Dropped: Procedure Syntax

Procedure syntax

def f() { ... }

has been dropped. You need to write one of the following instead:

def f() = { ... }
def f(): Unit = { ... }

Scala 3 accepts the old syntax under the -source:3.0-migration option. If the -migration option is set, it can even rewrite old syntax to new. The Scalafix tool also can rewrite procedure syntax to make it Scala 3 compatible.