[LLDB] Fix for synthetic children memory leak

The lifetime of a ValueObject and all its derivative ValueObjects (children, clones, etc.) is managed by a ClusterManager. These objects are only destroyed when every shared pointer to any of the managed objects in the cluster is destroyed. This means that no object in the cluster can store a shared pointer to another object in the cluster without creating a memory leak of the entire cluster. However, some of the synthetic children front-end implementations do exactly this; this patch fixes that.

Differential Revision: https://reviews.llvm.org/D68641

llvm-svn: 374195

1 files changed, 8 insertions, 3 deletions

diff --git a/lldb/source/Plugins/Language/CPlusPlus/LibCxxQueue.cpp b/lldb/source/Plugins/Language/CPlusPlus/LibCxxQueue.cpp
index 4b72089c6ba..2f06d684f95 100644
--- a/lldb/source/Plugins/Language/CPlusPlus/LibCxxQueue.cpp
+++ b/lldb/source/Plugins/Language/CPlusPlus/LibCxxQueue.cpp
@@ -38,16 +38,21 @@ public:
   }
 
 private:
-  ValueObjectSP m_container_sp;
+  // The lifetime of a ValueObject and all its derivative ValueObjects
+  // (children, clones, etc.) is managed by a ClusterManager. These
+  // objects are only destroyed when every shared pointer to any of them
+  // is destroyed, so we must not store a shared pointer to any ValueObject
+  // derived from our backend ValueObject (since we're in the same cluster).
+  ValueObject* m_container_sp = nullptr;
 };
 } // namespace
 
 bool QueueFrontEnd::Update() {
-  m_container_sp.reset();
+  m_container_sp = nullptr;
   ValueObjectSP c_sp = m_backend.GetChildMemberWithName(ConstString("c"), true);
   if (!c_sp)
     return false;
-  m_container_sp = c_sp->GetSyntheticValue();
+  m_container_sp = c_sp->GetSyntheticValue().get();
   return false;
 }