[jayhemnani9910]

POSIX awk: "a reference to a nonexistent element shall create that element", uninitialized. Here reading a[k] for a missing key returns an uninitialized value and doesn't add k:

$ awk 'BEGIN { x[1]; y = a["k"] a["j"]; print length(x), (1 in x), length(a) }'
0 0 0        # gawk 5.3.2: 1 1 2

Scripts that rely on it, such as { seen[$1] } END { for (k in seen) ... } or a guard like if (a[k] == "") followed by length(a), see an empty array. (k in a) still doesn't create anything.

get_array_elem (used by IndexS) now inserts an uninitialized value with entry_ref(..).or_insert_with(Value::new_untyped), the way array_elem_aoa already does for arrays of arrays.

Test test_referencing_an_element_creates_it (fails on main). cargo test --workspace: 219 pass (218 on main), clippy clean. Eight programs around element reads, in, counting and assignment give the same output as gawk 5.3.2.

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[github-actions]

GNU awk testsuite comparison:

Test results comparison:
  Current:   TOTAL: 666 / PASSED: 103 / FAILED: 465 / SKIPPED: 98
  Reference: TOTAL: 666 / PASSED: 101 / FAILED: 467 / SKIPPED: 98

Changes from main branch:
  TOTAL: +0
  PASSED: +2
  FAILED: -2

Test improvements (2):
  + aadelete1
  + tailrecurse

[Alonely0]

huh, I was under the impression this was already the case. Good catch, thanks for your contribution!