how do you use benchmark::RegisterBenchmark but with a fixtured benchmark that was previously defined using BENCHMARK_DEFINE_F(FixtureClass, MethodName)[BUG]

[ahmednofal]

Describe the bug
how do you use benchmark::RegisterBenchmark but with a fixtured benchmark that was previously defined using BENCHMARK_DEFINE_F(FixtureClass, MethodName)
whenever I use the MethodName in benchmark::RegisterBenchmark I get a compilation error
System
Which OS, compiler, and compiler version are you using:

• OS: linux
• Compiler and version: gcc 9.4

To reproduce
Steps to reproduce the behavior:

1. define fixture benchmark using : BENCHMARK_DEFINE_F(FixtureClass, MethodName)
2. use the MethodName in benchmark::RegisterBenchmark

Expected behavior
No compilation error
it gives me : undefined reference error to MethodName

[dmah42]

benchmarks using fixtures expect to be registered using BENCHMARK_REGISTER_F.

you could probably go through the macros and figure out what the callable ends up being. ie, BENCHMARK_REGISTER_F calls RegisterBenchmarkInternal(new FixtureClass_MethodName_Method()) essentially, so something like RegisterBenchmark("my_bm", FixtureClass_MethodName_Method, args) might get you close... but it's probably easier to stick with the macro registration.

[ahmednofal]

I wish I could do it using the macro, but I need to take in arguments from the user and configure the Args of the benchmark with those inputs programmatically. I tried your approach, but I am not sure I am doing it correctly, can you please give a full code example, if it is not too much trouble.

Thank you very much for response.

[dmah42]

can you share what you've tried?

[ahmednofal]

Of course, sorry for not posting it at first.

BENCHMARK_DEFINE_F(FixtureClassName, BM_Func)
(::benchmark::State& state) {
  for (auto _ : state) {
     [..... bench logic here .....]
  }
}

int main(int argc, char** argv){
  // Some arg parsing logic here (verified to work just fine)
  benchmark::Initialize(&rem_argv_len, rem_argv_c.data());
  benchmark::RegisterBenchmark("SomeArbitraryName", FixtureClassName_BM_Func_Benchmark)->Arg(0); // checked what the macro resolved to and it puts "_Benchmark" at the end and passing here dummy 0 in Arg but it represents what I would like to do
  benchmark::RunSpecifiedBenchmarks();
  benchmark::Shutdown();
}

This does not compile.
Thank you greatly for responding :)

[dmah42]

working on this as i get bits of time. i'll post progress here as maybe you can figure it out before i do.

the preprocessor output includes

class FixtureClass : public benchmark::Fixture {
 public:
  void SetUp(const ::benchmark::State& state) override {}
  void TearDown(const ::benchmark::State& state) override {}
};

class FixtureClass_BM_Func_Benchmark : public FixtureClass {
 public:
  FixtureClass_BM_Func_Benchmark() { this->SetName("FixtureClass" "/" "BM_Func"); }
 protected:
  void BenchmarkCase(::benchmark::State&)         override; };
  void FixtureClass_BM_Func_Benchmark::BenchmarkCase(::benchmark::State& state) {
    int i = 0;
    for (auto _ : state) {
      benchmark::DoNotOptimize(i += 1);
    }
  }

static ::benchmark::internal::Benchmark* benchmark_uniq_2FixtureClass_BM_Func_Benchmark __attribute__((unused)) =
  (::benchmark::internal::RegisterBenchmarkInternal(new FixtureClass_BM_Func_Benchmark()))->Arg(0);