SUMMARY
With some files, the perl syntax highlighting gets confused.


STEPS TO REPRODUCE
1. Create a new file
2. Paste in the two lines:
      $x = ns // "";
      print $x;
3. Save the file as foo.pl

OBSERVED RESULT
The syntax highlight goes wrong at the second slash. Everything after that is mostly green

EXPECTED RESULT
The highlighting should be right. "print" should be black.


SOFTWARE/OS VERSIONS
Debian/Buster
KDE Plasma Version: 4:5.14.5.1-1 (debian plasma-workspace)
KDE Frameworks Version: KDE Frameworks 5.54.0
Qt Version: Qt 5.11.3 (built against 5.11.3)
The xcb windowing system
Kate Part Version 5.54.0

ADDITIONAL INFORMATION

It looks like the problem has something to do with the "//" operator. In some contexts that works all right, like if I use $ns instead of ns.

The original code example is from Catmandu::Exporter::RDF, from libcatmandu-rdf-perl 0.32-2, where the line looks like this:

   RDF::aREF::Decoder->new( 
        ns => $_[0]->ns // ($_[0]->ns eq 0 ? { } : RDF::NS->new),
        callback => $_[0]->model 
    );