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toon: the list form does not round-trip a nested object value #188
Description
What
A nested object as a list item's value does not survive a round trip, in two shapes:
| input | encode |
decode |
reference |
|---|---|---|---|
[{'d': {}}] |
[1]:\n -\n d: |
[{}] — d dropped |
[1]:\n - d: — round-trips |
[{'d': {'x': 1}}, {'d': {'y': 2}}] |
[2]:\n -\n d:\n x: 1 |
ToonDecodeError: Expected 2 items, got 1 |
round-trips |
Both are present on master before the TOON 4.1 tracking work (#186), which leaves them untouched — found while reviewing it, not introduced there.
The first is the worse of the two: it silently returns a different object rather than raising. The second is a ToonDecodeError on the encoder's own output.
The encoding also differs from the reference, which writes the item header and its key on one line (- d:) rather than a bare - followed by an indented key.
Why it is not folded into #186
That PR's oracle is assert_encode_same, which compares encodings. Neither case is in its matrix, so the suite is green on both.
Fix
The list form's item header and the decoder's nested-block handling are the two places to look; the shapes above reproduce on master and on fix/toon-spec-4.1.
Activity
clementine-oaklight commentedon Oct 13, 2026
Scope correction, from measuring it rather than from the two shapes above.
I fuzzed 1200 generated documents against the reference and split by which path the encoder took:
Every one of those 974 list-form documents is byte-identical to what master encodes, so none of it is new — the two shapes in this issue are examples of a family, not the whole of it. The family is "an array of objects that does not qualify for a tabular header, containing a nested object or an array value": the list form writes a bare
-and an indented key rather than- key:, and its decoder does not rebuild the nested block.So this is not two edge cases to patch; the list form's item header and its nested-block decoding are both wrong against the reference. Worth knowing before someone estimates it as a small fix, and worth widening the gate beyond the two rows above.
docs(toon): spec 4.4, 564/564 conformance, 0.6.0 options
docs(toon)：TOON 4.4、564/564 一致性、0.6.0 选项
feat(toon): implement TOON 4.4 and fix list-form nested objects