stevedlawrence commented on a change in pull request #23: This fix done for
nato-stanag-5516 latest schema.
URL: https://github.com/apache/incubator-daffodil/pull/23#discussion_r159920319
##########
File path:
daffodil-runtime1/src/main/scala/edu/illinois/ncsa/daffodil/dsom/CompiledExpression1.scala
##########
@@ -377,10 +377,59 @@ class DPathElementCompileInfo(
retryMatchesERD.length match {
case 0 => noMatchError(step, possibles)
case 1 => retryMatchesERD(0)
- case _ => queryMatchError(step, matchesERD)
+ case _ => {
+ // it's ok if all the names are the same, so long as they are
+ // in separate choices, or otherwise cannot co-exist.
+ //
+ // For now we just check if they are siblings, i.e., have the
+ // same model group as parent.
+ //
+ // val ambiguousSiblings =
ambiguousModelGroupSiblings(retryMatchesERD)
+ // if (ambiguousSiblings.isEmpty)
+ // BUG
+ // This results in multiple siblings with same name, path that is
ambiguous
+ // just gets first one.
+ //
+ retryMatchesERD(0)
Review comment:
-1, I'm not sure I like this change as-is. Multiple times I've had to spend
time tracking down unexpected behavior where the issue was just that there were
ambiguous paths and Daffodil just always picked the first one. This patch
essential reverts back to that behavior, which was a pain.
In fact, I think if a query-style expression is used and actually references
multiple elements, we'll get an invariant failure assertion at parse time in
``def findChild`` with ``fastSeq.length == 1`` or ``found.length <= 1``.
How about instead we change ``queryMatchError`` to throw an SDW instead of
an SDE so that users will be made aware that a query-style expression exists,
which we don't yet support. This will still allow it though, so in ``def
findChild``, we change the invariant assertions to an SDE, causing a Runtime
SDE when a query-style expression returns more than one element? This way 1) we
get an warning when a query style expression exists 2) query style expressions
can still be used, but only if they ever refer to a single element at runtime
and 3) we get a Runtime SDE if a query style expression ever returns more than
one element. So we warn on potential ambiguity, and throw SDE when that
ambiguity is realized in practice.
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