Sample
Enabling Decoder.KnownFields(true) returns a yaml.TypeError when unmarshaling unknown keys, embedded struct fields missing yaml:",inline", or yaml:"-" ignored fields.
sha256:b6ff37d02e3e29da45e029812c5d21bf74b02359da326c1e17829bd0fc6a7bf6
PUBLISHED
L3_CONTRACT_PASS
MIT-0
Execution evidence
Declared environment and signed verification runs are separated so you can see exactly what this sample proves.
Evidence basisSigned contract pass
Verification receipts1
Verification levelL3_CONTRACT_PASS
Declared environment
- Execution context
- go
- Operating system
- linux
- Architecture
- x64
- Runtime
- go
- Language
- go
- Package manager
- go
Verification-run environments
- Execution context
- go 1.26
- Operating system
- linux alpine · musl
- Architecture
- x64
- Runtime
- go 1.26
- Language
- go
- Package manager
- go
- Execution
- container · docker
CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17
Case
- Goal
- Enabling Decoder.KnownFields(true) returns a yaml.TypeError when unmarshaling unknown keys, embedded struct fields missing yaml:",inline", or yaml:"-" ignored fields. HOW
- Packages
-
gopkg.in/yaml.v3 v3.0.1
- Environment
- go
- Created
- 2026-08-17T17:07:23Z
Commonly assumed
yaml.Decoder.Decode ignores unrecognized keys by default, and developers expecting encoding/json semantics assume embedded anonymous struct fields are automatically inlined without explicit tags.
The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.
Contract
- Enabling yaml.Decoder.KnownFields(true) returns a *yaml.TypeError reporting 'field <name> not found' for undeclared keys, un-inlined embedded struct fields, and yaml:"-" ignored fields, whereas default decoding silently discards them without error.
- Default yaml.Unmarshal or Decoder without KnownFields silently drops unknown keys and un-tagged embedded fields, returning a nil error.
- Decoder.Decode with KnownFields(true) returns a *yaml.TypeError containing line numbers and field names when encountering unknown keys.
- Embedded anonymous structs require an explicit yaml:",inline" tag to be decoded under KnownFields(true), otherwise their fields are rejected as unknown fields.
- Fields tagged with yaml:"-" are treated as unknown fields and rejected under KnownFields(true) when present in YAML input.
- Field tag matching under KnownFields(true) is case-sensitive, rejecting uppercase or mismatched keys with a *yaml.TypeError.
Files
- NOTES.md
- csx.json
- go.mod
- go.sum
- yaml_config_test.go
Download the source artifact (tar.gz)
Origin Seeder
csx-seed
Verification receipts
- go 1.26 · linux alpine/x64 · docker · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17 · ed25519:d91480838ac982c9