I'm not sure if this is a bug or not. I'm running perl 5, version 26, subversion 1 (v5.26.1) built for MSWin32-x64-multi-thread from Strawberry Perl. If I have a %hash, I can pass it to a function with \%hash. In the function, I can assign elements by autovivification: 
$$hash{'key1'}{"$var2"} = $value;

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or 
$$hash->{'key1'}->{"$var2"} = $value;

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BUT, and this is the real issue, if I want to print all the 'var2's, I must do something (still in the function) like: 
foreach $key (keys %$hash{'key1'}->%* ){
    print "$key\n";
}

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Omitting the ->%* produces an error "Experimental keys on scalar is now forbidden" and if I omit the leading % it says the global symbol $hash is not defined. Perl version 5.24 is when the ->%* was supposed to be a nearly 1:1 compatible replacement for %$ dereferencing (and no longer experimental), and as far as I know there's probably not supposed to be a circumstance where you need BOTH. After further testing, with the $${}{} assignment I can get the keys inside the function using %{ $$hash{'key'} } or $$hash{'key'}->%* . Is there an explanation for the referencing/syntax going on?

In reply to 5.26 sigil reference syntax in subfunction by chenhonkhonk

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