affected/package: encoding/json

[madkins23]

What version of Go are you using (go version)?

$ go version
go version go1.18.5 linux/amd64

Does this issue reproduce with the latest release?

AFAIK I'm using the latest release (or at least the latest snap release).

What operating system and processor architecture are you using (go env)?

go env Output

$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN="/home/marc/go/bin"
GOCACHE="/home/marc/.cache/go-build"
GOENV="/home/marc/.config/go/env"
GOEXE=""
GOEXPERIMENT=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOINSECURE=""
GOMODCACHE="/home/marc/go/pkg/mod"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="/home/marc/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/snap/go/9952"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/snap/go/9952/pkg/tool/linux_amd64"
GOVCS=""
GOVERSION="go1.18.5"
GCCGO="gccgo"
GOAMD64="v1"
AR="ar"
CC="gcc"
CXX="g++"
CGO_ENABLED="1"
GOMOD="/dev/null"
GOWORK=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build3232480261=/tmp/go-build -gno-record-gcc-switches"

What did you do?

Given a container struct with a map and an entity struct with custom Marshaler and Unmarshaler methods. The custom methods are defined using pointer references to the entity struct.

If the map values in the container struct are pointers to the entity struct everything works fine. If the map values are the actual entity structs then the MarshalJSON method isn't called.

Array values seem to work just fine with both pointers and objects.

https://go.dev/play/p/jNsHN9rKAZt

What did you expect to see?

The map value cases for pointer and object should be the same.

What did you see instead?

The Object case doesn't seem to call the custom MarshalJSON for map values that are objects, but it works for array values that are objects.

Ptr container:
  MarshalJSON()  'listed'->1
  MarshalJSON()  'mapped'->2
  UnmarshalJSON()  {"Text":"listed|1"}
  UnmarshalJSON()  {"Text":"mapped|2"}
! ptr == ptr2
  ptr1: {['listed'->1] map[ptrKey:'mapped'->2]}
  ptr2: {['listed'->1] map[ptrKey:'mapped'->2]}
Obj container:
  MarshalJSON()  'listed'->1
  UnmarshalJSON()  {"Text":"listed|1"}
  UnmarshalJSON()  {}
Error unmarshaling objContainer: wrong number of pieces: 1
* obj1 != obj2
  obj1: {[{listed 1}] map[objKey:{mapped 2}]}
  obj2: {[{listed 1}] map[]}

[seankhliao]

UnmarshalJSON is defined on *Example, not Example, and map values are unaddressable.

Closing as working as intended.

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