libgo: update to go1.7rc3

    
    Reviewed-on: https://go-review.googlesource.com/25150

From-SVN: r238662

11 files changed, 129 insertions, 74 deletions

diff --git a/libgo/go/encoding/gob/codec_test.go b/libgo/go/encoding/gob/codec_test.go
index 8efcdc7..d4002cb 100644
--- a/libgo/go/encoding/gob/codec_test.go
+++ b/libgo/go/encoding/gob/codec_test.go
@@ -970,7 +970,7 @@ func TestBadRecursiveType(t *testing.T) {
 	err := NewEncoder(b).Encode(&rec)
 	if err == nil {
 		t.Error("expected error; got none")
-	} else if strings.Index(err.Error(), "recursive") < 0 {
+	} else if !strings.Contains(err.Error(), "recursive") {
 		t.Error("expected recursive type error; got", err)
 	}
 	// Can't test decode easily because we can't encode one, so we can't pass one to a Decoder.
@@ -1253,7 +1253,7 @@ func TestIgnoreInterface(t *testing.T) {
 	if item2.I != item1.I {
 		t.Error("normal int did not decode correctly")
 	}
-	if item2.F != item2.F {
+	if item2.F != item1.F {
 		t.Error("normal float did not decode correctly")
 	}
 }
@@ -1280,7 +1280,7 @@ func TestUnexportedFields(t *testing.T) {
 	if err != nil {
 		t.Fatal("decode error:", err)
 	}
-	if u0.A != u0.A || u0.B != u1.B || u0.D != u1.D {
+	if u0.A != u1.A || u0.B != u1.B || u0.D != u1.D {
 		t.Errorf("u1->u0: expected %v; got %v", u0, u1)
 	}
 	if u1.c != 1234. {
diff --git a/libgo/go/encoding/gob/debug.go b/libgo/go/encoding/gob/debug.go
index 536bbdb..d69d36f 100644
--- a/libgo/go/encoding/gob/debug.go
+++ b/libgo/go/encoding/gob/debug.go
@@ -7,7 +7,7 @@
 
 package gob
 
-// This file is not normally included in the gob package.  Used only for debugging the package itself.
+// This file is not normally included in the gob package. Used only for debugging the package itself.
 // Except for reading uints, it is an implementation of a reader that is independent of
 // the one implemented by Decoder.
 // To enable the Debug function, delete the +build ignore line above and do
@@ -241,7 +241,7 @@ func (deb *debugger) delimitedMessage(indent tab) bool {
 // loadBlock preps us to read a message
 // of the length specified next in the input. It returns
 // the length of the block. The argument tells whether
-// an EOF is acceptable now.  If it is and one is found,
+// an EOF is acceptable now. If it is and one is found,
 // the return value is negative.
 func (deb *debugger) loadBlock(eofOK bool) int {
 	n64, w, err := decodeUintReader(deb.r, deb.tmp) // deb.uint64 will error at EOF
@@ -339,7 +339,7 @@ func (deb *debugger) string() string {
 	return string(b)
 }
 
-// delta returns the field delta at the input point.  The expect argument,
+// delta returns the field delta at the input point. The expect argument,
 // if non-negative, identifies what the value should be.
 func (deb *debugger) delta(expect int) int {
 	delta := int(deb.uint64())
diff --git a/libgo/go/encoding/gob/decode.go b/libgo/go/encoding/gob/decode.go
index 3b0dca8..9645dc5 100644
--- a/libgo/go/encoding/gob/decode.go
+++ b/libgo/go/encoding/gob/decode.go
@@ -216,10 +216,10 @@ func ignoreTwoUints(i *decInstr, state *decoderState, v reflect.Value) {
 }
 
 // Since the encoder writes no zeros, if we arrive at a decoder we have
-// a value to extract and store.  The field number has already been read
+// a value to extract and store. The field number has already been read
 // (it's how we knew to call this decoder).
 // Each decoder is responsible for handling any indirections associated
-// with the data structure.  If any pointer so reached is nil, allocation must
+// with the data structure. If any pointer so reached is nil, allocation must
 // be done.
 
