encoding: new package

See golang.org/s/go12encoding for design.

R=r
CC=golang-dev
https://golang.org/cl/12541051

src/cmd/dist/build.c

@@ -992,6 +992,8 @@ install(char *dir)
 			vadd(&compile, bprintf(&b, "GOOS_%s", goos));
 			vadd(&compile, "-D");
 			vadd(&compile, bprintf(&b, "GOARCH_%s", goarch));
+			vadd(&compile, "-D");
+			vadd(&compile, bprintf(&b, "GOOS_GOARCH_%s_%s", goos, goarch));
 		}
 
 		bpathf(&b, "%s/%s", workdir, lastelem(files.p[i]));
@@ -1265,6 +1267,7 @@ static char *buildorder[] = {
 	"pkg/os",
 	"pkg/reflect",
 	"pkg/fmt",
+	"pkg/encoding",
 	"pkg/encoding/json",
 	"pkg/flag",
 	"pkg/path/filepath",
@@ -1317,6 +1320,7 @@ static char *cleantab[] = {
 	"pkg/bufio",
 	"pkg/bytes",
 	"pkg/container/heap",
+	"pkg/encoding",
 	"pkg/encoding/base64",
 	"pkg/encoding/json",
 	"pkg/errors",

src/pkg/encoding/encoding.go

@@ -0,0 +1,48 @@
+// Copyright 2013 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.
+
+// Package encoding defines interfaces shared by other packages that
+// convert data to and from byte-level and textual representations.
+// Packages that check for these interfaces include encoding/gob,
+// encoding/json, and encoding/xml. As a result, implementing an
+// interface once can make a type useful in multiple encodings.
+// Standard types that implement these interfaces include time.Time and net.IP.
+// The interfaces come in pairs that produce and consume encoded data.
+package encoding
+
+// BinaryMarshaler is the interface implemented by an object that can
+// marshal itself into a binary form.
+//
+// MarshalBinary encodes the receiver into a binary form and returns the result.
+type BinaryMarshaler interface {
+	MarshalBinary() (data []byte, err error)
+}
+
+// BinaryUnmarshaler is the interface implemented by an object that can
+// unmarshal a binary representation of itself.
+//
+// UnmarshalBinary must be able to decode the form generated by MarshalBinary.
+// UnmarshalBinary must copy the data if it wishes to retain the data
+// after returning.
+type BinaryUnmarshaler interface {
+	UnmarshalBinary(data []byte) error
+}
+
+// TextMarshaler is the interface implemented by an object that can
+// marshal itself into a textual form.
+//
+// MarshalText encodes the receiver into UTF-8-encoded text and returns the result.
+type TextMarshaler interface {
+	MarshalText() (text []byte, err error)
+}
+
+// TextUnmarshaler is the interface implemented by an object that can
+// unmarshal a textual representation of itself.
+//
+// UnmarshalText must be able to decode the form generated by MarshalText.
+// UnmarshalText must copy the text if it wishes to retain the text
+// after returning.
+type TextUnmarshaler interface {
+	UnmarshalText(text []byte) error
+}

src/pkg/go/build/deps_test.go

@@ -192,12 +192,13 @@ var pkgDeps = map[string][]string{
 	"debug/gosym":         {"L4"},
 	"debug/macho":         {"L4", "OS", "debug/dwarf"},
 	"debug/pe":            {"L4", "OS", "debug/dwarf"},
+	"encoding":            {"L4"},
 	"encoding/ascii85":    {"L4"},
 	"encoding/asn1":       {"L4", "math/big"},
 	"encoding/csv":        {"L4"},
-	"encoding/gob":        {"L4", "OS"},
+	"encoding/gob":        {"L4", "OS", "encoding"},
 	"encoding/hex":        {"L4"},
-	"encoding/json":       {"L4"},
+	"encoding/json":       {"L4", "encoding"},
 	"encoding/pem":        {"L4"},
 	"encoding/xml":        {"L4"},
 	"flag":                {"L4", "OS"},