[GitHub] srowen commented on issue #23903: [SPARK-26977][CORE] Fix warn against subclassing scala.App

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srowen commented on issue #23903: [SPARK-26977][CORE] Fix warn against subclassing scala.App
URL: https://github.com/apache/spark/pull/23903#issuecomment-467933318
 
 
   I just tried compiling `object MyApp extends scala.App` with Scala 2.12 and I get in the bytecode...
   `public final class MyApp$ implements scala/App`.
   `class MyApp extends scala.App` yields `public class MyApp implements scala/App`. I don't see any `childMainClass`, etc.
   
   I am actually not sure if this ever worked with the `class` version... it tries to invoke a static main() method, but these classes don't get a static main(); they get a non-static main() though.
   
   I find that the current check works if you check whether "MyApp$" extends `scala.App`.
   I'd suggest we just add that to the condition?

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