Reject externally tagged variants with more than one field - #720
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ciprianf-flexion wants to merge 1 commit into
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Reject externally tagged variants with more than one field#720ciprianf-flexion wants to merge 1 commit into
ciprianf-flexion wants to merge 1 commit into
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Reading an rfl::Variant<rfl::Field<...>, ...> from an object with several keys silently kept the last recognized tag, and an unknown key followed by a valid tag overwrote the error. Serde, which this format models, rejects such objects. The reader now returns an error whenever a second field is encountered, mirroring the existing 'found none' error.
ciprianf-flexion
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August 28, 2026 09:55
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@liuzicheng1987 I cannot add you explicitly as a reviewer, but would you mind taking a look? Thanks! |
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Reading an
rfl::Variant<rfl::Field<...>, ...>from an object with several keys silently keeps the last recognized tag. Worse, an unknown key followed by a valid tag overwrites the "could not match field" error, so{"triangle": {...}, "circle": {...}}parses successfully as a circle.Serde, which this format models (per variants_and_tagged_unions.md), represents an externally tagged enum as a single-key map and rejects anything else, see serde.rs/enum-representations.html.
This change makes the reader return an error whenever a second field is encountered, mirroring the existing "expected the object to have exactly one field, but found none" error.
Added tests for both cases in
tests/json/test_field_variant_multiple_fields.cpp.