Inconsistent encoding of the empty string

[jixam]

Before I dig further, is this expected behavior?

An object stringifying to the empty string encodes to different JSON depending on its constructor:

Test program

use Cpanel::JSON::XS;

use v5.36;

{
    package E;

    use overload '""' => sub { "" };

    sub new1($class) { bless [undef] => $class };
    sub new2($class) { bless \(my $dummy=undef), $class; };
}

my $JSON = Cpanel::JSON::XS->new->convert_blessed;
say $JSON->encode( E->new1() );
say $JSON->encode( E->new2() );

Output

""
null

[Reini Urban]

We follow upstream

[jixam]

Hmm, this is a stringification overload which I believe upstream does not support?

(With TO_JSON it works as expected, both here and in upstream – but there is no TO_JSON in the test program)

[jixam]

Maybe the below is a better demonstration: with otherwise identical classes, the output is different between TO_JSON and overload '""'.

The empty stringification result is being replace with null here but I don't know how to modify the condition for this situation.

Test program 2

use Cpanel::JSON::XS;

use v5.36;

{
    package J;

    sub TO_JSON { ${$_[0]} }
    sub new($class, $string) { bless \(my $dummy = $string) => $class };
}

{
    package O;

    use overload '""' => sub { ${$_[0]} };
    sub new($class, $string) { bless \(my $dummy = $string) => $class };
}

my $JSON = Cpanel::JSON::XS->new->convert_blessed;
say $JSON->encode( J->new("") );    # ""
say $JSON->encode( O->new("") );    # null

[jixam]

Fixed in #221.