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https://issues.apache.org/jira/browse/DAFFODIL-1971?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17948965#comment-17948965
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Mike Beckerle commented on DAFFODIL-1971:
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I think a discriminator or assert written at the top of a model group, but
which is going to execute at the end of the model group, should produce a
schema definition warning telling you it's going to run after the group, and
suggesting that it be rewritten to be placed in a sub-sequence as the first
child of the sequence, not an annotation on the sequence.
That would avoid any need for a flag to control the evaluation order that can
be set to old-buggy mode vs. new-correct mode.
> Statement order of evaluation not per DFDL Spec
> -----------------------------------------------
>
> Key: DAFFODIL-1971
> URL: https://issues.apache.org/jira/browse/DAFFODIL-1971
> Project: Daffodil
> Issue Type: Bug
> Components: Middle "End"
> Affects Versions: 2.1.0
> Reporter: Mike Beckerle
> Assignee: Josh Adams
> Priority: Major
> Fix For: 4.0.0
>
>
> Per the DFDL spec section 9.5, the order of evaluation of statements for
> model groups is not correct.
> This appears in the grammar
> {code}
> final override lazy val termContentBody = prod("termContentBody") {
> dfdlStatementEvaluations ~ groupLeftFraming ~ _content ~ groupRightFraming
> }
> {code}
> This puts all the statement evaluations first.
> However, asserts or discriminators with test expressions (not patterns) are
> executed AFTER the content of the group. So this needs to be split up so that
> the statements that are supposed to execute before appear before, and the
> ones that execute after are after.
> Note that per DFDL spec section 7.4.1, discriminators and asserts are
> mutually exclusive, and while there can be multiple asserts, there can be
> only one discriminator at a single annotation point.
> Note also DFDL spec section 9.5.2, which specifies that discriminators are
> evaluated even if the parsing of the content fails. This will also require
> special treatment in the model group combinators to be sure discriminators
> execute. The same problem does not occur for elements because the element
> combinators explicitly execute discriminators regardless of failure of the
> element, and after they are parsed.
> test test_discrimExpression_04 behaves incorrectly because of this bug.
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