re PR go/66138 (json decoder Decode function fails for some structure return values)

PR go/66138
    reflect, encoding/json, encoding/xml: fix unexported embedded structs
    
    Bring in three changes from the master Go repository.  These changes
    will be in Go 1.6, but they are appropriate for gccgo now because they
    resolve a long-standing discrepancy between how gc and gccgo handle the
    PkgPath field for embedded unexported struct fields.  The core issue is
    described at https://golang.org/cl/7247.  This has been reported against
    gccgo as https://gcc.gnu.org/PR66138.
    
    The three changes being brought over are:
    
    https://golang.org/cl/14010
    
    reflect: adjust access to unexported embedded structs
    
    This CL changes reflect to allow access to exported fields and
    methods in unexported embedded structs for gccgo and after gc
    has been adjusted to disallow access to embedded unexported structs.
    
    Adresses #12367, #7363, #11007, and #7247.
    
    https://golang.org/cl/14011
    
    encoding/json: check for exported fields in embedded structs
    
    Addresses issue #12367.
    
    https://golang.org/cl/14012
    
    encoding/xml: check for exported fields in embedded structs
    
    Addresses issue #12367.
    
    Reviewed-on: https://go-review.googlesource.com/16723

From-SVN: r229907

gcc/go/gofrontend/MERGE

@@ -1,4 +1,4 @@
-10c1d6756ed1dcc814c49921c2a5e27f4677e0e6
+012ab5cb2ef1c26e8023ce90d3a2bba174da7b30
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/go/encoding/json/decode_test.go

@@ -118,6 +118,7 @@ type Top struct {
 	Loop
 	Embed0p // has Point with X, Y, used
 	Embed0q // has Point with Z, used
+	embed   // contains exported field
 }
 
 type Embed0 struct {
@@ -148,6 +149,10 @@ type Embed0q struct {
 	Point
 }
 
+type embed struct {
+	Q int
+}
+
 type Loop struct {
 	Loop1 int `json:",omitempty"`
 	Loop2 int `json:",omitempty"`
@@ -331,7 +336,8 @@ var unmarshalTests = []unmarshalTest{
 			"Loop2": 14,
 			"X": 15,
 			"Y": 16,
-			"Z": 17
+			"Z": 17,
+			"Q": 18
 		}`,
 		ptr: new(Top),
 		out: Top{
@@ -361,6 +367,9 @@ var unmarshalTests = []unmarshalTest{
 			Embed0q: Embed0q{
 				Point: Point{Z: 17},
 			},
+			embed: embed{
+				Q: 18,
+			},
 		},
 	},
 	{
@@ -507,12 +516,15 @@ func TestMarshalEmbeds(t *testing.T) {
 		Embed0q: Embed0q{
 			Point: Point{Z: 17},
 		},
+		embed: embed{
+			Q: 18,
+		},
 	}
 	b, err := Marshal(top)
 	if err != nil {
 		t.Fatal(err)
 	}
-	want := "{\"Level0\":1,\"Level1b\":2,\"Level1c\":3,\"Level1a\":5,\"LEVEL1B\":6,\"e\":{\"Level1a\":8,\"Level1b\":9,\"Level1c\":10,\"Level1d\":11,\"x\":12},\"Loop1\":13,\"Loop2\":14,\"X\":15,\"Y\":16,\"Z\":17}"
+	want := "{\"Level0\":1,\"Level1b\":2,\"Level1c\":3,\"Level1a\":5,\"LEVEL1B\":6,\"e\":{\"Level1a\":8,\"Level1b\":9,\"Level1c\":10,\"Level1d\":11,\"x\":12},\"Loop1\":13,\"Loop2\":14,\"X\":15,\"Y\":16,\"Z\":17,\"Q\":18}"
 	if string(b) != want {
 		t.Errorf("Wrong marshal result.\n got: %q\nwant: %q", b, want)
 	}

libgo/go/encoding/json/encode.go

@@ -1022,7 +1022,7 @@ 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 != "" { // unexported
+				if sf.PkgPath != "" && !sf.Anonymous { // unexported
 					continue
 				}
 				tag := sf.Tag.Get("json")

libgo/go/encoding/xml/marshal_test.go

@@ -139,6 +139,7 @@ type EmbedA struct {
 	EmbedC
 	EmbedB EmbedB
 	FieldA string
+	embedD
 }
 
 type EmbedB struct {
@@ -153,6 +154,11 @@ type EmbedC struct {
 	FieldC  string
 }
 
