go.tools/go/types: String method for Initializers

Plus a couple of minor fixes.

R=adonovan
CC=golang-dev
https://golang.org/cl/28540043

go/types/api.go

@@ -23,6 +23,7 @@
 package types
 
 import (
+	"bytes"
 	"fmt"
 	"go/ast"
 	"go/token"
@@ -189,6 +190,19 @@ type Initializer struct {
 	Rhs ast.Expr
 }
 
+func (init *Initializer) String() string {
+	var buf bytes.Buffer
+	for i, lhs := range init.Lhs {
+		if i > 0 {
+			buf.WriteString(", ")
+		}
+		buf.WriteString(lhs.Name())
+	}
+	buf.WriteString(" = ")
+	WriteExpr(&buf, init.Rhs)
+	return buf.String()
+}
+
 // Check type-checks a package and returns the resulting package object,
 // the first error if any, and if info != nil, additional type information.
 // The package is marked as complete if no errors occurred, otherwise it is

go/types/api_test.go

@@ -7,7 +7,6 @@
 package types_test
 
 import (
-	"bytes"
 	"go/ast"
 	"go/parser"
 	"go/token"
@@ -19,7 +18,7 @@ import (
 )
 
 func pkgFor(path, source string, info *Info) (*Package, error) {
-	fset = token.NewFileSet()
+	fset := token.NewFileSet()
 	f, err := parser.ParseFile(fset, path, source, 0)
 	if err != nil {
 		return nil, err
@@ -210,19 +209,6 @@ func TestScopesInfo(t *testing.T) {
 	}
 }
 
-func initString(init *Initializer) string {
-	var buf bytes.Buffer
-	for i, lhs := range init.Lhs {
-		if i > 0 {
-			buf.WriteString(", ")
-		}
-		buf.WriteString(lhs.Name())
-	}
-	buf.WriteString(" = ")
-	WriteExpr(&buf, init.Rhs)
-	return buf.String()
-}
-
 func TestInitOrder(t *testing.T) {
 	var tests = []struct {
 		src   string
@@ -272,7 +258,7 @@ func TestInitOrder(t *testing.T) {
 
 		// initializers must match
 		for i, want := range test.inits {
-			got := initString(info.InitOrder[i])
+			got := info.InitOrder[i].String()
 			if got != want {
 				t.Errorf("package %s, init %d: got %s; want %s", name, i, got, want)
 				continue

go/types/resolver.go

@@ -147,7 +147,7 @@ func (check *checker) resolveFiles(files []*ast.File) {
 	importer := check.conf.Import
 	if importer == nil {
 		if DefaultImport == nil {
-			panic("no Config.Import and no DefaultImport")
+			panic(`no Config.Import or DefaultImport (missing import _ "code.google.com/p/go.tools/go/gcimporter"?)`)
 		}
 		importer = DefaultImport
 	}