std::function vs y combinator benchmark

std_func_vs_y_comb.cpp

#include <functional>

int fact_std_func(int n) {
    std::function<int(int)> fact = [&](auto n) {
        if (n == 1) return 1;
        return n * fact(n-1);
    };
    return fact(n);
}

int fact_comb(int n) {
    auto fact = [](auto n, auto self) -> int {
        if (n == 1) return 1;
        return n * self(n-1, self);
    };
    return fact(n, fact);
}

const int n = 1000;

static void FactStdFunc(benchmark::State& state) {
  for (auto _ : state) {
    benchmark::DoNotOptimize(fact_std_func(n));
  }
}
BENCHMARK(FactStdFunc);

static void FactComb(benchmark::State& state) {
  for (auto _ : state) {
    benchmark::DoNotOptimize(fact_comb(n));
  }
}
BENCHMARK(FactComb);