[RF] Make sure RooProjectedPdf compiled for normset is still RooAbsPdf

Also have a `dynamic_cast` check if the pdfClone inside createNLLImpl is
actually a RooAbsPdf to prevent similar problems in the future.

Author: guitargeek

roofit/roofitcore/src/FitHelpers.cxx

@@ -764,7 +764,7 @@ std::unique_ptr<RooAbsReal> createNLL(RooAbsPdf &pdf, RooAbsData &data, const Ro
       RooFit::Detail::CompileContext ctx{normSet};
       ctx.setLikelihoodMode(true);
       std::unique_ptr<RooAbsArg> head = pdf.compileForNormSet(normSet, ctx);
-      std::unique_ptr<RooAbsPdf> pdfClone = std::unique_ptr<RooAbsPdf>{static_cast<RooAbsPdf *>(head.release())};
+      std::unique_ptr<RooAbsPdf> pdfClone = std::unique_ptr<RooAbsPdf>{&dynamic_cast<RooAbsPdf &>(*head.release())};
 
       // reset attributes
       pdf.setAttribute("SplitRange", false);

roofit/roofitcore/src/RooProjectedPdf.cxx

@@ -34,6 +34,7 @@ is therefore identical to that of <pre>f->createProjection(RooArgSet(x,y))</pre>
 #include "RooAbsReal.h"
 #include "RooRealVar.h"
 #include "RooNameReg.h"
+#include "RooWrapperPdf.h"
 
 
 
@@ -286,6 +287,15 @@ RooProjectedPdf::compileForNormSet(RooArgSet const &normSet, RooFit::Detail::Com
    nset2.add(intobs);
 
    auto newArg = std::unique_ptr<RooAbsReal>{intpdf->createIntegral(intobs, &nset2)};
+
+   std::string namePdf = std::string{newArg->GetName()} + "_wrapped_pdf";
+
+   auto newArgPdf = std::make_unique<RooWrapperPdf>(namePdf.c_str(), namePdf.c_str(), *newArg);
+
    ctx.markAsCompiled(*newArg);
-   return newArg;
+   ctx.markAsCompiled(*newArgPdf);
+
+   newArgPdf->addOwnedComponents(std::move(newArg));
+
+   return newArgPdf;
 }