i    = 1;
+          auto vec    = agg->get_checkpoint();
+          size_t size = vec.size();
+          int i       = 1;
 
           sout_ << "\n  values      : " << '[';
 
@@ -104,8 +105,8 @@ class OStreamMetricsExporter final : public sdkmetrics::MetricsExporter
         auto boundaries = agg->get_boundaries();
         auto counts     = agg->get_counts();
 
-        int boundaries_size = boundaries.size();
-        int counts_size     = counts.size();
+        size_t boundaries_size = boundaries.size();
+        size_t counts_size     = counts.size();
 
         sout_ << "\n  buckets     : " << '[';
 
@@ -134,8 +135,8 @@ class OStreamMetricsExporter final : public sdkmetrics::MetricsExporter
         auto boundaries = agg->get_boundaries();
         auto counts     = agg->get_counts();
 
-        int boundaries_size = boundaries.size();
-        int counts_size     = counts.size();
+        size_t boundaries_size = boundaries.size();
+        size_t counts_size     = counts.size();
 
         sout_ << "\n  buckets     : " << '[';
 

exporters/ostream/include/opentelemetry/exporters/ostream/span_exporter.h

@@ -146,8 +146,8 @@ class OStreamSpanExporter final : public sdktrace::SpanExporter
 
   void printAttributes(std::unordered_map<std::string, sdktrace::SpanDataAttributeValue> map)
   {
-    int size = map.size();
-    int i    = 1;
+    size_t size = map.size();
+    size_t i    = 1;
     for (auto kv : map)
     {
       sout_ << kv.first << ": ";

ext/test/zpages/tracez_data_aggregator_test.cc

@@ -51,8 +51,8 @@ class TracezDataAggregatorTest : public ::testing::Test
 void VerifySpanCountsInTracezData(
     const std::string &span_name,
     const TracezData &aggregated_data,
-    unsigned int running_span_count,
-    unsigned int error_span_count,
+    size_t running_span_count,
+    size_t error_span_count,
     std::array<unsigned int, kLatencyBoundaries.size()> completed_span_count_per_latency_bucket)
 {
   // Asserts are needed to check the size of the container because they may need

ext/test/zpages/tracez_processor_test.cc

@@ -49,8 +49,8 @@ void UpdateSpans(std::shared_ptr<TracezSpanProcessor> &processor,
  */
 bool ContainsNames(const std::vector<std::string> &names,
                    std::unordered_set<ThreadsafeSpanData *> &running,
-                   unsigned int name_start        = 0,
-                   unsigned int name_end          = 0,
+                   size_t name_start              = 0,
+                   size_t name_end                = 0,
                    bool one_to_one_correspondence = false)
 {
   if (name_end == 0)
@@ -97,15 +97,15 @@ bool ContainsNames(const std::vector<std::string> &names,
  */
 bool ContainsNames(const std::vector<std::string> &names,
                    std::vector<std::unique_ptr<ThreadsafeSpanData>> &completed,
-                   unsigned int name_start        = 0,
-                   unsigned int name_end          = 0,
+                   size_t name_start              = 0,
+                   size_t name_end                = 0,
                    bool one_to_one_correspondence = false)
 {
 
   if (name_end == 0)
     name_end = names.size();
 
-  unsigned int num_names = name_end - name_start;
+  size_t num_names = name_end - name_start;
 
   if (num_names > completed.size() || (one_to_one_correspondence && num_names != completed.size()))
   {

sdk/include/opentelemetry/sdk/common/atomic_unique_ptr.h

@@ -34,7 +34,7 @@ class AtomicUniquePtr
   /**
    * @return true if the pointer is null
    */
-  bool IsNull() const noexcept { return ptr_ == nullptr; }
+  bool IsNull() const noexcept { return ptr_.load() == nullptr; }
 
   /**
    * Atomically swap the pointer only if it's null.

sdk/include/opentelemetry/sdk/common/empty_attributes.h

@@ -1,6 +1,9 @@
 #include "opentelemetry/trace/key_value_iterable_view.h"
 
+#include <array>
 #include <map>
+#include <string>
+#include <utility>
 
 OPENTELEMETRY_BEGIN_NAMESPACE
 namespace sdk

sdk/include/opentelemetry/sdk/metrics/aggregator/exact_aggregator.h

@@ -145,8 +145,8 @@ class ExactAggregator : public Aggregator<T>
     }
     else
     {
-      float position = float(this->checkpoint_.size() - 1) * q;
-      int ceiling    = ceil(position);
+      float position = float(float(this->checkpoint_.size() - 1) * q);
+      int ceiling    = int(ceil(position));
       return this->checkpoint_[ceiling];
     }
   }

sdk/include/opentelemetry/sdk/metrics/aggregator/histogram_aggregator.h

@@ -63,8 +63,8 @@ class HistogramAggregator final : public Aggregator<T>
   void update(T val) override
   {
     this->mu_.lock();
-    this->updated_ = true;
-    int bucketID   = boundaries_.size();
+    this->updated_  = true;
+    size_t bucketID = boundaries_.size();
     for (size_t i = 0; i < boundaries_.size(); i++)
     {
       if (val < boundaries_[i])  // concurrent read is thread-safe

sdk/include/opentelemetry/sdk/metrics/aggregator/sketch_aggregator.h

@@ -118,7 +118,7 @@ class SketchAggregator final : public Aggregator<T>
       idx = iter->first;
       count += iter->second;
     }
-    return round(2 * pow(gamma, idx) / (gamma + 1));
+    return static_cast<T>(round(2 * pow(gamma, idx) / (gamma + 1)));
   }
 
   /**

sdk/test/common/circular_buffer_benchmark.cc

@@ -102,8 +102,8 @@ static void RunSimulation(Buffer &buffer, int num_threads, int n) noexcept
 static void BM_BaselineBuffer(benchmark::State &state)
 {
   const size_t max_elements = 500;
-  auto num_threads          = state.range(0);
-  const int n               = N / num_threads;
+  const int num_threads     = static_cast<int>(state.range(0));
+  const int n               = static_cast<int>(N / num_threads);
   BaselineCircularBuffer<uint64_t> buffer{max_elements};
   for (auto _ : state)
   {
@@ -116,8 +116,8 @@ BENCHMARK(BM_BaselineBuffer)->Arg(1)->Arg(2)->Arg(4);
 static void BM_LockFreeBuffer(benchmark::State &state)
 {
   const size_t max_elements = 500;
-  auto num_threads          = state.range(0);
-  const int n               = N / num_threads;
+  const int num_threads     = static_cast<int>(state.range(0));
+  const int n               = static_cast<int>(N / num_threads);
   CircularBuffer<uint64_t> buffer{max_elements};
   for (auto _ : state)
   {

sdk/test/common/circular_buffer_test.cc

@@ -1,5 +1,6 @@
 #include "opentelemetry/sdk/common/circular_buffer.h"
 
+#include <algorithm>
 #include <cassert>
 #include <random>
 #include <thread>