+type embedD struct {
+	fieldD string
+	FieldE string // Promoted and visible when embedD is embedded.
+}
+
 type NameCasing struct {
 	XMLName struct{} `xml:"casing"`
 	Xy      string
@@ -711,6 +717,9 @@ var marshalTests = []struct {
 				},
 			},
 			FieldA: "A.A",
+			embedD: embedD{
+				FieldE: "A.D.E",
+			},
 		},
 		ExpectXML: `<EmbedA>` +
 			`<FieldB>A.C.B</FieldB>` +
@@ -724,6 +733,7 @@ var marshalTests = []struct {
 			`<FieldC>A.B.C.C</FieldC>` +
 			`</EmbedB>` +
 			`<FieldA>A.A</FieldA>` +
+			`<FieldE>A.D.E</FieldE>` +
 			`</EmbedA>`,
 	},
 

libgo/go/encoding/xml/typeinfo.go

@@ -60,7 +60,7 @@ func getTypeInfo(typ reflect.Type) (*typeInfo, error) {
 		n := typ.NumField()
 		for i := 0; i < n; i++ {
 			f := typ.Field(i)
-			if f.PkgPath != "" || f.Tag.Get("xml") == "-" {
+			if (f.PkgPath != "" && !f.Anonymous) || f.Tag.Get("xml") == "-" {
 				continue // Private field
 			}
 

libgo/go/reflect/export_test.go

@@ -6,13 +6,13 @@ package reflect
 
 // MakeRO returns a copy of v with the read-only flag set.
 func MakeRO(v Value) Value {
-	v.flag |= flagRO
+	v.flag |= flagStickyRO
 	return v
 }
 
 // IsRO reports whether v's read-only flag is set.
 func IsRO(v Value) bool {
-	return v.flag&flagRO != 0
+	return v.flag&flagStickyRO != 0
 }
 
 var CallGC = &callGC

libgo/go/reflect/type.go

@@ -516,7 +516,7 @@ func (t *uncommonType) Method(i int) (m Method) {
 	fl := flag(Func)
 	if p.pkgPath != nil {
 		m.PkgPath = *p.pkgPath
-		fl |= flagRO
+		fl |= flagStickyRO
 	}
 	mt := p.typ
 	m.Type = toType(mt)

libgo/go/reflect/value.go

@@ -44,7 +44,8 @@ type Value struct {
 
 	// flag holds metadata about the value.
 	// The lowest bits are flag bits:
-	//	- flagRO: obtained via unexported field, so read-only
+	//	- flagStickyRO: obtained via unexported not embedded field, so read-only
+	//	- flagEmbedRO: obtained via unexported embedded field, so read-only
 	//	- flagIndir: val holds a pointer to the data
 	//	- flagAddr: v.CanAddr is true (implies flagIndir)
 	//	- flagMethod: v is a method value.
@@ -67,12 +68,14 @@ type flag uintptr
 const (
 	flagKindWidth        = 5 // there are 27 kinds
 	flagKindMask    flag = 1<<flagKindWidth - 1
-	flagRO          flag = 1 << 5
+	flagStickyRO    flag = 1 << 5
-	flagIndir       flag = 1 << 6
+	flagEmbedRO     flag = 1 << 6
-	flagAddr        flag = 1 << 7
+	flagIndir       flag = 1 << 7
-	flagMethod      flag = 1 << 8
+	flagAddr        flag = 1 << 8
-	flagMethodFn    flag = 1 << 9 // gccgo: first fn parameter is always pointer
+	flagMethod      flag = 1 << 9
-	flagMethodShift      = 10
+	flagMethodFn    flag = 1 << 10 // gccgo: first fn parameter is always pointer
+	flagMethodShift      = 11
+	flagRO          flag = flagStickyRO | flagEmbedRO
 )
 
 func (f flag) kind() Kind {
@@ -617,11 +620,15 @@ func (v Value) Field(i int) Value {
 	field := &tt.fields[i]
 	typ := field.typ
 
-	// Inherit permission bits from v.
+	// Inherit permission bits from v, but clear flagEmbedRO.
-	fl := v.flag&(flagRO|flagIndir|flagAddr) | flag(typ.Kind())
+	fl := v.flag&(flagStickyRO|flagIndir|flagAddr) | flag(typ.Kind())
 	// Using an unexported field forces flagRO.
 	if field.pkgPath != nil {
-		fl |= flagRO
+		if field.name == nil {
+			fl |= flagEmbedRO
+		} else {
+			fl |= flagStickyRO
+		}
 	}
 	// Either flagIndir is set and v.ptr points at struct,
 	// or flagIndir is not set and v.ptr is the actual struct data.
@@ -986,7 +993,7 @@ func (v Value) Method(i int) Value {
 	if v.typ.Kind() == Interface && v.IsNil() {
 		panic("reflect: Method on nil interface value")
 	}
-	fl := v.flag & (flagRO | flagIndir)
+	fl := v.flag & (flagStickyRO | flagIndir) // Clear flagEmbedRO
 	fl |= flag(Func)
 	fl |= flag(i)<<flagMethodShift | flagMethod
 	return Value{v.typ, v.ptr, fl}