diff -ur root-6.18.04.orig/graf2d/gpadv7/v7/src/RDrawingAttr.cxx root-6.18.04/graf2d/gpadv7/v7/src/RDrawingAttr.cxx
--- root-6.18.04.orig/graf2d/gpadv7/v7/src/RDrawingAttr.cxx	2019-09-11 15:36:49.000000000 +0200
+++ root-6.18.04/graf2d/gpadv7/v7/src/RDrawingAttr.cxx	2020-02-15 21:16:58.819735413 +0100
@@ -26,6 +26,8 @@
 {
 }
 
+constexpr const ROOT::Experimental::RDrawingAttrBase::FromOption_t ROOT::Experimental::RDrawingAttrBase::FromOption;
+
 ROOT::Experimental::RDrawingAttrBase::RDrawingAttrBase(FromOption_t, const Name &name, RDrawingOptsBase &opts) :
    fPath{name.fStr}, fHolder(opts.GetHolder())
 {