[Go] Exported ArrowArrayStream.get_next doesn't handle uninitialized ArrowArrays well

[lidavidm]

Describe the bug, including details regarding any error messages, version, and platform.

get_next should set ArrowArray.release to NULL when there are no more records. However, the current implementation instead tries to release the out-parameter. This is harmless when the out-parameter is 0-initialized (the implementation will skip the call) but otherwise it'll crash (after jumping to a random garbage address).

Component(s)

Go

[lidavidm]

@pitrou I noticed this while using PyArrow to import an ArrowArrayStream exported from Go. PyArrow apparently passes in an uninitialized ArrowArray to Go, and Go was assuming it would be initialized. Should we say that producers should not assume inputs are initialized, or that consumers should (zero-)initialize parameters?

[pitrou]

The out parameter should be handled as an out-parameter, so it can't be expected to be initialized (to what?).

[lidavidm]

That's what I thought :)

(It was expecting it to be zero-initialized, because it would call the release callback if present.)