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

src/awkward/contents/bitmaskedarray.py

@@ -614,14 +614,14 @@ def _numbers_to_type(self, name, including_unknown):
         return self.to_ByteMaskedArray()._numbers_to_type(name, including_unknown)
 
     def _is_unique(self, negaxis, starts, parents, outlength):
-        if self._mask.length == 0:
+        if self._mask.length is not unknown_length and self._mask.length == 0:
             return True
         return self.to_IndexedOptionArray64()._is_unique(
             negaxis, starts, parents, outlength
         )
 
     def _unique(self, negaxis, starts, parents, outlength):
-        if self._mask.length == 0:
+        if self._mask.length is not unknown_length and self._mask.length == 0:
             return self
         out = self.to_IndexedOptionArray64()._unique(
             negaxis, starts, parents, outlength
@@ -810,7 +810,10 @@ def to_packed(self, recursive: bool = True) -> Self:
 
         else:
             excess_length = int(math.ceil(self._length / 8.0))
-            if self._mask.length == excess_length:
+            if (
+                self._mask.length is not unknown_length
+                and self._mask.length == excess_length
+            ):
                 mask = self._mask
             else:
                 mask = self._mask[:excess_length]

src/awkward/contents/bytemaskedarray.py

@@ -684,7 +684,7 @@ def _offsets_and_flattened(self, axis: int, depth: int) -> tuple[Index, Content]
 
             offsets, flattened = next._offsets_and_flattened(axis, depth)
 
-            if offsets.length == 0:
+            if offsets.length is not unknown_length and offsets.length == 0:
                 return (
                     offsets,
                     ak.contents.IndexedOptionArray(
@@ -790,14 +790,14 @@ def _numbers_to_type(self, name, including_unknown):
         )
 
     def _is_unique(self, negaxis, starts, parents, outlength):
-        if self._mask.length == 0:
+        if self._mask.length is not unknown_length and self._mask.length == 0:
             return True
         return self.to_IndexedOptionArray64()._is_unique(
             negaxis, starts, parents, outlength
         )
 
     def _unique(self, negaxis, starts, parents, outlength):
-        if self._mask.length == 0:
+        if self._mask.length is not unknown_length and self._mask.length == 0:
             return self
         return self.to_IndexedOptionArray64()._unique(
             negaxis, starts, parents, outlength

src/awkward/contents/indexedarray.py

@@ -13,7 +13,7 @@
 from awkward._nplikes.numpy import Numpy
 from awkward._nplikes.numpy_like import IndexType, NumpyMetadata
 from awkward._nplikes.placeholder import PlaceholderArray
-from awkward._nplikes.shape import ShapeItem
+from awkward._nplikes.shape import ShapeItem, unknown_length
 from awkward._nplikes.typetracer import TypeTracer
 from awkward._parameters import (
     parameters_intersect,
@@ -781,7 +781,7 @@ def _numbers_to_type(self, name, including_unknown):
         )
 
     def _is_unique(self, negaxis, starts, parents, outlength):
-        if self._index.length == 0:
+        if self._index.length is not unknown_length and self._index.length == 0:
             return True
 
         nextindex = self._unique_index(self._index)
@@ -793,7 +793,7 @@ def _is_unique(self, negaxis, starts, parents, outlength):
         return next._is_unique(negaxis, starts, parents, outlength)
 
     def _unique(self, negaxis, starts, parents, outlength):
-        if self._index.length == 0:
+        if self._index.length is not unknown_length and self._index.length == 0:
             return self
 
         branch, depth = self.branch_depth
@@ -1044,7 +1044,7 @@ def _to_arrow(
                 return out
 
         else:
-            if self._content.length == 0:
+            if self._content.length is not unknown_length and self._content.length == 0:
                 # IndexedOptionArray._to_arrow replaces -1 in the index with 0. So behind
                 # every masked value is self._content[0], unless self._content.length == 0.
                 # In that case, don't call self._content[index]; it's empty anyway.
@@ -1058,7 +1058,7 @@ def _to_arrow(
             return next2._to_arrow(pyarrow, mask_node, validbytes, length, options)
 
     def _to_cudf(self, cudf: Any, mask: Content | None, length: int):
-        if self._content.length == 0:
+        if self._content.length is not unknown_length and self._content.length == 0:
             # IndexedOptionArray._to_arrow replaces -1 in the index with 0. So behind
             # every masked value is self._content[0], unless self._content.length == 0.
             # In that case, don't call self._content[index]; it's empty anyway.

