Fix std unique pointer not printing.

[alexandreyy]

Summary

Std unique pointers were not being printed. The unique pointer layout was changed in libstdc++ 6.0.23.

[labath]

source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp

65–76 ↗

(On Diff #136749)

This is somewhat nitpicky, but I think we should rename the tuple_sp variable, as in your case, it will not actually hold a tuple (it is some unique_ptr_impl object, IIRC). So, it should have some neutral name, and once you have the actual tuple object, then call it a "tuple". Feel free to move this code into a GetTuple() function or something...

Also, we prefer c++-style comments (//).

[alexandreyy]

Implemented GetTuple and moved code to get tuple pointer.

[labath]

Pretty close, just a couple of style issues.

source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp

62 ↗

(On Diff #137022)

nullptr.

78 ↗

(On Diff #137022)

no else after return

[alexandreyy]

Changed NULL pointer

[alexandreyy]

Thanks, @labath @clayborg .
@labath Could you please commit this patch?

lldb/trunk/source/Plugins/Language/CPlusPlus/LibStdcppUniquePointer.cpp

public:
   size_t GetIndexOfChildWithName(const ConstString &name) override;
 
   bool GetSummary(Stream &stream, const TypeSummaryOptions &options);
 
 private:
   ValueObjectSP m_ptr_obj;
   ValueObjectSP m_obj_obj;
   ValueObjectSP m_del_obj;
+
+  ValueObjectSP GetTuple();
 };
 
 } // end of anonymous namespace
 
 LibStdcppUniquePtrSyntheticFrontEnd::LibStdcppUniquePtrSyntheticFrontEnd(
     lldb::ValueObjectSP valobj_sp)
     : SyntheticChildrenFrontEnd(*valobj_sp) {
   Update();
 }
 
-bool LibStdcppUniquePtrSyntheticFrontEnd::Update() {
+ValueObjectSP LibStdcppUniquePtrSyntheticFrontEnd::GetTuple() {
   ValueObjectSP valobj_backend_sp = m_backend.GetSP();
+
   if (!valobj_backend_sp)
-    return false;
+    return nullptr;
 
   ValueObjectSP valobj_sp = valobj_backend_sp->GetNonSyntheticValue();
   if (!valobj_sp)
-    return false;
+    return nullptr;
 
-  ValueObjectSP tuple_sp =
+  ValueObjectSP obj_child_sp =
       valobj_sp->GetChildMemberWithName(ConstString("_M_t"), true);
+
+  ValueObjectSP obj_subchild_sp =
+      obj_child_sp->GetChildMemberWithName(ConstString("_M_t"), true);
+
+  // if there is a _M_t subchild, the tuple is found in
+  // the obj_subchild_sp (for libstdc++ 6.0.23).
+  if (obj_subchild_sp) {
+    return obj_subchild_sp;
+  }
+
+  return obj_child_sp;
+}
+
+bool LibStdcppUniquePtrSyntheticFrontEnd::Update() {
+  ValueObjectSP tuple_sp = GetTuple();
+
   if (!tuple_sp)
     return false;
 
   std::unique_ptr<SyntheticChildrenFrontEnd> tuple_frontend(
       LibStdcppTupleSyntheticFrontEndCreator(nullptr, tuple_sp));
 
   ValueObjectSP ptr_obj = tuple_frontend->GetChildAtIndex(0);
   if (ptr_obj)