Read a file's metadata the way netCDF-C 4.9.3 does (libhdf5/hdf5open.c),
for the whole file on first use (src/model.rs, replacing src/scope.rs):
- links in creation order when the group tracks it, else name order;
a group's datasets before its subgroups; dimension ids file-wide;
- variables' dimensions from _Netcdf4Coordinates (file-wide ids), else
the scales DIMENSION_LIST attaches when the first axis has one, else
netCDF-C's phony dimensions phony_dim_<id> (create_phony_dims: shared
by length and unlimitedness within a group, not between two axes of
one variable, numbered subgroups first, a zero length unlimited);
- datasets of types netCDF-C cannot represent are not variables
(references, bit fields, time, arrays, compounds/enums/VLENs over
them), replaying netCDF-C's file-wide type list, failed types
included;
- unlimited lengths as nc4_find_dim_len (its group and below).
NcType gains Enum, Compound, VLen, Opaque and is #[non_exhaustive];
Variable::nc_type is netCDF-C's type (1-byte strings NC_CHAR). New
clawhdf5_format::group_v2::links_in_creation_order_in.
Tests compare with netCDF-C itself (tests/netcdf_c_view.py calls the
libnetcdf netCDF4-python bundles through ctypes): new interop cases for
h5py files without dimension scales, every type class, link order; and
the gated corpus_vs_netcdf_c (CLAWHDF5_NETCDF_CORPUS): 420 of the 429
conformance-corpus files netCDF-C opens match (main: 68); the other 9
are explained in tests/corpus_known_differences.txt and known-issues.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
Variables got the first unused dimension of equal size, so a variable on
an unlimited dimension with fewer records got an anonymous dim_<n>, and
dimensions of one size could be swapped. Resolve them as netCDF-C does
(libhdf5/hdf5open.c): _Netcdf4Coordinates ids, else the scales
DIMENSION_LIST references (the last one attached to an axis), searched in
the variable's group and its parents; a coordinate variable is on its own
scale. Size matching remains only for axes the file names nothing for.
variables()/variable_names() leave out dimension scales that are only
dimensions, and _nc4_non_coord_<name> is the variable <name>.
Variable::shape is the netCDF shape (an unlimited dimension's length) and
the reads pad unwritten records with the fill value (_FillValue, else
NC_FILL_*; NaN from read_f64); Variable::stored_shape is the HDF5 extent.
New NetCDF4File::variable_names.
Tests compare with netCDF4-python variable by variable: the known-issues
reproducer, equal sizes, (p, p), scalars, inherited dimensions, unwritten
records, h5py dimension scales, h5netcdf and xarray files. CI installs
h5netcdf. known-issues entry moved to Fixed (history); stale open-table
row for the unlimited-size fix removed.
Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
