Fix separator not backtracked when complex-typed array element fails - #1716
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Fix separator not backtracked when complex-typed array element fails#1716olabusayoT wants to merge 2 commits into
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For a maxOccurs-bounded occursCountKind="implicit" array whose element type is complex with no possible zero-length representation (e.g. every branch of a choice requires a distinct non-empty initiator), the speculative attempt at an occurrence beyond the real data would parse its preceding separator successfully, then fail the content entirely with zero bits consumed. anyTypeElementFailedParseAttemptStatus classified this as AbsentRep, whose contract is to retain the bit position (keep the separator consumed); that is correct for a genuinely empty representation, but wrong here since there is no occurrence at all. This let the separator leak into whatever sequence child comes next, causing spurious "separator not found" / "terminator not found" errors. Gate the AbsentRep classification on isEmptyRepZeroLength for complex types, so a structurally-impossible zero-length failure returns MissingItem instead, which forces the caller to fully backtrack the point of uncertainty including the separator. Added tests to exercise. DAFFODIL-3094
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…backtracking The prior fix gated AbsentRep vs MissingItem on the static isEmptyRepZeroLength flag, but that only describes whether some successful parse of the type could be zero-length, not whether this particular failed attempt was genuinely empty. A choice whose real branch matches part of its content then fails nets zero bits once backed out, indistinguishable from a genuine empty match by bit position alone. Track this via pointOfUncertaintyResetCount, which counts resets that actually undo bit position movement, and a mark stack letting a sequence child's attempt check, via hadPointOfUncertaintyResetSinceMark, whether such a reset happened during it. Added tests for both cases. DAFFODIL-3094
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For a maxOccurs-bounded occursCountKind="implicit" array whose element type is complex with no possible zero-length representation (e.g. every branch of a choice requires a distinct non-empty initiator), the speculative attempt at an occurrence beyond the real data would parse its preceding separator successfully, then fail the content entirely with zero bits consumed. anyTypeElementFailedParseAttemptStatus classified this as AbsentRep, whose contract is to retain the bit position (keep the separator consumed); that is correct for a genuinely empty representation, but wrong here since there is no occurrence at all. This let the separator leak into whatever sequence child comes next, causing spurious "separator not found" / "terminator not found" errors.
Gate the AbsentRep classification on isEmptyRepZeroLength for complex types, so a structurally-impossible zero-length failure returns MissingItem instead, which forces the caller to fully backtrack the point of uncertainty including the separator.
DAFFODIL-3094