[libcxx testing] Remove ALLOW_RETRIES from lock_guard tests

These two tests were clumsily using time measurements to determine
whether std::lock_guard was working correctly. In practice, this
approach merely verified that the underlying lock properly waits.

Now these two tests verify that lock is acquired, not dropped
prematurely, and finally, actually dropped at the end of the scope.

libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/adopt_lock.pass.cpp

@@ -8,49 +8,30 @@
 //
 // UNSUPPORTED: libcpp-has-no-threads
 
-// ALLOW_RETRIES: 2
-
 // <mutex>
 
 // template <class Mutex> class lock_guard;
 
 // lock_guard(mutex_type& m, adopt_lock_t);
 
 #include <mutex>
-#include <thread>
 #include <cstdlib>
 #include <cassert>
 
 #include "test_macros.h"
 
 std::mutex m;
 
-typedef std::chrono::system_clock Clock;
-typedef Clock::time_point time_point;
-typedef Clock::duration duration;
-typedef std::chrono::milliseconds ms;
-typedef std::chrono::nanoseconds ns;
-
-void f()
+int main()
 {
-    time_point t0 = Clock::now();
-    time_point t1;
-    {
+  {
     m.lock();
     std::lock_guard<std::mutex> lg(m, std::adopt_lock);
-    t1 = Clock::now();
-    }
-    ns d = t1 - t0 - ms(250);
-    assert(d < ms(50));  // within 50ms
-}
+    assert(m.try_lock() == false);
+  }
 
-int main(int, char**)
-{
-    m.lock();
-    std::thread t(f);
-    std::this_thread::sleep_for(ms(250));
-    m.unlock();
-    t.join();
+  m.lock();
+  m.unlock();
 
   return 0;
 }

libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/mutex.pass.cpp

@@ -8,8 +8,6 @@
 //
 // UNSUPPORTED: libcpp-has-no-threads
 
-// ALLOW_RETRIES: 2
-
 // <mutex>
 
 // template <class Mutex> class lock_guard;
@@ -20,43 +18,26 @@
 //     -> lock_guard<_Mutex>;  // C++17
 
 #include <mutex>
-#include <thread>
 #include <cstdlib>
 #include <cassert>
 
 #include "test_macros.h"
 
 std::mutex m;
 
-typedef std::chrono::system_clock Clock;
-typedef Clock::time_point time_point;
-typedef Clock::duration duration;
-typedef std::chrono::milliseconds ms;
-typedef std::chrono::nanoseconds ns;
-
-void f()
+int main()
 {
-    time_point t0 = Clock::now();
-    time_point t1;
-    {
+  {
     std::lock_guard<std::mutex> lg(m);
-    t1 = Clock::now();
-    }
-    ns d = t1 - t0 - ms(250);
-    assert(d < ms(200));  // within 200ms
-}
+    assert(m.try_lock() == false);
+  }
 
-int main(int, char**)
-{
-    m.lock();
-    std::thread t(f);
-    std::this_thread::sleep_for(ms(250));
-    m.unlock();
-    t.join();
+  m.lock();
+  m.unlock();
 
 #ifdef __cpp_deduction_guides
-    std::lock_guard lg(m);
-    static_assert((std::is_same<decltype(lg), std::lock_guard<decltype(m)>>::value), "" );
+  std::lock_guard lg(m);
+  static_assert((std::is_same<decltype(lg), std::lock_guard<decltype(m)>>::value), "" );
 #endif
 
   return 0;