cmd/go: adjust import config debugging flag

Change-Id: I3afaefc154f9ccfac353cedac7aefcfb70afe265
Reviewed-on: https://go-review.googlesource.com/86996
Run-TryBot: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/go/internal/load/icfg.go

@@ -19,7 +19,8 @@ var DebugDeprecatedImportcfg debugDeprecatedImportcfgFlag
 
 type debugDeprecatedImportcfgFlag struct {
 	enabled bool
-	pkgs    map[string]*debugDeprecatedImportcfgPkg
+	Import  map[string]string
+	Pkg     map[string]*debugDeprecatedImportcfgPkg
 }
 
 type debugDeprecatedImportcfgPkg struct {
@@ -49,8 +50,9 @@ func (f *debugDeprecatedImportcfgFlag) Set(x string) error {
 	}
 	data = data[len(debugDeprecatedImportcfgMagic):]
 
-	f.pkgs = nil
-	if err := json.Unmarshal(data, &f.pkgs); err != nil {
+	f.Import = nil
+	f.Pkg = nil
+	if err := json.Unmarshal(data, &f); err != nil {
 		return errImportcfgSyntax
 	}
 	f.enabled = true
@@ -58,18 +60,19 @@ func (f *debugDeprecatedImportcfgFlag) Set(x string) error {
 }
 
 func (f *debugDeprecatedImportcfgFlag) lookup(parent *Package, path string) (dir, newPath string) {
-	if parent == nil {
-		if p1 := f.pkgs[path]; p1 != nil {
-			return p1.Dir, path
-		}
-		return "", ""
+	newPath = path
+	if p := f.Import[path]; p != "" {
+		newPath = p
 	}
-	if p1 := f.pkgs[parent.ImportPath]; p1 != nil {
-		if newPath := p1.Import[path]; newPath != "" {
-			if p2 := f.pkgs[newPath]; p2 != nil {
-				return p2.Dir, newPath
+	if parent != nil {
+		if p1 := f.Pkg[parent.ImportPath]; p1 != nil {
+			if p := p1.Import[path]; p != "" {
+				newPath = p
 			}
 		}
 	}
+	if p2 := f.Pkg[newPath]; p2 != nil {
+		return p2.Dir, newPath
+	}
 	return "", ""
 }