 // decAlloc takes a value and returns a settable value that can
@@ -308,9 +308,9 @@ func decUint64(i *decInstr, state *decoderState, value reflect.Value) {
 }
 
 // Floating-point numbers are transmitted as uint64s holding the bits
-// of the underlying representation.  They are sent byte-reversed, with
+// of the underlying representation. They are sent byte-reversed, with
 // the exponent end coming out first, so integer floating point numbers
-// (for example) transmit more compactly.  This routine does the
+// (for example) transmit more compactly. This routine does the
 // unswizzling.
 func float64FromBits(u uint64) float64 {
 	var v uint64
@@ -332,7 +332,7 @@ func float32FromBits(u uint64, ovfl error) float64 {
 	if av < 0 {
 		av = -av
 	}
-	// +Inf is OK in both 32- and 64-bit floats.  Underflow is always OK.
+	// +Inf is OK in both 32- and 64-bit floats. Underflow is always OK.
 	if math.MaxFloat32 < av && av <= math.MaxFloat64 {
 		error_(ovfl)
 	}
@@ -421,7 +421,7 @@ func ignoreUint8Array(i *decInstr, state *decoderState, value reflect.Value) {
 // Execution engine
 
 // The encoder engine is an array of instructions indexed by field number of the incoming
-// decoder.  It is executed with random access according to field number.
+// decoder. It is executed with random access according to field number.
 type decEngine struct {
 	instr    []decInstr
 	numInstr int // the number of active instructions
@@ -442,7 +442,7 @@ func (dec *Decoder) decodeSingle(engine *decEngine, ut *userTypeInfo, value refl
 }
 
 // decodeStruct decodes a top-level struct and stores it in value.
-// Indir is for the value, not the type.  At the time of the call it may
+// Indir is for the value, not the type. At the time of the call it may
 // differ from ut.indir, which was computed when the engine was built.
 // This state cannot arise for decodeSingle, which is called directly
 // from the user's value, not from the innards of an engine.
@@ -536,7 +536,7 @@ func (dec *Decoder) decodeArrayHelper(state *decoderState, value reflect.Value,
 }
 
 // decodeArray decodes an array and stores it in value.
-// The length is an unsigned integer preceding the elements.  Even though the length is redundant
+// The length is an unsigned integer preceding the elements. Even though the length is redundant
 // (it's part of the type), it's a useful check and is included in the encoding.
 func (dec *Decoder) decodeArray(atyp reflect.Type, state *decoderState, value reflect.Value, elemOp decOp, length int, ovfl error, helper decHelper) {
 	if n := state.decodeUint(); n != uint64(length) {
@@ -645,10 +645,10 @@ func (dec *Decoder) decodeInterface(ityp reflect.Type, state *decoderState, valu
 		errorf("invalid type name length %d: exceeds input size", nr)
 	}
 	n := int(nr)
-	name := string(state.b.Bytes()[:n])
+	name := state.b.Bytes()[:n]
 	state.b.Drop(n)
 	// Allocate the destination interface value.
-	if name == "" {
+	if len(name) == 0 {
 		// Copy the nil interface value to the target.
 		value.Set(reflect.Zero(value.Type()))
 		return
@@ -658,7 +658,7 @@ func (dec *Decoder) decodeInterface(ityp reflect.Type, state *decoderState, valu
 	}
 	// The concrete type must be registered.
 	registerLock.RLock()
-	typ, ok := nameToConcreteType[name]
+	typ, ok := nameToConcreteType[string(name)]
 	registerLock.RUnlock()
 	if !ok {
 		errorf("name not registered for interface: %q", name)
@@ -1075,7 +1075,7 @@ func (dec *Decoder) compileIgnoreSingle(remoteId typeId) (engine *decEngine, err
 	return
 }
 