src/awkward/contents/numpyarray.py

@@ -692,7 +692,7 @@ def _numbers_to_type(self, name, including_unknown):
             )
 
     def _is_unique(self, negaxis, starts, parents, outlength):
-        if self.length == 0:
+        if self.length is not unknown_length and self.length == 0:
             return True
         elif len(self.shape) != 1:
             return self.to_RegularArray()._is_unique(
@@ -711,9 +711,12 @@ def _is_unique(self, negaxis, starts, parents, outlength):
         else:
             out = self._unique(negaxis, starts, parents, outlength)
             if isinstance(out, ak.contents.ListOffsetArray):
-                return out.content.length == self.length
+                return (
+                    out.content.length is not unknown_length
+                    and out.content.length == self.length
+                )
             else:
-                return out.length == self.length
+                return out.length is not unknown_length and out.length == self.length
 
     def _unique(self, negaxis, starts, parents, outlength):
         if self.shape[0] == 0:

src/awkward/contents/unionarray.py

@@ -1359,7 +1359,7 @@ def _argsort_next(
             parameters=self._parameters,
             mergebool=True,
         )
-        if simplified.length == 0:
+        if simplified.length is not unknown_length and simplified.length == 0:
             return ak.contents.NumpyArray(
                 self._backend.nplike.empty(0, dtype=np.int64),
                 parameters=None,
@@ -1374,7 +1374,7 @@ def _argsort_next(
         )
 
     def _sort_next(self, negaxis, starts, parents, outlength, ascending, stable):
-        if self.length == 0:
+        if self.length is not unknown_length and self.length == 0:
             return self
 
         simplified = type(self).simplified(
@@ -1384,7 +1384,7 @@ def _sort_next(self, negaxis, starts, parents, outlength, ascending, stable):
             parameters=self._parameters,
             mergebool=True,
         )
-        if simplified.length == 0:
+        if simplified.length is not unknown_length and simplified.length == 0:
             return simplified
 
         if isinstance(simplified, ak.contents.UnionArray):

src/awkward/contents/unmaskedarray.py

@@ -13,7 +13,7 @@
 from awkward._nplikes.array_like import ArrayLike
 from awkward._nplikes.numpy import Numpy
 from awkward._nplikes.numpy_like import IndexType, NumpyMetadata
-from awkward._nplikes.shape import ShapeItem
+from awkward._nplikes.shape import ShapeItem, unknown_length
 from awkward._nplikes.typetracer import MaybeNone
 from awkward._parameters import (
     parameters_intersect,
@@ -340,7 +340,7 @@ def _offsets_and_flattened(self, axis: int, depth: int) -> tuple[Index, Content]
             raise AxisError("axis=0 not allowed for flatten")
         else:
             offsets, flattened = self._content._offsets_and_flattened(axis, depth)
-            if offsets.length == 0:
+            if offsets.length is not unknown_length and offsets.length == 0:
                 return (
                     offsets,
                     UnmaskedArray(flattened, parameters=self._parameters),
@@ -399,12 +399,12 @@ def _numbers_to_type(self, name, including_unknown):
         )
 
     def _is_unique(self, negaxis, starts, parents, outlength):
-        if self._content.length == 0:
+        if self._content.length is not unknown_length and self._content.length == 0:
             return True
         return self._content._is_unique(negaxis, starts, parents, outlength)
 
     def _unique(self, negaxis, starts, parents, outlength):
-        if self._content.length == 0:
+        if self._content.length is not unknown_length and self._content.length == 0:
             return self
         return self._content._unique(negaxis, starts, parents, outlength)
 

src/awkward/operations/ak_firsts.py

@@ -11,6 +11,7 @@
     _remove_named_axis,
 )
 from awkward._nplikes.numpy_like import NumpyMetadata
+from awkward._nplikes.shape import unknown_length
 from awkward._regularize import regularize_axis
 from awkward.errors import AxisError
 
@@ -85,7 +86,7 @@ def _impl(array, axis, highlevel, behavior, attrs):
         # and length > 0 cases.
         backend = ak.backend(array)
         slicer = ak.to_backend(ak.from_iter([None, 0]), backend)
-        if layout.length == 0:
+        if layout.length is not unknown_length and layout.length == 0:
             out = layout[slicer[[0]]][0]
         else:
             out = layout[slicer[[1]]][0]

src/awkward/record.py

@@ -194,7 +194,7 @@ def _getitem_fields(self, where, only_fields: tuple[str, ...] = ()):
         return self._array._getitem_fields(where)._getitem_at(self._at)
 
     def to_packed(self, recursive: bool = True) -> Self:
-        if self._array.length == 1:
+        if self._array.length is not unknown_length and self._array.length == 1:
             return Record(self._array.to_packed(recursive), self._at)
         else:
             return Record(self._array[self._at : self._at + 1].to_packed(recursive), 0)