Enable -Wconversion (#1390)

Requires some casts here and there, but nothing unreasonable.

Fixes #1268

include/benchmark/benchmark.h

@@ -546,7 +546,7 @@ typedef std::map<std::string, Counter> UserCounters;
 // calculated automatically to the best fit.
 enum BigO { oNone, o1, oN, oNSquared, oNCubed, oLogN, oNLogN, oAuto, oLambda };
 
-typedef uint64_t IterationCount;
+typedef int64_t IterationCount;
 
 enum StatisticUnit { kTime, kPercentage };
 

src/benchmark_register.h

@@ -32,7 +32,7 @@ typename std::vector<T>::iterator AddPowers(std::vector<T>* dst, T lo, T hi,
     if (i > kmax / mult) break;
   }
 
-  return dst->begin() + start_offset;
+  return dst->begin() + static_cast<int>(start_offset);
 }
 
 template <typename T>

src/json_reporter.cc

@@ -89,12 +89,6 @@ std::string FormatKV(std::string const& key, int64_t value) {
   return ss.str();
 }
 
-std::string FormatKV(std::string const& key, IterationCount value) {
-  std::stringstream ss;
-  ss << '"' << StrEscape(key) << "\": " << value;
-  return ss.str();
-}
-
 std::string FormatKV(std::string const& key, double value) {
   std::stringstream ss;
   ss << '"' << StrEscape(key) << "\": ";

test/BUILD

@@ -3,6 +3,7 @@ TEST_COPTS = [
     "-pedantic-errors",
     "-std=c++11",
     "-Wall",
+    "-Wconversion",
     "-Wextra",
     "-Wshadow",
     #    "-Wshorten-64-to-32",

test/benchmark_test.cc

@@ -26,7 +26,7 @@
 
 namespace {
 
-int BENCHMARK_NOINLINE Factorial(uint32_t n) {
+int BENCHMARK_NOINLINE Factorial(int n) {
   return (n == 1) ? 1 : n * Factorial(n - 1);
 }
 
@@ -90,7 +90,8 @@ static void BM_SetInsert(benchmark::State& state) {
     for (int j = 0; j < state.range(1); ++j) data.insert(rand());
   }
   state.SetItemsProcessed(state.iterations() * state.range(1));
-  state.SetBytesProcessed(state.iterations() * state.range(1) * sizeof(int));
+  state.SetBytesProcessed(state.iterations() * state.range(1) *
+                          static_cast<int64_t>(sizeof(int)));
 }
 
 // Test many inserts at once to reduce the total iterations needed. Otherwise,
@@ -108,7 +109,7 @@ static void BM_Sequential(benchmark::State& state) {
   }
   const int64_t items_processed = state.iterations() * state.range(0);
   state.SetItemsProcessed(items_processed);
-  state.SetBytesProcessed(items_processed * sizeof(v));
+  state.SetBytesProcessed(items_processed * static_cast<int64_t>(sizeof(v)));
 }
 BENCHMARK_TEMPLATE2(BM_Sequential, std::vector<int>, int)
     ->Range(1 << 0, 1 << 10);
@@ -169,7 +170,7 @@ static void BM_ParallelMemset(benchmark::State& state) {
     for (int i = from; i < to; i++) {
       // No need to lock test_vector_mu as ranges
       // do not overlap between threads.
-      benchmark::DoNotOptimize(test_vector->at(i) = 1);
+      benchmark::DoNotOptimize(test_vector->at(static_cast<size_t>(i)) = 1);
     }
   }
 

test/complexity_test.cc

@@ -109,7 +109,7 @@ ADD_COMPLEXITY_CASES(one_test_name, big_o_1_test_name, rms_o_1_test_name,
 
 std::vector<int> ConstructRandomVector(int64_t size) {
   std::vector<int> v;
-  v.reserve(static_cast<int>(size));
+  v.reserve(static_cast<size_t>(size));
   for (int i = 0; i < size; ++i) {
     v.push_back(static_cast<int>(std::rand() % size));
   }

test/donotoptimize_test.cc

@@ -4,9 +4,9 @@
 
 namespace {
 #if defined(__GNUC__)
-std::uint64_t double_up(const std::uint64_t x) __attribute__((const));
+std::int64_t double_up(const std::int64_t x) __attribute__((const));
 #endif
-std::uint64_t double_up(const std::uint64_t x) { return x * 2; }
+std::int64_t double_up(const std::int64_t x) { return x * 2; }
 }  // namespace
 
 // Using DoNotOptimize on types like BitRef seem to cause a lot of problems

test/filter_test.cc

@@ -20,8 +20,7 @@ class TestReporter : public benchmark::ConsoleReporter {
 
   virtual void ReportRuns(const std::vector<Run>& report) BENCHMARK_OVERRIDE {
     ++count_;
-    max_family_index_ =
-        std::max<size_t>(max_family_index_, report[0].family_index);
+    max_family_index_ = std::max(max_family_index_, report[0].family_index);
     ConsoleReporter::ReportRuns(report);
   };
 
@@ -29,13 +28,13 @@ class TestReporter : public benchmark::ConsoleReporter {
 
   virtual ~TestReporter() {}
 
-  size_t GetCount() const { return count_; }
+  int GetCount() const { return count_; }
 
-  size_t GetMaxFamilyIndex() const { return max_family_index_; }
+  int64_t GetMaxFamilyIndex() const { return max_family_index_; }
 
  private:
-  mutable size_t count_;
-  mutable size_t max_family_index_;
+  mutable int count_;
+  mutable int64_t max_family_index_;
 };
 
 }  // end namespace
@@ -79,13 +78,13 @@ int main(int argc, char** argv) {
   benchmark::Initialize(&argc, argv);
 
   TestReporter test_reporter;
-  const size_t returned_count =
-      benchmark::RunSpecifiedBenchmarks(&test_reporter);
+  const int64_t returned_count =
+      static_cast<int64_t>(benchmark::RunSpecifiedBenchmarks(&test_reporter));
 
   if (argc == 2) {
     // Make sure we ran all of the tests
     std::stringstream ss(argv[1]);
-    size_t expected_return;
+    int64_t expected_return;
     ss >> expected_return;
 
     if (returned_count != expected_return) {
@@ -95,8 +94,8 @@ int main(int argc, char** argv) {
       return -1;
     }
 
-    const size_t expected_reports = list_only ? 0 : expected_return;
-    const size_t reports_count = test_reporter.GetCount();
+    const int64_t expected_reports = list_only ? 0 : expected_return;
+    const int64_t reports_count = test_reporter.GetCount();
     if (reports_count != expected_reports) {
       std::cerr << "ERROR: Expected " << expected_reports
                 << " tests to be run but reported_count = " << reports_count
@@ -104,8 +103,8 @@ int main(int argc, char** argv) {
       return -1;
     }
 
-    const size_t max_family_index = test_reporter.GetMaxFamilyIndex();
-    const size_t num_families = reports_count == 0 ? 0 : 1 + max_family_index;
+    const int64_t max_family_index = test_reporter.GetMaxFamilyIndex();
+    const int64_t num_families = reports_count == 0 ? 0 : 1 + max_family_index;
     if (num_families != expected_reports) {
       std::cerr << "ERROR: Expected " << expected_reports
                 << " test families to be run but num_families = "