[libc++] Make std::lock_guard available with _LIBCPP_HAS_NO_THREADS

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

@@ -15,22 +15,18 @@
 // lock_guard(mutex_type& m, adopt_lock_t);
 
 #include <mutex>
-#include <cstdlib>
 #include <cassert>
 
 #include "types.h"
-#include "test_macros.h"
 
 int main(int, char**) {
-  MyMutex m;
   {
+    MyMutex m;
     m.lock();
     std::lock_guard<MyMutex> lg(m, std::adopt_lock);
     assert(m.locked);
   }
-
-  m.lock();
-  m.unlock();
+  assert(!m.locked);
 
   return 0;
 }

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

@@ -16,15 +16,15 @@
 #include <mutex>
 #include <type_traits>
 
-#include "test_macros.h"
 #include "types.h"
 
 int main(int, char**) {
   MyMutex m;
-  std::lock_guard<MyMutex> lg(m); // makes sure this compiles and runs
-#if TEST_STD_VER >= 17
-  static_assert(!std::is_convertible_v<MyMutex, std::lock_guard<MyMutex>>, "constructor must be explicit");
-#endif
+  assert(!m.locked);
+  std::lock_guard<MyMutex> lg(m);
+  assert(m.locked);
+
+  static_assert(!std::is_convertible<MyMutex, std::lock_guard<MyMutex>>::value, "constructor must be explicit");
 
   return 0;
 }

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

@@ -10,7 +10,7 @@
 
 // <mutex>
 
-// lock_guard
+// template <class Mutex> class lock_guard;
 
 // Make sure that the implicitly-generated CTAD works.
 

libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/mutex.pass.cpp → libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/mutex-interop.pass.cpp

@@ -5,44 +5,39 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-//
-// UNSUPPORTED: no-threads
-
-// <mutex>
 
-// template <class Mutex> class lock_guard;
-
-// explicit lock_guard(mutex_type& m);
+// UNSUPPORTED: no-threads
 
-// template<class _Mutex> lock_guard(lock_guard<_Mutex>)
-//     -> lock_guard<_Mutex>;  // C++17
+// Test the interoperation of std::lock_guard with std::mutex, since that is such
+// a common use case.
 
-#include <mutex>
-#include <cstdlib>
 #include <cassert>
+#include <mutex>
+#include <type_traits>
 
 #include "make_test_thread.h"
 #include "test_macros.h"
 
-std::mutex m;
-
-void do_try_lock() {
-  assert(m.try_lock() == false);
-}
+void do_try_lock(std::mutex& m) { assert(m.try_lock() == false); }
 
 int main(int, char**) {
   {
+    std::mutex m;
     std::lock_guard<std::mutex> lg(m);
-    std::thread t = support::make_test_thread(do_try_lock);
+    std::thread t = support::make_test_thread(do_try_lock, m);
     t.join();
   }
 
+  // This should work because the lock_guard unlocked the mutex when it was destroyed above.
   m.lock();
   m.unlock();
 
+  // Test CTAD
 #if TEST_STD_VER >= 17
-  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<std::mutex>>::value, "");
+  }
 #endif
 
   return 0;

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

@@ -19,7 +19,6 @@
 #include <mutex>
 #include <type_traits>
 
-#include "test_macros.h"
 #include "types.h"
 
-static_assert((std::is_same<std::lock_guard<MyMutex>::mutex_type, MyMutex>::value), "");
+static_assert(std::is_same<std::lock_guard<MyMutex>::mutex_type, MyMutex>::value, "");

libcxx/test/std/thread/thread.mutex/thread.lock/thread.lock.guard/types.h

@@ -1,3 +1,11 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
 #ifndef TEST_STD_THREAD_THREAD_MUTEX_THREAD_LOCK_THREAD_LOCK_GUARD_TYPES_H
 #define TEST_STD_THREAD_THREAD_MUTEX_THREAD_LOCK_THREAD_LOCK_GUARD_TYPES_H