[Go] Marshal break on map data type with slice

[forsaken628]

Describe the bug, including details regarding any error messages, version, and platform.

func TestName2(t *testing.T) {
	mem := memory.DefaultAllocator
	dt := arrow.MapOf(arrow.BinaryTypes.String, arrow.BinaryTypes.String)
	schema := arrow.NewSchema([]arrow.Field{{
		Name: "map",
		Type: dt,
	}}, nil)

	arr, _, err := array.FromJSON(mem, dt, bytes.NewReader(
		[]byte(`
[[{"key":"index1","value":"main2"}]
,[{"key":"index3","value":"main4"},{"key":"tag_int","value":""}]
,[{"key":"index5","value":"main6"},{"key":"tag_int","value":""}]
,[{"key":"index6","value":"main7"},{"key":"tag_int","value":""}]
,[{"key":"index7","value":"main8"},{"key":"tag_int","value":""}]
,[{"key":"index8","value":"main9"}]
]`),
	))
	if err != nil {
		panic(err)
	}

	rec := array.NewRecord(schema, []arrow.Array{arr}, int64(arr.Len()))
	// rec2 := rec // ok
	// rec2 := rec.NewSlice(0, 2) // ok
	rec2 := rec.NewSlice(1, 2)

	var buf bytes.Buffer
	w := ipc.NewWriter(&buf, ipc.WithSchema(rec.Schema()))
	err = w.Write(rec2)
	if err != nil {
		panic(err)
	}
	err = w.Close()
	if err != nil {
		panic(err)
	}

	r, err := ipc.NewReader(&buf)
	if err != nil {
		panic(err)
	}

	r.Next()
	fmt.Println(r.Record())
	// record:
	//  schema:
	//  fields: 1
	//    - map: type=map<utf8, utf8>
	//  rows: 1
	//  col[0][map]: %!v(PANIC=String method: arrow/array: index out of range)
}

Component(s)

Go

[pitrou]

cc @zeroshade

[zeroshade]

Taking a look into this, will comment back soon.

[zeroshade]

i found the issue which was the handling of the offsets for slices when building the IPC values. The attached PR fixes the issue and adds tests for it.