Compilation error due to use of Perl-only default variables
Syntax error thrown when some piece of code tries to use one of the old Perl variables (and it does not error for some other reason).
Unsupported use of $] variable; in Raku please use .version or .compiler.version
For every unsupported variable (which include most
$^'letter' constructs, as well as others like
$", the error message will mention that the variable is unsupported and the equivalent commands you could use.