Problems with std::vector<std::array> branches

ROOT
1

Hi,

We are having issues scanning and drawing branches of std::vector<std::vector<std::array<float, 2>>>.

In trying to create a simpler minimal working example of the problem, I see this error:

Error in <TBranchElement::InitializeOffsets>: Could not find the real data member '_M_elems[2]' when constructing the branch 'vector_array' [Likely missing ShowMember].

with the following short macro:

void mwe_no_dict() {
  gInterpreter->GenerateDictionary("vector<array<float,2>>", "array;vector");

  std::vector<std::array<float,2>> vector_array;

  TTree* tree = new TTree();
  tree->Branch("vector_array", &vector_array);
}

Does anyone know what I am doing wrong here?

Thanks,
Andy

ROOT Version: 6.30/04
Platform: linuxx8664gcc
Compiler: g++ (Spack GCC) 13.1.0