[DAFFODIL-2420] choice branch which is zero-occurrence array is missing - should cause backtracking

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.7.0
• Component/s: Back End, DFDL Language, QA
• Assignee: Unassigned
• Reporter: Mike Beckerle
• Created: 21/Oct/20 19:57
• Updated: 05/Feb/21 20:15

Description

Erratum 5.39 clarifies behavior on arrays in a choice branch, when there are zero occurrences of the array element

If the branch is an element declaration having dfdl:occursCountKind='expression' or dfdl:occursCountKind='parsed', then zero instances are possible. If the branch parses successfully without a discriminator but produces no element occurrences, then the branch is considered missing, and the parser looks for the next branch.

We need to ensure Daffodil implements this behavior, and/or add tests to verify it.

Note: it may be that this is daffodil's behavior, but I somehow doubt it.