fix: always check '.length' for 'unknown_length'

[jpivarski]

@pfackeldey, is this correct? Here are the matches, post-fix.

% fgrep -r '.length == ' src/
src/awkward/contents/bitmaskedarray.py:        if self._mask.length is not unknown_length and self._mask.length == 0:
src/awkward/contents/bitmaskedarray.py:        if self._mask.length is not unknown_length and self._mask.length == 0:
src/awkward/contents/bitmaskedarray.py:            if self._mask.length is not unknown_length and self._mask.length == excess_length:
src/awkward/contents/listarray.py:        if offsets.length is not unknown_length and offsets.length == 0:
src/awkward/contents/listarray.py:                advanced.length is not unknown_length and advanced.length == 0
src/awkward/contents/listarray.py:                advanced.length is not unknown_length and advanced.length == 0
src/awkward/contents/listarray.py:        if self._starts.length is not unknown_length and self._starts.length == 0:
src/awkward/contents/listarray.py:        if self._starts.length is not unknown_length and self._starts.length == 0:
src/awkward/contents/unmaskedarray.py:            if offsets.length is not unknown_length and offsets.length == 0:
src/awkward/contents/unmaskedarray.py:        if self._content.length is not unknown_length and self._content.length == 0:
src/awkward/contents/unmaskedarray.py:        if self._content.length is not unknown_length and self._content.length == 0:
src/awkward/contents/numpyarray.py:        if self.length is not unknown_length and self.length == 0:
src/awkward/contents/numpyarray.py:                return out.content.length is not unknown_length and out.content.length == self.length
src/awkward/contents/numpyarray.py:                return out.length is not unknown_length and out.length == self.length
src/awkward/contents/content.py:            if out.length is not unknown_length and out.length == 0:
src/awkward/contents/content.py:            if out.length is not unknown_length and out.length == 0:
src/awkward/contents/content.py:                or self.length == other.length
src/awkward/contents/indexedarray.py:        if self._index.length is not unknown_length and self._index.length == 0:
src/awkward/contents/indexedarray.py:        if self._index.length is not unknown_length and self._index.length == 0:
src/awkward/contents/indexedarray.py:            if self._content.length is not unknown_length and self._content.length == 0:
src/awkward/contents/indexedarray.py:                # every masked value is self._content[0], unless self._content.length == 0.
src/awkward/contents/indexedarray.py:        if self._content.length is not unknown_length and self._content.length == 0:
src/awkward/contents/indexedarray.py:            # every masked value is self._content[0], unless self._content.length == 0.
src/awkward/contents/indexedarray.py:        if not nplike.known_data or self._index.length == 0:
src/awkward/contents/unionarray.py:        if simplified.length is not unknown_length and simplified.length == 0:
src/awkward/contents/unionarray.py:        if self.length is not unknown_length and self.length == 0:
src/awkward/contents/unionarray.py:        if simplified.length is not unknown_length and simplified.length == 0:
src/awkward/contents/listoffsetarray.py:            and offsets.length == 0
src/awkward/contents/listoffsetarray.py:        if offsets.length is not unknown_length and offsets.length == 0:
src/awkward/contents/listoffsetarray.py:        if offsets.length is not unknown_length and offsets.length == 0:
src/awkward/contents/listoffsetarray.py:                advanced.length is not unknown_length and advanced.length == 0
src/awkward/contents/listoffsetarray.py:                advanced.length is not unknown_length and advanced.length == 0
src/awkward/contents/listoffsetarray.py:            if inneroffsets.length is not unknown_length and inneroffsets.length == 0:
src/awkward/contents/listoffsetarray.py:                self._offsets.length is not unknown_length and self._offsets.length == 1
src/awkward/contents/listoffsetarray.py:                return out2.length == self.length
src/awkward/contents/listoffsetarray.py:            if self.starts.length is not unknown_length and self.starts.length == 0:
src/awkward/contents/indexedoptionarray.py:        if self._content.length is not unknown_length and self._content.length == 0:
src/awkward/contents/indexedoptionarray.py:            if offsets.length is not unknown_length and offsets.length == 0:
src/awkward/contents/indexedoptionarray.py:        if self._index.length is not unknown_length and self._index.length == 0:
src/awkward/contents/indexedoptionarray.py:        if not nplike.known_data or self._index.length == 0:
src/awkward/contents/bytemaskedarray.py:            if offsets.length is not unknown_length and offsets.length == 0:
src/awkward/contents/bytemaskedarray.py:        if self._mask.length is not unknown_length and self._mask.length == 0:
src/awkward/contents/bytemaskedarray.py:        if self._mask.length is not unknown_length and self._mask.length == 0:
src/awkward/contents/emptyarray.py:        if not carry.nplike.known_data or carry.length == 0:
src/awkward/contents/emptyarray.py:            if not head.nplike.known_data or head.length == 0:
src/awkward/contents/regulararray.py:        if offsets.length is not unknown_length and offsets.length == 0:
src/awkward/contents/regulararray.py:                advanced.length is not unknown_length and advanced.length == 0
src/awkward/contents/regulararray.py:                advanced.length is not unknown_length and advanced.length == 0
src/awkward/contents/regulararray.py:                        or trimmed.length == self._size * outcontent.length
src/awkward/contents/recordarray.py:            or out.length == self._length
src/awkward/contents/recordarray.py:            (x if x.length == length else x[:length])._to_arrow(
src/awkward/_broadcasting.py:        if x.length is not unknown_length and x.length == 0:
src/awkward/_broadcasting.py:        if x.length is not unknown_length and x.length == 0:
src/awkward/record.py:        if self._array.length is not unknown_length and self._array.length == 1:
src/awkward/operations/ak_enforce_type.py:        if layout_regular.length is not unknown_length and layout_regular.length == 0:
src/awkward/operations/ak_firsts.py:        if layout.length is not unknown_length and layout.length == 0:

[pfackeldey]

These changes look reasonable to me 👍
I'm just confused why the JAX tests are failing for {ubuntu,macOS} with python 3.{10,11,12} ? This seems to be unrelated to this PR though...

[jpivarski]

It's hard to diagnose because of the JAX PyTrees control flow, but at least one of the errors was caused by this change:

awkward/src/awkward/contents/bytemaskedarray.py

Line 687 in b2d48e9

if offsets.length is not unknown_length and offsets.length == 0:

(from ak.unflatten). The pattern-match solution apparently doesn't work and we'll have to think carefully about each case. I'll make this a draft.

But this may be an indication that we need to rethink the JAX backend, too. (I'm still worried about that...)

[pfackeldey]

I tend to agree. Despite being a JAX fan, I think it is more important that awkward-array with typetracer backend works flawlessly.

[agoose77]

Yeah, unfortunately this kind of logic is not easy to pattern match. When I was reworking this handling, I started to make an effort to standardise unknown length handling, but I definitely think there's a long tail on this. Over time, though, we'll get them all :)

[pfackeldey]

These changes look reasonable to me, probably some of these additional checks would never be hit in practice, but better be safe than sorry as we hit exactly these kinds of problems several times in the past. 👍

[ianna]

looks good to me! Thanks!