go/ast: multiple "blank" imports are permitted

R=rsc, dsymonds
CC=golang-dev
https://golang.org/cl/6303099

src/pkg/exp/types/check_test.go

@@ -203,7 +203,7 @@ func check(t *testing.T, testname string, testfiles []string) {
 func TestCheck(t *testing.T) {
 	// For easy debugging w/o changing the testing code,
 	// if there is a local test file, only test that file.
-	const testfile = "test.go"
+	const testfile = "testdata/test.go"
 	if fi, err := os.Stat(testfile); err == nil && !fi.IsDir() {
 		fmt.Printf("WARNING: Testing only %s (remove it to run all tests)\n", testfile)
 		check(t, testfile, []string{testfile})

src/pkg/exp/types/testdata/test0.src

@@ -6,7 +6,12 @@
 
 package test0
 
-import "unsafe"
+import (
+	"unsafe"
+	// we can have multiple blank imports (was bug)
+	_ "math"
+	_ "net/rpc"
+)
 
 const pi = 3.1415
 

src/pkg/go/ast/resolve.go

@@ -136,7 +136,7 @@ func NewPackage(fset *token.FileSet, files map[string]*File, importer Importer,
 				for _, obj := range pkg.Data.(*Scope).Objects {
 					p.declare(fileScope, pkgScope, obj)
 				}
-			} else {
+			} else if name != "_" {
 				// declare imported package object in file scope
 				// (do not re-use pkg in the file scope but create
 				// a new object instead; the Decl field is different