cobra bridge

.gitignore

@@ -3,6 +3,7 @@ caraparse/caraparse
 docs/book
 example/cmd/_test_files/*.txt
 example/example
+example-nonposix/example-nonposix
 integration.cov
 unit.cov
 .vscode

carapace.go

@@ -57,7 +57,7 @@ func (c Carapace) PositionalCompletion(action ...Action) {
 
 // PositionalAnyCompletion defines completion for any positional arguments not already defined.
 func (c Carapace) PositionalAnyCompletion(action Action) {
-	storage.get(c.cmd).positionalAny = action
+	storage.get(c.cmd).positionalAny = &action
 }
 
 // DashCompletion defines completion for positional arguments after dash (`--`) using a list of Actions.
@@ -67,7 +67,7 @@ func (c Carapace) DashCompletion(action ...Action) {
 
 // DashAnyCompletion defines completion for any positional arguments after dash (`--`) not already defined.
 func (c Carapace) DashAnyCompletion(action Action) {
-	storage.get(c.cmd).dashAny = action
+	storage.get(c.cmd).dashAny = &action
 }
 
 // FlagCompletion defines completion for flags using a map consisting of name and Action.

compat.go

@@ -2,6 +2,7 @@ package carapace
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
@@ -10,17 +11,27 @@ import (
 func registerValidArgsFunction(cmd *cobra.Command) {
 	if cmd.ValidArgsFunction == nil {
 		cmd.ValidArgsFunction = func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
-			action := storage.getPositional(cmd, len(args)).Invoke(Context{Args: args, Value: toComplete})
+			action := Action{}.Invoke(Context{Args: args, Value: toComplete}) // TODO just IvokedAction{} ok?
+			if storage.hasPositional(cmd, len(args)) {
+				action = storage.getPositional(cmd, len(args)).Invoke(Context{Args: args, Value: toComplete})
+			}
 			return cobraValuesFor(action), cobraDirectiveFor(action)
 		}
 	}
 }
 
 func registerFlagCompletion(cmd *cobra.Command) {
 	cmd.LocalFlags().VisitAll(func(f *pflag.Flag) {
+		if !storage.hasFlag(cmd, f.Name) {
+			return // skip if not defined in carapace
+		}
+		if _, ok := cmd.GetFlagCompletionFunc(f.Name); ok {
+			return // skip if already defined in cobra
+		}
+
 		err := cmd.RegisterFlagCompletionFunc(f.Name, func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
 			a := storage.getFlag(cmd, f.Name)
-			action := a.Invoke(Context{Args: args, Value: toComplete})
+			action := a.Invoke(Context{Args: args, Value: toComplete}) // TODO cmd might differ for persistentflags and either way args or cmd will be wrong
 			return cobraValuesFor(action), cobraDirectiveFor(action)
 		})
 		if err != nil {
@@ -51,3 +62,48 @@ func cobraDirectiveFor(action InvokedAction) cobra.ShellCompDirective {
 	}
 	return directive
 }
+
+type compDirective cobra.ShellCompDirective
+
+func (d compDirective) matches(cobraDirective cobra.ShellCompDirective) bool {
+	return d&compDirective(cobraDirective) != 0
+}
+
+func (d compDirective) ToA(values ...string) Action {
+	var action Action
+	switch {
+	case d.matches(cobra.ShellCompDirectiveError):
+		return ActionMessage("an error occured")
+	case d.matches(cobra.ShellCompDirectiveFilterDirs):
+		switch len(values) {
+		case 0:
+			action = ActionDirectories()
+		default:
+			action = ActionDirectories().Chdir(values[0])
+		}
+	case d.matches(cobra.ShellCompDirectiveFilterFileExt):
+		extensions := make([]string, 0)
+		for _, v := range values {
+			extensions = append(extensions, "."+v)
+		}
+		return ActionFiles(extensions...)
+	case len(values) == 0 && !d.matches(cobra.ShellCompDirectiveNoFileComp):
+		action = ActionFiles()
+	default:
+		vals := make([]string, 0)
+		for _, v := range values {
+			if splitted := strings.SplitN(v, "\t", 2); len(splitted) == 2 {
+				vals = append(vals, splitted[0], splitted[1])
+			} else {
+				vals = append(vals, splitted[0], "")
+			}
+		}
+		action = ActionValuesDescribed(vals...)
+	}
+
+	if d.matches(cobra.ShellCompDirectiveNoSpace) {
+		action = action.NoSpace()
+	}
+
+	return action
+}

