[df] Add regression test for #19104

Author: vepadulano

tree/dataframe/test/CMakeLists.txt

@@ -69,7 +69,7 @@ endif()
 
 ROOT_ADD_GTEST(dataframe_display dataframe_display.cxx LIBRARIES ROOTDataFrame)
 ROOT_ADD_GTEST(dataframe_ranges dataframe_ranges.cxx LIBRARIES ROOTDataFrame)
-ROOT_ADD_GTEST(dataframe_leaves dataframe_leaves.cxx LIBRARIES ROOTDataFrame)
+ROOT_ADD_GTEST(dataframe_leaves dataframe_leaves.cxx LIBRARIES ROOTDataFrame Physics)
 ROOT_ADD_GTEST(dataframe_resptr dataframe_resptr.cxx LIBRARIES ROOTDataFrame)
 ROOT_ADD_GTEST(dataframe_take dataframe_take.cxx LIBRARIES ROOTDataFrame)
 ROOT_ADD_GTEST(dataframe_entrylist dataframe_entrylist.cxx LIBRARIES ROOTDataFrame)

tree/dataframe/test/dataframe_leaves.cxx

@@ -3,9 +3,23 @@
 #include "TTree.h"
 #include "gtest/gtest.h"
 
+#include <memory>
+#include <TClonesArray.h>
+#include <TLorentzVector.h>
+#include <ROOT/RVec.hxx>
+#include <ROOT/TestSupport.hxx>
 
 using namespace ROOT::VecOps;
 
+template <typename T0, typename T1>
+void expect_vec_float_eq(const T0 &v1, const T1 &v2)
+{
+   ASSERT_EQ(v1.size(), v2.size()) << "Vectors 'v1' and 'v2' are of unequal length";
+   for (std::size_t i = 0ull; i < v1.size(); ++i) {
+      EXPECT_FLOAT_EQ(v1[i], v2[i]) << "Vectors 'v1' and 'v2' differ at index " << i;
+   }
+}
+
 struct BrVal {
    Float_t a;
    Int_t i;
@@ -72,3 +86,44 @@ TEST(RDFLeaves, OneLeafWithDotNameClass)
    EXPECT_EQ(*res, 40);
 }
 
+TEST(RDFLeaves, LeafFromTClonesArray)
+{
+   // Regression test for https://github.com/root-project/root/issues/19104
+   ROOT::TestSupport::CheckDiagsRAII diagRAII;
+   diagRAII.requiredDiag(kWarning, "TTree::Bronch",
+                         "Using split mode on a class: TLorentzVector with a custom Streamer");
+#ifndef NDEBUG
+   diagRAII.requiredDiag(
+      kWarning, "RTreeColumnReader::Get",
+      "Branch ca.fE hangs from a non-split branch. A copy is being performed in order to properly read the content.");
+#endif
+   constexpr static auto fName{"leaffromtclonesarray.root"};
+   struct Dataset {
+      Dataset()
+      {
+         auto f = std::make_unique<TFile>(fName, "recreate");
+         auto t = std::make_unique<TTree>("t", "t");
+         auto ca = std::make_unique<TClonesArray>("TLorentzVector");
+         auto branchData = ca.get();
+         auto &caRef = *ca;
+         t->Branch("ca", &branchData);
+         // Fill the array with two elements. The issue arose from the fact
+         // we were not computing the correct size of the correction value
+         // type, so the wrong offset was used when reading back next elements
+         // of the array
+         new (caRef[0]) TLorentzVector(0, 0, 0, 42.42);
+         new (caRef[1]) TLorentzVector(0, 0, 0, 84.84);
+         t->Fill();
+         f->Write();
+      }
+
+      ~Dataset() { std::remove(fName); }
+   } _;
+
+   std::vector expected{42.42, 84.84};
+
+   ROOT::RDataFrame df("t", fName);
+   auto resultptr = df.Take<ROOT::RVecD>("ca.fE");
+   ASSERT_EQ(resultptr->size(), 1);
+   expect_vec_float_eq(expected, resultptr->at(0));
+}