spenczar opened a new issue, #37072:
URL: https://github.com/apache/arrow/issues/37072
### Describe the bug, including details regarding any error messages,
version, and platform.
This code should work:
```py
import pyarrow as pa
struct_type = pa.struct([pa.field("x", pa.int32(), nullable=False)])
nulls = pa.nulls(5, struct_type)
# The following is an error:
nulls = nulls.cast(struct_type)
```
The error message is:
```
ArrowInvalid: Can't view array of type struct<x: int32 not null> as
struct<x: int32 not null>: nulls in input cannot be viewed as non-nullable
```
Indeed, if we `print(nulls)`, it contains null values in the non-nullable
field `x`:
```
-- is_valid:
[
false,
false,
false,
false,
false
]
-- child 0 type: int32
[
null,
null,
null,
null,
null
]
```
But those are all invalid at the top-level _anyway_, so there's no reason
`cast` ought to care. Either that, or it should be impossible to call
`pa.nulls` on a struct with a non-nullable field anywhere in its hierarchy of
fields, but that seems wrong too. That would imply that if _any_ field is
non-nullable then the whole struct would be non-nullable, which clearly is not
the intent. You should be able to have a null struct with non-nullable fields.
Ultimately, this is a C++ issue; Python is merely calling those functions.
### Component(s)
C++
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