compat_test.go

@@ -1,7 +1,7 @@
 package carapace
 
 import (
-	"io/ioutil"
+	"io"
 	"os"
 	"strings"
 	"testing"
@@ -54,7 +54,7 @@ func TestRegisterFlagCompletion(t *testing.T) {
 	_ = cmd.Execute()
 
 	w.Close()
-	out, _ := ioutil.ReadAll(r)
+	out, _ := io.ReadAll(r)
 	os.Stdout = rescueStdout
 
 	if lines := strings.Split(string(out), "\n"); lines[0] != "1\tone" {

context.go

@@ -12,6 +12,7 @@ import (
 	"github.com/rsteube/carapace/pkg/util"
 	"github.com/rsteube/carapace/third_party/github.com/drone/envsubst"
 	"github.com/rsteube/carapace/third_party/golang.org/x/sys/execabs"
+	"github.com/spf13/cobra"
 )
 
 // Context provides information during completion.
@@ -28,6 +29,7 @@ type Context struct {
 	Dir string
 
 	mockedReplies map[string]string
+	cmd           *cobra.Command // needed for ActionCobra
 }
 
 // NewContext creates a new context for given arguments.

defaultActions.go

@@ -474,7 +474,11 @@ func ActionPositional(cmd *cobra.Command) Action {
 		c.Args = cmd.Flags().Args()
 		entry := storage.get(cmd)
 
-		a := entry.positionalAny
+		var a Action
+		if entry.positionalAny != nil {
+			a = *entry.positionalAny
+		}
+
 		if index := len(c.Args); index < len(entry.positional) {
 			a = entry.positional[len(c.Args)]
 		}
@@ -514,3 +518,18 @@ func ActionCommands(cmd *cobra.Command) Action {
 		return batch.ToA()
 	})
 }
+
+// ActionCora bridges given cobra completion function.
+func ActionCobra(f func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective)) Action {
+	return ActionCallback(func(c Context) Action {
+		switch {
+		case f == nil:
+			return ActionValues()
+		case c.cmd == nil: // ensure cmd is never nil even if context does not contain one
+			LOG.Print("cmd is nil [ActionCobra]")
+			c.cmd = &cobra.Command{Use: "_carapace_actioncobra", Hidden: true, Deprecated: "dummy command for ActionCobra"}
+		}
+		values, directive := f(c.cmd, c.cmd.Flags().Args(), c.Value)
+		return compDirective(directive).ToA(values...)
+	})
+}

docs/src/SUMMARY.md

@@ -55,6 +55,7 @@
     - [ToMultiPartsA](./carapace/invokedAction/toMultiPartsA.md)
   - [DefaultActions](./carapace/defaultActions.md)
     - [ActionCallback](./carapace/defaultActions/actionCallback.md)
+    - [ActionCobra](./carapace/defaultActions/actionCobra.md)
     - [ActionCommands](./carapace/defaultActions/actionCommands.md)
     - [ActionDirectories](./carapace/defaultActions/actionDirectories.md)
     - [ActionExecCommand](./carapace/defaultActions/actionExecCommand.md)

