gofix: netdial

R=adg
CC=golang-dev
https://golang.org/cl/4278053

src/cmd/gofix/Makefile

@@ -7,6 +7,7 @@ include ../../Make.inc
 TARG=gofix
 GOFILES=\
 	fix.go\
+	netdial.go\
 	main.go\
 	httpserver.go\
 	procattr.go\

src/cmd/gofix/fix.go

@@ -242,7 +242,7 @@ func isPkgDot(t ast.Expr, pkg, name string) bool {
 	if !ok {
 		return false
 	}
-	return isName(sel.X, pkg) && sel.Sel.String() == name
+	return isTopName(sel.X, pkg) && sel.Sel.String() == name
 }
 
 func isPtrPkgDot(t ast.Expr, pkg, name string) bool {
@@ -253,6 +253,14 @@ func isPtrPkgDot(t ast.Expr, pkg, name string) bool {
 	return isPkgDot(ptr.X, pkg, name)
 }
 
+func isTopName(n ast.Expr, name string) bool {
+	id, ok := n.(*ast.Ident)
+	if !ok {
+		return false
+	}
+	return id.Name == name && id.Obj == nil
+}
+
 func isName(n ast.Expr, name string) bool {
 	id, ok := n.(*ast.Ident)
 	if !ok {
@@ -291,9 +299,10 @@ func isEmptyString(n ast.Expr) bool {
 }
 
 func warn(pos token.Pos, msg string, args ...interface{}) {
-	s := ""
 	if pos.IsValid() {
-		s = fmt.Sprintf("%s: ", fset.Position(pos).String())
+		msg = "%s: " + msg
+		arg1 := []interface{}{fset.Position(pos).String()}
+		args = append(arg1, args...)
 	}
-	fmt.Fprintf(os.Stderr, "%s"+msg+"\n", append([]interface{}{s}, args...))
+	fmt.Fprintf(os.Stderr, msg+"\n", args...)
 }

src/cmd/gofix/main.go

@@ -124,7 +124,7 @@ func processFile(filename string, useStdin bool) os.Error {
 	if !fixed {
 		return nil
 	}
-	fmt.Fprintf(os.Stderr, "%s: %s\n", filename, buf.String()[1:])
+	fmt.Fprintf(os.Stderr, "%s: fixed %s\n", filename, buf.String()[1:])
 
 	buf.Reset()
 	_, err = (&printer.Config{printerMode, tabWidth}).Fprint(&buf, fset, file)

src/cmd/gofix/netdial.go

+// Copyright 2011 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"
+)
+
+var netdialFix = fix{
+	"netdial",
+	netdial,
+`Adapt 3-argument calls of net.Dial to use 2-argument form.
+
+http://codereview.appspot.com/4244055
+`,
+}
+
+var tlsdialFix = fix{
+	"tlsdial",
+	tlsdial,
+`Adapt 4-argument calls of tls.Dial to use 3-argument form.
+
+http://codereview.appspot.com/4244055
+`,
+}
+
+var netlookupFix = fix{
+	"netlookup",
+	netlookup,
+`Adapt 3-result calls to net.LookupHost to use 2-result form.
+
+http://codereview.appspot.com/4244055
+`,
+}
+
+func init() {
+	register(netdialFix)
+	register(tlsdialFix)
+	register(netlookupFix)
+}
+
+func netdial(f *ast.File) bool {
+	if !imports(f, "net") {
+		return false
+	}
+
+	fixed := false
+	rewrite(f, func(n interface{}) {
+		call, ok := n.(*ast.CallExpr)
+		if !ok || !isPkgDot(call.Fun, "net", "Dial") || len(call.Args) != 3 {
+			return
+		}
+		// net.Dial(a, "", b) -> net.Dial(a, b)
+		if !isEmptyString(call.Args[1]) {
+			warn(call.Pos(), "call to net.Dial with non-empty second argument")
+			return
+		}
+		call.Args[1] = call.Args[2]
+		call.Args = call.Args[:2]
+		fixed = true
+	})
+	return fixed
+}
+
+func tlsdial(f *ast.File) bool {
+	if !imports(f, "crypto/tls") {
+		return false
+	}
+
+	fixed := false
+	rewrite(f, func(n interface{}) {
+		call, ok := n.(*ast.CallExpr)
+		if !ok || !isPkgDot(call.Fun, "tls", "Dial") || len(call.Args) != 4 {
+			return
+		}
+		// tls.Dial(a, "", b, c) -> tls.Dial(a, b, c)
+		if !isEmptyString(call.Args[1]) {
+			warn(call.Pos(), "call to tls.Dial with non-empty second argument")
+			return
+		}
+		call.Args[1] = call.Args[2]
+		call.Args[2] = call.Args[3]
+		call.Args = call.Args[:3]
+		fixed = true
+	})
+	return fixed
+}
+
+func netlookup(f *ast.File) bool {
+	if !imports(f, "net") {
+		return false
+	}
+
+	fixed := false
+	rewrite(f, func(n interface{}) {
+		as, ok := n.(*ast.AssignStmt)
+		if !ok || len(as.Lhs) != 3 || len(as.Rhs) != 1 {
+			return
+		}
+		call, ok := as.Rhs[0].(*ast.CallExpr)
+		if !ok || !isPkgDot(call.Fun, "net", "LookupHost") {
+			return
+		}
+		if !isBlank(as.Lhs[2]) {
+			warn(as.Pos(), "call to net.LookupHost expecting cname; use net.LookupCNAME")
+			return
+		}
+		as.Lhs = as.Lhs[:2]
+		fixed = true
+	})
+	return fixed
+}

src/cmd/gofix/netdial_test.go

+package main
+
+func init() {
+	addTestCases(netdialTests)
+}
+
+var netdialTests = []testCase{
+	{
+		Name: "netdial.0",
+		In: `package main
+
+import "net"
+
+func f() {
+	c, err := net.Dial(net, "", addr)
+	c, err = net.Dial(net, "", addr)
+}
+`,
+		Out: `package main
+
+import "net"
+
+func f() {
+	c, err := net.Dial(net, addr)
+	c, err = net.Dial(net, addr)
+}
+`,
+	},
+
+	{
+		Name: "netlookup.0",
+		In: `package main
+
+import "net"
+
+func f() {
+	foo, bar, _ := net.LookupHost(host)
+	foo, bar, _ = net.LookupHost(host)
+}
+`,
+		Out: `package main
+
+import "net"
+
+func f() {
+	foo, bar := net.LookupHost(host)
+	foo, bar = net.LookupHost(host)
+}
+`,
+	},
+}