Disable completion after the 'help'/'version' flag

If the 'help' and/or 'version' flag are the ones added by Cobra, we
know they should not be followed by anything, we therefore turn off
file completion.

If a program sets its own 'help' or 'version' flag, it can disable
file completion following those flags by using ValidArgsFunction on
the command on which those flags apply.

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

command.go

@@ -30,6 +30,8 @@ import (
 	flag "github.com/spf13/pflag"
 )
 
+const FlagSetByCobraAnnotation = "cobra_annotation_flag_set_by_cobra"
+
 // FParseErrWhitelist configures Flag parse errors to be ignored
 type FParseErrWhitelist flag.ParseErrorsWhitelist
 
@@ -1055,6 +1057,7 @@ func (c *Command) InitDefaultHelpFlag() {
 			usage += c.Name()
 		}
 		c.Flags().BoolP("help", "h", false, usage)
+		_ = c.Flags().SetAnnotation("help", FlagSetByCobraAnnotation, []string{"true"})
 	}
 }
 
@@ -1080,6 +1083,7 @@ func (c *Command) InitDefaultVersionFlag() {
 		} else {
 			c.Flags().Bool("version", false, usage)
 		}
+		_ = c.Flags().SetAnnotation("version", FlagSetByCobraAnnotation, []string{"true"})
 	}
 }
 

completions.go

@@ -407,6 +407,12 @@ func (c *Command) getCompletions(args []string) (*Command, []string, ShellCompDi
 				finalCmd.NonInheritedFlags().VisitAll(func(flag *pflag.Flag) {
 					if localNonPersistentFlags.Lookup(flag.Name) != nil && flag.Changed {
 						foundLocalNonPersistentFlag = true
+						if (flag.Name == "help" || flag.Name == "version") &&
+							len(flag.Annotations[FlagSetByCobraAnnotation]) > 0 {
+							// We have the 'help' or 'version' flag and it was set
+							// by Cobra.  We know neither should be followed by anything.
+							directive = ShellCompDirectiveNoFileComp
+						}
 					}
 				})
 			}

completions_test.go

@@ -2923,3 +2923,93 @@ func TestCompletionForMutuallyExclusiveFlags(t *testing.T) {
 		})
 	}
 }
+
+func TestCompletionCobraFlags(t *testing.T) {
+	getCmd := func() *Command {
+		rootCmd := &Command{
+			Use:     "root",
+			Version: "1.1.1",
+			Run:     emptyRun,
+		}
+		childCmd := &Command{
+			Use: "child",
+			Run: emptyRun,
+		}
+		rootCmd.AddCommand(childCmd)
+
+		return rootCmd
+	}
+
+	// Each test case uses a unique command from the function above.
+	testcases := []struct {
+		desc           string
+		args           []string
+		expectedOutput string
+	}{
+		{
+			desc: "completion of --help flag",
+			args: []string{"-"},
+			expectedOutput: strings.Join([]string{
+				"--help",
+				"-h",
+				"--version",
+				"-v",
+				":4",
+				"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n"),
+		},
+		{
+			desc: "completion of --help flag value",
+			args: []string{"--help", ""},
+			expectedOutput: strings.Join([]string{
+				":4",
+				"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n"),
+		},
+		{
+			desc: "completion of -h flag value",
+			args: []string{"-h", ""},
+			expectedOutput: strings.Join([]string{
+				":4",
+				"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n"),
+		},
+		{
+			desc: "completion of --version flag",
+			args: []string{"-"},
+			expectedOutput: strings.Join([]string{
+				"--help",
+				"-h",
+				"--version",
+				"-v",
+				":4",
+				"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n"),
+		},
+		{
+			desc: "completion of --version flag value",
+			args: []string{"--version", ""},
+			expectedOutput: strings.Join([]string{
+				":4",
+				"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n"),
+		},
+		{
+			desc: "completion of -v flag value",
+			args: []string{"-v", ""},
+			expectedOutput: strings.Join([]string{
+				":4",
+				"Completion ended with directive: ShellCompDirectiveNoFileComp", ""}, "\n"),
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.desc, func(t *testing.T) {
+			c := getCmd()
+			args := []string{ShellCompNoDescRequestCmd}
+			args = append(args, tc.args...)
+			output, err := executeCommand(c, args...)
+			switch {
+			case err == nil && output != tc.expectedOutput:
+				t.Errorf("expected: %q, got: %q", tc.expectedOutput, output)
+			case err != nil:
+				t.Errorf("Unexpected error %q", err)
+			}
+		})
+	}
+}