docs/src/carapace/defaultActions/actionCobra.cast

@@ -0,0 +1,50 @@
+{"version": 2, "width": 108, "height": 24, "timestamp": 1701100000, "env": {"SHELL": "elvish", "TERM": "tmux-256color"}}
+[0.122617, "o", "\u001b[?7h\u001b[7m⏎\u001b[m                                                                                                           \r \r\u001b[?7l\u001b[?2004h\u001b[?25l\r???>                                                                                                   ???> \r\u001b[5C\u001b[?25h"]
+[0.123322, "o", "\u001b[?25l\r\u001b[5C\u001b[K\r\u001b[5C\u001b[?25h"]
+[0.139511, "o", "\u001b[?25l\r\r\u001b[5C\u001b[?25h"]
+[0.139635, "o", "\u001b[?25l\r\u001b[K\r\n\u001b[0;1;36mcarapace/example\u001b[0;m on \u001b[0;1;35m cobra-bridge\u001b[0;m \u001b[0;1;31m[$!?]\u001b[0;m via \u001b[0;1;36m🐹 v1.21.4 \r\n\u001b[0;1;37mesh\u001b[0;m \u001b[0;1;32m❯\u001b[0;m \r\u001b[6C\u001b[?25h"]
+[0.456695, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[0;32me\u001b[0;m\r\u001b[7C\u001b[?25h"]
+[0.457047, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[7C\u001b[?25h"]
+[0.457406, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[7C\u001b[?25h"]
+[0.476703, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[7C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[7C\u001b[?25h"]
+[0.476774, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[7C\u001b[?25h"]
+[0.661672, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[K\u001b[0;31mex\u001b[0;m\r\u001b[8C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[8C\u001b[?25h"]
+[0.756942, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[K\u001b[0;32mexa\u001b[0;m\r\u001b[9C\u001b[?25h"]
+[0.757869, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[9C\u001b[?25h"]
+[0.758057, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[9C\u001b[?25h"]
+[0.915507, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[K\u001b[0;31mexam\u001b[0;m\r\u001b[10C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[10C\u001b[?25h"]
+[0.972819, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[10C\u001b[0;31mp\u001b[0;m\r\u001b[11C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[11C\u001b[?25h"]
+[1.088957, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[11C\u001b[0;31ml\u001b[0;m\r\u001b[12C\u001b[?25h"]
+[1.242635, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[K\u001b[0;32mexample\u001b[0;m\r\u001b[13C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[13C\u001b[?25h"]
+[1.318984, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[13C \r\u001b[14C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[14C\u001b[?25h"]
+[1.421313, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[14Ca\r\u001b[15C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[15C\u001b[?25h"]
+[1.565644, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[15Cc\r\u001b[16C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[16C\u001b[?25h"]
+[1.789857, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[16Ct\r\u001b[17C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[17C\u001b[?25h"]
+[1.861419, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[17Ci\r\u001b[18C\u001b[?25h"]
+[1.861572, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[18C\u001b[?25h"]
+[1.953279, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[18Co\r\u001b[19C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[19C\u001b[?25h"]
+[2.001547, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[19Cn\r\u001b[20C\u001b[?25h"]
+[2.001701, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[20C\u001b[?25h"]
+[2.133981, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[20C \r\u001b[21C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[21C\u001b[?25h"]
+[2.297596, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[21C-\r\u001b[22C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[22C\u001b[?25h"]
+[2.449595, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[22C-\r\u001b[23C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[23C\u001b[?25h"]
+[2.665291, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[23Cc\r\u001b[24C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[24C\u001b[?25h"]
+[2.769879, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[24Co\r\u001b[25C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[25C\u001b[?25h"]
+[2.920473, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[21C\u001b[K\u001b[0;4m--cobra \r\n\u001b[0;1;37;45m COMPLETING argument \u001b[0;m \r\n\u001b[0;7;34m--cobra\u001b[0;2;7m (ActionCobra())\u001b[0;m  \u001b[0;34m--commands\u001b[0;2m (ActionCommands())\u001b[0;m\u001b[1A\r\u001b[22C\u001b[?25h"]
+[3.679034, "o", "\u001b[?25l\u001b[3A\r\r\n\r\n\u001b[21C\u001b[K--cobra \r\n\u001b[J\u001b[A\r\u001b[29C\u001b[?25h"]
+[4.167667, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[29C\u001b[0;4mone\r\n\u001b[0;1;37;45m COMPLETING argument \u001b[0;m \r\n\u001b[0;7mone\u001b[0;m  two\u001b[1A\r\u001b[22C\u001b[?25h"]
+[5.054262, "o", "\u001b[?25l\u001b[3A\r\r\n\r\n\u001b[29C\u001b[K\u001b[0;4mtwo\r\n\r\n\u001b[0;m\u001b[Kone  \u001b[0;7mtwo\u001b[0;m\u001b[1A\r\u001b[22C\u001b[?25h"]
+[6.629692, "o", "\u001b[?25l\u001b[3A\r\r\n\r\n\u001b[29C\u001b[Ktwo\r\n\u001b[J\u001b[A\r\u001b[32C\u001b[?25h"]
+[6.629826, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[32C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[32C\u001b[?25h"]
+[7.230671, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[K\r\u001b[6C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[6C\u001b[?25h"]
+[7.231617, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[6C\u001b[?25h"]
+[7.25196, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[6C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[6C\u001b[?25h"]
+[7.471051, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[0;32me\u001b[0;m\r\u001b[7C\u001b[?25h"]
+[7.471209, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[7C\u001b[?25h"]
+[7.684061, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[K\u001b[0;31mex\u001b[0;m\r\u001b[8C\u001b[?25h"]
+[7.684762, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[8C\u001b[?25h"]
+[7.688565, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[8C\u001b[?25h"]
+[7.688621, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[8C\u001b[?25h"]
+[7.816432, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[8C\u001b[0;31mi\u001b[0;m\r\u001b[9C\u001b[?25h"]
+[7.907227, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\u001b[6C\u001b[K\u001b[0;32mexit\u001b[0;m\r\u001b[10C\u001b[?25h\u001b[?25l\u001b[2A\r\r\n\r\n\r\u001b[10C\u001b[?25h"]
+[8.0253, "o", "\u001b[?25l\u001b[2A\r\r\n\r\n\r\n\r\u001b[?25h\u001b[?7h\u001b[?2004l\r"]

