Sometimes, the use of B::Deparse is helpful:

> perl -MO=Deparse script_1.pl 
my(@perls) = (1, 2, 3, 4);
sub foo {
    my(@foo) = @{shift @_;};
    return join($/, @foo);
}
print foo(\@perls);
script_1.pl syntax OK

> perl -MO=Deparse script_2.pl 
my(@perls) = (1, 2, 3, 4);
sub foo {
    my(@foo) = @shift;
    return join($/, @foo);
}
print foo(\@perls);
script_2.pl syntax OK
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