[mrishi]

I encounter the following error trying to compile the OpenQBMM code pulled from github (https://github.com/OpenQBMM).
It appears across versions 6 through 8 and dev. It should be noted that 8 and dev have consolidated the transportModel and TurbulenceModel libraries into one (MomentumTransportModel), so the Make/options has to be changed accordingly.

What is puzzling me is that such a trivial compilation issue (type conversion) could not have survived as part of the code, and further no issue has been raised on the project git, so I am not sure what I am doing wrong here - I merely downloaded and compiled on docker images in macOS (6,7,8 and dev) as well as a built from source OF-6 on Ubuntu 18.04 and encountered the same error.

In file included from ../quadratureNode/lnInclude/quadratureNode.H:316:0,
                 from ../quadratureNode/lnInclude/quadratureNodes.H:43,
                 from ../fieldMomentInversion/lnInclude/fieldMomentInversion.H:45,
                 from lnInclude/quadratureApproximation.H:53,
                 from monoKineticQuadratureApproximation/monoKineticQuadratureApproximation.H:47,
                 from monoKineticQuadratureApproximation/monoKineticQuadratureApproximation.C:31:
../quadratureNode/lnInclude/quadratureNode.C: In instantiation of 'Foam::autoPtr<Foam::quadratureNode<scalarType, vectorType> > Foam::quadratureNode<scalarType, vectorType>::clone() const [with scalarType = Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>; vectorType = Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh>]':
/opt/openfoam-dev/src/OpenFOAM/lnInclude/PtrListIO.C:86:24:   required from 'void Foam::PtrList<T>::read(Foam::Istream&, const INew&) [with INew = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >::iNew; T = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >]'
/opt/openfoam-dev/src/OpenFOAM/lnInclude/PtrListIO.C:162:9:   required from 'Foam::PtrList<T>::PtrList(Foam::Istream&, const INew&) [with INew = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >::iNew; T = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >]'
../../mappedPtrList/mappedPtrList.C:153:13:   required from 'Foam::mappedPtrList<mappedType>::mappedPtrList(Foam::Istream&, const INew&) [with INew = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >::iNew; mappedType = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >]'
lnInclude/quadratureApproximation.C:142:9:   required from 'Foam::quadratureApproximation<momentType, nodeType>::quadratureApproximation(const Foam::word&, const Foam::fvMesh&, const Foam::word&) [with momentType = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >; nodeType = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >]'
monoKineticQuadratureApproximation/monoKineticQuadratureApproximation.C:67:68:   required from here
../quadratureNode/lnInclude/quadratureNode.C:509:12: error: could not convert 'nullptr' from 'std::nullptr_t' to 'Foam::autoPtr<Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >'
     return nullptr;
            ^~~~~~~
In file included from ../moments/moment.H:226:0,
                 from ../moments/moments.H:43,
                 from ../moments/momentFieldSets.H:43,
                 from ../fieldMomentInversion/lnInclude/fieldMomentInversion.H:48,
                 from lnInclude/quadratureApproximation.H:53,
                 from monoKineticQuadratureApproximation/monoKineticQuadratureApproximation.H:47,
                 from monoKineticQuadratureApproximation/monoKineticQuadratureApproximation.C:31:
../moments/moment.C: In instantiation of 'Foam::autoPtr<Foam::moment<fieldType, nodeType> > Foam::moment<fieldType, nodeType>::clone() const [with fieldType = Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>; nodeType = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >]':
/opt/openfoam-dev/src/OpenFOAM/lnInclude/PtrListIO.C:86:24:   required from 'void Foam::PtrList<T>::read(Foam::Istream&, const INew&) [with INew = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >::iNew; T = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >]'
/opt/openfoam-dev/src/OpenFOAM/lnInclude/PtrListIO.C:162:9:   required from 'Foam::PtrList<T>::PtrList(Foam::Istream&, const INew&) [with INew = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >::iNew; T = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >]'
../../mappedPtrList/mappedPtrList.C:153:13:   required from 'Foam::mappedPtrList<mappedType>::mappedPtrList(Foam::Istream&, const INew&) [with INew = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >::iNew; mappedType = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >]'
../moments/momentFieldSet.C:59:21:   required from 'Foam::momentFieldSet<momentType, nodeType>::momentFieldSet(const Foam::word&, const Foam::dictionary&, const Foam::fvMesh&, const Foam::autoPtr<Foam::mappedPtrList<nodeType> >&, const Foam::word&) [with momentType = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >; nodeType = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >]'
lnInclude/quadratureApproximation.C:89:26:   required from 'Foam::quadratureApproximation<momentType, nodeType>::quadratureApproximation(const Foam::word&, const Foam::fvMesh&, const Foam::word&) [with momentType = Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > >; nodeType = Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> >]'
monoKineticQuadratureApproximation/monoKineticQuadratureApproximation.C:67:68:   required from here
../moments/moment.C:158:12: error: could not convert 'nullptr' from 'std::nullptr_t' to 'Foam::autoPtr<Foam::moment<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::quadratureNode<Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> > > >'
     return nullptr;
            ^~~~~~~
/opt/openfoam-dev/wmake/rules/General/transform:25: recipe for target 'Make/linux64GccDPInt32Opt/monoKineticQuadratureApproximation/monoKineticQuadratureApproximation.o' failed