containerLocationMap stored `loc ?? rootLocation` into a [ObjectIdentifier:
String?]. Because the value type is itself optional the coalescing bound at the
outer optional and rootLocation was never used (the compiler flagged it), so a
container with no location of its own (the compile root) mapped to nil even when
a circular import had loaded the root under a schemaLocation. An explicit String?
annotation keeps the coalescing at the String level so the root inherits
rootLocation.
Conformance is unchanged: 1448 unit tests pass and the full XSTS suite still
settles at 0/43/0/31. The SchemaNameUniqueness root-index dedup case is kept, not
removed: an experiment removing it on the theory it was now redundant regressed
three valid schemas to rejected, so it does real work beyond the fixed fallback.
Mihaela Mihaljevic
cd6201ca5c