libgo: update to Go1.12beta2

    
    Reviewed-on: https://go-review.googlesource.com/c/158019

gotools/:
	* Makefile.am (go_cmd_vet_files): Update for Go1.12beta2 release.
	(GOTOOLS_TEST_TIMEOUT): Increase to 600.
	(check-runtime): Export LD_LIBRARY_PATH before computing GOARCH
	and GOOS.
	(check-vet): Copy golang.org/x/tools into check-vet-dir.
	* Makefile.in: Regenerate.

gcc/testsuite/:
	* go.go-torture/execute/names-1.go: Stop using debug/xcoff, which
	is no longer externally visible.

From-SVN: r268084

24 files changed, 660 insertions, 314 deletions

diff --git a/libgo/go/encoding/asn1/asn1.go b/libgo/go/encoding/asn1/asn1.go
index 1ed357a..3cfd9d1 100644
--- a/libgo/go/encoding/asn1/asn1.go
+++ b/libgo/go/encoding/asn1/asn1.go
@@ -633,7 +633,7 @@ var (
 	bigIntType           = reflect.TypeOf(new(big.Int))
 )
 
-// invalidLength returns true iff offset + length > sliceLength, or if the
+// invalidLength reports whether offset + length > sliceLength, or if the
 // addition would overflow.
 func invalidLength(offset, length, sliceLength int) bool {
 	return offset+length < offset || offset+length > sliceLength
diff --git a/libgo/go/encoding/base32/base32_test.go b/libgo/go/encoding/base32/base32_test.go
index c5506ed..b74054b 100644
--- a/libgo/go/encoding/base32/base32_test.go
+++ b/libgo/go/encoding/base32/base32_test.go
@@ -425,7 +425,7 @@ IZJAOZSWY2LUEBSXG43FEBRWS3DMOVWSAZDPNRXXEZJAMV2SAZTVM5UWC5BANZ2WY3DBBJYGC4TJMF
 NZ2CYIDTOVXHIIDJNYFGG5LMOBQSA4LVNEQG6ZTGNFRWSYJAMRSXGZLSOVXHIIDNN5WGY2LUEBQW42
 LNEBUWIIDFON2CA3DBMJXXE5LNFY==
 ====`
-	encodedShort := strings.Replace(encoded, "\n", "", -1)
+	encodedShort := strings.ReplaceAll(encoded, "\n", "")
 
 	dec := NewDecoder(StdEncoding, strings.NewReader(encoded))
 	res1, err := ioutil.ReadAll(dec)
@@ -465,7 +465,7 @@ func TestWithCustomPadding(t *testing.T) {
 	for _, testcase := range pairs {
 		defaultPadding := StdEncoding.EncodeToString([]byte(testcase.decoded))
 		customPadding := StdEncoding.WithPadding('@').EncodeToString([]byte(testcase.decoded))
-		expected := strings.Replace(defaultPadding, "=", "@", -1)
+		expected := strings.ReplaceAll(defaultPadding, "=", "@")
 
 		if expected != customPadding {
 			t.Errorf("Expected custom %s, got %s", expected, customPadding)
@@ -675,7 +675,7 @@ func TestWithoutPaddingClose(t *testing.T) {
 
 			expected := testpair.encoded
 			if encoding.padChar == NoPadding {
-				expected = strings.Replace(expected, "=", "", -1)
+				expected = strings.ReplaceAll(expected, "=", "")
 			}
 
 			res := buf.String()
@@ -697,7 +697,7 @@ func TestDecodeReadAll(t *testing.T) {
 		for encIndex, encoding := range encodings {
 			encoded := pair.encoded
 			if encoding.padChar == NoPadding {
-				encoded = strings.Replace(encoded, "=", "", -1)
+				encoded = strings.ReplaceAll(encoded, "=", "")
 			}
 
 			decReader, err := ioutil.ReadAll(NewDecoder(encoding, strings.NewReader(encoded)))
@@ -723,7 +723,7 @@ func TestDecodeSmallBuffer(t *testing.T) {
 			for encIndex, encoding := range encodings {
 				encoded := pair.encoded
 				if encoding.padChar == NoPadding {
-					encoded = strings.Replace(encoded, "=", "", -1)
+					encoded = strings.ReplaceAll(encoded, "=", "")
 				}
 
 				decoder := NewDecoder(encoding, strings.NewReader(encoded))
diff --git a/libgo/go/encoding/base64/base64.go b/libgo/go/encoding/base64/base64.go
index 9a99370..0bb37b3 100644
--- a/libgo/go/encoding/base64/base64.go
+++ b/libgo/go/encoding/base64/base64.go
@@ -270,7 +270,7 @@ func (e CorruptInputError) Error() string {
 	return "illegal base64 data at input byte " + strconv.FormatInt(int64(e), 10)
 }
 
-// decodeQuantum decodes up to 4 base64 bytes. It takes for parameters
+// decodeQuantum decodes up to 4 base64 bytes. The received parameters are
 // the destination buffer dst, the source buffer src and an index in the
 // source buffer si.
 // It returns the number of bytes read from src, the number of bytes written
@@ -465,10 +465,9 @@ func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
 	}
 
 	si := 0
-	ilen := len(src)
-	olen := len(dst)
-	for strconv.IntSize >= 64 && ilen-si >= 8 && olen-n >= 8 {
-		if ok := enc.decode64(dst[n:], src[si:]); ok {
+	for strconv.IntSize >= 64 && len(src)-si >= 8 && len(dst)-n >= 8 {
+		if dn, ok := enc.decode64(src[si:]); ok {
+			binary.BigEndian.PutUint64(dst[n:], dn)
 			n += 6
 			si += 8
 		} else {
@@ -481,8 +480,9 @@ func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
 		}
 	}
 
-	for ilen-si >= 4 && olen-n >= 4 {
-		if ok := enc.decode32(dst[n:], src[si:]); ok {
+	for len(src)-si >= 4 && len(dst)-n >= 4 {
+		if dn, ok := enc.decode32(src[si:]); ok {
+			binary.BigEndian.PutUint32(dst[n:], dn)
 			n += 3
 			si += 4
 		} else {
@@ -506,72 +506,70 @@ func (enc *Encoding) Decode(dst, src []byte) (n int, err error) {
 	return n, err
 }
 
-// decode32 tries to decode 4 base64 char into 3 bytes.
-// len(dst) and len(src) must both be >= 4.
-// Returns true if decode succeeded.
-func (enc *Encoding) decode32(dst, src []byte) bool {
-	var dn, n uint32
+// decode32 tries to decode 4 base64 characters into 3 bytes, and returns those
+// bytes. len(src) must be >= 4.
+// Returns (0, false) if decoding failed.
+func (enc *Encoding) decode32(src []byte) (dn uint32, ok bool) {
+	var n uint32
+	_ = src[3]
 	if n = uint32(enc.decodeMap[src[0]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 26
 	if n = uint32(enc.decodeMap[src[1]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 20
 	if n = uint32(enc.decodeMap[src[2]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 14
 	if n = uint32(enc.decodeMap[src[3]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 8
-
-	binary.BigEndian.PutUint32(dst, dn)
-	return true
+	return dn, true
 }
 
-// decode64 tries to decode 8 base64 char into 6 bytes.
-// len(dst) and len(src) must both be >= 8.
-// Returns true if decode succeeded.
-func (enc *Encoding) decode64(dst, src []byte) bool {
-	var dn, n uint64
+// decode64 tries to decode 8 base64 characters into 6 bytes, and returns those
+// bytes. len(src) must be >= 8.
+// Returns (0, false) if decoding failed.
+func (enc *Encoding) decode64(src []byte) (dn uint64, ok bool) {
+	var n uint64
+	_ = src[7]
 	if n = uint64(enc.decodeMap[src[0]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 58
 	if n = uint64(enc.decodeMap[src[1]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 52
 	if n = uint64(enc.decodeMap[src[2]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 46
 	if n = uint64(enc.decodeMap[src[3]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 40
 	if n = uint64(enc.decodeMap[src[4]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 34
 	if n = uint64(enc.decodeMap[src[5]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 28
 	if n = uint64(enc.decodeMap[src[6]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 22
 	if n = uint64(enc.decodeMap[src[7]]); n == 0xff {
-		return false
+		return 0, false
 	}
 	dn |= n << 16
-
-	binary.BigEndian.PutUint64(dst, dn)
-	return true
+	return dn, true
 }
 
 type newlineFilteringReader struct {
diff --git a/libgo/go/encoding/base64/base64_test.go b/libgo/go/encoding/base64/base64_test.go
index f019654..f7f312c 100644
--- a/libgo/go/encoding/base64/base64_test.go
+++ b/libgo/go/encoding/base64/base64_test.go
@@ -53,8 +53,8 @@ func stdRef(ref string) string {
 
 // Convert a reference string to URL-encoding
 func urlRef(ref string) string {
-	ref = strings.Replace(ref, "+", "-", -1)
-	ref = strings.Replace(ref, "/", "_", -1)
+	ref = strings.ReplaceAll(ref, "+", "-")
+	ref = strings.ReplaceAll(ref, "/", "_")
 	return ref
 }
 
