Fix overwrite by SetDefault for options that share Value

command_test.go

@@ -49,8 +49,14 @@ func sampleCommand(t *testing.T) *serpent.Command {
 		Use: "root [subcommand]",
 		Options: serpent.OptionSet{
 			serpent.Option{
-				Name:  "verbose",
-				Flag:  "verbose",
+				Name:    "verbose",
+				Flag:    "verbose",
+				Default: "false",
+				Value:   serpent.BoolOf(&verbose),
+			},
+			serpent.Option{
+				Name:  "verbose-old",
+				Flag:  "verbode-old",
 				Value: serpent.BoolOf(&verbose),
 			},
 			serpent.Option{
@@ -742,6 +748,12 @@ func TestCommand_DefaultsOverride(t *testing.T) {
 						Value:   serpent.StringOf(&got),
 						YAML:    "url",
 					},
+					{
+						Name:  "url-deprecated",
+						Flag:  "url-deprecated",
+						Env:   "URL_DEPRECATED",
+						Value: serpent.StringOf(&got),
+					},
 					{
 						Name:    "config",
 						Flag:    "config",
@@ -790,6 +802,17 @@ func TestCommand_DefaultsOverride(t *testing.T) {
 		inv.Args = []string{"--config", fi.Name(), "--url", "good.com"}
 	})
 
+	test("EnvOverYAML", "good.com", func(t *testing.T, inv *serpent.Invocation) {
+		fi, err := os.CreateTemp(t.TempDir(), "config.yaml")
+		require.NoError(t, err)
+		defer fi.Close()
+
+		_, err = fi.WriteString("url: bad.com")
+		require.NoError(t, err)
+
+		inv.Environ.Set("URL", "good.com")
+	})
+
 	test("YAMLOverDefault", "good.com", func(t *testing.T, inv *serpent.Invocation) {
 		fi, err := os.CreateTemp(t.TempDir(), "config.yaml")
 		require.NoError(t, err)
@@ -800,4 +823,57 @@ func TestCommand_DefaultsOverride(t *testing.T) {
 
 		inv.Args = []string{"--config", fi.Name()}
 	})
+
+	test("AltFlagOverDefault", "good.com", func(t *testing.T, inv *serpent.Invocation) {
+		inv.Args = []string{"--url-deprecated", "good.com"}
+	})
+}
+
+func TestCommand_OptionsWithSharedValue(t *testing.T) {
+	t.Parallel()
+
+	var got string
+	makeCmd := func(def, altDef string) *serpent.Command {
+		got = ""
+		return &serpent.Command{
+			Options: serpent.OptionSet{
+				{
+					Name:    "url",
+					Flag:    "url",
+					Default: def,
+					Value:   serpent.StringOf(&got),
+				},
+				{
+					Name:    "alt-url",
+					Flag:    "alt-url",
+					Default: altDef,
+					Value:   serpent.StringOf(&got),
+				},
+			},
+			Handler: (func(i *serpent.Invocation) error {
+				return nil
+			}),
+		}
+	}
+
+	// Check proper value propagation.
+	err := makeCmd("def.com", "def.com").Invoke().Run()
+	require.NoError(t, err, "default values are same")
+	require.Equal(t, "def.com", got)
+
+	err = makeCmd("def.com", "").Invoke().Run()
+	require.NoError(t, err, "other default value is empty")
+	require.Equal(t, "def.com", got)
+
+	err = makeCmd("def.com", "").Invoke("--url", "sup").Run()
+	require.NoError(t, err)
+	require.Equal(t, "sup", got)
+
+	err = makeCmd("def.com", "").Invoke("--alt-url", "hup").Run()
+	require.NoError(t, err)
+	require.Equal(t, "hup", got)
+
+	// Catch invalid configuration.
+	err = makeCmd("def.com", "alt-def.com").Invoke().Run()
+	require.Error(t, err, "default values are different")
 }

option.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"os"
+	"slices"
 	"strings"
 
 	"github.com/hashicorp/go-multierror"
@@ -21,6 +22,14 @@ const (
 	ValueSourceDefault ValueSource = "default"
 )
 
+var valueSourcePriority = []ValueSource{
+	ValueSourceFlag,
+	ValueSourceEnv,
+	ValueSourceYAML,
+	ValueSourceDefault,
+	ValueSourceNone,
+}
+
 // Option is a configuration option for a CLI application.
 type Option struct {
 	Name        string `json:"name,omitempty"`
@@ -305,16 +314,12 @@ func (optSet *OptionSet) SetDefaults() error {
 
 	var merr *multierror.Error
 
-	for i, opt := range *optSet {
-		// Skip values that may have already been set by the user.
-		if opt.ValueSource != ValueSourceNone {
-			continue
-		}
-
-		if opt.Default == "" {
-			continue
-		}
-
+	// It's common to have multiple options with the same value to
+	// handle deprecation. We group the options by value so that we
+	// don't let other options overwrite user input.
+	groupByValue := make(map[pflag.Value][]*Option)
+	for i := range *optSet {
+		opt := &(*optSet)[i]
 		if opt.Value == nil {
 			merr = multierror.Append(
 				merr,
@@ -325,13 +330,74 @@ func (optSet *OptionSet) SetDefaults() error {
 			)
 			continue
 		}
-		(*optSet)[i].ValueSource = ValueSourceDefault
-		if err := opt.Value.Set(opt.Default); err != nil {
+		groupByValue[opt.Value] = append(groupByValue[opt.Value], opt)
+	}
+
+	for _, opts := range groupByValue {
+		// Sort the options by priority and whether or not a default is
+		// set. This won't affect the value but represents correctness
+		// from whence the value originated.
+		slices.SortFunc(opts, func(a, b *Option) int {
+			if a.ValueSource != b.ValueSource {
+				for _, vs := range valueSourcePriority {
+					if a.ValueSource == vs {
+						return -1
+					}
+					if b.ValueSource == vs {
+						return 1
+					}
+				}
+			}
+			if a.Default != b.Default {
+				if a.Default == "" {
+					return 1
+				}
+				if b.Default == "" {
+					return -1
+				}
+			}
+			return 0
+		})
+
+		// If the first option has a value source, then we don't need to
+		// set the default, but mark the source for all options.
+		if opts[0].ValueSource != ValueSourceNone {
+			for _, opt := range opts[1:] {
+				opt.ValueSource = opts[0].ValueSource
+			}
+			continue
+		}
+
+		var optWithDefault *Option
+		for _, opt := range opts {
+			if opt.Default == "" {
+				continue
+			}
+			if optWithDefault != nil && optWithDefault.Default != opt.Default {
+				merr = multierror.Append(
+					merr,
+					xerrors.Errorf(
+						"parse %q: multiple defaults set for the same value: %q and %q (%q)",
+						opt.Name, opt.Default, optWithDefault.Default, optWithDefault.Name,
+					),
+				)
+				continue
+			}
+			optWithDefault = opt
+		}
+		if optWithDefault == nil {
+			continue
+		}
+		if err := optWithDefault.Value.Set(optWithDefault.Default); err != nil {
 			merr = multierror.Append(
-				merr, xerrors.Errorf("parse %q: %w", opt.Name, err),
+				merr, xerrors.Errorf("parse %q: %w", optWithDefault.Name, err),
 			)
 		}
+		for _, opt := range opts {
+			opt.ValueSource = ValueSourceDefault
+		}
 	}
+
 	return merr.ErrorOrNil()
 }