[release-branch.go1.2] encoding/gob: do not use MarshalText, UnmarshalText

««« CL 22770044 / 23fc3139589c
encoding/gob: do not use MarshalText, UnmarshalText

This seems to be the best of a long list of bad ways to fix this issue.

Fixes #6760.

R=r
CC=golang-dev
https://golang.org/cl/22770044
»»»

R=golang-dev
CC=golang-dev
https://golang.org/cl/28110043

diff --git a/doc/go1.2.html b/doc/go1.2.html
index 9d890b290676a2f0ca9f9bc4d39a3d439320d361..c7a9f844264c90c60f9f5a5eaa1fc7eefd08249d 100644 (file)
--- a/doc/go1.2.html
+++ b/doc/go1.2.html
@@ -736,7 +736,8 @@ now treats channel and function fields of structures as if they were unexported,
 even if they are not. That is, it ignores them completely. Previously they would
 trigger an error, which could cause unexpected compatibility problems if an
 embedded structure added such a field.
-The package also now supports the generic encoding interfaces of the
+The package also now supports the generic <code>BinaryMarshaler</code> and
+<code>BinaryUnmarshaler</code> interfaces of the
 <a href="/pkg/encoding/"><code>encoding</code></a> package
 described above.
 </li>

diff --git a/src/pkg/encoding/gob/doc.go b/src/pkg/encoding/gob/doc.go
index 28f0c05a5c5fdc3d919f8fa7b29eec95f02ac98f..d0acaba1adcb61d00b83bcfa1399a95c8aa2d7d6 100644 (file)
--- a/src/pkg/encoding/gob/doc.go
+++ b/src/pkg/encoding/gob/doc.go
@@ -86,13 +86,13 @@ Functions and channels will not be sent in a gob. Attempting to encode such a va
 at top the level will fail. A struct field of chan or func type is treated exactly
 like an unexported field and is ignored.
 
-Gob can encode a value of any type implementing the GobEncoder,
-encoding.BinaryMarshaler, or encoding.TextMarshaler interfaces by calling the
-corresponding method, in that order of preference.
+Gob can encode a value of any type implementing the GobEncoder or
+encoding.BinaryMarshaler interfaces by calling the corresponding method,
+in that order of preference.
 
-Gob can decode a value of any type implementing the GobDecoder,
-encoding.BinaryUnmarshaler, or encoding.TextUnmarshaler interfaces by calling
-the corresponding method, again in that order of preference.
+Gob can decode a value of any type implementing the GobDecoder or
+encoding.BinaryUnmarshaler interfaces by calling the corresponding method,
+again in that order of preference.
 
 Encoding Details
 

diff --git a/src/pkg/encoding/gob/gobencdec_test.go b/src/pkg/encoding/gob/gobencdec_test.go
index 301551db48a7158c70db9d3f21a5daf96c958a22..0193e2b67d4312b452676cbd787b0563eed55998 100644 (file)
--- a/src/pkg/encoding/gob/gobencdec_test.go
+++ b/src/pkg/encoding/gob/gobencdec_test.go
@@ -11,6 +11,7 @@ import (
        "errors"
        "fmt"
        "io"
+       "net"
        "strings"
        "testing"
        "time"
@@ -767,3 +768,17 @@ func TestGobEncodePtrError(t *testing.T) {
                t.Fatalf("expected nil, got %v", err2)
        }
 }
+
+func TestNetIP(t *testing.T) {
+       // Encoding of net.IP{1,2,3,4} in Go 1.1.
+       enc := []byte{0x07, 0x0a, 0x00, 0x04, 0x01, 0x02, 0x03, 0x04}
+
+       var ip net.IP
+       err := NewDecoder(bytes.NewReader(enc)).Decode(&ip)
+       if err != nil {
+               t.Fatalf("decode: %v", err)
+       }
+       if ip.String() != "1.2.3.4" {
+               t.Errorf("decoded to %v, want 1.2.3.4", ip.String())
+       }
+}

diff --git a/src/pkg/encoding/gob/type.go b/src/pkg/encoding/gob/type.go
index 65bf17b7f02b33bf56af6f5a48bdf7d05efe9643..cad1452795318e55700849fa093c5945525e3562 100644 (file)
--- a/src/pkg/encoding/gob/type.go
+++ b/src/pkg/encoding/gob/type.go
@@ -88,18 +88,25 @@ func validUserType(rt reflect.Type) (ut *userTypeInfo, err error) {
                ut.externalEnc, ut.encIndir = xGob, indir
        } else if ok, indir := implementsInterface(ut.user, binaryMarshalerInterfaceType); ok {
                ut.externalEnc, ut.encIndir = xBinary, indir
-       } else if ok, indir := implementsInterface(ut.user, textMarshalerInterfaceType); ok {
-               ut.externalEnc, ut.encIndir = xText, indir
        }
 
+       // NOTE(rsc): Would like to allow MarshalText here, but results in incompatibility
+       // with older encodings for net.IP. See golang.org/issue/6760.
+       // } else if ok, indir := implementsInterface(ut.user, textMarshalerInterfaceType); ok {
+       //      ut.externalEnc, ut.encIndir = xText, indir
+       // }
+
        if ok, indir := implementsInterface(ut.user, gobDecoderInterfaceType); ok {
                ut.externalDec, ut.decIndir = xGob, indir
        } else if ok, indir := implementsInterface(ut.user, binaryUnmarshalerInterfaceType); ok {
                ut.externalDec, ut.decIndir = xBinary, indir
-       } else if ok, indir := implementsInterface(ut.user, textUnmarshalerInterfaceType); ok {
-               ut.externalDec, ut.decIndir = xText, indir
        }
 
+       // See note above.
+       // } else if ok, indir := implementsInterface(ut.user, textUnmarshalerInterfaceType); ok {
+       //      ut.externalDec, ut.decIndir = xText, indir
+       // }
+
        userTypeCache[rt] = ut
        return
 }