[ThreadSafety] Ignore parameter destructors

clang/lib/Analysis/ThreadSafety.cpp

@@ -43,6 +43,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/Allocator.h"
+#include "llvm/Support/Casting.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/TrailingObjects.h"
 #include "llvm/Support/raw_ostream.h"
@@ -2820,6 +2821,12 @@ void ThreadSafetyAnalyzer::runAnalysis(AnalysisDeclContext &AC) {
         case CFGElement::AutomaticObjectDtor: {
           CFGAutomaticObjDtor AD = BI.castAs<CFGAutomaticObjDtor>();
           const auto *DD = AD.getDestructorDecl(AC.getASTContext());
+          // Function parameters as they are constructed in caller's context and
+          // the CFG does not contain the ctors. Ignore them as their
+          // capabilities cannot be analysed because of this missing
+          // information.
+          if (isa_and_nonnull<ParmVarDecl>(AD.getVarDecl()))
+            break;
           if (!DD || !DD->hasAttrs())
             break;
 

clang/test/SemaCXX/warn-thread-safety-analysis.cpp

@@ -1849,6 +1849,43 @@ struct TestScopedLockable {
   }
 };
 
+namespace test_function_param_lock_unlock {
+class A {
+ public:
+  A() EXCLUSIVE_LOCK_FUNCTION(mu_) { mu_.Lock(); }
+  ~A() UNLOCK_FUNCTION(mu_) { mu_.Unlock(); }
+ private:
+  Mutex mu_;
+};
+int do_something(A a) { return 0; }
+
+// Unlock in dtor without lock in ctor.
+// FIXME: We cannot detect that we are releasing a lock that was never held!
+class B {
+ public:
+  B() {}
+  B(int) {}
+  ~B() UNLOCK_FUNCTION(mu_) { mu_.Unlock(); }
+ private:
+  Mutex mu_;
+};
+int do_something(B b) { return 0; }
+
+class SCOPED_LOCKABLE MutexWrapper {
+public:
+  MutexWrapper(Mutex *mu) : mu_(mu) {}
+  ~MutexWrapper() UNLOCK_FUNCTION(mu_) { mu_->Unlock(); }
+  void Lock() EXCLUSIVE_LOCK_FUNCTION(mu_) { mu_->Lock(); }
+
+  Mutex *mu_;
+};
+// FIXME: This is a false-positive as the lock is released by the dtor.
+void do_something(MutexWrapper mw) {
+  mw.Lock(); // expected-note {{mutex acquired here}}
+}            // expected-warning {{mutex 'mw.mu_' is still held at the end of function}}
+
+} // namespace test_function_param_lock_unlock
+
 } // end namespace test_scoped_lockable