docs/src/carapace/defaultActions/actionCobra.md

@@ -0,0 +1,13 @@
+# ActionCobra
+
+[`ActionCobra`] bridges given cobra completion function.
+
+```go
+carapace.ActionCobra(func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+	return []string{"one", "two"}, cobra.ShellCompDirectiveNoSpace
+})
+```
+
+![](./actionCobra.cast)
+
+[`ActionCobra`]:https://pkg.go.dev/github.com/rsteube/carapace#ActionCobra

example/cmd/action.go

@@ -21,6 +21,7 @@ func init() {
 	rootCmd.AddCommand(actionCmd)
 
 	actionCmd.Flags().String("callback", "", "ActionCallback()")
+	actionCmd.Flags().String("cobra", "", "ActionCobra()")
 	actionCmd.Flags().String("commands", "", "ActionCommands()")
 	actionCmd.Flags().String("directories", "", "ActionDirectories()")
 	actionCmd.Flags().String("execcommand", "", "ActionExecCommand()")
@@ -49,6 +50,9 @@ func init() {
 			}
 			return carapace.ActionMessage("values flag is not set")
 		}),
+		"cobra": carapace.ActionCobra(func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+			return []string{"one", "two"}, cobra.ShellCompDirectiveNoSpace
+		}),
 		"commands":    carapace.ActionCommands(rootCmd).Split(),
 		"directories": carapace.ActionDirectories(),
 		"execcommand": carapace.ActionExecCommand("git", "remote")(func(output []byte) carapace.Action {

example/cmd/action_test.go

@@ -24,6 +24,13 @@ func TestAction(t *testing.T) {
 			Expect(carapace.ActionMessage("values flag is not set").
 				Usage("ActionCallback()"))
 