@@ -72,7 +72,7 @@ func rawURLRef(ref string) string {
 var funnyEncoding = NewEncoding(encodeStd).WithPadding(rune('@'))
 
 func funnyRef(ref string) string {
-	return strings.Replace(ref, "=", "@", -1)
+	return strings.ReplaceAll(ref, "=", "@")
 }
 
 type encodingTest struct {
@@ -418,7 +418,7 @@ j+mSARB/17pKVXYWHXjsj7yIex0PadzXMO1zT5KHoNA3HT8ietoGhgjsfA+CSnvvqh/jJtqsrwOv
 2b6NGNzXfTYexzJ+nU7/ALkf4P8Awv6P9KvTQQ4AgyDqCF85Pho3CTB7eHwXoH+LT65uZbX9X+o2
 bqbPb06551Y4
 `
-	encodedShort := strings.Replace(encoded, "\n", "", -1)
+	encodedShort := strings.ReplaceAll(encoded, "\n", "")
 
 	dec := NewDecoder(StdEncoding, strings.NewReader(encoded))
 	res1, err := ioutil.ReadAll(dec)
diff --git a/libgo/go/encoding/binary/binary.go b/libgo/go/encoding/binary/binary.go
index 85b3bc2..8c2d1d9 100644
--- a/libgo/go/encoding/binary/binary.go
+++ b/libgo/go/encoding/binary/binary.go
@@ -161,23 +161,17 @@ func (bigEndian) GoString() string { return "binary.BigEndian" }
 func Read(r io.Reader, order ByteOrder, data interface{}) error {
 	// Fast path for basic types and slices.
 	if n := intDataSize(data); n != 0 {
-		var b [8]byte
-		var bs []byte
-		if n > len(b) {
-			bs = make([]byte, n)
-		} else {
-			bs = b[:n]
-		}
+		bs := make([]byte, n)
 		if _, err := io.ReadFull(r, bs); err != nil {
 			return err
 		}
 		switch data := data.(type) {
 		case *bool:
-			*data = b[0] != 0
+			*data = bs[0] != 0
 		case *int8:
-			*data = int8(b[0])
+			*data = int8(bs[0])
 		case *uint8:
-			*data = b[0]
+			*data = bs[0]
 		case *int16:
 			*data = int16(order.Uint16(bs))
 		case *uint16:
@@ -260,25 +254,19 @@ func Read(r io.Reader, order ByteOrder, data interface{}) error {
 func Write(w io.Writer, order ByteOrder, data interface{}) error {
 	// Fast path for basic types and slices.
 	if n := intDataSize(data); n != 0 {
-		var b [8]byte
-		var bs []byte
-		if n > len(b) {
-			bs = make([]byte, n)
-		} else {
-			bs = b[:n]
-		}
+		bs := make([]byte, n)
 		switch v := data.(type) {
 		case *bool:
 			if *v {
-				b[0] = 1
+				bs[0] = 1
 			} else {
-				b[0] = 0
+				bs[0] = 0
 			}
 		case bool:
 			if v {
-				b[0] = 1
+				bs[0] = 1
 			} else {
-				b[0] = 0
+				bs[0] = 0
 			}
 		case []bool:
 			for i, x := range v {
@@ -289,19 +277,19 @@ func Write(w io.Writer, order ByteOrder, data interface{}) error {
 				}
 			}
 		case *int8:
-			b[0] = byte(*v)
+			bs[0] = byte(*v)
 		case int8:
-			b[0] = byte(v)
+			bs[0] = byte(v)
 		case []int8:
 			for i, x := range v {
 				bs[i] = byte(x)
 			}
 		case *uint8:
-			b[0] = *v
+			bs[0] = *v
 		case uint8:
-			b[0] = v
+			bs[0] = v
 		case []uint8:
-			bs = v
+			bs = v // TODO(josharian): avoid allocating bs in this case?
 		case *int16:
 			order.PutUint16(bs, uint16(*v))
 		case int16:
diff --git a/libgo/go/encoding/gob/decoder.go b/libgo/go/encoding/gob/decoder.go
index 5ef0388..b52aabe 100644
--- a/libgo/go/encoding/gob/decoder.go
+++ b/libgo/go/encoding/gob/decoder.go
@@ -12,13 +12,14 @@ import (
 	"sync"
 )
 
-// tooBig provides a sanity check for sizes; used in several places.
-// Upper limit of 1GB, allowing room to grow a little without overflow.
-// TODO: make this adjustable?
-const tooBig = 1 << 30
+// tooBig provides a sanity check for sizes; used in several places. Upper limit
+// of is 1GB on 32-bit systems, 8GB on 64-bit, allowing room to grow a little
+// without overflow.
+const tooBig = (1 << 30) << (^uint(0) >> 62)
 
 // A Decoder manages the receipt of type and data information read from the
-// remote side of a connection.
+// remote side of a connection.  It is safe for concurrent use by multiple
+// goroutines.
 //
 // The Decoder does only basic sanity checking on decoded input sizes,
 // and its limits are not configurable. Take caution when decoding gob data
diff --git a/libgo/go/encoding/gob/encoder.go b/libgo/go/encoding/gob/encoder.go
index 40ec81b..53e2cac 100644
--- a/libgo/go/encoding/gob/encoder.go
+++ b/libgo/go/encoding/gob/encoder.go
@@ -12,7 +12,8 @@ import (
 )
 
 // An Encoder manages the transmission of type and data information to the
-// other side of a connection.
+// other side of a connection.  It is safe for concurrent use by multiple
+// goroutines.
 type Encoder struct {
 	mutex      sync.Mutex              // each item must be sent atomically
 	w          []io.Writer             // where to send the data
diff --git a/libgo/go/encoding/gob/encoder_test.go b/libgo/go/encoding/gob/encoder_test.go
index dc9bbcf..825f0d6 100644
--- a/libgo/go/encoding/gob/encoder_test.go
+++ b/libgo/go/encoding/gob/encoder_test.go
@@ -10,7 +10,6 @@ import (
 	"fmt"
 	"io/ioutil"
 	"reflect"
-	"runtime"
 	"strings"
 	"testing"
 )
@@ -1128,24 +1127,3 @@ func TestBadData(t *testing.T) {
 		}
 	}
 }
-
-// TestHugeWriteFails tests that enormous messages trigger an error.
-func TestHugeWriteFails(t *testing.T) {
-	if runtime.GOARCH == "wasm" {
-		t.Skip("out of memory on wasm")
-	}
-	if testing.Short() {
-		// Requires allocating a monster, so don't do this from all.bash.
-		t.Skip("skipping huge allocation in short mode")
-	}
-	huge := make([]byte, tooBig)
-	huge[0] = 7 // Make sure it's not all zeros.
-	buf := new(bytes.Buffer)
-	err := NewEncoder(buf).Encode(huge)
-	if err == nil {
-		t.Fatalf("expected error for huge slice")
-	}
-	if !strings.Contains(err.Error(), "message too big") {
-		t.Fatalf("expected 'too big' error; got %s\n", err.Error())
-	}
-}
diff --git a/libgo/go/encoding/hex/hex.go b/libgo/go/encoding/hex/hex.go
index aee5aec..2bb2b57 100644
--- a/libgo/go/encoding/hex/hex.go
+++ b/libgo/go/encoding/hex/hex.go
@@ -6,10 +6,10 @@
 package hex
 
 import (
-	"bytes"
 	"errors"
 	"fmt"
 	"io"
+	"strings"
 )
 
 const hextable = "0123456789abcdef"
@@ -116,7 +116,16 @@ func DecodeString(s string) ([]byte, error) {
 // Dump returns a string that contains a hex dump of the given data. The format
 // of the hex dump matches the output of `hexdump -C` on the command line.
 func Dump(data []byte) string {
-	var buf bytes.Buffer
+	if len(data) == 0 {
+		return ""
+	}
+
+	var buf strings.Builder
+	// Dumper will write 79 bytes per complete 16 byte chunk, and at least
+	// 64 bytes for whatever remains. Round the allocation up, since only a
+	// maximum of 15 bytes will be wasted.
+	buf.Grow((1 + ((len(data) - 1) / 16)) * 79)
+
 	dumper := Dumper(&buf)
 	dumper.Write(data)
 	dumper.Close()
diff --git a/libgo/go/encoding/hex/hex_test.go b/libgo/go/encoding/hex/hex_test.go
index 6ba054e..e9f4b3a 100644
--- a/libgo/go/encoding/hex/hex_test.go
+++ b/libgo/go/encoding/hex/hex_test.go
@@ -248,3 +248,16 @@ func BenchmarkEncode(b *testing.B) {
 		})
 	}
 }
+
+func BenchmarkDump(b *testing.B) {
+	for _, size := range []int{256, 1024, 4096, 16384} {
+		src := bytes.Repeat([]byte{2, 3, 5, 7, 9, 11, 13, 17}, size/8)
+		sink = make([]byte, 2*size)
+
+		b.Run(fmt.Sprintf("%v", size), func(b *testing.B) {
+			for i := 0; i < b.N; i++ {
+				Dump(src)
+			}
+		})
+	}
+}
diff --git a/libgo/go/encoding/json/bench_test.go b/libgo/go/encoding/json/bench_test.go
index bd322db..72cb349 100644
--- a/libgo/go/encoding/json/bench_test.go
+++ b/libgo/go/encoding/json/bench_test.go
@@ -114,6 +114,34 @@ func BenchmarkCodeMarshal(b *testing.B) {
 	b.SetBytes(int64(len(codeJSON)))
 }
 