-// compileDec compiles the decoder engine for a value.  If the value is not a struct,
+// compileDec compiles the decoder engine for a value. If the value is not a struct,
 // it calls out to compileSingle.
 func (dec *Decoder) compileDec(remoteId typeId, ut *userTypeInfo) (engine *decEngine, err error) {
 	defer catchError(&err)
diff --git a/libgo/go/encoding/gob/decoder.go b/libgo/go/encoding/gob/decoder.go
index c453e9b..c182941 100644
--- a/libgo/go/encoding/gob/decoder.go
+++ b/libgo/go/encoding/gob/decoder.go
@@ -130,9 +130,9 @@ func (dec *Decoder) nextUint() uint64 {
 // decodeTypeSequence parses:
 // TypeSequence
 //	(TypeDefinition DelimitedTypeDefinition*)?
-// and returns the type id of the next value.  It returns -1 at
+// and returns the type id of the next value. It returns -1 at
 // EOF.  Upon return, the remainder of dec.buf is the value to be
-// decoded.  If this is an interface value, it can be ignored by
+// decoded. If this is an interface value, it can be ignored by
 // resetting that buffer.
 func (dec *Decoder) decodeTypeSequence(isInterface bool) typeId {
 	for dec.err == nil {
@@ -150,7 +150,7 @@ func (dec *Decoder) decodeTypeSequence(isInterface bool) typeId {
 		// Type definition for (-id) follows.
 		dec.recvType(-id)
 		// When decoding an interface, after a type there may be a
-		// DelimitedValue still in the buffer.  Skip its count.
+		// DelimitedValue still in the buffer. Skip its count.
 		// (Alternatively, the buffer is empty and the byte count
 		// will be absorbed by recvMessage.)
 		if dec.buf.Len() > 0 {
@@ -177,7 +177,7 @@ func (dec *Decoder) Decode(e interface{}) error {
 	}
 	value := reflect.ValueOf(e)
 	// If e represents a value as opposed to a pointer, the answer won't
-	// get back to the caller.  Make sure it's a pointer.
+	// get back to the caller. Make sure it's a pointer.
 	if value.Type().Kind() != reflect.Ptr {
 		dec.err = errors.New("gob: attempt to decode into a non-pointer")
 		return dec.err
@@ -187,7 +187,7 @@ func (dec *Decoder) Decode(e interface{}) error {
 
 // DecodeValue reads the next value from the input stream.
 // If v is the zero reflect.Value (v.Kind() == Invalid), DecodeValue discards the value.
-// Otherwise, it stores the value into v.  In that case, v must represent
+// Otherwise, it stores the value into v. In that case, v must represent
 // a non-nil pointer to data or be an assignable reflect.Value (v.CanSet())
 // If the input is at EOF, DecodeValue returns io.EOF and
 // does not modify v.
diff --git a/libgo/go/encoding/gob/doc.go b/libgo/go/encoding/gob/doc.go
index cf878f4..1536574 100644
--- a/libgo/go/encoding/gob/doc.go
+++ b/libgo/go/encoding/gob/doc.go
@@ -17,7 +17,8 @@ Basics
 A stream of gobs is self-describing.  Each data item in the stream is preceded by
 a specification of its type, expressed in terms of a small set of predefined
 types.  Pointers are not transmitted, but the things they point to are
-transmitted; that is, the values are flattened.  Recursive types work fine, but
+transmitted; that is, the values are flattened. Nil pointers are not permitted,
+as they have no value. Recursive types work fine, but
 recursive values (data with cycles) are problematic.  This may change.
 
 To use gobs, create an Encoder and present it with a series of data items as
@@ -254,6 +255,12 @@ In summary, a gob stream looks like
 where * signifies zero or more repetitions and the type id of a value must
 be predefined or be defined before the value in the stream.
 
