net, cmd/fix: add IPv6 scoped addressing zone to INET, INET6 address structs

This CL starts to introduce IPv6 scoped addressing capability
into the net package.

The Public API changes are:
+pkg net, type IPAddr struct, Zone string
+pkg net, type IPNet struct, Zone string
+pkg net, type TCPAddr struct, Zone string
+pkg net, type UDPAddr struct, Zone string

Update #4234.

R=rsc, bradfitz, iant
CC=golang-dev
https://golang.org/cl/6849045

2 files changed, 122 insertions, 0 deletions

diff --git a/src/cmd/fix/netipv6zone.go b/src/cmd/fix/netipv6zone.go
new file mode 100644
index 0000000000..587b9ffec6
--- /dev/null
+++ b/src/cmd/fix/netipv6zone.go
@@ -0,0 +1,71 @@
+// Copyright 2012 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 main
+
+import "go/ast"
+
+func init() {
+	register(netipv6zoneFix)
+}
+
+var netipv6zoneFix = fix{
+	"netipv6zone",
+	"2012-11-26",
+	netipv6zone,
+	`Adapt element key to IPNet, IPAddr, UDPAddr or TCPAddr composite literals.
+
+https://codereview.appspot.com/6849045/
+`,
+}
+
+func netipv6zone(f *ast.File) bool {
+	if !imports(f, "net") {
+		return false
+	}
+
+	fixed := false
+	walk(f, func(n interface{}) {
+		cl, ok := n.(*ast.CompositeLit)
+		if !ok {
+			return
+		}
+		se, ok := cl.Type.(*ast.SelectorExpr)
+		if !ok {
+			return
+		}
+		if !isTopName(se.X, "net") || se.Sel == nil {
+			return
+		}
+		switch ss := se.Sel.String(); ss {
+		case "IPNet", "IPAddr", "UDPAddr", "TCPAddr":
+			for i, e := range cl.Elts {
+				if _, ok := e.(*ast.KeyValueExpr); ok {
+					break
+				}
+				switch i {
+				case 0:
+					cl.Elts[i] = &ast.KeyValueExpr{
+						Key:   ast.NewIdent("IP"),
+						Value: e,
+					}
+				case 1:
+					if ss == "IPNet" {
+						cl.Elts[i] = &ast.KeyValueExpr{
+							Key:   ast.NewIdent("Mask"),
+							Value: e,
+						}
+					} else {
+						cl.Elts[i] = &ast.KeyValueExpr{
+							Key:   ast.NewIdent("Port"),
+							Value: e,
+						}
+					}
+				}
+				fixed = true
+			}
+		}
+	})
+	return fixed
+}
diff --git a/src/cmd/fix/netipv6zone_test.go b/src/cmd/fix/netipv6zone_test.go
new file mode 100644
index 0000000000..229daa386d
--- /dev/null
+++ b/src/cmd/fix/netipv6zone_test.go
@@ -0,0 +1,51 @@
+// Copyright 2012 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 main
+
+func init() {
+	addTestCases(netipv6zoneTests, netipv6zone)
+}
+
+var netipv6zoneTests = []testCase{
+	{
+		Name: "netipv6zone.0",
+		In: `package main
+
+import "net"
+
+var a = []struct {
+	*net.IPNet
+}{
+	&net.IPNet{net.ParseIP("2001:DB8::"), net.IPMask(net.ParseIP("ffff:ffff:ffff::"))},
+}
+
+func f() net.Addr {
+	b := net.IPNet{net.IPv4(127, 0, 0, 1), net.IPv4Mask(255, 0, 0, 0)}
+	c := &net.IPAddr{ip1}
+	sub(&net.UDPAddr{ip2, 12345})
+	d := &net.TCPAddr{IP: ip3, Port: 54321}
+	return &net.TCPAddr{ip4}, nil
+}
+`,
+		Out: `package main
+
+import "net"
+
+var a = []struct {
+	*net.IPNet
+}{
+	&net.IPNet{IP: net.ParseIP("2001:DB8::"), Mask: net.IPMask(net.ParseIP("ffff:ffff:ffff::"))},
+}
+
+func f() net.Addr {
+	b := net.IPNet{IP: net.IPv4(127, 0, 0, 1), Mask: net.IPv4Mask(255, 0, 0, 0)}
+	c := &net.IPAddr{IP: ip1}
+	sub(&net.UDPAddr{IP: ip2, Port: 12345})
+	d := &net.TCPAddr{IP: ip3, Port: 54321}
+	return &net.TCPAddr{IP: ip4}, nil
+}
+`,
+	},
+}