+func benchMarshalBytes(n int) func(*testing.B) {
+	sample := []byte("hello world")
+	// Use a struct pointer, to avoid an allocation when passing it as an
+	// interface parameter to Marshal.
+	v := &struct {
+		Bytes []byte
+	}{
+		bytes.Repeat(sample, (n/len(sample))+1)[:n],
+	}
+	return func(b *testing.B) {
+		for i := 0; i < b.N; i++ {
+			if _, err := Marshal(v); err != nil {
+				b.Fatal("Marshal:", err)
+			}
+		}
+	}
+}
+
+func BenchmarkMarshalBytes(b *testing.B) {
+	// 32 fits within encodeState.scratch.
+	b.Run("32", benchMarshalBytes(32))
+	// 256 doesn't fit in encodeState.scratch, but is small enough to
+	// allocate and avoid the slower base64.NewEncoder.
+	b.Run("256", benchMarshalBytes(256))
+	// 4096 is large enough that we want to avoid allocating for it.
+	b.Run("4096", benchMarshalBytes(4096))
+}
+
 func BenchmarkCodeDecoder(b *testing.B) {
 	if codeJSON == nil {
 		b.StopTimer()
diff --git a/libgo/go/encoding/json/decode.go b/libgo/go/encoding/json/decode.go
index 7d23508..731553d 100644
--- a/libgo/go/encoding/json/decode.go
+++ b/libgo/go/encoding/json/decode.go
@@ -11,7 +11,6 @@ import (
 	"bytes"
 	"encoding"
 	"encoding/base64"
-	"errors"
 	"fmt"
 	"reflect"
 	"strconv"
@@ -179,7 +178,7 @@ func (d *decodeState) unmarshal(v interface{}) error {
 	// test must be applied at the top level of the value.
 	err := d.value(rv)
 	if err != nil {
-		return err
+		return d.addErrorContext(err)
 	}
 	return d.savedError
 }
@@ -267,7 +266,7 @@ type decodeState struct {
 	opcode       int // last read result
 	scan         scanner
 	errorContext struct { // provides context for type errors
-		Struct string
+		Struct reflect.Type
 		Field  string
 	}
 	savedError            error
@@ -280,16 +279,16 @@ func (d *decodeState) readIndex() int {
 	return d.off - 1
 }
 
-// errPhase is used for errors that should not happen unless
-// there is a bug in the JSON decoder or something is editing
-// the data slice while the decoder executes.
-var errPhase = errors.New("JSON decoder out of sync - data changing underfoot?")
+// phasePanicMsg is used as a panic message when we end up with something that
+// shouldn't happen. It can indicate a bug in the JSON decoder, or that
+// something is editing the data slice while the decoder executes.
+const phasePanicMsg = "JSON decoder out of sync - data changing underfoot?"
 
 func (d *decodeState) init(data []byte) *decodeState {
 	d.data = data
 	d.off = 0
 	d.savedError = nil
-	d.errorContext.Struct = ""
+	d.errorContext.Struct = nil
 	d.errorContext.Field = ""
 	return d
 }
@@ -304,10 +303,10 @@ func (d *decodeState) saveError(err error) {
 
 // addErrorContext returns a new error enhanced with information from d.errorContext
 func (d *decodeState) addErrorContext(err error) error {
-	if d.errorContext.Struct != "" || d.errorContext.Field != "" {
+	if d.errorContext.Struct != nil || d.errorContext.Field != "" {
 		switch err := err.(type) {
 		case *UnmarshalTypeError:
-			err.Struct = d.errorContext.Struct
+			err.Struct = d.errorContext.Struct.Name()
 			err.Field = d.errorContext.Field
 			return err
 		}
@@ -332,13 +331,12 @@ func (d *decodeState) skip() {
 
 // scanNext processes the byte at d.data[d.off].
 func (d *decodeState) scanNext() {
-	s, data, i := &d.scan, d.data, d.off
-	if i < len(data) {
-		d.opcode = s.step(s, data[i])
-		d.off = i + 1
+	if d.off < len(d.data) {
+		d.opcode = d.scan.step(&d.scan, d.data[d.off])
+		d.off++
 	} else {
-		d.opcode = s.eof()
-		d.off = len(data) + 1 // mark processed EOF with len+1
+		d.opcode = d.scan.eof()
+		d.off = len(d.data) + 1 // mark processed EOF with len+1
 	}
 }
 
@@ -346,7 +344,7 @@ func (d *decodeState) scanNext() {
 // receives a scan code not equal to op.
 func (d *decodeState) scanWhile(op int) {
 	s, data, i := &d.scan, d.data, d.off
-	for i < len(d.data) {
+	for i < len(data) {
 		newOp := s.step(s, data[i])
 		i++
 		if newOp != op {
@@ -356,7 +354,7 @@ func (d *decodeState) scanWhile(op int) {
 		}
 	}
 
-	d.off = len(d.data) + 1 // mark processed EOF with len+1
+	d.off = len(data) + 1 // mark processed EOF with len+1
 	d.opcode = d.scan.eof()
 }
 
@@ -366,7 +364,7 @@ func (d *decodeState) scanWhile(op int) {
 func (d *decodeState) value(v reflect.Value) error {
 	switch d.opcode {
 	default:
-		return errPhase
+		panic(phasePanicMsg)
 
 	case scanBeginArray:
 		if v.IsValid() {
@@ -408,30 +406,23 @@ type unquotedValue struct{}
 // quoted string literal or literal null into an interface value.
 // If it finds anything other than a quoted string literal or null,
 // valueQuoted returns unquotedValue{}.
-func (d *decodeState) valueQuoted() (interface{}, error) {
+func (d *decodeState) valueQuoted() interface{} {
 	switch d.opcode {
 	default:
-		return nil, errPhase
+		panic(phasePanicMsg)
 
-	case scanBeginArray:
-		d.skip()
-		d.scanNext()
-
-	case scanBeginObject:
+	case scanBeginArray, scanBeginObject:
 		d.skip()
 		d.scanNext()
 
 	case scanBeginLiteral:
-		v, err := d.literalInterface()
-		if err != nil {
-			return nil, err
-		}
+		v := d.literalInterface()
 		switch v.(type) {
 		case nil, string:
-			return v, nil
+			return v
 		}
 	}
-	return unquotedValue{}, nil
+	return unquotedValue{}
 }
 
 // indirect walks down v allocating pointers as needed,
@@ -482,7 +473,7 @@ func indirect(v reflect.Value, decodingNull bool) (Unmarshaler, encoding.TextUnm
 		if v.IsNil() {
 			v.Set(reflect.New(v.Type().Elem()))
 		}
-		if v.Type().NumMethod() > 0 {
+		if v.Type().NumMethod() > 0 && v.CanInterface() {
 			if u, ok := v.Interface().(Unmarshaler); ok {
 				return u, nil, reflect.Value{}
 			}
@@ -525,10 +516,7 @@ func (d *decodeState) array(v reflect.Value) error {
 	case reflect.Interface:
 		if v.NumMethod() == 0 {
 			// Decoding into nil interface? Switch to non-reflect code.
-			ai, err := d.arrayInterface()
-			if err != nil {
-				return err
-			}
+			ai := d.arrayInterface()
 			v.Set(reflect.ValueOf(ai))
 			return nil
 		}
@@ -538,8 +526,7 @@ func (d *decodeState) array(v reflect.Value) error {
 		d.saveError(&UnmarshalTypeError{Value: "array", Type: v.Type(), Offset: int64(d.off)})
 		d.skip()
 		return nil
-	case reflect.Array:
-	case reflect.Slice:
+	case reflect.Array, reflect.Slice:
 		break
 	}
 
@@ -589,7 +576,7 @@ func (d *decodeState) array(v reflect.Value) error {
 			break
 		}
 		if d.opcode != scanArrayValue {
-			return errPhase
+			panic(phasePanicMsg)
 		}
 	}
 
@@ -611,7 +598,7 @@ func (d *decodeState) array(v reflect.Value) error {
 }
 
 var nullLiteral = []byte("null")
-var textUnmarshalerType = reflect.TypeOf(new(encoding.TextUnmarshaler)).Elem()
+var textUnmarshalerType = reflect.TypeOf((*encoding.TextUnmarshaler)(nil)).Elem()
 
 // object consumes an object from d.data[d.off-1:], decoding into v.
 // The first byte ('{') of the object has been read already.
@@ -629,17 +616,17 @@ func (d *decodeState) object(v reflect.Value) error {
 		return nil
 	}
 	v = pv
+	t := v.Type()
 
 	// Decoding into nil interface? Switch to non-reflect code.
 	if v.Kind() == reflect.Interface && v.NumMethod() == 0 {
-		oi, err := d.objectInterface()
-		if err != nil {
-			return err
-		}
+		oi := d.objectInterface()
 		v.Set(reflect.ValueOf(oi))
 		return nil
 	}
 
+	var fields []field
+
 	// Check type of target:
 	//   struct or
 	//   map[T1]T2 where T1 is string, an integer type,
@@ -648,14 +635,13 @@ func (d *decodeState) object(v reflect.Value) error {
 	case reflect.Map:
 		// Map key must either have string kind, have an integer kind,
 		// or be an encoding.TextUnmarshaler.
-		t := v.Type()
 		switch t.Key().Kind() {
 		case reflect.String,
 			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
 			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		default:
 			if !reflect.PtrTo(t.Key()).Implements(textUnmarshalerType) {
-				d.saveError(&UnmarshalTypeError{Value: "object", Type: v.Type(), Offset: int64(d.off)})
+				d.saveError(&UnmarshalTypeError{Value: "object", Type: t, Offset: int64(d.off)})
 				d.skip()
 				return nil
 			}
@@ -664,9 +650,10 @@ func (d *decodeState) object(v reflect.Value) error {
 			v.Set(reflect.MakeMap(t))
 		}
 	case reflect.Struct:
+		fields = cachedTypeFields(t)
 		// ok
 	default:
-		d.saveError(&UnmarshalTypeError{Value: "object", Type: v.Type(), Offset: int64(d.off)})
+		d.saveError(&UnmarshalTypeError{Value: "object", Type: t, Offset: int64(d.off)})
 		d.skip()
 		return nil
 	}
@@ -682,7 +669,7 @@ func (d *decodeState) object(v reflect.Value) error {
 			break
 		}
 		if d.opcode != scanBeginLiteral {
-			return errPhase
+			panic(phasePanicMsg)
 		}
 
 		// Read key.
@@ -691,7 +678,7 @@ func (d *decodeState) object(v reflect.Value) error {
 		item := d.data[start:d.readIndex()]
 		key, ok := unquoteBytes(item)
 		if !ok {
-			return errPhase
+			panic(phasePanicMsg)
 		}
 
