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

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/v2: reject unquoted dash as a JSON field name

2025-06-24T13:41:42Z

In this blog: https://blog.trailofbits.com/2025/06/17/unexpected-security-footguns-in-gos-parsers/ the concern was raised that whenever "-" is combined with other options, the "-" is intepreted as as a name, rather than an ignored field, which may go contrary to user expectation. Static analysis demonstrates that there are ~2k instances of `json:"-,omitempty" in the wild, where almost all of them intended for the field to be ignored. To prevent this footgun, reject any tags that has "-," as a prefix and warn the user to choose one of the reasonable alternatives. The documentation of json/v2 already suggests `json:"'-'"` as the recommended way to explicitly specify dash as the name. See Example_fieldNames for example usages of the single-quoted literal. Update the v1 json documentation to suggest the same thing. Updates #71497 Change-Id: I7687b6eecdf82a5d894d057c78a4a90af4f5a6e4 Reviewed-on: https://go-review.googlesource.com/c/go/+/683175 LUCI-TryBot-Result: Go LUCI Reviewed-by: Johan Brandhorst-Satzkorn Reviewed-by: Damien Neil Auto-Submit: Joseph Tsai Reviewed-by: Daniel Martí Reviewed-by: Dmitri Shuralyov

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

encoding/json: cleanup tests

2025-01-14T22:54:07Z

Perform minor cleanups in tests to improve printout of diffs and/or follow modern coding style. This reduces the amount of diffs between v1 and the v2 prototype. Change-Id: I019bb9642e2135f2fa3eac6abfa6df91c397aa82 Reviewed-on: https://go-review.googlesource.com/c/go/+/642257 Reviewed-by: Damien Neil Auto-Submit: Joseph Tsai LUCI-TryBot-Result: Go LUCI Reviewed-by: Ian Lance Taylor

encoding/json: add cases to TestUnmarshal for fatal syntactic errors

2025-01-13T16:27:22Z

The presence of a syntax error in the input immediately unmarshaling before unmarshaling into the underlying value. Otherwise, semantic errors are generally lazily reported and allow unmarshaling to continue on. Change-Id: Icf1cfc684e415312d9c8bf739c396ede15299d7d Reviewed-on: https://go-review.googlesource.com/c/go/+/642295 LUCI-TryBot-Result: Go LUCI Reviewed-by: Ian Lance Taylor Auto-Submit: Joseph Tsai Reviewed-by: Michael Knyszek

encoding/json: always check resulting Go value for unmarshaling

2025-01-13T16:27:19Z

Even if an error occurs during unmarshal, check the resulting Go value. The documented API specifies no guarantees on how much of a Go value will be populated when an error occurs and the "json" package is technically not bounded by the Go compatibility agreement to ensure this behavior never changes. However, there is still value in running checks for what exactly what is partially mutated in the event of an error even if this is not guaranteed behavior. Change-Id: I6e923a31f77768a14c4adfb0d37dbeee5807a4a2 Reviewed-on: https://go-review.googlesource.com/c/go/+/642275 Auto-Submit: Joseph Tsai LUCI-TryBot-Result: Go LUCI Reviewed-by: Michael Knyszek Reviewed-by: Ian Lance Taylor

encoding/json: improve fidelity of TestUnmarshal for Numbers

2025-01-08T22:37:21Z

In particular, cover the behavior of unmarshaling a JSON string into a Number type regardless of whether the `string` option is specified or not. Change-Id: Ibc55f16860442240bcfeea1fd51aaa76f7e50f67 Reviewed-on: https://go-review.googlesource.com/c/go/+/641416 LUCI-TryBot-Result: Go LUCI Auto-Submit: Joseph Tsai Reviewed-by: Damien Neil Reviewed-by: Dmitri Shuralyov

encoding/json: expand and modernize TestInterfaceSet

2024-12-28T01:23:24Z

Add more test cases to cover a wider range of edge cases. Use a generic addr function to take the address of a value. Even though redudant, explicitly include a cast to the top-level Go type so that it is more readable what the expected input and ouput types are. Change-Id: I3ef68df6f1beb903ae237cd49f3dcb91e5270fe7 Reviewed-on: https://go-review.googlesource.com/c/go/+/638256 Reviewed-by: Daniel Martí Reviewed-by: Damien Neil Reviewed-by: Ian Lance Taylor LUCI-TryBot-Result: Go LUCI

encoding/json: check exact structure of local error types in tests

2024-11-19T18:48:19Z

During the development of error wrapping (#29934), the tests were modified to stop using reflect.DeepEqual since the prototype for error wrapping at the time included frame information of where the error was created. However, that change diminished the fidelity of the test so that it is no longer as strict, which affects the endeavor to implement v1 in terms of the v2 prototype. For locally declared error types, use reflect.DeepEqual to check that the exact structure of the error value matches. Change-Id: I443d418533866ab8d533bca3785fdc741e2c140e Reviewed-on: https://go-review.googlesource.com/c/go/+/629517 Auto-Submit: Damien Neil Reviewed-by: Ian Lance Taylor Reviewed-by: Daniel Martí Reviewed-by: Damien Neil LUCI-TryBot-Result: Go LUCI

encoding/json: add embedded structs to the UnmarshalTypeError's Field

2024-09-03T15:49:47Z

Including embedded struct inforamtion in error message. Fixes #68941 Change-Id: I6a6f7d506104839a9a7cf1a2c3003272f5534a79 GitHub-Last-Rev: 717f680acafd3f6509c0495f9092e028be502750 GitHub-Pull-Request: golang/go#68966 Reviewed-on: https://go-review.googlesource.com/c/go/+/606956 LUCI-TryBot-Result: Go LUCI Auto-Submit: Ian Lance Taylor Reviewed-by: Ian Lance Taylor Reviewed-by: Dmitri Shuralyov