Got it! Using ->can() wrapped in eval{} does the trick nicely:

package Util::Stuff::abc;
sub attrib1 { 1  }
sub attrib2 { 10 }
...

eval {
if ($symref->can('attrib1')) {
   ... $symref->attrib1 is OK ...
}};
[download]

Thanks to GrandFather and moritz.