I tried compiling from the master branch (OpenQBMM/OpenQBMM) and encountered an error from type conversion of nullPtr in the clone() members, namely in these files under quadratureApproximations:
moment.C, quadratureNode.C and velocityQuadratureNode.C.
I see that the stable releases have proper return type (NULL autoPtr<respective type>). However, it seems that was replaced for nullPtr subsequently (The original appears in commented form in velocityQuadratureNode.C and using it allows compilation.) I am curious about the reason behind this choice of change of return type, if you could enlighten me. Further, wouldn't everyone encounter this error when this change was made (I have documented it here: www.cfd-online.com/Forums/openfoam-installation/229060-openqbmm-compile-error-v6-7-8-dev.html ) ?