Variable Not In Scope for Lambda – CentOS

I’m trying to diagnose a timing issue on a multi-core processor [Xeon Silver]. I think that the clocks have not been configured or synced between the processor. I’m using Eli Bendersky’s [credited in the code snippet] threading examples to build a test instrument. I have made three changes. I made made the sleep occur first, and I added a call to std::chrono::system_clock::now() and tried to print it out. I’m building with gcc 4.8.5 on CentOS 7.5.

The code is as follows:

// // Eli Bendersky [http://eli.thegreenplace.net]
// This code is in the public domain.
#include <algorithm>
#include <chrono>
#include <iostream>
#include <mutex>
#include <thread>
#include <vector>
#include <pthread.h>

int main(int argc, const char** argv) {
  unsigned num_cpus = std::thread::hardware_concurrency();
  std::cout << "Launching " << num_cpus << " threadsn";

  // A mutex ensures orderly access to std::cout from multiple threads.
  std::mutex iomutex;
  std::vector<std::thread> threads(num_cpus);
  for (unsigned i = 0; i < num_cpus; ++i)
  {
    threads[i] = std::thread([&iomutex, i]
    {
       // Simulate important work done by the tread by sleeping for a bit...
      std::this_thread::sleep_for(std::chrono::milliseconds(200));
      {
         std::chrono::time_point ti = std::chrono::system_clock::now();
         // Use a lexical scope and lock_guard to safely lock the mutex only for
         // the duration of std::cout usage.
         std::lock_guard<std::mutex> iolock(iomutex);
         std::cout << "Thread #" << i << " hit its clock at: " << ti.time_since_epoch() << "n";
       }
    });
  }

  for (auto& t : threads) {
      t.join();
  }
  return 0;
}

I build with make:

CXX = g++
CXXFLAGS = -std=c++11 -Wall -O3 -g -DNDEBUG -pthread
LDFLAGS = -lpthread -pthread

clock-check: clock-check.cpp
    $(CXX) $(CXXFLAGS) $^ -o $@ $(LDFLAGS)

GCC gives me the following error:

[user@sbc1 concur]$ make clock-check
g++ -std=c++11 -Wall -O3 -g -DNDEBUG -pthread clock-check.cpp -o clock-check -lpthread -pthread
clock-check.cpp: In lambda function:
clock-check.cpp:32:67: error: ‘ti’ was not declared in this scope
      std::cout << "Thread #" << i << " hit its clock at: " << ti.time_since_epoch() << "n";
                                                               ^
make: *** [clock-check] Error 1

ti is clearly in the same block scope as the print statement, and I’m baffled why the compiler is complaining. I have not found any restrictions on variables local to the lambda. Most of what I have found has been references to captures.