StrFormat() is a printf-like function, mark it as such, fix fallout. (#727)

src/benchmark_register.cc

@@ -182,14 +182,19 @@ bool BenchmarkFamilies::FindBenchmarks(
             }
           }
 
-          instance.name += StrFormat("%d", arg);
+          // we know that the args are always non-negative (see 'AddRange()'),
+          // thus print as 'unsigned'. BUT, do a cast due to the 32-bit builds.
+          instance.name += StrFormat("%lu", static_cast<unsigned long>(arg));
           ++arg_i;
         }
 
         if (!IsZero(family->min_time_))
           instance.name += StrFormat("/min_time:%0.3f", family->min_time_);
-        if (family->iterations_ != 0)
-          instance.name += StrFormat("/iterations:%d", family->iterations_);
+        if (family->iterations_ != 0) {
+          instance.name +=
+              StrFormat("/iterations:%lu",
+                        static_cast<unsigned long>(family->iterations_));
+        }
         if (family->repetitions_ != 0)
           instance.name += StrFormat("/repeats:%d", family->repetitions_);
 

src/string_util.h

@@ -12,7 +12,11 @@ void AppendHumanReadable(int n, std::string* str);
 
 std::string HumanReadableNumber(double n, double one_k = 1024.0);
 
-std::string StrFormat(const char* format, ...);
+#ifdef __GNUC__
+__attribute__((format(printf, 1, 2)))
+#endif
+std::string
+StrFormat(const char* format, ...);
 
 inline std::ostream& StrCatImp(std::ostream& out) BENCHMARK_NOEXCEPT {
   return out;

test/reporter_output_test.cc

@@ -220,6 +220,18 @@ ADD_CASES(TC_JSONOut,
 ADD_CASES(TC_CSVOut, {{"^\"BM_arg_names/first:2/5/third:4\",%csv_report$"}});
 
 // ========================================================================= //
+// ------------------------ Testing Big Args Output ------------------------ //
+// ========================================================================= //
+
+void BM_BigArgs(benchmark::State& state) {
+  for (auto _ : state) {
+  }
+}
+BENCHMARK(BM_BigArgs)->RangeMultiplier(2)->Range(1U << 30U, 1U << 31U);
+ADD_CASES(TC_ConsoleOut, {{"^BM_BigArgs/1073741824 %console_report$"},
+                          {"^BM_BigArgs/2147483648 %console_report$"}});
+
+// ========================================================================= //
 // ----------------------- Testing Complexity Output ----------------------- //
 // ========================================================================= //