Scala 2.13.1 regression: Crash on lazy vals initialised from class parameters

[TJC]

Description

Regression when upgrading from Scala 2.12.10 to 2.13.1:
'lazy vals' cause java.lang.IllegalAccessError if they are initialised with a class parameter.

class LazyConstructors(thingCons: (String) => MyThing) {
  lazy val thing: MyThing = thingCons("foo")
  def callMe = thing.toString
}

java.lang.IllegalAccessError: Update to non-static final field example.LazyConstructors.thingCons attempted from a different method (thing$lzycompute) than the initializer method <init> .

Workaround

In the above code, making this change results in the code no longer crashing -- just defining the class parameter as a val

class LazyConstructors(val thingCons: (String) => MyThing)

Environment:

• Scala 2.13.1
• OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.3+7, mixed mode)
• sbt 1.3.7

Runnable code demonstrating issue

https://github.com/TJC/scala-2.13-lazy-val-issue

Check out the repo, ensure you have JDK 11, and then run sbt test

[TJC]

Looks like this is a duplicate of #11781 ?

[som-snytt]

Did that fix not merge forward?

Maybe scala/scala#8648

[som-snytt]

The fix just missed the previous forward merge by a couple of days.

[TJC]

Ah, oh no!
But it'll definitely be coming along in 2.13.2 then? That's good to know.

[dwijnand]

Yep.