The facade equivalence harness turned every data-read error into "Err", so
it could not see File::open_storage failing differently from File::open
(a Storage or ContiguousStorageRequired error where the mmap path gives a
decode error, say).
- value() keeps the whole error. The only allowance is for a line on which
File::open itself varies between opens — the chunk cache lists a damaged
dataset's chunks in hash-map order, so which failing chunk a full read
reports varies (cve-2025-2310.h5, the one corpus file where this shows):
both sides must fail there, and a fresh File::open (up to 64) must
reproduce the storage's exact error. Open errors were already compared
in full; they still agree.
- The storage transcript may not contain ContiguousStorageRequired.
- More selections: a strided hyperslab (every third row) through
read_f64_selection, and out-of-order points through read_selection and
read_i64_selection.
- harness_compares_errors_not_just_failures checks the harness itself:
two different errors are different values, and a difference File::open
does not produce is reported.
With full errors the harness passes on the 61 fixtures and on the corpus
(701 files, 621 open).
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
