From a4e27fcccf22cc99cf15410366f165e4b00fe1bd Mon Sep 17 00:00:00 2001
From: David Francoeur <dfrancoeur04@gmail.com>
Date: Fri, 1 Apr 2022 16:00:29 -0400
Subject: [PATCH] CommandApp exit with non-zero code on parse failure

JS implementation from:
https://github.com/alexarchambault/case-app/blob/d1da1ac55e97ce49748b84b2a99aecbb2d8452cd/core/js/src/main/scala/caseapp/core/app/PlatformUtil.scala
---
 .../src/main/scala/com/monovore/decline/PlatformApp.scala  | 7 +++++++
 .../src/main/scala/com/monovore/decline/PlatformApp.scala  | 4 ++++
 .../src/main/scala/com/monovore/decline/PlatformApp.scala  | 4 ++++
 .../src/main/scala/com/monovore/decline/CommandApp.scala   | 4 +++-
 4 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/core/js/src/main/scala/com/monovore/decline/PlatformApp.scala b/core/js/src/main/scala/com/monovore/decline/PlatformApp.scala
index 2ffa8ade..979ef905 100644
--- a/core/js/src/main/scala/com/monovore/decline/PlatformApp.scala
+++ b/core/js/src/main/scala/com/monovore/decline/PlatformApp.scala
@@ -2,6 +2,7 @@ package com.monovore.decline
 
 import scala.scalajs.js
 import scala.scalajs.js.annotation.JSGlobalScope
+import js.Dynamic.global
 
 object PlatformApp {
 
@@ -21,4 +22,10 @@ object PlatformApp {
    * otherwise.
    */
   def ambientArgs: Option[Seq[String]] = Process.process.toOption.map { _.argv.drop(2).toSeq }
+
+  private lazy val process = global.require("process")
+  def exit(code: Int): Nothing = {
+    process.exit(code)
+    sys.error(s"Attempt to exit with code $code failed")
+  }
 }
diff --git a/core/jvm/src/main/scala/com/monovore/decline/PlatformApp.scala b/core/jvm/src/main/scala/com/monovore/decline/PlatformApp.scala
index fbccb460..a6b7f278 100644
--- a/core/jvm/src/main/scala/com/monovore/decline/PlatformApp.scala
+++ b/core/jvm/src/main/scala/com/monovore/decline/PlatformApp.scala
@@ -7,4 +7,8 @@ object PlatformApp {
    * otherwise.
    */
   def ambientArgs: Option[Seq[String]] = None
+
+  def exit(code: Int): Nothing = {
+    sys.exit(code)
+  }
 }
diff --git a/core/native/src/main/scala/com/monovore/decline/PlatformApp.scala b/core/native/src/main/scala/com/monovore/decline/PlatformApp.scala
index fbccb460..a6b7f278 100644
--- a/core/native/src/main/scala/com/monovore/decline/PlatformApp.scala
+++ b/core/native/src/main/scala/com/monovore/decline/PlatformApp.scala
@@ -7,4 +7,8 @@ object PlatformApp {
    * otherwise.
    */
   def ambientArgs: Option[Seq[String]] = None
+
+  def exit(code: Int): Nothing = {
+    sys.exit(code)
+  }
 }
diff --git a/core/shared/src/main/scala/com/monovore/decline/CommandApp.scala b/core/shared/src/main/scala/com/monovore/decline/CommandApp.scala
index 5600fb02..02cc2718 100644
--- a/core/shared/src/main/scala/com/monovore/decline/CommandApp.scala
+++ b/core/shared/src/main/scala/com/monovore/decline/CommandApp.scala
@@ -50,7 +50,9 @@ For suggested usage, see: http://monovore.com/decline/usage.html#defining-an-app
   )
   final def main(args: Array[String]): Unit =
     command.parse(PlatformApp.ambientArgs getOrElse args, sys.env) match {
-      case Left(help) => System.err.println(help)
+      case Left(help) =>
+        System.err.println(help)
+        PlatformApp.exit(1)
       case Right(_) => ()
     }
 }