test/tsan/tls_race.cc

// RUN: %clangxx_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s
#include <pthread.h>
#include <stddef.h>
#include <unistd.h>

void *Thread(void *a) {
  sleep(1);
  *(int*)a = 43;
  return 0;
}

int main() {
  static __thread int Var = 42;
  pthread_t t;
  pthread_create(&t, 0, Thread, &Var);
  Var = 43;
  pthread_join(t, 0);
}

// CHECK: WARNING: ThreadSanitizer: data race
// CHECK:   Location is TLS of main thread.