Simplified improvement for absint() that always returns an int

[josephscott]

With a long list of tests

https://core.trac.wordpress.org/ticket/65826

This will cause return values to change compared to the old absint() - https://3v4l.org/MssWC - because the old one wasn't actually limited to returning only an int

AI assistance: Yes
Tool(s): Claude
Model(s): Fable 5
Used for: Discussion on potential approaches on how to fix absint() to only return an int in a more simplified way. Claude also wrote all of the new tests.

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[irozum]

This tightens up absint() well for int/string/bool/object/resource inputs, and the return-value discussion with @dmsnell/@westonruter on the ticket (PHP_INT_MIN → PHP_INT_MAX instead of overflowing to float) looks like the right call given the name of the function. I ran the full Tests_Functions_Absint suite (78 tests, all green on PHP 8.3) plus PHPCS and PHPStan against load.php and the test file — no new errors from this diff.

That said, I think this is exactly what's causing the CI failures on every PHP 8.5 job (24/24 red, all in test_absint_returns_non_negative_int_for_unrepresentable_floats): load.php:1470's $maybeint = (int) $maybeint; casts the raw input before any range/finiteness check, so a non-finite or out-of-range float (INF, NAN, 1.0e20, (float) PHP_INT_MAX) hits PHP 8.5's new "float ... is not representable as an int, cast occurred" deprecation right there — the existing PHP_INT_MIN === $maybeint guard only runs after the cast has already happened. I confirmed the cast itself is silently undefined-behavior-but-not-yet-deprecated on PHP 8.3 ((int) 1.0e20 returns a platform-dependent garbage int rather than PHP_INT_MAX), which is why it passes locally but not on 8.5 — this needs a is_finite() / range check on $maybeint while it's still a float, before the cast, not just the post-cast PHP_INT_MIN special case.

One smaller thing: the ticket this PR references (#65826) is already closed via the revert in r63158, so once this lands it'll probably want its own fresh ticket for props/changelog purposes — not blocking, just a heads up for whoever picks this up for 7.2.