[SPARK-33285] Too many "Auto-application to `()` is deprecated." related compilation warnings

• Type: Improvement
• Status: In Progress
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 3.1.0
• Component/s: Build
• Assignee: Unassigned
• Reporter: Yang Jie
• Created: 29/Oct/20 09:34
• Updated: 08/Dec/20 05:51

Description

There are too many  "Auto-application to `()` is deprecated." related compilation warnings when compile with Scala 2.13 like

[WARNING] [Warn] /spark-src/core/src/test/scala/org/apache/spark/PartitioningSuite.scala:246: Auto-application to `()` is deprecated. Supply the empty argument list `()` explicitly to invoke method stdev,
or remove the empty argument list from its definition (Java-defined methods are exempt).
In Scala 3, an unapplied method like this will be eta-expanded into a function.

A lot of them, but it's easy to fix.

If there is a definition as follows:

Class Foo {
   def bar(): Unit = {}
}

val foo = new Foo

Should be

foo.bar()

not

foo.bar 

Issue Links

• links to: [Github] Pull Request #30234 (LuciferYang)