Quantifier follows nothing in regex; marked by <-- HERE in m/+ <-- HERE l/

C:\>perl -e "print '+++' =~ /\+/"
1
C:\>

    #add
    if ($permissions =~ /\+ ([a-z])/xms ) {
        $new_permissions = qq{$old_permissions$permissions};
    }

$ perl -wle ' if ( "+w" =~ m/\+ ([a-z])/xms ) { print "yo"; } else { print "no"; }'
yo

C:\>perl -Mstrict -wle " if ( '+w' =~ m/\+ ([a-z])/xms ) { print 'yo'; } else { print 'no'; }"
yo

$ perl -Mstrict  -wle ' if ( "+w" =~ m/\+ ([a-z])/xms ) { print "yo"; } else { print "no"; }'
yo

~$ perl -Mstrict  -wle 'my $re = "\+ ([a-z])"; if ( "+w" =~ m/$re/xms ) { print "yo"; } else { print "no"; }'
Quantifier follows nothing in regex; marked by <-- HERE in m/+ <-- HERE  ([a-z])/ at -e line 1.

my $string = "+[a-z]";
if( '+w' =~ /\Q$string\E/ ){
  print "yes";
}