Dropped: Procedure Syntax

Procedure syntax

def f() { ... }

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

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

Dotty will accept the old syntax under the -language:Scala2Compat 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 Dotty-compatible.