From 0088b7ecd7687e8eeb7a30e4a3a491ef55f87d42 Mon Sep 17 00:00:00 2001
From: Alan Donovan <adonovan@google.com>
Date: Mon, 17 Nov 2014 15:24:12 -0500
Subject: [PATCH] go/types: don't panic if DefaultImport==nil, until we
 actually use it.

LGTM=gri
R=gri
CC=golang-codereviews
https://golang.org/cl/178860044
---
 go/types/resolver.go              | 10 +++++++---
 go/types/typeutil/example_test.go |  2 --
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/go/types/resolver.go b/go/types/resolver.go
index e8b28235..7eb18a2e 100644
--- a/go/types/resolver.go
+++ b/go/types/resolver.go
@@ -130,10 +130,14 @@ func (check *Checker) collectObjects() {
 
 	importer := check.conf.Import
 	if importer == nil {
-		if DefaultImport == nil {
-			panic(`no Config.Import or DefaultImport (missing import _ "golang.org/x/tools/go/gcimporter"?)`)
+		if DefaultImport != nil {
+			importer = DefaultImport
+		} else {
+			// Panic if we encounter an import.
+			importer = func(map[string]*Package, string) (*Package, error) {
+				panic(`no Config.Import or DefaultImport (missing import _ "golang.org/x/tools/go/gcimporter"?)`)
+			}
 		}
-		importer = DefaultImport
 	}
 
 	// pkgImports is the set of packages already imported by any package file seen
diff --git a/go/types/typeutil/example_test.go b/go/types/typeutil/example_test.go
index 6fe9279a..67ee34f7 100644
--- a/go/types/typeutil/example_test.go
+++ b/go/types/typeutil/example_test.go
@@ -10,8 +10,6 @@ import (
 
 	"golang.org/x/tools/go/types"
 	"golang.org/x/tools/go/types/typeutil"
-
-	_ "golang.org/x/tools/go/gcimporter" // no imports; why is this necessary?
 )
 
 func ExampleMap() {