Fix bug where subcommand's positional args aren't captured

command.go

@@ -210,6 +210,8 @@ func (c *Command) Execute() error {
 	// cmd here will be c.
 	cmd, args := findRequestedCommand(c, c.args)
 
+	// Below this point, use cmd not c!
+
 	if err := cmd.flagSet().Parse(args); err != nil {
 		return fmt.Errorf("failed to parse command flags: %w", err)
 	}
@@ -257,22 +259,22 @@ func (c *Command) Execute() error {
 	//
 	// We're modifying the slice in place here, hence not using a range loop as it
 	// would take a copy of the c.positionalArgs slice
-	for i := 0; i < len(c.positionalArgs); i++ {
+	for i := 0; i < len(cmd.positionalArgs); i++ {
 		if i >= len(argsWithoutFlags) {
-			arg := c.positionalArgs[i]
+			arg := cmd.positionalArgs[i]
 
 			// If we've fallen off the end of argsWithoutFlags and the positionalArg at this
 			// index does not have a default, it means the arg was required but not provided
 			if arg.defaultValue == "" {
 				return fmt.Errorf("missing required argument %q, expected at position %d", arg.name, i)
 			}
 			// It does have a default, so use that instead
-			c.positionalArgs[i].value = arg.defaultValue
+			cmd.positionalArgs[i].value = arg.defaultValue
 		} else {
 			// We are in a valid index in both slices which means the named positional
 			// argument at this index was provided on the command line, so all we need
 			// to do is set its value
-			c.positionalArgs[i].value = argsWithoutFlags[i]
+			cmd.positionalArgs[i].value = argsWithoutFlags[i]
 		}
 	}
 

command_test.go

@@ -228,6 +228,18 @@ func TestSubCommandExecute(t *testing.T) {
 }
 
 func TestPositionalArgs(t *testing.T) {
+	sub := func() (*cli.Command, error) {
+		return cli.New(
+			"sub",
+			cli.Short("Sub command"),
+			cli.Arg("subarg", "Argument given to a subcommand", ""),
+			cli.Run(func(cmd *cli.Command, args []string) error {
+				fmt.Fprintf(cmd.Stdout(), "Hello from sub command, subarg: %s", cmd.Arg("subarg"))
+				return nil
+			}),
+		)
+	}
+
 	tests := []struct {
 		name    string       // The name of the test case
 		stdout  string       // The expected stdout
@@ -320,6 +332,15 @@ func TestPositionalArgs(t *testing.T) {
 			wantErr: true,
 			errMsg:  `missing required argument "something", expected at position 2`,
 		},
+		{
+			name: "subcommand with named arg",
+			options: []cli.Option{
+				cli.SubCommands(sub),
+			},
+			stdout:  "Hello from sub command, subarg: blah",
+			args:    []string{"sub", "blah"}, // subarg should be "blah"
+			wantErr: false,
+		},
 	}
 
 	for _, tt := range tests {