+Compatibility: Any future changes to the package will endeavor to maintain
+compatibility with streams encoded using previous versions.  That is, any released
+version of this package should be able to decode data written with any previously
+released version, subject to issues such as security fixes. See the Go compatibility
+document for background: https://golang.org/doc/go1compat
+
 See "Gobs of data" for a design discussion of the gob wire format:
 https://blog.golang.org/gobs-of-data
 */
diff --git a/libgo/go/encoding/gob/encode.go b/libgo/go/encoding/gob/encode.go
index 96052ef..50cd6ad 100644
--- a/libgo/go/encoding/gob/encode.go
+++ b/libgo/go/encoding/gob/encode.go
@@ -96,7 +96,7 @@ func (enc *Encoder) freeEncoderState(e *encoderState) {
 	enc.freeList = e
 }
 
-// Unsigned integers have a two-state encoding.  If the number is less
+// Unsigned integers have a two-state encoding. If the number is less
 // than 128 (0 through 0x7F), its value is written directly.
 // Otherwise the value is written in big-endian byte order preceded
 // by the byte length, negated.
@@ -127,7 +127,7 @@ func (state *encoderState) encodeInt(i int64) {
 	} else {
 		x = uint64(i << 1)
 	}
-	state.encodeUint(uint64(x))
+	state.encodeUint(x)
 }
 
 // encOp is the signature of an encoding operator for a given type.
@@ -152,8 +152,8 @@ func (state *encoderState) update(instr *encInstr) {
 
 // Each encoder for a composite is responsible for handling any
 // indirections associated with the elements of the data structure.
-// If any pointer so reached is nil, no bytes are written.  If the
-// data item is zero, no bytes are written.  Single values - ints,
+// If any pointer so reached is nil, no bytes are written. If the
+// data item is zero, no bytes are written. Single values - ints,
 // strings etc. - are indirected before calling their encoders.
 // Otherwise, the output (for a scalar) is the field number, as an
 // encoded integer, followed by the field data in its appropriate
@@ -203,9 +203,9 @@ func encUint(i *encInstr, state *encoderState, v reflect.Value) {
 
 // floatBits returns a uint64 holding the bits of a floating-point number.
 // Floating-point numbers are transmitted as uint64s holding the bits
-// of the underlying representation.  They are sent byte-reversed, with
+// of the underlying representation. They are sent byte-reversed, with
 // the exponent end coming out first, so integer floating point numbers
-// (for example) transmit more compactly.  This routine does the
+// (for example) transmit more compactly. This routine does the
 // swizzling.
 func floatBits(f float64) uint64 {
 	u := math.Float64bits(f)
@@ -272,7 +272,7 @@ func encStructTerminator(i *encInstr, state *encoderState, v reflect.Value) {
 // Execution engine
 
 // encEngine an array of instructions indexed by field number of the encoding
-// data, typically a struct.  It is executed top to bottom, walking the struct.
+// data, typically a struct. It is executed top to bottom, walking the struct.
 type encEngine struct {
 	instr []encInstr
 }
@@ -297,7 +297,7 @@ func (enc *Encoder) encodeSingle(b *encBuffer, engine *encEngine, value reflect.
 	defer enc.freeEncoderState(state)
 	state.fieldnum = singletonField
 	// There is no surrounding struct to frame the transmission, so we must
-	// generate data even if the item is zero.  To do this, set sendZero.
+	// generate data even if the item is zero. To do this, set sendZero.
 	state.sendZero = true
 	instr := &engine.instr[singletonField]
 	if instr.indir > 0 {
@@ -386,7 +386,7 @@ func (enc *Encoder) encodeMap(b *encBuffer, mv reflect.Value, keyOp, elemOp encO
 // encodeInterface encodes the interface value iv.
 // To send an interface, we send a string identifying the concrete type, followed
 // by the type identifier (which might require defining that type right now), followed
-// by the concrete value.  A nil value gets sent as the empty string for the name,
+// by the concrete value. A nil value gets sent as the empty string for the name,
 // followed by no value.
 func (enc *Encoder) encodeInterface(b *encBuffer, iv reflect.Value) {
 	// Gobs can encode nil interface values but not typed interface
@@ -417,7 +417,7 @@ func (enc *Encoder) encodeInterface(b *encBuffer, iv reflect.Value) {
 	enc.sendTypeDescriptor(enc.writer(), state, ut)
 	// Send the type id.
 	enc.sendTypeId(state, ut)
-	// Encode the value into a new buffer.  Any nested type definitions
+	// Encode the value into a new buffer. Any nested type definitions
 	// should be written to b, before the encoded value.
 	enc.pushWriter(b)
 	data := encBufferPool.Get().(*encBuffer)
diff --git a/libgo/go/encoding/gob/encoder.go b/libgo/go/encoding/gob/encoder.go
index 62d0f42..d6c8fdd 100644
--- a/libgo/go/encoding/gob/encoder.go
+++ b/libgo/go/encoding/gob/encoder.go
@@ -170,6 +170,7 @@ func (enc *Encoder) sendType(w io.Writer, state *encoderState, origt reflect.Typ
 
