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serde deny_unknown_fields stops rejecting unknown keys once the struct is flattened, while the pair the documentation calls unsupported compiles and works in the ordinary case

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serde deny_unknown_fields stops rejecting unknown keys once the struct is flattened, while the pair the documentation calls unsupported compiles and works in the ordinary case FIX

パッケージ

serde 1.0.229 serde_json 1.0.151

環境

rust 1

作成日

2026-08-14T13:02:45Z

コントラクト

• assert deny_unknown_fields rejects an extra key as a Category::Data error naming the field and the accepted names
• assert rename_all is applied first, so the Rust field name is itself rejected as unknown
• assert the accepted-names list is worded three different ways depending on how many fields there are
• compile a probe file with rustc to prove deny_unknown_fields together with flatten emits no error and no warning, because serde_derive implements the pair rather than rejecting it
• compile a probe file with rustc to prove flatten on a newtype struct is the combination serde_derive does reject
• assert deny_unknown_fields with a flattened map rejects every key the map was supposed to collect, so only an empty map is accepted
• assert that rejection carries no expected-names list, unlike deny_unknown_fields on its own
• assert deny_unknown_fields with a flattened struct accepts the flattened fields and rejects only the leftovers
• assert deny_unknown_fields on a struct that is flattened into another one never rejects anything
• assert the key that flattened struct ignored is dropped rather than kept, so it is gone from the re-serialized output
• assert an Option field is filled in with None when absent, with no attribute on it
• assert a field that is neither Option nor defaulted is reported as a missing field
• assert #[serde(default)] covers an absent field but not an explicit null
• assert Option answers None for both absent and null, so the two cannot be told apart
• assert Option serializes as null rather than omitting the key
• assert rename_all on a struct renames its fields but not the variant values of an enum field
• assert rename_all on an enum renames variants and rename_all_fields is what renames their fields
• assert skip_serializing_if omits an Option key entirely instead of writing null
• assert skip_serializing_if on a non-Option field breaks the round trip with a missing field error
• assert an internally tagged enum reports an unknown tag with the tag values it knows
• assert a missing tag is reported as a missing field and an externally tagged enum names its variants
• assert an internally tagged enum drops unknown payload keys, and that deny_unknown_fields on the enum does fire and reject them
• assert that enum rejection arrives with no line and column suffix, unlike every other error here

ファイル

• Cargo.lock
• Cargo.toml
• csx.json
• rustc_probe/deny_unknown_with_flatten.rs
• rustc_probe/flatten_on_newtype.rs
• src/main.rs

オリジンシーダー

anonymous

検証レシート

• rust 1 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · cargo@1 · 2026-08-14 · ed25519:a2ec939a4c60e243
• · CONTAINER_RUN · compile:SKIPPED · contract:FAIL · load:SKIPPED · resolve:PASS · cargo@1 · 2026-08-14 · ed25519:7da3f610facce8bf