refactor/rename: fix crash when renaming type embedded in another package.

Fixes golang/go#12038.

Change-Id: I9026edef7f8769b451f2b1502c107d6b2bb45096
Reviewed-on: https://go-review.googlesource.com/13451
Reviewed-by: Alan Donovan <adonovan@google.com>

refactor/rename/rename_test.go

@@ -720,6 +720,57 @@ type _ struct{ *foo.U }
 			},
 		},
 
+		// Renaming of embedded field that is a qualified reference with the '-from' flag.
+		// (Regression test for bug 12038.)
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo": {`package foo; type T int`},
+				"main": {`package main
+
+import "foo"
+
+type V struct{ *foo.T }
+`},
+			}),
+			from: "(main.V).T", to: "U", // the "T" in *foo.T
+			want: map[string]string{
+				"/go/src/foo/0.go": `package foo
+
+type U int
+`,
+				"/go/src/main/0.go": `package main
+
+import "foo"
+
+type V struct{ *foo.U }
+`,
+			},
+		},
+		{
+			ctxt: fakeContext(map[string][]string{
+				"foo": {`package foo; type T int`},
+				"main": {`package main
+
+import "foo"
+
+type V struct{ foo.T }
+`},
+			}),
+			from: "(main.V).T", to: "U", // the "T" in *foo.T
+			want: map[string]string{
+				"/go/src/foo/0.go": `package foo
+
+type U int
+`,
+				"/go/src/main/0.go": `package main
+
+import "foo"
+
+type V struct{ foo.U }
+`,
+			},
+		},
+
 		// Interface method renaming.
 		{
 			ctxt: fakeContext(map[string][]string{

refactor/rename/spec.go

@@ -452,6 +452,15 @@ func findObjects(info *loader.PackageInfo, spec *spec) ([]types.Object, error) {
 		}
 
 		if spec.searchFor == "" {
+			// If it is an embedded field, return the type of the field.
+			if v, ok := obj.(*types.Var); ok && v.Anonymous() {
+				switch t := v.Type().(type) {
+				case *types.Pointer:
+					return []types.Object{t.Elem().(*types.Named).Obj()}, nil
+				case *types.Named:
+					return []types.Object{t.Obj()}, nil
+				}
+			}
 			return []types.Object{obj}, nil
 		}