TClass Real Data: proper tracking of transientness.

We do want to record as transient a real data member that is inside a
nested object that is itself marked as transient.

However, the `isTransient` parameter to `TBuildRealData::Inspect`
is set to true in the case where the object is really nested
and the real data is being added to the current class (what we want)
and in the case where we want to setup a related class but the
real data will not be added to the current class (eg. collection
or pointer to a class).

Author: pcanal

core/base/inc/TMemberInspector.h

@@ -39,6 +39,7 @@ class TMemberInspector {
    class TParentBuf;
    TParentBuf* fParent; // current inspection "path"
    EObjectPointerState fObjectPointerState; // whether the address is valid or only an offset
+   UInt_t fNestedTransient;
 
    TMemberInspector(const TMemberInspector &) = delete;
    TMemberInspector &operator=(const TMemberInspector &) = delete;
@@ -76,6 +77,10 @@ class TMemberInspector {
    void GenericShowMembers(const char *topClassName, const void *obj,
                            Bool_t transientMember);
 
+   void DecrementNestedTransient() { --fNestedTransient; }
+   void IncrementNestedTransient() { ++fNestedTransient; }
+   bool IsNestedTransient() { return fNestedTransient != 0; }
+
    ClassDef(TMemberInspector,0)  //ABC for inspecting class data members
 };
 

core/base/src/TMemberInspector.cxx

@@ -60,7 +60,7 @@ void TMemberInspector::TParentBuf::Remove(Ssiz_t startingAt)
 ClassImp(TMemberInspector);
 
 TMemberInspector::TMemberInspector():
-   fObjectPointerState(kUnset)
+   fObjectPointerState(kUnset), fNestedTransient(0)
 {
    // Construct a member inspector
 

core/meta/src/TClass.cxx

@@ -775,7 +775,7 @@ void TBuildRealData::Inspect(TClass* cl, const char* pname, const char* mname, c
       return;
    }
 
-   Bool_t isTransientMember = isTransient;
+   Bool_t isTransientMember = kFALSE;
 
    if (!dm->IsPersistent()) {
       // For the DataModelEvolution we need access to the transient member.
@@ -824,6 +824,8 @@ void TBuildRealData::Inspect(TClass* cl, const char* pname, const char* mname, c
       TRealData::GetName(rdName,dm);
       rname += rdName;
       TRealData* rd = new TRealData(rname.Data(), offset, dm);
+      if (isTransientMember || IsNestedTransient())
+         rd->SetBit(TRealData::kTransient);
       fRealDataClass->GetListOfRealData()->Add(rd);
       return;
    }
@@ -833,12 +835,14 @@ void TBuildRealData::Inspect(TClass* cl, const char* pname, const char* mname, c
    if (dm->IsaPointer()) {
       // Data member is a pointer.
       TRealData* rd = new TRealData(rname, offset, dm);
-      if (isTransientMember) { rd->SetBit(TRealData::kTransient); };
+      if (isTransientMember || IsNestedTransient())
+         rd->SetBit(TRealData::kTransient);
       fRealDataClass->GetListOfRealData()->Add(rd);
    } else {
       // Data Member is a basic data type.
       TRealData* rd = new TRealData(rname, offset, dm);
-      if (isTransientMember) { rd->SetBit(TRealData::kTransient); };
+      if (isTransientMember || IsNestedTransient())
+         rd->SetBit(TRealData::kTransient);
       if (!dm->IsBasic()) {
          rd->SetIsObject(kTRUE);
 

core/metacling/src/TCling.cxx

@@ -2980,9 +2980,12 @@ void TCling::InspectMembers(TMemberInspector& insp, const void* obj,
             // if we can not find the member (which should not really happen),
             // let's consider it transient.
             Bool_t transient = isTransient || !mbr || !mbr->IsPersistent();
-
+            if (transient)
+               insp.IncrementNestedTransient();
             insp.InspectMember(sFieldRecName.c_str(), cobj + fieldOffset,
                                (fieldName + '.').c_str(), transient);
+            if (transient)
+               insp.DecrementNestedTransient();
 
          }
       }