 // Encode transmits the data item represented by the empty interface value,
 // guaranteeing that all necessary type information has been transmitted first.
+// Passing a nil pointer to Encoder will panic, as they cannot be transmitted by gob.
 func (enc *Encoder) Encode(e interface{}) error {
 	return enc.EncodeValue(reflect.ValueOf(e))
 }
@@ -191,7 +192,7 @@ func (enc *Encoder) sendTypeDescriptor(w io.Writer, state *encoderState, ut *use
 			return
 		}
 		// If the type info has still not been transmitted, it means we have
-		// a singleton basic type (int, []byte etc.) at top level.  We don't
+		// a singleton basic type (int, []byte etc.) at top level. We don't
 		// need to send the type info but we do need to update enc.sent.
 		if !sent {
 			info, err := getTypeInfo(ut)
@@ -212,9 +213,8 @@ func (enc *Encoder) sendTypeId(state *encoderState, ut *userTypeInfo) {
 
 // EncodeValue transmits the data item represented by the reflection value,
 // guaranteeing that all necessary type information has been transmitted first.
+// Passing a nil pointer to EncodeValue will panic, as they cannot be transmitted by gob.
 func (enc *Encoder) EncodeValue(value reflect.Value) error {
-	// Gobs contain values. They cannot represent nil pointers, which
-	// have no value to encode.
 	if value.Kind() == reflect.Ptr && value.IsNil() {
 		panic("gob: cannot encode nil pointer of type " + value.Type().String())
 	}
diff --git a/libgo/go/encoding/gob/encoder_test.go b/libgo/go/encoding/gob/encoder_test.go
index 570d796..22090a1 100644
--- a/libgo/go/encoding/gob/encoder_test.go
+++ b/libgo/go/encoding/gob/encoder_test.go
@@ -8,6 +8,7 @@ import (
 	"bytes"
 	"encoding/hex"
 	"fmt"
+	"io/ioutil"
 	"reflect"
 	"strings"
 	"testing"
@@ -280,7 +281,7 @@ func TestValueError(t *testing.T) {
 	}
 	t4p := &Type4{3}
 	var t4 Type4 // note: not a pointer.
-	if err := encAndDec(t4p, t4); err == nil || strings.Index(err.Error(), "pointer") < 0 {
+	if err := encAndDec(t4p, t4); err == nil || !strings.Contains(err.Error(), "pointer") {
 		t.Error("expected error about pointer; got", err)
 	}
 }
@@ -388,7 +389,7 @@ func TestSingletons(t *testing.T) {
 			t.Errorf("expected error decoding %v: %s", test.in, test.err)
 			continue
 		case err != nil && test.err != "":
-			if strings.Index(err.Error(), test.err) < 0 {
+			if !strings.Contains(err.Error(), test.err) {
 				t.Errorf("wrong error decoding %v: wanted %s, got %v", test.in, test.err, err)
 			}
 			continue
@@ -414,7 +415,7 @@ func TestStructNonStruct(t *testing.T) {
 	var ns NonStruct
 	if err := encAndDec(s, &ns); err == nil {
 		t.Error("should get error for struct/non-struct")
-	} else if strings.Index(err.Error(), "type") < 0 {
+	} else if !strings.Contains(err.Error(), "type") {
 		t.Error("for struct/non-struct expected type error; got", err)
 	}
 	// Now try the other way
@@ -424,7 +425,7 @@ func TestStructNonStruct(t *testing.T) {
 	}
 	if err := encAndDec(ns, &s); err == nil {
 		t.Error("should get error for non-struct/struct")
-	} else if strings.Index(err.Error(), "type") < 0 {
+	} else if !strings.Contains(err.Error(), "type") {
 		t.Error("for non-struct/struct expected type error; got", err)
 	}
 }
@@ -439,8 +440,8 @@ func (this *interfaceIndirectTestT) F() bool {
 	return true
 }
 