 		// Figure out field corresponding to key.
@@ -699,7 +686,7 @@ func (d *decodeState) object(v reflect.Value) error {
 		destring := false // whether the value is wrapped in a string to be decoded first
 
 		if v.Kind() == reflect.Map {
-			elemType := v.Type().Elem()
+			elemType := t.Elem()
 			if !mapElem.IsValid() {
 				mapElem = reflect.New(elemType).Elem()
 			} else {
@@ -708,7 +695,6 @@ func (d *decodeState) object(v reflect.Value) error {
 			subv = mapElem
 		} else {
 			var f *field
-			fields := cachedTypeFields(v.Type())
 			for i := range fields {
 				ff := &fields[i]
 				if bytes.Equal(ff.nameBytes, key) {
@@ -745,7 +731,7 @@ func (d *decodeState) object(v reflect.Value) error {
 					subv = subv.Field(i)
 				}
 				d.errorContext.Field = f.name
-				d.errorContext.Struct = v.Type().Name()
+				d.errorContext.Struct = t
 			} else if d.disallowUnknownFields {
 				d.saveError(fmt.Errorf("json: unknown field %q", key))
 			}
@@ -756,16 +742,12 @@ func (d *decodeState) object(v reflect.Value) error {
 			d.scanWhile(scanSkipSpace)
 		}
 		if d.opcode != scanObjectKey {
-			return errPhase
+			panic(phasePanicMsg)
 		}
 		d.scanWhile(scanSkipSpace)
 
 		if destring {
-			q, err := d.valueQuoted()
-			if err != nil {
-				return err
-			}
-			switch qv := q.(type) {
+			switch qv := d.valueQuoted().(type) {
 			case nil:
 				if err := d.literalStore(nullLiteral, subv, false); err != nil {
 					return err
@@ -786,13 +768,13 @@ func (d *decodeState) object(v reflect.Value) error {
 		// Write value back to map;
 		// if using struct, subv points into struct already.
 		if v.Kind() == reflect.Map {
-			kt := v.Type().Key()
+			kt := t.Key()
 			var kv reflect.Value
 			switch {
 			case kt.Kind() == reflect.String:
 				kv = reflect.ValueOf(key).Convert(kt)
 			case reflect.PtrTo(kt).Implements(textUnmarshalerType):
-				kv = reflect.New(v.Type().Key())
+				kv = reflect.New(kt)
 				if err := d.literalStore(item, kv, true); err != nil {
 					return err
 				}
@@ -804,7 +786,7 @@ func (d *decodeState) object(v reflect.Value) error {
 					n, err := strconv.ParseInt(s, 10, 64)
 					if err != nil || reflect.Zero(kt).OverflowInt(n) {
 						d.saveError(&UnmarshalTypeError{Value: "number " + s, Type: kt, Offset: int64(start + 1)})
-						return nil
+						break
 					}
 					kv = reflect.ValueOf(n).Convert(kt)
 				case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
@@ -812,14 +794,16 @@ func (d *decodeState) object(v reflect.Value) error {
 					n, err := strconv.ParseUint(s, 10, 64)
 					if err != nil || reflect.Zero(kt).OverflowUint(n) {
 						d.saveError(&UnmarshalTypeError{Value: "number " + s, Type: kt, Offset: int64(start + 1)})
-						return nil
+						break
 					}
 					kv = reflect.ValueOf(n).Convert(kt)
 				default:
 					panic("json: Unexpected key type") // should never occur
 				}
 			}
-			v.SetMapIndex(kv, subv)
+			if kv.IsValid() {
+				v.SetMapIndex(kv, subv)
+			}
 		}
 
 		// Next token must be , or }.
@@ -830,7 +814,7 @@ func (d *decodeState) object(v reflect.Value) error {
 			break
 		}
 		if d.opcode != scanObjectValue {
-			return errPhase
+			panic(phasePanicMsg)
 		}
 
 		d.errorContext = originalErrorContext
@@ -874,18 +858,16 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
 		if item[0] != '"' {
 			if fromQuoted {
 				d.saveError(fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type()))
-			} else {
-				var val string
-				switch item[0] {
-				case 'n':
-					val = "null"
-				case 't', 'f':
-					val = "bool"
-				default:
-					val = "number"
-				}
-				d.saveError(&UnmarshalTypeError{Value: val, Type: v.Type(), Offset: int64(d.readIndex())})
+				return nil
+			}
+			val := "number"
+			switch item[0] {
+			case 'n':
+				val = "null"
+			case 't', 'f':
+				val = "bool"
 			}
+			d.saveError(&UnmarshalTypeError{Value: val, Type: v.Type(), Offset: int64(d.readIndex())})
 			return nil
 		}
 		s, ok := unquoteBytes(item)
@@ -893,7 +875,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
 			if fromQuoted {
 				return fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type())
 			}
-			return errPhase
+			panic(phasePanicMsg)
 		}
 		return ut.UnmarshalText(s)
 	}
@@ -944,7 +926,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
 			if fromQuoted {
 				return fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type())
 			}
-			return errPhase
+			panic(phasePanicMsg)
 		}
 		switch v.Kind() {
 		default:
@@ -976,7 +958,7 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
 			if fromQuoted {
 				return fmt.Errorf("json: invalid use of ,string struct tag, trying to unmarshal %q into %v", item, v.Type())
 			}
-			return errPhase
+			panic(phasePanicMsg)
 		}
 		s := string(item)
 		switch v.Kind() {
@@ -1037,24 +1019,24 @@ func (d *decodeState) literalStore(item []byte, v reflect.Value, fromQuoted bool
 // but they avoid the weight of reflection in this common case.
 
 // valueInterface is like value but returns interface{}
-func (d *decodeState) valueInterface() (val interface{}, err error) {
+func (d *decodeState) valueInterface() (val interface{}) {
 	switch d.opcode {
 	default:
-		err = errPhase
+		panic(phasePanicMsg)
 	case scanBeginArray:
-		val, err = d.arrayInterface()
+		val = d.arrayInterface()
 		d.scanNext()
 	case scanBeginObject:
-		val, err = d.objectInterface()
+		val = d.objectInterface()
 		d.scanNext()
 	case scanBeginLiteral:
-		val, err = d.literalInterface()
+		val = d.literalInterface()
 	}
 	return
 }
 
 // arrayInterface is like array but returns []interface{}.
-func (d *decodeState) arrayInterface() ([]interface{}, error) {
+func (d *decodeState) arrayInterface() []interface{} {
 	var v = make([]interface{}, 0)
 	for {
 		// Look ahead for ] - can only happen on first iteration.
@@ -1063,11 +1045,7 @@ func (d *decodeState) arrayInterface() ([]interface{}, error) {
 			break
 		}
 
-		vi, err := d.valueInterface()
-		if err != nil {
-			return nil, err
-		}
-		v = append(v, vi)
+		v = append(v, d.valueInterface())
 
 		// Next token must be , or ].
 		if d.opcode == scanSkipSpace {
@@ -1077,14 +1055,14 @@ func (d *decodeState) arrayInterface() ([]interface{}, error) {
 			break
 		}
 		if d.opcode != scanArrayValue {
-			return nil, errPhase
+			panic(phasePanicMsg)
 		}
 	}
-	return v, nil
+	return v
 }
 
 // objectInterface is like object but returns map[string]interface{}.
-func (d *decodeState) objectInterface() (map[string]interface{}, error) {
+func (d *decodeState) objectInterface() map[string]interface{} {
 	m := make(map[string]interface{})
 	for {
 		// Read opening " of string key or closing }.
@@ -1094,7 +1072,7 @@ func (d *decodeState) objectInterface() (map[string]interface{}, error) {
 			break
 		}
 		if d.opcode != scanBeginLiteral {
-			return nil, errPhase
+			panic(phasePanicMsg)
 		}
 
 		// Read string key.
@@ -1103,7 +1081,7 @@ func (d *decodeState) objectInterface() (map[string]interface{}, error) {
 		item := d.data[start:d.readIndex()]
 		key, ok := unquote(item)
 		if !ok {
-			return nil, errPhase
+			panic(phasePanicMsg)
 		}
 
 		// Read : before value.
@@ -1111,16 +1089,12 @@ func (d *decodeState) objectInterface() (map[string]interface{}, error) {
 			d.scanWhile(scanSkipSpace)
 		}
 		if d.opcode != scanObjectKey {
-			return nil, errPhase
+			panic(phasePanicMsg)
 		}
 		d.scanWhile(scanSkipSpace)
 
 		// Read value.
-		vi, err := d.valueInterface()
-		if err != nil {
-			return nil, err
-		}
-		m[key] = vi
+		m[key] = d.valueInterface()
 
 		// Next token must be , or }.
 		if d.opcode == scanSkipSpace {
@@ -1130,16 +1104,16 @@ func (d *decodeState) objectInterface() (map[string]interface{}, error) {
 			break
 		}
 		if d.opcode != scanObjectValue {
-			return nil, errPhase
+			panic(phasePanicMsg)
 		}
 	}
-	return m, nil
+	return m
 }
 
