Add nice error message if someone uses native type with pointer. #8

flagarize.go

@@ -216,6 +216,10 @@ func parseStruct(r KingpinRegistry, value reflect.Value, o opts) error {
 			return errors.Errorf("flagarize struct Tag found on non-addressable field %q", field.Name)
 		}
 
+		if _, ok := pointerToNativeMap[field.Type.String()]; ok {
+			return errors.Errorf("flagarize pointer to native type is not allowed for field %q", field.Name)
+		}
+
 		// Favor custom Flagarizers if specified.
 		d := &dedupFlagRegisterer{KingpinRegistry: r}
 		ok, err := invokeFlagarizersIfImplements(d, tag, fieldValue, field.Name)
@@ -521,3 +525,20 @@ func isTrue(v string) bool {
 	}
 	return b
 }
+
+var pointerToNativeMap = map[string]bool {
+	"*string":  true,
+	"*bool":    true,
+	"*uint":    true,
+	"*uint8":   true,
+	"*uint16":  true,
+	"*uint32":  true,
+	"*uint64":  true,
+	"*int":     true,
+	"*int8":    true,
+	"*int16":   true,
+	"*int32":   true,
+	"*int64":   true,
+	"*float32": true,
+	"*float64": true,
+}

flagarize_ext_test.go

@@ -47,6 +47,50 @@ func newTestKingpin(t *testing.T) *kingpin.Application {
 	return app
 }
 
+func TestFlagarize_PointerToNative(t *testing.T) {
+	t.Run("flagarize on field with pointer to int", func(t *testing.T) {
+		x := 2
+		type wrong struct {
+			F *int `flagarize:"help=help"`
+		}
+		w := &wrong{F: &x}
+
+		app := newTestKingpin(t)
+		err := flagarize.Flagarize(app, w)
+		testutil.NotOk(t, err)
+		testutil.Equals(t, "flagarize: flagarize pointer to native type is not allowed for field \"F\"", err.Error())
+	})
+	t.Run("flagarize on field with pointer to string", func(t *testing.T) {
+		x := ""
+		type wrong struct {
+			F *string `flagarize:"help=help"`
+		}
+		w := &wrong{F: &x}
+
+		app := newTestKingpin(t)
+		err := flagarize.Flagarize(app, w)
+		testutil.NotOk(t, err)
+		testutil.Equals(t, "flagarize: flagarize pointer to native type is not allowed for field \"F\"", err.Error())
+	})
+	t.Run("flagarize on field with pointer to bool", func(t *testing.T) {
+		x := true
+
+		type wrongInner struct {
+			F *bool `flagarize:"help=help"`
+		}
+		type wrongOuter struct {
+			WrongInner *wrongInner `flagarize:"help=help"`
+		}
+
+		wInner := wrongInner{F: &x}
+		wOuter := &wrongOuter{WrongInner: &wInner}
+
+		app := newTestKingpin(t)
+		err := flagarize.Flagarize(app, wOuter)
+		testutil.NotOk(t, err)
+		testutil.Equals(t, "flagarize: flagarize struct Tag found on not supported type ptr *flagarize_test.wrongInner for field \"WrongInner\"", err.Error())
+	})
+}
 func TestFlagarize_Errors(t *testing.T) {
 	t.Run("flagarize on basic private field", func(t *testing.T) {
 		type wrong struct {