A version-1 shared message reference is version, type, six reserved bytes
and then an old-style symbol table entry: link-name offset (length size),
object header address, cache type, reserved, scratch. We read the address
straight after the reserved bytes, i.e. the link-name offset, and the
committed datatype lookup failed with InvalidObjectHeaderVersion (the bytes
checked in tcompound.h5: name offset 0x10, then 0x590 = /type1). Datasets
of 1.4/1.6-era files that use a committed datatype were unreadable.
Skip the name offset. parse_shared_ref has no length size, so add
parse_shared_ref_sized and use it in every internal caller;
parse_shared_ref keeps its signature and assumes length size == offset
size. The old parse_v1_ref unit test encoded the wrong layout and now uses
the real bytes.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
