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Radar · Go · Archive · Week 22 · May 25 – 31, 2026

Decoder.DisallowDuplicateFields

Worth knowingstdlib

What changed
The standard library now offers a Decoder.DisallowDuplicateFields option that, when enabled, rejects JSON input containing duplicate field names.
Production impact
The source does not say.
Try it
Create a json.Decoder, set DisallowDuplicateFields to true, and attempt to unmarshal JSON with repeated keys.
Source
github.com/golang/go/issues/48298

Written by gpt-oss-20b from the linked source · claims checked against the sources · archive, not individually reviewed