[KAFKA-9665] Scala compiler not producing unused warnings

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Component/s: build
• Assignee: David Arthur
• Reporter: David Arthur
• Created: 05/Mar/20 16:35
• Updated: 05/Mar/20 16:52

Description

While reviewing KAFKA-9661, I wondered about the compiler giving us a warning for unused locals. I ran the build locally and didn't see any warnings. Turns out Scala 2.12 doesn't support the compiler flag -Xlint:unused. Since we build with 2.12 by default, we can easily miss these warnings.

We should instead use -Ywarn-unused:locals and others which work for scalac 2.12 and 2.13.