I disagree, this is not an autovivification problem.

Autovivification happens when you have an undefined scalar, you dereference it in an lvalue context, then a new scalar/array/hash gets allocated, and the formerly undefined scalar is set to a reference to this new scalar/array/hash.

The simplest example to autovivification is this: my $x; $$x = 42; After this, the content of $x is no longer undef, but instead, it's a reference to 42. Similarly, any of these create a new array and sets the scalar to a reference to it: 

my $x; @$x = (5, 7);
my $y; $$y[2] = 9;
my $z; @$z[2 .. 4] = (5, 7);
my $w; grep 0, @$w[2 .. 4];

[download]

Now compare this to my example, which was, in its simplest form: 

my @x; grep 0, $x[2];

[download]
This has not set any (formerly undefined) scalar to a reference. While it has allocated a scalar, that's for a different reason.

In reply to Re^2: Aliasing bites by ambrus
in thread Aliasing bites by ambrus

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