From ead246455adf1a215ec2715dad6533073a6beb4e Mon Sep 17 00:00:00 2001
From: Dimitry Andric <dim@FreeBSD.org>
Date: Wed, 23 Oct 2019 17:53:01 +0000
Subject: Vendor import of stripped lldb trunk r375505, the last commit before
 the upstream Subversion repository was made read-only, and the LLVM project
 migrated to GitHub:

https://llvm.org/svn/llvm-project/lldb/trunk@375505
---
 source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

(limited to 'source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp')

diff --git a/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp b/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp
index 815dafb6c724..78c453cd1b3c 100644
--- a/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp
+++ b/source/Plugins/Language/CPlusPlus/LibCxxBitset.cpp
@@ -30,8 +30,15 @@ public:
   ValueObjectSP GetChildAtIndex(size_t idx) override;
 
 private:
+  // 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).
+  // Value objects created from raw data (i.e. in a different cluster) must
+  // be referenced via shared pointer to keep them alive, however.
   std::vector<ValueObjectSP> m_elements;
-  ValueObjectSP m_first;
+  ValueObject* m_first = nullptr;
   CompilerType m_bool_type;
   ByteOrder m_byte_order = eByteOrderInvalid;
   uint8_t m_byte_size = 0;
@@ -50,7 +57,7 @@ BitsetFrontEnd::BitsetFrontEnd(ValueObject &valobj)
 
 bool BitsetFrontEnd::Update() {
   m_elements.clear();
-  m_first.reset();
+  m_first = nullptr;
 
   TargetSP target_sp = m_backend.GetTargetSP();
   if (!target_sp)
@@ -63,7 +70,7 @@ bool BitsetFrontEnd::Update() {
 
   m_elements.assign(size, ValueObjectSP());
 
-  m_first = m_backend.GetChildMemberWithName(ConstString("__first_"), true);
+  m_first = m_backend.GetChildMemberWithName(ConstString("__first_"), true).get();
   return false;
 }
 
@@ -86,7 +93,7 @@ ValueObjectSP BitsetFrontEnd::GetChildAtIndex(size_t idx) {
     chunk = m_first->GetChildAtIndex(idx / *bit_size, true);
   } else {
     type = m_first->GetCompilerType();
-    chunk = m_first;
+    chunk = m_first->GetSP();
   }
   if (!type || !chunk)
     return {};
-- 
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