[meta] Return exec id of TRef, TRefArray and derived data members

Instead of all data members the type of which has a name beginning
with "TRef".

Fixes ROOT-7052

Author: dpiparo

core/base/test/CMakeLists.txt

@@ -23,6 +23,7 @@ ROOT_ADD_GTEST(CoreBaseTests
   TStringTest.cxx
   TUrlTest.cxx
   TBitsTests.cxx
+  TRefTests.cxx
   LIBRARIES ${extralibs} RIO Core)
 
 ROOT_ADD_GTEST(CoreErrorTests TErrorTests.cxx LIBRARIES Core)

core/base/test/TRefTests.cxx

@@ -0,0 +1,47 @@
+#include "gtest/gtest.h"
+
+#include "TClass.h"
+#include "TInterpreter.h"
+#include "TStreamerElement.h"
+#include "TVirtualStreamerInfo.h"
+
+#include <ROOT/TestSupport.hxx>
+
+// See ROOT-7052
+TEST(TRef, Exec)
+{
+
+   // Needed because we do not generate dictionaries and we do no not want to see warnings
+   ROOT::TestSupport::CheckDiagsRAII checkDiag;
+   checkDiag.requiredDiag(kWarning, "TStreamerInfo::Build", "MyClass: ", /*matchFullMessage=*/false);
+
+   gInterpreter->ProcessLine("class Foo1 : public TRef {\n"
+                             "   int i;\n"
+                             "ClassDef(Foo1, 1);\n"
+                             "};"
+                             "class Foo2 : public TRefArray {\n"
+                             "   int i;\n"
+                             "ClassDef(Foo2, 1);\n"
+                             "};"
+                             "class TRefFoo {int i;};\n"
+                             "class Foo3 {int i;};\n"
+                             " class MyClass {\n"
+                             "    Foo1 m1; // EXEC:GetFoo\n"
+                             "    Foo2 m2; // EXEC:GetFoo\n"
+                             "    TRefFoo m3; // EXEC:GetFoo\n"
+                             "    Foo3 m4; // EXEC:GetFoo\n"
+                             "};");
+
+   auto c = TClass::GetClass("MyClass");
+   auto si = c->GetStreamerInfo();
+   int o;
+   auto se1 = si->GetStreamerElement("m1", o);
+   auto se2 = si->GetStreamerElement("m2", o);
+   auto se3 = si->GetStreamerElement("m3", o);
+   auto se4 = si->GetStreamerElement("m4", o);
+
+   EXPECT_EQ(1, se1->GetExecID());
+   EXPECT_EQ(1, se2->GetExecID());
+   EXPECT_EQ(0, se3->GetExecID());
+   EXPECT_EQ(0, se4->GetExecID());
+}

core/meta/src/TStreamerElement.cxx

@@ -9,12 +9,6 @@
  * For the list of contributors see $ROOTSYS/README/CREDITS.             *
  *************************************************************************/
 
-//////////////////////////////////////////////////////////////////////////
-//                                                                      //
-//                                                                      //
-//////////////////////////////////////////////////////////////////////////
-
-
 #include "TROOT.h"
 #include "TStreamerElement.h"
 #include "TVirtualStreamerInfo.h"
@@ -308,8 +302,15 @@ TClass *TStreamerElement::GetClassPointer() const
 
 Int_t TStreamerElement::GetExecID() const
 {
-   //check if element is a TRef or TRefArray
-   if (strncmp(fTypeName.Data(),"TRef",4) != 0) return 0;
+   TString typeName = fTypeName;
+   if (typeName != "TRef" && typeName != "TRefArray") {
+      // It's not a ROOT standard TRef or TRefArray class, but it could be a user class
+      // inheriting from it (see ROOT-7052)
+      const TString clName = ExtractClassName(fTypeName);
+      const auto cl = TClass::GetClass(clName, kFALSE, kTRUE);
+      if (!cl || (nullptr == cl->GetBaseClass("TRef") && nullptr == cl->GetBaseClass("TRefArray")))
+         return 0;
+   }
 
    //if the UniqueID of this element has already been set, we assume
    //that it contains the exec id of a TRef object.