use universal reference

Author: EfesX

include/benchmark/benchmark.h

@@ -1163,8 +1163,8 @@ class BENCHMARK_EXPORT Benchmark {
   // of threads, thread-index, benchmark arguments, etc.
   //
   // The callback must not be NULL or self-deleting.
-  Benchmark* Setup(callback_function);
-  Benchmark* Teardown(callback_function);
+  Benchmark* Setup(callback_function&&);
+  Benchmark* Teardown(callback_function&&);
 
   // Pass this benchmark object to *func, which can customize
   // the benchmark by calling various methods like Arg, Args,

src/benchmark_register.cc

@@ -337,15 +337,15 @@ Benchmark* Benchmark::Apply(void (*custom_arguments)(Benchmark* benchmark)) {
   return this;
 }
 
-Benchmark* Benchmark::Setup(callback_function setup) {
+Benchmark* Benchmark::Setup(callback_function&& setup) {
   BM_CHECK(setup != nullptr);
-  setup_ = setup;
+  setup_ = std::forward<callback_function>(setup);
   return this;
 }
 
-Benchmark* Benchmark::Teardown(callback_function teardown) {
+Benchmark* Benchmark::Teardown(callback_function&& teardown) {
   BM_CHECK(teardown != nullptr);
-  teardown_ = teardown;
+  teardown_ = std::forward<callback_function>(teardown);
   return this;
 }