cmd/compile: include pkgPath on all struct types

Fixes #15026.

Change-Id: I61ed71152b99973270d79264d1e8f466f7343c02
Reviewed-on: https://go-review.googlesource.com/21286
Run-TryBot: David Crawshaw <crawshaw@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/cmd/compile/internal/gc/reflect.go

@@ -1277,7 +1277,7 @@ ok:
 		}
 
 		ot = dcommontype(s, ot, t)
-		var pkg *Pkg
+		pkg := localpkg
 		if t.Sym != nil {
 			pkg = t.Sym.Pkg
 		}

src/reflect/all_test.go

@@ -2321,6 +2321,33 @@ func TestImportPath(t *testing.T) {
 	}
 }
 
+func TestFieldPkgPath(t *testing.T) {
+	typ := TypeOf(struct {
+		Exported   string
+		unexported string
+		OtherPkgFields
+	}{})
+	for _, test := range []struct {
+		index     []int
+		pkgPath   string
+		anonymous bool
+	}{
+		{[]int{0}, "", false},             // Exported
+		{[]int{1}, "reflect_test", false}, // unexported
+		{[]int{2}, "", true},              // OtherPkgFields
+		{[]int{2, 0}, "", false},          // OtherExported
+		{[]int{2, 1}, "reflect", false},   // otherUnexported
+	} {
+		f := typ.FieldByIndex(test.index)
+		if got, want := f.PkgPath, test.pkgPath; got != want {
+			t.Errorf("Field(%d).PkgPath = %q, want %q", test.index, got, want)
+		}
+		if got, want := f.Anonymous, test.anonymous; got != want {
+			t.Errorf("Field(%d).Anonymous = %v, want %v", test.index, got, want)
+		}
+	}
+}
+
 func TestVariadicType(t *testing.T) {
 	// Test example from Type documentation.
 	var f func(x int, y ...float64)

src/reflect/export_test.go

@@ -94,3 +94,8 @@ func FirstMethodNameBytes(t Type) *byte {
 	}
 	return m.name.bytes
 }
+
+type OtherPkgFields struct {
+	OtherExported   int
+	otherUnexported int
+}