Commits
Antoine Pitrou authored and Wes McKinney committed b3c8631097b
ARROW-9265: [C++] Allow writing and reading V4-compliant IPC data V4 Union arrays with top-level null slots are disallowed, though. Closes #7664 from pitrou/ARROW-9265-metadata-version-unions Lead-authored-by: Antoine Pitrou <antoine@python.org> Co-authored-by: Wes McKinney <wesm@apache.org> Signed-off-by: Wes McKinney <wesm@apache.org>