[SPARK-29291] Remove use of procedure-like method definition for 2.13

• Type: Sub-task
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: 3.0.0
• Fix Version/s: 3.0.0
• Component/s: Build, Spark Core
• Assignee: Sean R. Owen
• Reporter: Sean R. Owen
• Created: 29/Sep/19 19:55
• Updated: 04/Nov/20 11:09
• Resolved: 30/Sep/19 17:03

Description

Scala 2.13 warns where procedure-like syntax is used to define methods:

[WARNING] [Warn] /Users/seanowen/Documents/spark_2.13/core/src/main/scala/org/apache/spark/ContextCleaner.scala:74: procedure syntax is deprecated: instead, add `: Unit =` to explicitly declare `run`'s return type
...

There are a lot of them, but it's easy to fix.

def foo(): Unit = { }

not

def foo() { }

Issue Links

• links to: GitHub Pull Request #25968