 // literalInterface consumes and returns a literal from d.data[d.off-1:] and
 // it reads the following byte ahead. The first byte of the literal has been
 // read already (that's how the caller knows it's a literal).
-func (d *decodeState) literalInterface() (interface{}, error) {
+func (d *decodeState) literalInterface() interface{} {
 	// All bytes inside literal return scanContinue op code.
 	start := d.readIndex()
 	d.scanWhile(scanContinue)
@@ -1148,27 +1122,27 @@ func (d *decodeState) literalInterface() (interface{}, error) {
 
 	switch c := item[0]; c {
 	case 'n': // null
-		return nil, nil
+		return nil
 
 	case 't', 'f': // true, false
-		return c == 't', nil
+		return c == 't'
 
 	case '"': // string
 		s, ok := unquote(item)
 		if !ok {
-			return nil, errPhase
+			panic(phasePanicMsg)
 		}
-		return s, nil
+		return s
 
 	default: // number
 		if c != '-' && (c < '0' || c > '9') {
-			return nil, errPhase
+			panic(phasePanicMsg)
 		}
 		n, err := d.convertNumber(string(item))
 		if err != nil {
 			d.saveError(err)
 		}
-		return n, nil
+		return n
 	}
 }
 
diff --git a/libgo/go/encoding/json/decode_test.go b/libgo/go/encoding/json/decode_test.go
index 5746ddf..5443260 100644
--- a/libgo/go/encoding/json/decode_test.go
+++ b/libgo/go/encoding/json/decode_test.go
@@ -41,6 +41,16 @@ type VOuter struct {
 	V V
 }
 
+type W struct {
+	S SS
+}
+
+type SS string
+
+func (*SS) UnmarshalJSON(data []byte) error {
+	return &UnmarshalTypeError{Value: "number", Type: reflect.TypeOf(SS(""))}
+}
+
 // ifaceNumAsFloat64/ifaceNumAsNumber are used to test unmarshaling with and
 // without UseNumber
 var ifaceNumAsFloat64 = map[string]interface{}{
@@ -142,7 +152,7 @@ var (
 	umstructXY   = ustructText{unmarshalerText{"x", "y"}}
 
 	ummapType = map[unmarshalerText]bool{}
-	ummapXY   = map[unmarshalerText]bool{unmarshalerText{"x", "y"}: true}
+	ummapXY   = map[unmarshalerText]bool{{"x", "y"}: true}
 )
 
 // Test data structures for anonymous fields.
@@ -256,6 +266,10 @@ type XYZ struct {
 	Z interface{}
 }
 
+type unexportedWithMethods struct{}
+
+func (unexportedWithMethods) F() {}
+
 func sliceAddr(x []int) *[]int                 { return &x }
 func mapAddr(x map[string]int) *map[string]int { return &x }
 
@@ -408,6 +422,7 @@ var unmarshalTests = []unmarshalTest{
 	{in: `{"X": 23}`, ptr: new(T), out: T{}, err: &UnmarshalTypeError{"number", reflect.TypeOf(""), 8, "T", "X"}}, {in: `{"x": 1}`, ptr: new(tx), out: tx{}},
 	{in: `{"x": 1}`, ptr: new(tx), out: tx{}},
 	{in: `{"x": 1}`, ptr: new(tx), err: fmt.Errorf("json: unknown field \"x\""), disallowUnknownFields: true},
+	{in: `{"S": 23}`, ptr: new(W), out: W{}, err: &UnmarshalTypeError{"number", reflect.TypeOf(SS("")), 0, "W", "S"}},
 	{in: `{"F1":1,"F2":2,"F3":3}`, ptr: new(V), out: V{F1: float64(1), F2: int32(2), F3: Number("3")}},
 	{in: `{"F1":1,"F2":2,"F3":3}`, ptr: new(V), out: V{F1: Number("1"), F2: int32(2), F3: Number("3")}, useNumber: true},
 	{in: `{"k1":1,"k2":"s","k3":[1,2.0,3e-3],"k4":{"kk1":"s","kk2":2}}`, ptr: new(interface{}), out: ifaceNumAsFloat64},
@@ -434,6 +449,7 @@ var unmarshalTests = []unmarshalTest{
 	{in: `{"X": "foo", "Y"}`, err: &SyntaxError{"invalid character '}' after object key", 17}},
 	{in: `[1, 2, 3+]`, err: &SyntaxError{"invalid character '+' after array element", 9}},
 	{in: `{"X":12x}`, err: &SyntaxError{"invalid character 'x' after object key:value pair", 8}, useNumber: true},
+	{in: `[2, 3`, err: &SyntaxError{msg: "unexpected end of JSON input", Offset: 5}},
 
 	// raw value errors
 	{in: "\x01 42", err: &SyntaxError{"invalid character '\\x01' looking for beginning of value", 1}},
@@ -449,6 +465,7 @@ var unmarshalTests = []unmarshalTest{
 	{in: `[1, 2, 3]`, ptr: new([3]int), out: [3]int{1, 2, 3}},
 	{in: `[1, 2, 3]`, ptr: new([1]int), out: [1]int{1}},
 	{in: `[1, 2, 3]`, ptr: new([5]int), out: [5]int{1, 2, 3, 0, 0}},
+	{in: `[1, 2, 3]`, ptr: new(MustNotUnmarshalJSON), err: errors.New("MustNotUnmarshalJSON was used")},
 
 	// empty array to interface test
 	{in: `[]`, ptr: new([]interface{}), out: []interface{}{}},
@@ -541,6 +558,16 @@ var unmarshalTests = []unmarshalTest{
 		ptr: new(map[uint8]string),
 		err: &UnmarshalTypeError{Value: "number -1", Type: reflect.TypeOf(uint8(0)), Offset: 2},
 	},
+	{
+		in:  `{"F":{"a":2,"3":4}}`,
+		ptr: new(map[string]map[int]int),
+		err: &UnmarshalTypeError{Value: "number a", Type: reflect.TypeOf(int(0)), Offset: 7},
+	},
+	{
+		in:  `{"F":{"a":2,"3":4}}`,
+		ptr: new(map[string]map[uint]int),
+		err: &UnmarshalTypeError{Value: "number a", Type: reflect.TypeOf(uint(0)), Offset: 7},
+	},
 
 	// Map keys can be encoding.TextUnmarshalers.
 	{in: `{"x:y":true}`, ptr: &ummapType, out: ummapXY},
@@ -815,6 +842,7 @@ var unmarshalTests = []unmarshalTest{
 	{in: `{"B": "False"}`, ptr: new(B), err: errors.New(`json: invalid use of ,string struct tag, trying to unmarshal "False" into bool`)},
 	{in: `{"B": "null"}`, ptr: new(B), out: B{false}},
 	{in: `{"B": "nul"}`, ptr: new(B), err: errors.New(`json: invalid use of ,string struct tag, trying to unmarshal "nul" into bool`)},
+	{in: `{"B": [2, 3]}`, ptr: new(B), err: errors.New(`json: invalid use of ,string struct tag, trying to unmarshal unquoted value into bool`)},
 
 	// additional tests for disallowUnknownFields
 	{
@@ -883,6 +911,18 @@ var unmarshalTests = []unmarshalTest{
 		ptr: new(mapStringToStringData),
 		err: &UnmarshalTypeError{Value: "number", Type: reflect.TypeOf(""), Offset: 21, Struct: "mapStringToStringData", Field: "data"},
 	},
+
+	// trying to decode JSON arrays or objects via TextUnmarshaler
+	{
+		in:  `[1, 2, 3]`,
+		ptr: new(MustNotUnmarshalText),
+		err: &UnmarshalTypeError{Value: "array", Type: reflect.TypeOf(&MustNotUnmarshalText{}), Offset: 1},
+	},
+	{
+		in:  `{"foo": "bar"}`,
+		ptr: new(MustNotUnmarshalText),
+		err: &UnmarshalTypeError{Value: "object", Type: reflect.TypeOf(&MustNotUnmarshalText{}), Offset: 1},
+	},
 }
 
 func TestMarshal(t *testing.T) {
@@ -1944,10 +1984,12 @@ type unexportedFields struct {
 	Name string
 	m    map[string]interface{} `json:"-"`
 	m2   map[string]interface{} `json:"abcd"`
+
+	s []int `json:"-"`
 }
 
 func TestUnmarshalUnexported(t *testing.T) {
-	input := `{"Name": "Bob", "m": {"x": 123}, "m2": {"y": 456}, "abcd": {"z": 789}}`
+	input := `{"Name": "Bob", "m": {"x": 123}, "m2": {"y": 456}, "abcd": {"z": 789}, "s": [2, 3]}`
 	want := &unexportedFields{Name: "Bob"}
 
 	out := &unexportedFields{}
@@ -2113,6 +2155,9 @@ func TestInvalidStringOption(t *testing.T) {
 //
 // (Issue 24152) If the embedded struct is given an explicit name,
 // ensure that the normal unmarshal logic does not panic in reflect.
+//
+// (Issue 28145) If the embedded struct is given an explicit name and has
+// exported methods, don't cause a panic trying to get its value.
 func TestUnmarshalEmbeddedUnexported(t *testing.T) {
 	type (
 		embed1 struct{ Q int }
@@ -2152,6 +2197,9 @@ func TestUnmarshalEmbeddedUnexported(t *testing.T) {
 			embed2 `json:"embed2"`
 			Q      int
 		}
+		S9 struct {
+			unexportedWithMethods `json:"embed"`
+		}
 	)
 
 	tests := []struct {
@@ -2213,6 +2261,11 @@ func TestUnmarshalEmbeddedUnexported(t *testing.T) {
 		in:  `{"embed1": {"Q": 1}, "embed2": {"Q": 2}, "Q": 3}`,
 		ptr: new(S8),
 		out: &S8{embed1{1}, embed2{2}, 3},
+	}, {
+		// Issue 228145, similar to the cases above.
+		in:  `{"embed": {}}`,
+		ptr: new(S9),
+		out: &S9{},
 	}}
 
 	for i, tt := range tests {
diff --git a/libgo/go/encoding/json/encode.go b/libgo/go/encoding/json/encode.go
index 28ca5fe..f10124e 100644
--- a/libgo/go/encoding/json/encode.go
+++ b/libgo/go/encoding/json/encode.go
@@ -381,8 +381,8 @@ func typeEncoder(t reflect.Type) encoderFunc {
 }
 
 var (
-	marshalerType     = reflect.TypeOf(new(Marshaler)).Elem()
-	textMarshalerType = reflect.TypeOf(new(encoding.TextMarshaler)).Elem()
+	marshalerType     = reflect.TypeOf((*Marshaler)(nil)).Elem()
+	textMarshalerType = reflect.TypeOf((*encoding.TextMarshaler)(nil)).Elem()
 )
 
