fix: byte-order handling for structured dtypes in the bytes codec#4142
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d-v-b merged 7 commits intoJul 14, 2026
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The bytes codec neither byte-swapped structured-dtype fields to its configured endian on encode (numpy reports byteorder '|' for void dtypes, so the top-level byteorder comparison never detected a mismatch) nor honored its endian when decoding, silently corrupting any structured data whose field byte order differed from the stored one (e.g. virtual references to external big-endian data). Encode now detects byte-order mismatches by comparing full dtypes via newbyteorder, and decode reinterprets raw bytes in the stored byte order before converting to the data type's declared byte order, so the stored layout (codec state) and the in-memory layout (array data type) are independent. Closes zarr-developers#4141 Assisted-by: ClaudeCode:claude-fable-5
Extend test_endian's parametrization with structured dtypes and test_bytes_codec_sync_roundtrip with endian/dtype parametrization plus stored-layout and decoded-dtype assertions, instead of adding parallel test functions for the same properties. Assisted-by: ClaudeCode:claude-fable-5
The variable is the dtype used to view the raw chunk bytes (byte order from the codec's endian configuration), not a property of the stored data or of the returned buffer, which always carries the array's declared dtype. Assisted-by: ClaudeCode:claude-fable-5
Assisted-by: ClaudeCode:claude-fable-5
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this fix reveals a flaw in our |
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## main #4142 +/- ##
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- Coverage 93.87% 93.84% -0.04%
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Files 91 91
Lines 12564 12570 +6
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+ Hits 11795 11796 +1
- Misses 769 774 +5
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ilan-gold
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Jul 14, 2026
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Summary
This fix ensures that structured data types are properly recognized as having byte-order sensitivity by the
bytescodec atdecodetime.Because
structandstructureddon't implementHasEndianness, chunks with these data types were not handled correctly in thebytescodec decode and encode routines. This change ensures that the byteswapping is correctly applied when the in-memory chunk doesn't match the endianness pledged by the bytes codec during encoding, and also that byteswapping is done when a decoded chunk doesn't match the expected memory order of the output data type.Note that these byteswaps will incur a copy.
closes #4141
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TODO
docs/user-guide/*.mdchanges/