Pass arguments to the help function

Signed-off-by: Marc Khouzam <marc.khouzam@gmail.com>

command.go

@@ -470,8 +470,11 @@ func (c *Command) HelpFunc() func(*Command, []string) {
 }
 
 // Help puts out the help for the command.
-// Used when a user calls help [command].
-// Can be defined by user by overriding HelpFunc.
+// Kept for backwards compatibility.
+// No longer used because it does not allow
+// to pass arguments to the help command.
+// Can be a simple way to trigger the help
+// if arguments are not needed.
 func (c *Command) Help() error {
 	c.HelpFunc()(c, []string{})
 	return nil
@@ -1119,7 +1122,13 @@ func (c *Command) ExecuteC() (cmd *Command, err error) {
 		// Always show help if requested, even if SilenceErrors is in
 		// effect
 		if errors.Is(err, flag.ErrHelp) {
-			cmd.HelpFunc()(cmd, args)
+			// The call to execute() above has parsed the flags.
+			// We therefore only pass the remaining arguments to the help function.
+			argWoFlags := cmd.Flags().Args()
+			if cmd.DisableFlagParsing {
+				argWoFlags = flags
+			}
+			cmd.HelpFunc()(cmd, argWoFlags)
 			return cmd, nil
 		}
 
@@ -1260,14 +1269,14 @@ Simply type ` + c.displayName() + ` help [path to command] for full details.`,
 				return completions, ShellCompDirectiveNoFileComp
 			},
 			Run: func(c *Command, args []string) {
-				cmd, _, e := c.Root().Find(args)
+				cmd, remainingArgs, e := c.Root().Find(args)
 				if cmd == nil || e != nil {
 					c.Printf("Unknown help topic %#q\n", args)
 					CheckErr(c.Root().Usage())
 				} else {
 					cmd.InitDefaultHelpFlag()    // make possible 'help' flag to be shown
 					cmd.InitDefaultVersionFlag() // make possible 'version' flag to be shown
-					CheckErr(cmd.Help())
+					cmd.HelpFunc()(cmd, remainingArgs)
 				}
 			},
 			GroupID: c.helpCommandGroupID,

command_test.go

@@ -12,6 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
+//nolint:goconst
 package cobra
 
 import (
@@ -1079,6 +1080,192 @@ func TestHelpExecutedOnNonRunnableChild(t *testing.T) {
 	checkStringContains(t, output, childCmd.Long)
 }
 
