encoding/json/v2: report wrapped io.ErrUnexpectedEOF

2025-07-11T21:27:16Z

In the event that the input is just JSON whitespace, the underlying jsontext.Decoder treats this as an empty stream and reports io.EOF. The logic in unmarshalFull simply casted io.EOF as io.ErrUnexpectedEOF, which is inconsistent with how all other io.ErrUnexpectedEOF are reported, which are wrapped within a jsontext.SyntacticError. Do the same thing for consistency. We add a v1 test (without goexperiment.jsonv2) to verify that the behavior is identical to how v1 has always behaved. We add a v1in2 test (with goexperiment.jsonv2) to verify that the v1in2 behavior correctly replicates historical v1 behavior. We also fix a faulty check in v1 Decoder.Decode, where it tried to detect errUnexpectedEnd and return an unwrapped io.ErrUnexpectedEOF error. This is the exact semantic that v1 has always done in streaming Decoder.Decode (but not non-streaming Unmarshal). There is a prior bug reported in #25956 about this inconsistency, but we aim to preserve historical v1 behavior to reduce the probability of churn when v1 is re-implemented in terms of v2. Fixes #74548 Change-Id: Ibca52c3699ff3c09141e081c85f853781a86ec8e Reviewed-on: https://go-review.googlesource.com/c/go/+/687115 Auto-Submit: Joseph Tsai Reviewed-by: Carlos Amedee LUCI-TryBot-Result: Go LUCI Reviewed-by: Damien Neil

encoding/json: add json/v2 with GOEXPERIMENT=jsonv2 guard

2025-04-18T15:24:07Z

This imports the proposed new v2 JSON API implemented in github.com/go-json-experiment/json as of commit d3c622f1b874954c355e60c8e6b6baa5f60d2fed. When GOEXPERIMENT=jsonv2 is set, the encoding/json/v2 and encoding/jsontext packages are visible, the encoding/json package is implemented in terms of encoding/json/v2, and the encoding/json package include various additional APIs. (See #71497 for details.) When GOEXPERIMENT=jsonv2 is not set, the new API is not present and the encoding/json package is unchanged. The experimental API is not bound by the Go compatibility promise and is expected to evolve as updates are made to the json/v2 proposal. The contents of encoding/json/internal/jsontest/testdata are compressed with zstd v1.5.7 with the -19 option. Fixes #71845 For #71497 Change-Id: Ib8c94e5f0586b6aaa22833190b41cf6ef59f4f01 Reviewed-on: https://go-review.googlesource.com/c/go/+/665796 Auto-Submit: Damien Neil LUCI-TryBot-Result: Go LUCI Reviewed-by: Michael Pratt Reviewed-by: Joseph Tsai Reviewed-by: Dmitri Shuralyov

go/src/encoding/json/v2_scanner.go, branch fix-runtime-test-GOMAXPROCS

encoding/json/v2: report wrapped io.ErrUnexpectedEOF

encoding/json: add json/v2 with GOEXPERIMENT=jsonv2 guard