+		s.Run("action", "--cobra", "").
+			Expect(carapace.ActionValues(
+				"one",
+				"two",
+			).NoSpace().
+				Usage("ActionCobra()"))
+
 		s.Run("action", "--commands", "s").
 			Expect(carapace.ActionValuesDescribed(
 				"special", "",

example/cmd/compat.go

@@ -0,0 +1,87 @@
+package cmd
+
+import (
+	"fmt"
+
+	"github.com/rsteube/carapace"
+	"github.com/spf13/cobra"
+)
+
+var compatCmd = &cobra.Command{
+	Use:   "compat",
+	Short: "",
+	Run:   func(cmd *cobra.Command, args []string) {},
+}
+
+func init() {
+	carapace.Gen(compatCmd).Standalone()
+
+	compatCmd.Flags()
+
+	compatCmd.Flags().String("error", "", "ShellCompDirectiveError")
+	compatCmd.Flags().String("nospace", "", "ShellCompDirectiveNoSpace")
+	compatCmd.Flags().String("nofilecomp", "", "ShellCompDirectiveNoFileComp")
+	compatCmd.Flags().String("filterfileext", "", "ShellCompDirectiveFilterFileExt")
+	compatCmd.Flags().String("filterdirs", "", "ShellCompDirectiveFilterDirs")
+	compatCmd.Flags().String("filterdirs-chdir", "", "ShellCompDirectiveFilterDirs")
+	compatCmd.Flags().String("keeporder", "", "ShellCompDirectiveKeepOrder")
+	compatCmd.Flags().String("default", "", "ShellCompDirectiveDefault")
+
+	compatCmd.Flags().String("unset", "", "no completions defined")
+	compatCmd.PersistentFlags().String("persistent-compat", "", "persistent flag defined with cobra")
+
+	rootCmd.AddCommand(compatCmd)
+
+	_ = compatCmd.RegisterFlagCompletionFunc("error", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return nil, cobra.ShellCompDirectiveError
+	})
+	_ = compatCmd.RegisterFlagCompletionFunc("nospace", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return []string{"one", "two"}, cobra.ShellCompDirectiveNoSpace
+	})
+	_ = compatCmd.RegisterFlagCompletionFunc("nofilecomp", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	})
+
+	_ = compatCmd.RegisterFlagCompletionFunc("filterfileext", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return []string{"mod", "sum"}, cobra.ShellCompDirectiveFilterFileExt
+	})
+
+	_ = compatCmd.RegisterFlagCompletionFunc("filterdirs", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return nil, cobra.ShellCompDirectiveFilterDirs
+	})
+
+	_ = compatCmd.RegisterFlagCompletionFunc("filterdirs-chdir", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return []string{"subdir"}, cobra.ShellCompDirectiveFilterDirs
+	})
+
+	_ = compatCmd.RegisterFlagCompletionFunc("keeporder", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return []string{"one", "three", "two"}, cobra.ShellCompDirectiveKeepOrder
+	})
+
+	_ = compatCmd.RegisterFlagCompletionFunc("default", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return nil, cobra.ShellCompDirectiveDefault
+	})
+
+	_ = compatCmd.RegisterFlagCompletionFunc("persistent-compat", func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		return []string{
+			fmt.Sprintf("args: %#v toComplete: %#v", args, toComplete),
+			"alternative",
+		}, cobra.ShellCompDirectiveNoFileComp
+	})
+
+	compatCmd.ValidArgsFunction = func(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
+		switch len(args) {
+		case 0:
+			return []string{"p1", "positional1"}, cobra.ShellCompDirectiveDefault
+		case 1:
+			return nil, cobra.ShellCompDirectiveDefault
+		case 2:
+			return []string{
+				fmt.Sprintf("args: %#v toComplete: %#v", args, toComplete),
+				"alternative",
+			}, cobra.ShellCompDirectiveNoFileComp
+		default:
+			return nil, cobra.ShellCompDirectiveNoFileComp
+		}
+	}
+}

example/cmd/compat_sub.go

@@ -0,0 +1,18 @@
+package cmd
+
+import (
+	"github.com/rsteube/carapace"
+	"github.com/spf13/cobra"
+)
+
+var compat_subCmd = &cobra.Command{
+	Use:   "sub",
+	Short: "",
+	Run:   func(cmd *cobra.Command, args []string) {},
+}
+
+func init() {
+	carapace.Gen(compat_subCmd).Standalone()
+
+	compatCmd.AddCommand(compat_subCmd)
+}