serde_bser: serialize struct enum variants in object form - #1358
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rootkiller6788 wants to merge 1 commit into
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serde_bser: serialize struct enum variants in object form#1358rootkiller6788 wants to merge 1 commit into
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serialize_struct_variant delegated to serialize_tuple_variant, emitting a
struct variant as {"Variant": [field_name, value, ...]} instead of the
{"Variant": {"field": value, ...}} form that the deserializer expects
when decoding a struct variant. Enums with struct variants therefore could
not round-trip through serde_bser (deserializing the emitted bytes failed
with a type mismatch).
Emit the variant as an object keyed by field name, matching the format
already exercised by de::test::test_struct_variant, and add a round-trip
regression test.
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August 22, 2026 14:52
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Summary
serde_bser::Serializer::serialize_struct_variantwas implemented by delegating toserialize_tuple_variant, which emits the variant payload as a BSER array:{"TestStruct": ["abc", null, "def", "💩"]}But the deserializer (
VariantAccess::struct_variant→deserialize_any) decodes the payload as a map — the object form{"TestStruct": {"abc": null, "def": "💩"}}thatde::test::test_struct_variantalready exercises. Struct-variant enums therefore could not round-trip:serialize→from_slicefailed withinvalid type: string "abc", expected unit.Fix
Serialize struct variants in object form, writing
<BSER_OBJECT> 1 <variant name> <BSER_OBJECT nfields> (key value)*, instead of reusing the tuple-variant path. TheCompoundtype is shared by bothSerializeStructVariantandSerializeStruct, so the field-name-keyed output is produced by the sameSerializeStructmachinery used for ordinary structs.Test
BASIC_SERIALIZEDexpectation inser/test.rsto the object form (only the container tag byte changes; PDU length is unchanged).test_struct_variant_round_trip, which serializesTestStruct { abc: (), def: '💩' }and deserializes it back — this failed before the fix and passes after.cargo testinwatchman/rust/serde_bser: 16 passed.