 // newTypeEncoder constructs an encoderFunc for a type.
@@ -624,40 +624,49 @@ func unsupportedTypeEncoder(e *encodeState, v reflect.Value, _ encOpts) {
 }
 
 type structEncoder struct {
-	fields    []field
-	fieldEncs []encoderFunc
+	fields []field
 }
 
-func (se *structEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
-	e.WriteByte('{')
-	first := true
-	for i, f := range se.fields {
-		fv := fieldByIndex(v, f.index)
-		if !fv.IsValid() || f.omitEmpty && isEmptyValue(fv) {
+func (se structEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+	next := byte('{')
+FieldLoop:
+	for i := range se.fields {
+		f := &se.fields[i]
+
+		// Find the nested struct field by following f.index.
+		fv := v
+		for _, i := range f.index {
+			if fv.Kind() == reflect.Ptr {
+				if fv.IsNil() {
+					continue FieldLoop
+				}
+				fv = fv.Elem()
+			}
+			fv = fv.Field(i)
+		}
+
+		if f.omitEmpty && isEmptyValue(fv) {
 			continue
 		}
-		if first {
-			first = false
+		e.WriteByte(next)
+		next = ','
+		if opts.escapeHTML {
+			e.WriteString(f.nameEscHTML)
 		} else {
-			e.WriteByte(',')
+			e.WriteString(f.nameNonEsc)
 		}
-		e.string(f.name, opts.escapeHTML)
-		e.WriteByte(':')
 		opts.quoted = f.quoted
-		se.fieldEncs[i](e, fv, opts)
+		f.encoder(e, fv, opts)
+	}
+	if next == '{' {
+		e.WriteString("{}")
+	} else {
+		e.WriteByte('}')
 	}
-	e.WriteByte('}')
 }
 
 func newStructEncoder(t reflect.Type) encoderFunc {
-	fields := cachedTypeFields(t)
-	se := &structEncoder{
-		fields:    fields,
-		fieldEncs: make([]encoderFunc, len(fields)),
-	}
-	for i, f := range fields {
-		se.fieldEncs[i] = typeEncoder(typeByIndex(t, f.index))
-	}
+	se := structEncoder{fields: cachedTypeFields(t)}
 	return se.encode
 }
 
@@ -665,7 +674,7 @@ type mapEncoder struct {
 	elemEnc encoderFunc
 }
 
-func (me *mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+func (me mapEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
@@ -704,7 +713,7 @@ func newMapEncoder(t reflect.Type) encoderFunc {
 			return unsupportedTypeEncoder
 		}
 	}
-	me := &mapEncoder{typeEncoder(t.Elem())}
+	me := mapEncoder{typeEncoder(t.Elem())}
 	return me.encode
 }
 
@@ -715,14 +724,22 @@ func encodeByteSlice(e *encodeState, v reflect.Value, _ encOpts) {
 	}
 	s := v.Bytes()
 	e.WriteByte('"')
-	if len(s) < 1024 {
-		// for small buffers, using Encode directly is much faster.
-		dst := make([]byte, base64.StdEncoding.EncodedLen(len(s)))
+	encodedLen := base64.StdEncoding.EncodedLen(len(s))
+	if encodedLen <= len(e.scratch) {
+		// If the encoded bytes fit in e.scratch, avoid an extra
+		// allocation and use the cheaper Encoding.Encode.
+		dst := e.scratch[:encodedLen]
+		base64.StdEncoding.Encode(dst, s)
+		e.Write(dst)
+	} else if encodedLen <= 1024 {
+		// The encoded bytes are short enough to allocate for, and
+		// Encoding.Encode is still cheaper.
+		dst := make([]byte, encodedLen)
 		base64.StdEncoding.Encode(dst, s)
 		e.Write(dst)
 	} else {
-		// for large buffers, avoid unnecessary extra temporary
-		// buffer space.
+		// The encoded bytes are too long to cheaply allocate, and
+		// Encoding.Encode is no longer noticeably cheaper.
 		enc := base64.NewEncoder(base64.StdEncoding, e)
 		enc.Write(s)
 		enc.Close()
@@ -735,7 +752,7 @@ type sliceEncoder struct {
 	arrayEnc encoderFunc
 }
 
-func (se *sliceEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+func (se sliceEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
@@ -751,7 +768,7 @@ func newSliceEncoder(t reflect.Type) encoderFunc {
 			return encodeByteSlice
 		}
 	}
-	enc := &sliceEncoder{newArrayEncoder(t)}
+	enc := sliceEncoder{newArrayEncoder(t)}
 	return enc.encode
 }
 
@@ -759,7 +776,7 @@ type arrayEncoder struct {
 	elemEnc encoderFunc
 }
 
-func (ae *arrayEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+func (ae arrayEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	e.WriteByte('[')
 	n := v.Len()
 	for i := 0; i < n; i++ {
@@ -772,7 +789,7 @@ func (ae *arrayEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 }
 
 func newArrayEncoder(t reflect.Type) encoderFunc {
-	enc := &arrayEncoder{typeEncoder(t.Elem())}
+	enc := arrayEncoder{typeEncoder(t.Elem())}
 	return enc.encode
 }
 
@@ -780,7 +797,7 @@ type ptrEncoder struct {
 	elemEnc encoderFunc
 }
 
-func (pe *ptrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+func (pe ptrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.IsNil() {
 		e.WriteString("null")
 		return
@@ -789,7 +806,7 @@ func (pe *ptrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 }
 
 func newPtrEncoder(t reflect.Type) encoderFunc {
-	enc := &ptrEncoder{typeEncoder(t.Elem())}
+	enc := ptrEncoder{typeEncoder(t.Elem())}
 	return enc.encode
 }
 
@@ -797,7 +814,7 @@ type condAddrEncoder struct {
 	canAddrEnc, elseEnc encoderFunc
 }
 
-func (ce *condAddrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
+func (ce condAddrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts) {
 	if v.CanAddr() {
 		ce.canAddrEnc(e, v, opts)
 	} else {
@@ -808,7 +825,7 @@ func (ce *condAddrEncoder) encode(e *encodeState, v reflect.Value, opts encOpts)
 // newCondAddrEncoder returns an encoder that checks whether its value
 // CanAddr and delegates to canAddrEnc if so, else to elseEnc.
 func newCondAddrEncoder(canAddrEnc, elseEnc encoderFunc) encoderFunc {
-	enc := &condAddrEncoder{canAddrEnc: canAddrEnc, elseEnc: elseEnc}
+	enc := condAddrEncoder{canAddrEnc: canAddrEnc, elseEnc: elseEnc}
 	return enc.encode
 }
 
@@ -822,28 +839,13 @@ func isValidTag(s string) bool {
 			// Backslash and quote chars are reserved, but
 			// otherwise any punctuation chars are allowed
 			// in a tag name.
-		default:
-			if !unicode.IsLetter(c) && !unicode.IsDigit(c) {
-				return false
-			}
+		case !unicode.IsLetter(c) && !unicode.IsDigit(c):
+			return false
 		}
 	}
 	return true
 }
 
-func fieldByIndex(v reflect.Value, index []int) reflect.Value {
-	for _, i := range index {
-		if v.Kind() == reflect.Ptr {
-			if v.IsNil() {
-				return reflect.Value{}
-			}
-			v = v.Elem()
-		}
-		v = v.Field(i)
-	}
-	return v
-}
-
 func typeByIndex(t reflect.Type, index []int) reflect.Type {
 	for _, i := range index {
 		if t.Kind() == reflect.Ptr {
@@ -893,18 +895,15 @@ func (e *encodeState) string(s string, escapeHTML bool) {
 			if start < i {
 				e.WriteString(s[start:i])
 			}
+			e.WriteByte('\\')
 			switch b {
 			case '\\', '"':
-				e.WriteByte('\\')
 				e.WriteByte(b)
 			case '\n':
-				e.WriteByte('\\')
 				e.WriteByte('n')
 			case '\r':
-				e.WriteByte('\\')
 				e.WriteByte('r')
 			case '\t':
-				e.WriteByte('\\')
 				e.WriteByte('t')
 			default:
 				// This encodes bytes < 0x20 except for \t, \n and \r.
@@ -912,7 +911,7 @@ func (e *encodeState) string(s string, escapeHTML bool) {
 				// because they can lead to security holes when
 				// user-controlled strings are rendered into JSON
 				// and served to some browsers.
-				e.WriteString(`\u00`)
+				e.WriteString(`u00`)
 				e.WriteByte(hex[b>>4])
 				e.WriteByte(hex[b&0xF])
 			}
@@ -968,18 +967,15 @@ func (e *encodeState) stringBytes(s []byte, escapeHTML bool) {
 			if start < i {
 				e.Write(s[start:i])
 			}
+			e.WriteByte('\\')
 			switch b {
 			case '\\', '"':
-				e.WriteByte('\\')
 				e.WriteByte(b)
 			case '\n':
-				e.WriteByte('\\')
 				e.WriteByte('n')
 			case '\r':
-				e.WriteByte('\\')
 				e.WriteByte('r')
 			case '\t':
-				e.WriteByte('\\')
 				e.WriteByte('t')
 			default:
 				// This encodes bytes < 0x20 except for \t, \n and \r.
@@ -987,7 +983,7 @@ func (e *encodeState) stringBytes(s []byte, escapeHTML bool) {
 				// because they can lead to security holes when
 				// user-controlled strings are rendered into JSON
 				// and served to some browsers.
-				e.WriteString(`\u00`)
+				e.WriteString(`u00`)
 				e.WriteByte(hex[b>>4])
 				e.WriteByte(hex[b&0xF])
 			}
@@ -1036,17 +1032,16 @@ type field struct {
 	nameBytes []byte                 // []byte(name)
 	equalFold func(s, t []byte) bool // bytes.EqualFold or equivalent
 