+func TestHelpOverrideOnRoot(t *testing.T) {
+	var helpCalled bool
+	rootCmd := &Command{Use: "root"}
+	rootCmd.SetHelpFunc(func(c *Command, args []string) {
+		helpCalled = true
+		if c.Name() != "root" {
+			t.Errorf(`Expected command name: "root", got %q`, c.Name())
+		}
+		if len(args) != 2 || args[0] != "arg1" || args[1] != "arg2" {
+			t.Errorf("Expected args [args1 arg2], got %v", args)
+		}
+	})
+
+	_, err := executeCommand(rootCmd, "arg1", "arg2", "--help")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !helpCalled {
+		t.Error("Overridden help function not called")
+	}
+}
+
+func TestHelpOverrideOnChild(t *testing.T) {
+	var helpCalled bool
+	rootCmd := &Command{Use: "root"}
+	subCmd := &Command{Use: "child"}
+	rootCmd.AddCommand(subCmd)
+
+	subCmd.SetHelpFunc(func(c *Command, args []string) {
+		helpCalled = true
+		if c.Name() != "child" {
+			t.Errorf(`Expected command name: "child", got %q`, c.Name())
+		}
+		if len(args) != 2 || args[0] != "arg1" || args[1] != "arg2" {
+			t.Errorf("Expected args [args1 arg2], got %v", args)
+		}
+	})
+
+	_, err := executeCommand(rootCmd, "child", "arg1", "arg2", "--help")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !helpCalled {
+		t.Error("Overridden help function not called")
+	}
+}
+
+func TestHelpOverrideOnRootWithChild(t *testing.T) {
+	var helpCalled bool
+	rootCmd := &Command{Use: "root"}
+	subCmd := &Command{Use: "child"}
+	rootCmd.AddCommand(subCmd)
+
+	rootCmd.SetHelpFunc(func(c *Command, args []string) {
+		helpCalled = true
+		if c.Name() != "child" {
+			t.Errorf(`Expected command name: "child", got %q`, c.Name())
+		}
+		if len(args) != 2 || args[0] != "arg1" || args[1] != "arg2" {
+			t.Errorf("Expected args [args1 arg2], got %v", args)
+		}
+	})
+
+	_, err := executeCommand(rootCmd, "child", "arg1", "arg2", "--help")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !helpCalled {
+		t.Error("Overridden help function not called")
+	}
+}
+
+func TestHelpOverrideOnRootWithChildAndFlags(t *testing.T) {
+	var helpCalled bool
+	rootCmd := &Command{Use: "root"}
+	subCmd := &Command{Use: "child"}
+	rootCmd.AddCommand(subCmd)
+
+	var myFlag bool
+	subCmd.Flags().BoolVar(&myFlag, "myflag", false, "")
+
+	rootCmd.SetHelpFunc(func(c *Command, args []string) {
+		helpCalled = true
+		if c.Name() != "child" {
+			t.Errorf(`Expected command name: "child", got %q`, c.Name())
+		}
+		if len(args) != 2 || args[0] != "arg1" || args[1] != "arg2" {
+			t.Errorf("Expected args [args1 arg2], got %v", args)
+		}
+	})
+
+	_, err := executeCommand(rootCmd, "child", "arg1", "--myflag", "arg2", "--help")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !helpCalled {
+		t.Error("Overridden help function not called")
+	}
+}
+
+func TestHelpOverrideOnRootWithChildAndFlagsButParsingDisabled(t *testing.T) {
+	var helpCalled bool
+	rootCmd := &Command{Use: "root"}
+	subCmd := &Command{Use: "child", DisableFlagParsing: true}
+	rootCmd.AddCommand(subCmd)
+
+	var myFlag bool
+	subCmd.Flags().BoolVar(&myFlag, "myflag", false, "")
+
+	rootCmd.SetHelpFunc(func(c *Command, args []string) {
+		helpCalled = true
+		if c.Name() != "child" {
+			t.Errorf(`Expected command name: "child", got %q`, c.Name())
+		}
+		if len(args) != 4 ||
+			args[0] != "arg1" || args[1] != "--myflag" || args[2] != "arg2" || args[3] != "--help" {
+			t.Errorf("Expected args [args1 --myflag arg2 --help], got %v", args)
+		}
+	})
+
+	_, err := executeCommand(rootCmd, "child", "arg1", "--myflag", "arg2", "--help")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !helpCalled {
+		t.Error("Overridden help function not called")
+	}
+}
+
+func TestHelpCommandOverrideOnChild(t *testing.T) {
+	var helpCalled bool
+	rootCmd := &Command{Use: "root"}
+	subCmd := &Command{Use: "child"}
+	rootCmd.AddCommand(subCmd)
+
+	subCmd.SetHelpFunc(func(c *Command, args []string) {
+		helpCalled = true
+		if c.Name() != "child" {
+			t.Errorf(`Expected command name: "child", got %q`, c.Name())
+		}
+		if len(args) != 2 || args[0] != "arg1" || args[1] != "arg2" {
+			t.Errorf("Expected args [args1 arg2], got %v", args)
+		}
+	})
+
+	_, err := executeCommand(rootCmd, "help", "child", "arg1", "arg2")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !helpCalled {
+		t.Error("Overridden help function not called")
+	}
+}
+
+func TestHelpCommandOverrideOnRootWithChild(t *testing.T) {
+	var helpCalled bool
+	rootCmd := &Command{Use: "root"}
+	subCmd := &Command{Use: "child"}
+	rootCmd.AddCommand(subCmd)
+
+	rootCmd.SetHelpFunc(func(c *Command, args []string) {
+		helpCalled = true
+		if c.Name() != "child" {
+			t.Errorf(`Expected command name: "child", got %q`, c.Name())
+		}
+		if len(args) != 2 || args[0] != "arg1" || args[1] != "arg2" {
+			t.Errorf("Expected args [args1 arg2], got %v", args)
+		}
+	})
+
+	_, err := executeCommand(rootCmd, "help", "child", "arg1", "arg2")
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if !helpCalled {
+		t.Error("Overridden help function not called")
+	}
+}
+
 func TestVersionFlagExecuted(t *testing.T) {
 	rootCmd := &Command{Use: "root", Version: "1.0.0", Run: emptyRun}