[C++] Scalar::hash may segfault for null scalars #27619
Description
Scalar::Hash does not check Scalar::is_valid, which can result in inconsistent hashes when applied to uninitialized /.*Scalar::value/ or may segfault (since null binary scalars may have a null buffer).
Reporter: Ben Kietzman / @bkietz
Assignee: Ben Kietzman / @bkietz
PRs and other links:
Note: This issue was originally created as ARROW-11767. Please see the migration documentation for further details.