Tweak some type class derivations

Hopefully will address more-or-less random failures, on the CI in
particular

cli/src/main/scala-2.11/coursier/cli/Coursier.scala

@@ -2,8 +2,12 @@ package coursier
 package cli
 
 import caseapp._
-import caseapp.core.{ ArgsApp, CommandsMessages }
+import caseapp.core.{ ArgsApp, CommandMessages, CommandsMessages }
+import caseapp.core.util.pascalCaseSplit
+import caseapp.util.AnnotationOption
 
+import shapeless._
+import shapeless.labelled.FieldType
 import shapeless.union.Union
 
 // Temporary, see comment in Coursier below
@@ -21,10 +25,95 @@ final case class CoursierCommandHelper(
 object CoursierCommandHelper {
   type U = Union.`'bootstrap -> Bootstrap, 'fetch -> Fetch, 'launch -> Launch, 'resolve -> Resolve, 'sparksubmit -> SparkSubmit`.T
 
-  implicit val commandParser: CommandParser[CoursierCommandHelper] =
+  // Partially deriving these ones manually, to circumvent more-or-less random failures during auto derivation
-    CommandParser[U].map(CoursierCommandHelper(_))
+  // Only running into those with the new custom sbt launcher though :-|
-  implicit val commandsMessages: CommandsMessages[CoursierCommandHelper] =
+
-    CommandsMessages(CommandsMessages[U].messages)
+  implicit def commandParser: CommandParser[CoursierCommandHelper] =
+    CommandParser.ccons(
+      Witness('bootstrap),
+      AnnotationOption[CommandName, Bootstrap],
+      Parser[Bootstrap],
+      CommandParser.ccons(
+        Witness('fetch),
+        AnnotationOption[CommandName, Fetch],
+        Parser[Fetch],
+        CommandParser.ccons(
+          Witness('launch),
+          AnnotationOption[CommandName, Launch],
+          Parser[Launch],
+          CommandParser.ccons(
+            Witness('resolve),
+            AnnotationOption[CommandName, Resolve],
+            Parser[Resolve],
+            CommandParser.ccons(
+              Witness('sparksubmit),
+              AnnotationOption[CommandName, SparkSubmit],
+              Parser[SparkSubmit],
+              CommandParser.cnil
+            )
+          )
+        )
+      )
+    ).map(CoursierCommandHelper(_))
+
+
+  // Cut-n-pasted from caseapp.core.CommandsMessages.ccons, fixing the type of argsName
+  private def commandsMessagesCCons[K <: Symbol, H, T <: Coproduct]
+   (implicit
+     key: Witness.Aux[K],
+     commandName: AnnotationOption[CommandName, H],
+     parser: Strict[Parser[H]],
+     argsName: AnnotationOption[ArgsName, H],
+     tail: CommandsMessages[T]
+   ): CommandsMessages[FieldType[K, H] :+: T] = {
+    // FIXME Duplicated in CommandParser.ccons
+    val name = commandName().map(_.commandName).getOrElse {
+      pascalCaseSplit(key.value.name.toList.takeWhile(_ != '$'))
+        .map(_.toLowerCase)
+        .mkString("-")
+    }
+
+    CommandsMessages((name -> CommandMessages(
+      parser.value.args,
+      argsName().map(_.argsName)
+    )) +: tail.messages)
+  }
+
+
+  implicit def commandsMessages: CommandsMessages[CoursierCommandHelper] =
+    CommandsMessages(
+      commandsMessagesCCons(
+        Witness('bootstrap),
+        AnnotationOption[CommandName, Bootstrap],
+        Parser[Bootstrap],
+        AnnotationOption[ArgsName, Bootstrap],
+        commandsMessagesCCons(
+          Witness('fetch),
+          AnnotationOption[CommandName, Fetch],
+          Parser[Fetch],
+          AnnotationOption[ArgsName, Fetch],
+          commandsMessagesCCons(
+            Witness('launch),
+            AnnotationOption[CommandName, Launch],
+            Parser[Launch],
+            AnnotationOption[ArgsName, Launch],
+            commandsMessagesCCons(
+              Witness('resolve),
+              AnnotationOption[CommandName, Resolve],
+              Parser[Resolve],
+              AnnotationOption[ArgsName, Resolve],
+              commandsMessagesCCons(
+                Witness('sparksubmit),
+                AnnotationOption[CommandName, SparkSubmit],
+                Parser[SparkSubmit],
+                AnnotationOption[ArgsName, SparkSubmit],
+                CommandsMessages.cnil
+              )
+            )
+          )
+        )
+      ).messages
+    )
 }
 
 object Coursier extends CommandAppOf[