First instance-bucket reduction of the campaign. An instance xsi:type naming a
complex type must be derived from the element's declared type. notDerivedSubstitutionError
flags a complex substitute on a different branch of the hierarchy; previously
only a derived-but-blocked substitution was caught (blockedSubstitutionError
returns nil when there is no derivation path), so a non-derived xsi:type was
silently accepted (the test006 cluster, 32 instances, and more).
Conservatively scoped after a broader first cut took 20 false positives (now
reverted): it fires only when the substitute resolves to a COMPLEX type and both
substitute and declared names are in the derivation backbone with no path between
them. Simple/list/union substitutes, ur-types, and unresolvable references are
left alone -- under-reject, never over-reject. An adversarial review confirmed
the conservative guards eliminate the prior false positives; the one residual is
the pre-existing bare-local-name keying of the derivation backbone (shared with
blockedSubstitutionError), disclosed in the code, corpus-absent.
The three xsi:type override checks (blocked / not-derived / abstract) are folded
into one xsiTypeOverrideError helper to keep validateChild under the complexity limit.
XSTS: invalid-instances-accepted 133 to 107 (26 caught), valid-instances-rejected
and valid-schemas-rejected both held at 0, no other bucket moved.
Mihaela Mihaljevic
8e873dc929