-// A version of a bug reported on golang-nuts.  Also tests top-level
-// slice of interfaces.  The issue was registering *T caused T to be
+// A version of a bug reported on golang-nuts. Also tests top-level
+// slice of interfaces. The issue was registering *T caused T to be
 // stored as the concrete type.
 func TestInterfaceIndirect(t *testing.T) {
 	Register(&interfaceIndirectTestT{})
@@ -463,7 +464,7 @@ func TestInterfaceIndirect(t *testing.T) {
 
 // Also, when the ignored object contains an interface value, it may define
 // types. Make sure that skipping the value still defines the types by using
-// the encoder/decoder pair to send a value afterwards.  If an interface
+// the encoder/decoder pair to send a value afterwards. If an interface
 // is sent, its type in the test is always NewType0, so this checks that the
 // encoder and decoder don't skew with respect to type definitions.
 
@@ -603,10 +604,6 @@ type Bug1Elem struct {
 
 type Bug1StructMap map[string]Bug1Elem
 
-func bug1EncDec(in Bug1StructMap, out *Bug1StructMap) error {
-	return nil
-}
-
 func TestMapBug1(t *testing.T) {
 	in := make(Bug1StructMap)
 	in["val1"] = Bug1Elem{"elem1", 1}
@@ -835,30 +832,81 @@ func TestPtrToMapOfMap(t *testing.T) {
 
 // A top-level nil pointer generates a panic with a helpful string-valued message.
 func TestTopLevelNilPointer(t *testing.T) {
-	errMsg := topLevelNilPanic(t)
-	if errMsg == "" {
+	var ip *int
+	encodeErr, panicErr := encodeAndRecover(ip)
+	if encodeErr != nil {
+		t.Fatal("error in encode:", encodeErr)
+	}
+	if panicErr == nil {
 		t.Fatal("top-level nil pointer did not panic")
 	}
+	errMsg := panicErr.Error()
 	if !strings.Contains(errMsg, "nil pointer") {
 		t.Fatal("expected nil pointer error, got:", errMsg)
 	}
 }
 
-func topLevelNilPanic(t *testing.T) (panicErr string) {
+func encodeAndRecover(value interface{}) (encodeErr, panicErr error) {
 	defer func() {
 		e := recover()
-		if err, ok := e.(string); ok {
-			panicErr = err
+		if e != nil {
+			switch err := e.(type) {
+			case error:
+				panicErr = err
+			default:
+				panicErr = fmt.Errorf("%v", err)
+			}
 		}
 	}()
-	var ip *int
-	buf := new(bytes.Buffer)
-	if err := NewEncoder(buf).Encode(ip); err != nil {
-		t.Fatal("error in encode:", err)
-	}
+
+	encodeErr = NewEncoder(ioutil.Discard).Encode(value)
 	return
 }
 
