Use RooFit::Cut with RooSuperCategory

[fwilk]

I have the following setup:

RooCategory cp( "cp", "CP Tag" );
cp.defineType( "plus", +1 );
cp.defineType( "minus", -1 );

RooCategory flv( "flv", "Flavour Tag" );
flv.defineType( "B0", +1 );
flv.defineType( "b0", -1 );

RooSuperCategory tag( "tag", "[flv X cp]", RooArgSet( flv, cp ) );

A bit later, I’m trying to plot the different categories seperately, naturally I expected this

ds.plotOn( frame, Cut( "tag == tag::{B0;plus}" ) );

to work as expected, however, the code terminates with a segfault:

[#0] ERROR:Eval – RooFormula::DefinedVariable(tag == tag::{B0;plus}) ERROR ‘{B0’ is not a state of tag
Error in RooFormula::Compile: Bad numerical expression : “tag::{B0”
[#0] ERROR:InputArguments – RooFormula::RooFormula(tag == tag::{B0;plus}): compile error
[#0] ERROR:InputArguments – RooDataSet::ds:fillHistogram: invalid cuts “tag == tag::{B0;plus}”
[#0] ERROR:Plotting – RooDataSet::ds:plotOn: fillHistogram() failed

Edit: Is guess I should add that calling

RooTable * tb_tag = ds.table( tag );
tb_tag->Print();

prints the expected number of entries per sub-category.

Is this a bug or is my expectation wrong? If this is a bug, is there a workaround (other than the one I’m using now, which is listed below)?

For the moment I’m using

ds.plotOn( frame, Cut( "cp == cp::plus && flv == flv::B0" ) );

but given that there exists such a thing as a super category I’d really like it to work as the normal category does.