SEGFAULT while assembling a MixedBilinearForm

[denislachapelle]

I got a segmentation fault while assembling a MixedBilinearForm.

One space is H1 on main mesh while the other space is L2 on an extracted SubMesh using CreateFromBoundary.

Here the code snippets...

//Create the mesh.
mesh = new Mesh();
*mesh = Mesh::MakeCartesian2D(nbrSeg, static_cast<int>(endTime / deltaT),
                                  Element::QUADRILATERAL, false, lenght, endTime, true);

//create a submesh of the boundary.
Array<int> is_bdr_attrs;
is_bdr_attrs.Append(1); // Attribute ID to extract, e.g., boundary marker 1
ismesh = new SubMesh(SubMesh::CreateFromBoundary(*mesh, is_bdr_attrs));
for (int i = 0; i < ismesh->GetNBE(); i++)
{
     ismesh->SetBdrAttribute(i, 1); // Set to attribute 1
}

//space for current.
   IFEC = new H1_FECollection(order, 2);
   IFESpace = new FiniteElementSpace(mesh, IFEC);

   //space for lagrange multiplier relate to Vs Rs,
   //which cause boundary cnditions on I(0,y).
   ISFEC = new L2_FECollection(order, 1);
   ISFESpace = new FiniteElementSpace(ismesh, ISFEC);   

//Mixed Bilinear form VL.
   MBLFVL = new MixedBilinearForm(VFESpace, ISFESpace); //I swap both FESpace and get the same result.
   ConstantCoefficient oneOverRs(1.0/Rs);
   MBLFVL->AddBoundaryIntegrator(new BoundaryMassIntegrator(oneOverRs));
   MBLFVL->Assemble();

//SEGFAULT happens here.

Here is the GDB output snippet...

Program received signal SIGSEGV, Segmentation fault.
0x000055555575a938 in mfem::MixedBilinearForm::Assemble(int) ()
(gdb) bt
#0 0x000055555575a938 in mfem::MixedBilinearForm::Assemble(int) ()
#1 0x00005555555c5eca in Stltfe2d::CreateForms (this=0x7fffffffdf10) at stltfe2d.cpp:310
#2 0x00005555555c6651 in main (argc=1, argv=0x7fffffffe1a8) at stltfe2d.cpp:414
(gdb)

Any help will be very appreciated,
Denis