Fix spurious cascading errors on when-false nodes in multi-error validation#2528
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szabolcs-szekely wants to merge 3 commits into
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Fix spurious cascading errors on when-false nodes in multi-error validation#2528szabolcs-szekely wants to merge 3 commits into
szabolcs-szekely wants to merge 3 commits into
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…errors Mark when-false nodes with a new LYD_WHEN_FALSE flag so XPath evaluation treats them as non-existent (LY_ENOT) instead of incomplete (LY_EINCOMPLETE). This prevents the internal-error crash in lyd_validate_dummy_when and spurious cascading errors on must, leafref, and child when expressions under LYD_VALIDATE_MULTI_ERROR. Clean up node_types and node_when entries for descendants of a when-false node so leafref validation and child when evaluations do not run against a logically non-existent subtree. Add regression tests covering the when/must cross-reference scenario and the leafref-inside-when-false-container case. Fixes CESNET#2516
Add a fourth sub-case to test_when_must_cross_ref that places the when-false node on a list with a key and references it through a [key='...'] predicate in a sibling must constraint. This routes the XPath step through moveto_node_hash_child rather than moveto_node_check, exercising the second LYD_WHEN_FALSE branch in src/xpath.c explicitly. The data deliberately sets item[name='a']/value to 'expected' so that a regression in the hash-lookup branch would cause the must to pass silently. Both the when error and the must failure must be reported. Fixes CESNET#2516
Address review findings on the LYD_WHEN_FALSE handling. - Initialize the return code before skipping a when-false node in lyd_validate_final_r so a when-false first sibling no longer reads an uninitialized value. - Clear a stale LYD_WHEN_FALSE mark when a when later resolves to true so XPath no longer treats a now-valid node as non-existent on revalidation. - Skip container default handling for when-false nodes in addition to their child validation. - Add a nested when-in-when regression test confirming the node_when descendant cleanup suppresses the spurious child when error.
michalvasko
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Jun 4, 2026
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michalvasko
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michalvasko
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Okay, I suppose, since it does not add too much code. But like I said before, this feature was added later and the original design did not anticipate it so it is expected it does not work perfectly. For a proper implementation, the validation would need significant refactoring, which seems not worth it.
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| /* invalid data; mark the when as resolved-to-false so subsequent XPath | ||
| * evaluations on this node return "no match" instead of LY_EINCOMPLETE */ | ||
| node->flags |= LYD_WHEN_FALSE; | ||
| /* remove descendants from node_types so their leafrefs are not validated | ||
| * against the when-false subtree, which would produce spurious cascading | ||
| * errors (mirrors the cleanup done by lyd_validate_autodel_node_del) */ | ||
| if (node_types && node_types->count) { | ||
| struct lyd_node *iter; | ||
| uint32_t idx; | ||
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| LYD_TREE_DFS_BEGIN(node, iter) { | ||
| if ((iter->schema->nodetype & LYD_NODE_TERM) && | ||
| LYSC_GET_TYPE_PLG(((struct lysc_node_leaf *)iter->schema)->type->plugin_ref)->validate_tree && | ||
| ly_set_contains(node_types, iter, &idx)) { | ||
| ly_set_rm_index(node_types, idx, NULL); | ||
| } | ||
| LYD_TREE_DFS_END(node, iter); | ||
| } | ||
| } | ||
| /* remove descendants from node_when so their own when conditions are not | ||
| * evaluated; a when-false subtree is logically non-existent, so child | ||
| * whens are moot and would otherwise produce spurious cascading errors */ | ||
| if (node_when->count > 1) { | ||
| struct lyd_node *iter; | ||
| uint32_t idx; | ||
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| count = node_when->count; | ||
| LYD_TREE_DFS_BEGIN(node, iter) { | ||
| if ((iter != node) && ly_set_contains(node_when, iter, &idx)) { | ||
| ly_set_rm_index_ordered(node_when, idx, NULL); | ||
| } | ||
| LYD_TREE_DFS_END(node, iter); | ||
| } | ||
| if (count > node_when->count) { | ||
| /* descendants were removed, refresh the iteration index */ | ||
| ly_set_contains(node_when, node, &i); | ||
| } | ||
| } |
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With this code, the function is too long, please put this into a separate function. Also, it may impact performance so why not use the new flag LYD_WHEN_FALSE only for LYD_VALIDATE_MULTI_ERROR validation?
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Relates to #2516.
We want to use yanglint's multi-error mode (
LYD_VALIDATE_MULTI_ERROR) for testing. Building on the crash fix in ff3cd62, awhen-false node was still indistinguishable from a not-yet-evaluatedwhen: XPath returnedLY_EINCOMPLETEfor it, andmust/leafref/child-whenran against the logically non-existent subtree, producing spurious cascading errors.Changes:
LYD_WHEN_FALSEflag to mark awhen-false node distinctly from a not-yet-evaluated one, cleared again if thewhenlater resolves to true.LYD_WHEN_FALSEnodes as non-existent (LY_ENOT) instead ofLY_EINCOMPLETE.must/obsolete/child/container-default checks for these nodes and removes their descendants fromnode_types/node_when.when/mustcross-reference (incl. keyed-list hash lookup), the leafref-inside-when-false-container case, and a nestedwhen-in-whencase.