+	nameNonEsc  string // `"` + name + `":`
+	nameEscHTML string // `"` + HTMLEscape(name) + `":`
+
 	tag       bool
 	index     []int
 	typ       reflect.Type
 	omitEmpty bool
 	quoted    bool
-}
 
-func fillField(f field) field {
-	f.nameBytes = []byte(f.name)
-	f.equalFold = foldFunc(f.nameBytes)
-	return f
+	encoder encoderFunc
 }
 
 // byIndex sorts field by index sequence.
@@ -1086,6 +1081,9 @@ func typeFields(t reflect.Type) []field {
 	// Fields found.
 	var fields []field
 
+	// Buffer to run HTMLEscape on field names.
+	var nameEscBuf bytes.Buffer
+
 	for len(next) > 0 {
 		current, next = next, current[:0]
 		count, nextCount = nextCount, map[reflect.Type]int{}
@@ -1152,14 +1150,26 @@ func typeFields(t reflect.Type) []field {
 					if name == "" {
 						name = sf.Name
 					}
-					fields = append(fields, fillField(field{
+					field := field{
 						name:      name,
 						tag:       tagged,
 						index:     index,
 						typ:       ft,
 						omitEmpty: opts.Contains("omitempty"),
 						quoted:    quoted,
-					}))
+					}
+					field.nameBytes = []byte(field.name)
+					field.equalFold = foldFunc(field.nameBytes)
+
+					// Build nameEscHTML and nameNonEsc ahead of time.
+					nameEscBuf.Reset()
+					nameEscBuf.WriteString(`"`)
+					HTMLEscape(&nameEscBuf, field.nameBytes)
+					nameEscBuf.WriteString(`":`)
+					field.nameEscHTML = nameEscBuf.String()
+					field.nameNonEsc = `"` + field.name + `":`
+
+					fields = append(fields, field)
 					if count[f.typ] > 1 {
 						// If there were multiple instances, add a second,
 						// so that the annihilation code will see a duplicate.
@@ -1173,7 +1183,7 @@ func typeFields(t reflect.Type) []field {
 				// Record new anonymous struct to explore in next round.
 				nextCount[ft]++
 				if nextCount[ft] == 1 {
-					next = append(next, fillField(field{name: ft.Name(), index: index, typ: ft}))
+					next = append(next, field{name: ft.Name(), index: index, typ: ft})
 				}
 			}
 		}
@@ -1227,6 +1237,10 @@ func typeFields(t reflect.Type) []field {
 	fields = out
 	sort.Sort(byIndex(fields))
 
+	for i := range fields {
+		f := &fields[i]
+		f.encoder = typeEncoder(typeByIndex(t, f.index))
+	}
 	return fields
 }
 
diff --git a/libgo/go/encoding/json/encode_test.go b/libgo/go/encoding/json/encode_test.go
index b90483c..cd5eadf 100644
--- a/libgo/go/encoding/json/encode_test.go
+++ b/libgo/go/encoding/json/encode_test.go
@@ -405,6 +405,19 @@ func TestAnonymousFields(t *testing.T) {
 			return S{s1{1, 2, s2{3, 4}}, 6}
 		},
 		want: `{"MyInt1":1,"MyInt2":3}`,
+	}, {
+		// If an anonymous struct pointer field is nil, we should ignore
+		// the embedded fields behind it. Not properly doing so may
+		// result in the wrong output or reflect panics.
+		label: "EmbeddedFieldBehindNilPointer",
+		makeInput: func() interface{} {
+			type (
+				S2 struct{ Field string }
+				S  struct{ *S2 }
+			)
+			return S{}
+		},
+		want: `{}`,
 	}}
 
 	for _, tt := range tests {
@@ -995,3 +1008,18 @@ func TestMarshalPanic(t *testing.T) {
 	Marshal(&marshalPanic{})
 	t.Error("Marshal should have panicked")
 }
+
+func TestMarshalUncommonFieldNames(t *testing.T) {
+	v := struct {
+		A0, À, Aβ int
+	}{}
+	b, err := Marshal(v)
+	if err != nil {
+		t.Fatal("Marshal:", err)
+	}
+	want := `{"A0":0,"À":0,"Aβ":0}`
+	got := string(b)
+	if got != want {
+		t.Fatalf("Marshal: got %s want %s", got, want)
+	}
+}
diff --git a/libgo/go/encoding/json/example_text_marshaling_test.go b/libgo/go/encoding/json/example_text_marshaling_test.go
new file mode 100644
index 0000000..a8a3f83
--- /dev/null
+++ b/libgo/go/encoding/json/example_text_marshaling_test.go
@@ -0,0 +1,69 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package json_test
+
+import (
+	"encoding/json"
+	"fmt"
+	"log"
+	"strings"
+)
+
+type Size int
+
+const (
+	Unrecognized Size = iota
+	Small
+	Large
+)
+
+func (s *Size) UnmarshalText(text []byte) error {
+	switch strings.ToLower(string(text)) {
+	default:
+		*s = Unrecognized
+	case "small":
+		*s = Small
+	case "large":
+		*s = Large
+	}
+	return nil
+}
+
+func (s Size) MarshalText() ([]byte, error) {
+	var name string
+	switch s {
+	default:
+		name = "unrecognized"
+	case Small:
+		name = "small"
+	case Large:
+		name = "large"
+	}
+	return []byte(name), nil
+}
+
+func Example_textMarshalJSON() {
+	blob := `["small","regular","large","unrecognized","small","normal","small","large"]`
+	var inventory []Size
+	if err := json.Unmarshal([]byte(blob), &inventory); err != nil {
+		log.Fatal(err)
+	}
+
+	counts := make(map[Size]int)
+	for _, size := range inventory {
+		counts[size] += 1
+	}
+
+	fmt.Printf("Inventory Counts:\n* Small:        %d\n* Large:        %d\n* Unrecognized: %d\n",
+		counts[Small], counts[Large], counts[Unrecognized])
+
+	// Output:
+	// Inventory Counts:
+	// * Small:        3
+	// * Large:        2
+	// * Unrecognized: 3
+}
diff --git a/libgo/go/encoding/json/scanner.go b/libgo/go/encoding/json/scanner.go
index 9e6d482..8857224 100644
--- a/libgo/go/encoding/json/scanner.go
+++ b/libgo/go/encoding/json/scanner.go
@@ -289,7 +289,7 @@ func stateEndValue(s *scanner, c byte) int {
 // such as after reading `{}` or `[1,2,3]`.
 // Only space characters should be seen now.
 func stateEndTop(s *scanner, c byte) int {
-	if c != ' ' && c != '\t' && c != '\r' && c != '\n' {
+	if !isSpace(c) {
 		// Complain about non-space byte on next call.
 		s.error(c, "after top-level value")
 	}
diff --git a/libgo/go/encoding/json/stream.go b/libgo/go/encoding/json/stream.go
index 75a4270..7d5137f 100644
--- a/libgo/go/encoding/json/stream.go
+++ b/libgo/go/encoding/json/stream.go
@@ -96,19 +96,19 @@ Input:
 		// Look in the buffer for a new value.
 		for i, c := range dec.buf[scanp:] {
 			dec.scan.bytes++
-			v := dec.scan.step(&dec.scan, c)
-			if v == scanEnd {
+			switch dec.scan.step(&dec.scan, c) {
+			case scanEnd:
 				scanp += i
 				break Input
-			}
-			// scanEnd is delayed one byte.
-			// We might block trying to get that byte from src,
-			// so instead invent a space byte.
-			if (v == scanEndObject || v == scanEndArray) && dec.scan.step(&dec.scan, ' ') == scanEnd {
-				scanp += i + 1
-				break Input
-			}
-			if v == scanError {
+			case scanEndObject, scanEndArray:
+				// scanEnd is delayed one byte.
+				// We might block trying to get that byte from src,
+				// so instead invent a space byte.
+				if stateEndValue(&dec.scan, ' ') == scanEnd {
+					scanp += i + 1
+					break Input
+				}
+			case scanError:
 				dec.err = dec.scan.err
 				return 0, dec.scan.err
 			}
@@ -471,7 +471,7 @@ func (dec *Decoder) tokenError(c byte) (Token, error) {
 	case tokenObjectComma:
 		context = " after object key:value pair"
 	}
-	return nil, &SyntaxError{"invalid character " + quoteChar(c) + " " + context, dec.offset()}
+	return nil, &SyntaxError{"invalid character " + quoteChar(c) + context, dec.offset()}
 }
 
