Improve parse error reporting of apt and apama plugins

2 files changed, 12 insertions, 4 deletions

diff --git a/plugins/tedge_apama_plugin/src/main.rs b/plugins/tedge_apama_plugin/src/main.rs
index 9614e6f3..7ec18a8d 100644
--- a/plugins/tedge_apama_plugin/src/main.rs
+++ b/plugins/tedge_apama_plugin/src/main.rs
@@ -1,7 +1,7 @@
 mod error;
 
 use crate::error::InternalError;
-use clap::Parser;
+use clap::{IntoApp, Parser};
 use std::fs::{self, File};
 use std::io::ErrorKind;
 use std::path::Path;
@@ -302,7 +302,11 @@ fn main() {
     // On usage error, the process exits with a status code of 1
     let apama = match ApamaCli::try_parse() {
         Ok(apamacli) => apamacli,
-        Err(_e) => {
+        Err(err) => {
+            eprintln!("ERROR: {}", err);
+            ApamaCli::command()
+                .print_help()
+                .expect("Failed to print command usage help message");
             // re-write the clap exit_status from 2 to 1, if parse fails
             std::process::exit(1)
         }
diff --git a/plugins/tedge_apt_plugin/src/main.rs b/plugins/tedge_apt_plugin/src/main.rs
index cd74fe60..ed221d39 100644
--- a/plugins/tedge_apt_plugin/src/main.rs
+++ b/plugins/tedge_apt_plugin/src/main.rs
@@ -3,7 +3,7 @@ mod module_check;
 
 use crate::error::InternalError;
 use crate::module_check::PackageMetadata;
-use clap::Parser;
+use clap::{IntoApp, Parser};
 use serde::Deserialize;
 use std::io::{self};
 use std::process::{Command, ExitStatus, Stdio};
@@ -238,7 +238,11 @@ fn main() {
 
     let apt = match AptCli::try_parse() {
         Ok(aptcli) => aptcli,
-        Err(_e) => {
+        Err(err) => {
+            eprintln!("ERROR: {}", err);
+            AptCli::command()
+                .print_help()
+                .expect("Failed to print usage help");
             // re-write the clap exit_status from 2 to 1, if parse fails
             std::process::exit(1)
         }