[jayhemnani9910]

An unset variable compared with a number uses string comparison, so if (n == 0) is false for an unset n:

$ awk 'BEGIN { print (x == 0), (x > -1), (x >= 0), (x != 0) }'
0 0 0 1
$ gawk 'BEGIN { print (x == 0), (x > -1), (x >= 0), (x != 0) }'    # gawk 5.3.2
1 1 1 0

POSIX gives an uninitialized value both the string value "" and the numeric value 0, and compares numerically when the other side is a number. == and the ordered comparisons now do that for Untyped/Unassigned against Float, Int and Bool. Against a string it is still a string comparison (x < "a" is 1, x == "0" is 0). While there: the (_, Untyped | Unassigned) arm in eq read other.as_str() instead of self.as_str(), so "" == x was 0.

Known gap: a field past NF is also Unassigned, so $9 == 0 now prints 1 (gawk and mawk print 0, main printed 0). Telling the two apart is left for the type rework.

Tests: uninitialized_value_compares_as_zero_with_a_number fails without the change. cargo test --workspace passes (test_awk 100), clippy and cargo fmt --check are clean.

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[Alonely0]

This PR does two jobs at once, which is not bad, but I'm afraid we shouldn't merge the field-related changes at the moment; let's just keep the different type comparisons for unassigned values for now. I think first we should refactor the internal type implementation to use tagged pointers or other form of algebraic property management; the current disjoint representation is hard to manage and starts to suffer from combinatorial explosion.

[Alonely0]

See my previous comment.

[jayhemnani9910]

Dropped the field part in eb7ebc6 and rebased on main. One side effect: fields past NF are Unassigned too, so $9 == 0 now prints 1 (gawk prints 0). I noted it in the description; it should go away with the type rework.

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[Alonely0]

Nice! Merging this once CI passes.