+func TestNilPointerPanics(t *testing.T) {
+	var (
+		nilStringPtr      *string
+		intMap            = make(map[int]int)
+		intMapPtr         = &intMap
+		nilIntMapPtr      *map[int]int
+		zero              int
+		nilBoolChannel    chan bool
+		nilBoolChannelPtr *chan bool
+		nilStringSlice    []string
+		stringSlice       = make([]string, 1)
+		nilStringSlicePtr *[]string
+	)
+
+	testCases := []struct {
+		value     interface{}
+		mustPanic bool
+	}{
+		{nilStringPtr, true},
+		{intMap, false},
+		{intMapPtr, false},
+		{nilIntMapPtr, true},
+		{zero, false},
+		{nilStringSlice, false},
+		{stringSlice, false},
+		{nilStringSlicePtr, true},
+		{nilBoolChannel, false},
+		{nilBoolChannelPtr, true},
+	}
+
+	for _, tt := range testCases {
+		_, panicErr := encodeAndRecover(tt.value)
+		if tt.mustPanic {
+			if panicErr == nil {
+				t.Errorf("expected panic with input %#v, did not panic", tt.value)
+			}
+			continue
+		}
+		if panicErr != nil {
+			t.Fatalf("expected no panic with input %#v, got panic=%v", tt.value, panicErr)
+		}
+	}
+}
+
 func TestNilPointerInsideInterface(t *testing.T) {
 	var ip *int
 	si := struct {
@@ -913,7 +961,7 @@ func TestMutipleEncodingsOfBadType(t *testing.T) {
 // There was an error check comparing the length of the input with the
 // length of the slice being decoded. It was wrong because the next
 // thing in the input might be a type definition, which would lead to
-// an incorrect length check.  This test reproduces the corner case.
+// an incorrect length check. This test reproduces the corner case.
 
 type Z struct {
 }
diff --git a/libgo/go/encoding/gob/error.go b/libgo/go/encoding/gob/error.go
index 92cc0c6..8b5265c 100644
--- a/libgo/go/encoding/gob/error.go
+++ b/libgo/go/encoding/gob/error.go
@@ -9,7 +9,7 @@ import "fmt"
 // Errors in decoding and encoding are handled using panic and recover.
 // Panics caused by user error (that is, everything except run-time panics
 // such as "index out of bounds" errors) do not leave the file that caused
-// them, but are instead turned into plain error returns.  Encoding and
+// them, but are instead turned into plain error returns. Encoding and
 // decoding functions and methods that do not return an error either use
 // panic to report an error or are guaranteed error-free.
 
@@ -30,7 +30,7 @@ func error_(err error) {
 }
 
 // catchError is meant to be used as a deferred function to turn a panic(gobError) into a
-// plain error.  It overwrites the error return of the function that deferred its call.
+// plain error. It overwrites the error return of the function that deferred its call.
 func catchError(err *error) {
 	if e := recover(); e != nil {
 		ge, ok := e.(gobError)
diff --git a/libgo/go/encoding/gob/gobencdec_test.go b/libgo/go/encoding/gob/gobencdec_test.go
index eb76b48..ecc91ee 100644
--- a/libgo/go/encoding/gob/gobencdec_test.go
+++ b/libgo/go/encoding/gob/gobencdec_test.go
@@ -376,7 +376,7 @@ func TestGobEncoderIndirectArrayField(t *testing.T) {
 }
 
 // As long as the fields have the same name and implement the
-// interface, we can cross-connect them.  Not sure it's useful
+// interface, we can cross-connect them. Not sure it's useful
 // and may even be bad but it works and it's hard to prevent
 // without exposing the contents of the object, which would
 // defeat the purpose.
@@ -434,7 +434,7 @@ func TestGobEncoderValueEncoder(t *testing.T) {
 }
 
 // Test that we can use a value then a pointer type of a GobEncoder
-// in the same encoded value.  Bug 4647.
+// in the same encoded value. Bug 4647.
 func TestGobEncoderValueThenPointer(t *testing.T) {
 	v := ValueGobber("forty-two")
 	w := ValueGobber("six-by-nine")
@@ -548,7 +548,7 @@ func TestGobEncoderFieldTypeError(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected decode error for mismatched fields (encoder to non-decoder)")
 	}
-	if strings.Index(err.Error(), "type") < 0 {
+	if !strings.Contains(err.Error(), "type") {
 		t.Fatal("expected type error; got", err)
 	}
 	// Non-encoder to GobDecoder: error
@@ -562,7 +562,7 @@ func TestGobEncoderFieldTypeError(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected decode error for mismatched fields (non-encoder to decoder)")
 	}
-	if strings.Index(err.Error(), "type") < 0 {
+	if !strings.Contains(err.Error(), "type") {
 		t.Fatal("expected type error; got", err)
 	}
 }
diff --git a/libgo/go/encoding/gob/type.go b/libgo/go/encoding/gob/type.go
index cf5cec0..c27f7e9 100644
--- a/libgo/go/encoding/gob/type.go
+++ b/libgo/go/encoding/gob/type.go
@@ -17,7 +17,7 @@ import (
 )
 
