Annotate scoped_lock as with scoped_lockable attribute

[aaronpuchert]

Summary

Scoped capabilities need to be annotated as such, otherwise the thread
safety analysis won't work as intended.

Fixes PR39234.

[ldionne]

test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp

28

What is the purpose of this added function?

[ldionne]

Thanks a lot for taking a look so quickly!

test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp

28

Nevermind, I just read the comment on PR39234 and understood.

[NoQ]

Hmm, this seems to be causing buildbot failures, could you take a look?

Eg., http://lab.llvm.org:8080/green/job/libcxx_master_cmake/5459/consoleFull

/Users/buildslave/jenkins/sharedspace/libcxx/libcxx.src/test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp:28:8: error: no member named 'scoped_lock' in namespace 'std'
  std::scoped_lock<std::mutex> lock(m);
  ~~~~~^
/Users/buildslave/jenkins/sharedspace/libcxx/libcxx.src/test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp:28:30: error: expected '(' for function-style cast or type construction
  std::scoped_lock<std::mutex> lock(m);
                   ~~~~~~~~~~^
/Users/buildslave/jenkins/sharedspace/libcxx/libcxx.src/test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp:28:32: error: no matching function for call to 'lock'
  std::scoped_lock<std::mutex> lock(m);
                               ^~~~
/Users/buildslave/jenkins/sharedspace/libcxx/libcxx.src/include/mutex:372:1: note: candidate function template not viable: requires 2 arguments, but 1 was provided
lock(_L0& __l0, _L1& __l1)
^
/Users/buildslave/jenkins/sharedspace/libcxx/libcxx.src/include/mutex:446:1: note: candidate function template not viable: requires at least 3 arguments, but 1 was provided
lock(_L0& __l0, _L1& __l1, _L2& __l2, _L3& ...__l3)
^
3 errors generated.
--

Compilation failed unexpectedly!

[aaronpuchert]

In D53049#1260836, @NoQ wrote:

Hmm, this seems to be causing buildbot failures, could you take a look?

Hmm, std::scoped_lock is only available with C++17. I'll put an #ifdef around it if you don't mind.

[ldionne]

In D53049#1261141, @aaronpuchert wrote:

In D53049#1260836, @NoQ wrote:

Hmm, this seems to be causing buildbot failures, could you take a look?

Hmm, std::scoped_lock is only available with C++17. I'll put an #ifdef around it if you don't mind.

#if TEST_STD_VER >= 17 is what you're looking for. And don't forget to `#include "test_macros.h".

[aaronpuchert]

In D53049#1261142, @ldionne wrote:

#if TEST_STD_VER >= 17 is what you're looking for. And don't forget to `#include "test_macros.h".

Oh, I was a bit to quick and used __cplusplus. Should I change it?

[aaronpuchert]

In D53049#1261176, @aaronpuchert wrote:

In D53049#1261142, @ldionne wrote:

#if TEST_STD_VER >= 17 is what you're looking for. And don't forget to `#include "test_macros.h".

Oh, I was a bit to quick and used __cplusplus. Should I change it?

Ok, I cleaned this up a bit in rCXX344194. I hope you don't mind, the change is rather small.

include/mutex

public:
     _LIBCPP_INLINE_VISIBILITY
     explicit scoped_lock(adopt_lock_t) {}
 
     scoped_lock(scoped_lock const&) = delete;
     scoped_lock& operator=(scoped_lock const&) = delete;
 };
 
 template <class _Mutex>
-class _LIBCPP_TEMPLATE_VIS scoped_lock<_Mutex> {
+class _LIBCPP_TEMPLATE_VIS _LIBCPP_THREAD_SAFETY_ANNOTATION(scoped_lockable) scoped_lock<_Mutex> {
 public:
     typedef _Mutex  mutex_type;
 private:
     mutex_type& __m_;
 public:
     explicit scoped_lock(mutex_type & __m) _LIBCPP_THREAD_SAFETY_ANNOTATION(acquire_capability(__m))
         : __m_(__m) {__m_.lock();}
 

test/libcxx/thread/thread.mutex/thread_safety_lock_guard.pass.cpp

 // MODULES_DEFINES: _LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS
 #define _LIBCPP_ENABLE_THREAD_SAFETY_ANNOTATIONS
 
 #include <mutex>
 
 std::mutex m;
 int foo __attribute__((guarded_by(m)));
 
+static void scoped() {
+  std::scoped_lock<std::mutex> lock(m);
+  foo++;
+}
+
 int main() {
+  scoped();
   std::lock_guard<std::mutex> lock(m);
   foo++;
 }