... it wastes time, and extra space, to go back and modify the foreach loop to the equivalent for loop (ignoring for a moment the synonymity of foreach and for):

for (my $i = 0; $i < @array; $i++) {
    my $item  = $array[$i];
    do_something_with($item, $i);
}
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Even a shorter idiom takes an extra line, and isn't quite as "clean" (imo), as the $i has to be defined outside of the loop:

my $i;
foreach (@array) {
    do_something_with($item, $i++);
}
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I think the following is just as simple as using state or any other variation, and doesn't require any more lines of code than your original:

for my $i (0..$#array) {
    do_something_with($array[$i], $i);
}
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...unless I'm missing something.