 // More reports whether there is another element in the
diff --git a/libgo/go/encoding/json/stream_test.go b/libgo/go/encoding/json/stream_test.go
index 83c01d1..aaf32e0 100644
--- a/libgo/go/encoding/json/stream_test.go
+++ b/libgo/go/encoding/json/stream_test.go
@@ -93,6 +93,10 @@ func TestEncoderIndent(t *testing.T) {
 func TestEncoderSetEscapeHTML(t *testing.T) {
 	var c C
 	var ct CText
+	var tagStruct struct {
+		Valid   int `json:"<>&#! "`
+		Invalid int `json:"\\"`
+	}
 	for _, tt := range []struct {
 		name       string
 		v          interface{}
@@ -102,6 +106,11 @@ func TestEncoderSetEscapeHTML(t *testing.T) {
 		{"c", c, `"\u003c\u0026\u003e"`, `"<&>"`},
 		{"ct", ct, `"\"\u003c\u0026\u003e\""`, `"\"<&>\""`},
 		{`"<&>"`, "<&>", `"\u003c\u0026\u003e"`, `"<&>"`},
+		{
+			"tagStruct", tagStruct,
+			`{"\u003c\u003e\u0026#! ":0,"Invalid":0}`,
+			`{"<>&#! ":0,"Invalid":0}`,
+		},
 	} {
 		var buf bytes.Buffer
 		enc := NewEncoder(&buf)
@@ -192,10 +201,9 @@ func nlines(s string, n int) string {
 }
 
 func TestRawMessage(t *testing.T) {
-	// TODO(rsc): Should not need the * in *RawMessage
 	var data struct {
 		X  float64
-		Id *RawMessage
+		Id RawMessage
 		Y  float32
 	}
 	const raw = `["\u0056",null]`
@@ -204,8 +212,8 @@ func TestRawMessage(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Unmarshal: %v", err)
 	}
-	if string([]byte(*data.Id)) != raw {
-		t.Fatalf("Raw mismatch: have %#q want %#q", []byte(*data.Id), raw)
+	if string([]byte(data.Id)) != raw {
+		t.Fatalf("Raw mismatch: have %#q want %#q", []byte(data.Id), raw)
 	}
 	b, err := Marshal(&data)
 	if err != nil {
@@ -217,20 +225,22 @@ func TestRawMessage(t *testing.T) {
 }
 
 func TestNullRawMessage(t *testing.T) {
-	// TODO(rsc): Should not need the * in *RawMessage
 	var data struct {
-		X  float64
-		Id *RawMessage
-		Y  float32
+		X     float64
+		Id    RawMessage
+		IdPtr *RawMessage
+		Y     float32
 	}
-	data.Id = new(RawMessage)
-	const msg = `{"X":0.1,"Id":null,"Y":0.2}`
+	const msg = `{"X":0.1,"Id":null,"IdPtr":null,"Y":0.2}`
 	err := Unmarshal([]byte(msg), &data)
 	if err != nil {
 		t.Fatalf("Unmarshal: %v", err)
 	}
-	if data.Id != nil {
-		t.Fatalf("Raw mismatch: have non-nil, want nil")
+	if want, got := "null", string(data.Id); want != got {
+		t.Fatalf("Raw mismatch: have %q, want %q", got, want)
+	}
+	if data.IdPtr != nil {
+		t.Fatalf("Raw pointer mismatch: have non-nil, want nil")
 	}
 	b, err := Marshal(&data)
 	if err != nil {
diff --git a/libgo/go/encoding/pem/pem_test.go b/libgo/go/encoding/pem/pem_test.go
index 6a17516..204611b 100644
--- a/libgo/go/encoding/pem/pem_test.go
+++ b/libgo/go/encoding/pem/pem_test.go
@@ -26,6 +26,10 @@ var getLineTests = []GetLineTest{
 	{"abc\r\nd", "abc", "d"},
 	{"\nabc", "", "abc"},
 	{"\r\nabc", "", "abc"},
+	{"abc\t \nd", "abc", "d"},
+	{"\t abc\nd", "\t abc", "d"},
+	{"abc\n\t d", "abc", "\t d"},
+	{"abc\nd\t ", "abc", "d\t "},
 }
 
 func TestGetLine(t *testing.T) {
@@ -213,7 +217,9 @@ func TestFuzz(t *testing.T) {
 	}
 
 	testRoundtrip := func(block Block) bool {
-		if isBad(block.Type) {
+		// Reject bad Type
+		// Type with colons will proceed as key/val pair and cause an error.
+		if isBad(block.Type) || strings.Contains(block.Type, ":") {
 			return true
 		}
 		for key, val := range block.Headers {
diff --git a/libgo/go/encoding/xml/example_marshaling_test.go b/libgo/go/encoding/xml/example_marshaling_test.go
new file mode 100644
index 0000000..04d3470
--- /dev/null
+++ b/libgo/go/encoding/xml/example_marshaling_test.go
@@ -0,0 +1,86 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package xml_test
+
+import (
+	"encoding/xml"
+	"fmt"
+	"log"
+	"strings"
+)
+
+type Animal int
+
+const (
+	Unknown Animal = iota
+	Gopher
+	Zebra
+)
+
+func (a *Animal) UnmarshalXML(d *xml.Decoder, start xml.StartElement) error {
+	var s string
+	if err := d.DecodeElement(&s, &start); err != nil {
+		return err
+	}
+	switch strings.ToLower(s) {
+	default:
+		*a = Unknown
+	case "gopher":
+		*a = Gopher
+	case "zebra":
+		*a = Zebra
+	}
+
+	return nil
+}
+
+func (a Animal) MarshalXML(e *xml.Encoder, start xml.StartElement) error {
+	var s string
+	switch a {
+	default:
+		s = "unknown"
+	case Gopher:
+		s = "gopher"
+	case Zebra:
+		s = "zebra"
+	}
+	return e.EncodeElement(s, start)
+}
+
+func Example_customMarshalXML() {
+	blob := `
+	<animals>
+		<animal>gopher</animal>
+		<animal>armadillo</animal>
+		<animal>zebra</animal>
+		<animal>unknown</animal>
+		<animal>gopher</animal>
+		<animal>bee</animal>
+		<animal>gopher</animal>
+		<animal>zebra</animal>
+	</animals>`
+	var zoo struct {
+		Animals []Animal `xml:"animal"`
+	}
+	if err := xml.Unmarshal([]byte(blob), &zoo); err != nil {
+		log.Fatal(err)
+	}
+
+	census := make(map[Animal]int)
+	for _, animal := range zoo.Animals {
+		census[animal] += 1
+	}
+
+	fmt.Printf("Zoo Census:\n* Gophers: %d\n* Zebras:  %d\n* Unknown: %d\n",
+		census[Gopher], census[Zebra], census[Unknown])
+
+	// Output:
+	// Zoo Census:
+	// * Gophers: 3
+	// * Zebras:  2
+	// * Unknown: 3
+}
diff --git a/libgo/go/encoding/xml/example_text_marshaling_test.go b/libgo/go/encoding/xml/example_text_marshaling_test.go
new file mode 100644
index 0000000..8d1f332
--- /dev/null
+++ b/libgo/go/encoding/xml/example_text_marshaling_test.go
@@ -0,0 +1,81 @@
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build ignore
+
+package xml_test
+
+import (
+	"encoding/xml"
+	"fmt"
+	"log"
+	"strings"
+)
+
+type Size int
+
+const (
+	Unrecognized Size = iota
+	Small
+	Large
+)
+
+func (s *Size) UnmarshalText(text []byte) error {
+	switch strings.ToLower(string(text)) {
+	default:
+		*s = Unrecognized
+	case "small":
+		*s = Small
+	case "large":
+		*s = Large
+	}
+	return nil
+}
+
+func (s Size) MarshalText() ([]byte, error) {
+	var name string
+	switch s {
+	default:
+		name = "unrecognized"
+	case Small:
+		name = "small"
+	case Large:
+		name = "large"
+	}
+	return []byte(name), nil
+}
+
+func Example_textMarshalXML() {
+	blob := `
+	<sizes>
+		<size>small</size>
+		<size>regular</size>
+		<size>large</size>
+		<size>unrecognized</size>
+		<size>small</size>
+		<size>normal</size>
+		<size>small</size>
+		<size>large</size>
+	</sizes>`
+	var inventory struct {
+		Sizes []Size `xml:"size"`
+	}
+	if err := xml.Unmarshal([]byte(blob), &inventory); err != nil {
+		log.Fatal(err)
+	}
+
+	counts := make(map[Size]int)
+	for _, size := range inventory.Sizes {
+		counts[size] += 1
+	}
+
+	fmt.Printf("Inventory Counts:\n* Small:        %d\n* Large:        %d\n* Unrecognized: %d\n",
+		counts[Small], counts[Large], counts[Unrecognized])
+
+	// Output:
+	// Inventory Counts:
+	// * Small:        3
+	// * Large:        2
+	// * Unrecognized: 3
+}
diff --git a/libgo/go/encoding/xml/marshal.go b/libgo/go/encoding/xml/marshal.go
index d393d06..add5ece 100644
--- a/libgo/go/encoding/xml/marshal.go
+++ b/libgo/go/encoding/xml/marshal.go
@@ -61,6 +61,10 @@ const (
 //       string of length zero.
 //     - an anonymous struct field is handled as if the fields of its
 //       value were part of the outer struct.
+//     - a field implementing Marshaler is written by calling its MarshalXML
+//       method.
+//     - a field implementing encoding.TextMarshaler is written by encoding the
+//       result of its MarshalText method as text.
 //
 // If a field uses a tag "a>b>c", then the element c will be nested inside
 // parent elements a and b. Fields that appear next to each other that name
diff --git a/libgo/go/encoding/xml/read.go b/libgo/go/encoding/xml/read.go
index 36c7ba6..12102bc 100644
--- a/libgo/go/encoding/xml/read.go
+++ b/libgo/go/encoding/xml/read.go
@@ -92,6 +92,11 @@ import (
 //
 //   * A struct field with tag "-" is never unmarshaled into.
 //
+// If Unmarshal encounters a field type that implements the Unmarshaler
+// interface, Unmarshal calls its UnmarshalXML method to produce the value from
+// the XML element.  Otherwise, if the value implements
+// encoding.TextUnmarshaler, Unmarshal calls that value's UnmarshalText method.
+//
 // Unmarshal maps an XML element to a string or []byte by saving the
 // concatenation of that element's character data in the string or
 // []byte. The saved []byte is never nil.