[SPARK-26977] Warn against subclassing scala.App doesn't work

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 2.4.0
• Fix Version/s: 3.0.0
• Component/s: Spark Submit
• Assignee: Manu Zhang
• Reporter: Manu Zhang
• Created: 23/Feb/19 03:18
• Updated: 02/Mar/19 08:33
• Resolved: 01/Mar/19 23:38

Description

As per discussion in PR#3497, the warn against subclassing scala.App doesn't work. For example,

object Test extends scala.App {
   // spark code
}

Scala will compile object Test into two Java classes, Test passed in by user and Test$ subclassing scala.App. Currect code checks against Test and thus there will be no warn when user's application subclassing scala.App

Issue Links

• links to: GitHub Pull Request #23896
• links to: GitHub Pull Request #23903