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encoding/json: ignore embedded fields of pointers to unexported non-structs

Browse source 
https://golang.org/cl/33773 fixes the JSON marshaler to avoid serializing
embedded fields on unexported types of non-struct types. However, Go allows
embedding pointer to types, so the check for whether the field is a non-struct
type must first dereference the pointer to get at the underlying type.

Furthermore, due to a edge-case in the behavior of StructField.PkgPath not
being a reliable indicator of whether the field is unexported (see #21122),
we use our own logic to determine whether the field is exported or not.

The logic in this CL may be simplified depending on what happens in #21122.

Fixes #21121
Updates #21122

Change-Id: I8dfd1cdfac8a87950df294a566fb96dfd04fd749
Reviewed-on: https://go-review.googlesource.com/50711
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Joe Tsai 2017-07-21 16:53:54 -07:00 • committed by Joe Tsai
parent 5f7a03e148
commit b817359249
2 changed files with 182 additions and 70 deletions
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23
src/encoding/json/encode.go
View file

@ -1093,7 +1093,22 @@ func typeFields(t reflect.Type) []field {
// Scan f.typ for fields to include.
for i := 0; i < f.typ.NumField(); i++ {
sf := f.typ.Field(i)
if sf.PkgPath != "" && (!sf.Anonymous || sf.Type.Kind() != reflect.Struct) { // unexported
if sf.Anonymous {
t := sf.Type
if t.Kind() == reflect.Ptr {
t = t.Elem()
}
// If embedded, StructField.PkgPath is not a reliable
// indicator of whether the field is exported.
// See https://golang.org/issue/21122
if !isExported(t.Name()) && t.Kind() != reflect.Struct {
// Ignore embedded fields of unexported non-struct types.
// Do not ignore embedded fields of unexported struct types
// since they may have exported fields.
continue
}
} else if sf.PkgPath != "" {
// Ignore unexported non-embedded fields.
continue
}
tag := sf.Tag.Get("json")
@ -1211,6 +1226,12 @@ func typeFields(t reflect.Type) []field {
return fields
}
// isExported reports whether the identifier is exported.
func isExported(id string) bool {
r, _ := utf8.DecodeRuneInString(id)
return unicode.IsUpper(r)
}
// dominantField looks through the fields, all of which are known to
// have the same name, to find the single field that dominates the
// others using Go's embedding rules, modified by the presence of