Handle null completions with a default callback

Credits to thaJeztah

Signed-off-by: Harald Albers <github@albersweb.de>
(cherry picked from commit 06260e68f3)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

cli/command/container/create.go

@@ -80,6 +80,13 @@ func NewCreateCommand(dockerCli command.Cli) *cobra.Command {
 
 	addCompletions(cmd, dockerCli)
 
+	flags.VisitAll(func(flag *pflag.Flag) {
+		// Set a default completion function if none was set. We don't look
+		// up if it does already have one set, because Cobra does this for
+		// us, and returns an error (which we ignore for this reason).
+		_ = cmd.RegisterFlagCompletionFunc(flag.Name, completion.NoComplete)
+	})
+
 	return cmd
 }
 

cli/command/container/run.go

@@ -72,6 +72,13 @@ func NewRunCommand(dockerCli command.Cli) *cobra.Command {
 	_ = cmd.RegisterFlagCompletionFunc("detach-keys", completeDetachKeys)
 	addCompletions(cmd, dockerCli)
 
+	flags.VisitAll(func(flag *pflag.Flag) {
+		// Set a default completion function if none was set. We don't look
+		// up if it does already have one set, because Cobra does this for
+		// us, and returns an error (which we ignore for this reason).
+		_ = cmd.RegisterFlagCompletionFunc(flag.Name, completion.NoComplete)
+	})
+
 	return cmd
 }