 // userTypeInfo stores the information associated with a type the user has handed
-// to the package.  It's computed once and stored in a map keyed by reflection
+// to the package. It's computed once and stored in a map keyed by reflection
 // type.
 type userTypeInfo struct {
 	user        reflect.Type // the type the user handed us
@@ -44,7 +44,7 @@ var (
 )
 
 // validType returns, and saves, the information associated with user-provided type rt.
-// If the user type is not valid, err will be non-nil.  To be used when the error handler
+// If the user type is not valid, err will be non-nil. To be used when the error handler
 // is not set up.
 func validUserType(rt reflect.Type) (ut *userTypeInfo, err error) {
 	userTypeLock.RLock()
@@ -64,7 +64,7 @@ func validUserType(rt reflect.Type) (ut *userTypeInfo, err error) {
 	ut.base = rt
 	ut.user = rt
 	// A type that is just a cycle of pointers (such as type T *T) cannot
-	// be represented in gobs, which need some concrete data.  We use a
+	// be represented in gobs, which need some concrete data. We use a
 	// cycle detection algorithm from Knuth, Vol 2, Section 3.1, Ex 6,
 	// pp 539-540.  As we step through indirections, run another type at
 	// half speed. If they meet up, there's a cycle.
@@ -493,7 +493,7 @@ func newTypeObject(name string, ut *userTypeInfo, rt reflect.Type) (gobType, err
 		// For arrays, maps, and slices, we set the type id after the elements
 		// are constructed. This is to retain the order of type id allocation after
 		// a fix made to handle recursive types, which changed the order in
-		// which types are built.  Delaying the setting in this way preserves
+		// which types are built. Delaying the setting in this way preserves
 		// type ids while allowing recursive types to be described. Structs,
 		// done below, were already handling recursion correctly so they
 		// assign the top-level id before those of the field.
@@ -597,7 +597,7 @@ func getBaseType(name string, rt reflect.Type) (gobType, error) {
 
 // getType returns the Gob type describing the given reflect.Type.
 // Should be called only when handling GobEncoders/Decoders,
-// which may be pointers.  All other types are handled through the
+// which may be pointers. All other types are handled through the
 // base type, never a pointer.
 // typeLock must be held.
 func getType(name string, ut *userTypeInfo, rt reflect.Type) (gobType, error) {
@@ -642,7 +642,7 @@ func bootstrapType(name string, e interface{}, expect typeId) typeId {
 // For bootstrapping purposes, we assume that the recipient knows how
 // to decode a wireType; it is exactly the wireType struct here, interpreted
 // using the gob rules for sending a structure, except that we assume the
-// ids for wireType and structType etc. are known.  The relevant pieces
+// ids for wireType and structType etc. are known. The relevant pieces
 // are built in encode.go's init() function.
 // To maintain binary compatibility, if you extend this type, always put
 // the new fields last.
@@ -789,7 +789,7 @@ func mustGetTypeInfo(rt reflect.Type) *typeInfo {
 //
 // Note: Since gobs can be stored permanently, it is good design
 // to guarantee the encoding used by a GobEncoder is stable as the
-// software evolves.  For instance, it might make sense for GobEncode
+// software evolves. For instance, it might make sense for GobEncode
 // to include a version number in the encoding.
 type GobEncoder interface {
 	// GobEncode returns a byte slice representing the encoding of the
@@ -838,8 +838,8 @@ func RegisterName(name string, value interface{}) {
 }
 
 // Register records a type, identified by a value for that type, under its
-// internal type name.  That name will identify the concrete type of a value
-// sent or received as an interface variable.  Only types that will be
+// internal type name. That name will identify the concrete type of a value
+// sent or received as an interface variable. Only types that will be
 // transferred as implementations of interface values need to be registered.
 // Expecting to be used only during initialization, it panics if the mapping
 // between types and names is not a bijection.