Re^2: Dereferencing undef as an array: Bug or WAD?

[BrowserUk]

Is it because map code can change the list argument...

That is the implication of ikegami's post.

For a definitive answer we'd need someone from p5p to comfirm that.

Update: That said, if it was being autovivified in the normal sense, you'd expect that either it would persist, or at least values derived from it to persist, but neither is the case:

C:\test>perl -Mstrict -wle
"my $r= undef; my @x= map ++$_,@{$r};print qq[[@$r]\n[@x]]"
[]
[]

I think there is a bug there somewhere, but it might be hard to define.

[ChemBoy]

It does persist—you've autovivified $r as a reference to an array, but that array is still empty:

% perl -Mstrict -wle 'my $r = undef; map ++$_, @$r; print $r;'
ARRAY(0x10116180)