From perl5160delta#Lvalue-subroutines (second bullet point):

Lvalue subroutines used to enforce lvalue syntax (i.e., whatever can go on the left-hand side of =) for the last statement and the arguments to return. Since lvalue subroutines are not always called in lvalue context, this restriction has been lifted.

The “last statement” immediately before line 108 is:

if ($rfv eq ARRAY )
{
    if (defined($wa)) {               # arrays  special
        $wa? @{$p->{$vn}} : $addrof ? \$p->{$vn} : $p->{$vn}
    }
}
elsif ($rfv eq HASH ) { $p->{$vn} } 
elsif ($addrof) { return $p->{$vn} }
else  { return $p->{$vn} }

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In the case where $rfv does equal ARRAY but $wa is not defined, this “last statement” does nothing, so the sub will return undef, which is not a valid lvalue.

That’s just my guess as to what is going on. I don’t know where the && in the error message is coming from, but I note that a similar message was reported in http://www.perladvent.org/2005/21/. I can’t experiment as I don’t have version 5.14 installed.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

In reply to Re: weird error message in middle-aged-perl(5.14) by Athanasius
in thread weird error message in middle-aged-perl(5.14) by perl-diddler

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