Scala3 support patch 1 #29930

andreaTP · 2021-01-06T08:39:49Z

The first batch of unharmful patches toward Scala 3 compatibility.
If the CI is happy everything should be good 🙂

From the findings and discussions in #29929

Special thanks to @smarter for the support!

akka-ci · 2021-01-06T08:41:21Z

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raboof · 2021-01-06T08:59:49Z

project/Dependencies.scala

@@ -32,7 +32,7 @@ object Dependencies {

  val sslConfigVersion = "0.4.2"

-  val scalaTestVersion = "3.1.4"
+  val scalaTestVersion = "3.2.3"


looks like org.scalatestplus:mockito-3-3 was not released for scalaTest 3.2.3 (https://repo1.maven.org/maven2/org/scalatestplus/mockito-3-3_2.12/) - perhaps we should update to org.scalatestplus:mockito-3-4?

there's been some discussion on when to update to scalatest 3.2 in #29368

Thanks for the context @raboof !
Two options for moving forward:

I revert back the bump of ScalaTest for having this PR merged

we are in 2021 and we can possibly unblock the bump since @patriknw said:

we should be careful to not upset users with forcing another update this soon again

as you prefer.

can we use a different version of ScalaTest for Scala 3?

no, 3.2.3 is the only single release of scalatest published for Scala 3.
https://repo1.maven.org/maven2/org/scalatest/scalatest-core_3.0.0-M3/

Sorry, my question was unclear. I mean, can we use ScalaTest 3.1 for Scala 2 and ScalaTest 3.2 for Scala 3?

well, yes, this is an option.
If it unblocks this PR I can do that, but I think is much cleaner for Akka to keep using a single version of ScalaTest.
Also, I will probably have to switch also the Mockito and ScalaCheck versions, is it acceptable?

I don't think we have the bandwidth to investigate what an incompatible bumb of ScalaTest would mean for our Scala 2.12 and 2.13 users and especially the full Akka ecosystem of dependent libraries at this moment.
Quickest way forward for this PR would be to use a 3.2.3 only for Scala 3.

Ok, reverted the bump of ScalaTest and ScalaCheck (will do the switch after #29932 to avoid conflicts).
Kept the bump of Mockito though.

raboof · 2021-01-06T13:23:48Z

OK TO TEST

akka-ci · 2021-01-06T13:34:11Z

Test FAILed.

akka-ci · 2021-01-06T16:23:20Z

Test PASSed.

patriknw · 2021-01-09T14:02:01Z

akka-actor-tests/src/test/scala/akka/actor/TypedActorSpec.scala

@@ -72,7 +72,7 @@ object TypedActorSpec {

    @silent
    @throws(classOf[TimeoutException])
-    def self = TypedActor.self[Foo]
+    def self = akka.actor.TypedActor.self[Foo]


not that I care about this test, but why is this needed? isn't it in the same package?

In this file, Scala 3 is complaining about the ambiguous reference to TypedActor.
In between this object and a local class that comes from somewhere.

patriknw · 2021-01-09T14:10:13Z

akka-actor/src/main/scala/akka/actor/ActorPath.scala

@@ -87,7 +87,7 @@ object ActorPath {
  final def validatePathElement(element: String, fullPath: String): Unit = {
    def fullPathMsg = if (fullPath ne null) s""" (in path [$fullPath])""" else ""

-    (findInvalidPathElementCharPosition(element): @switch) match {
+    (findInvalidPathElementCharPosition(element)) match {


Does this make the match less efficient for Scala 2.12 and 2.13?
I'm not sure if this is used in any hot path but it could be since it's validating actor names. We use switch at more places so this might become a bigger problem if switch isn't supported.

Please note that I haven't removed all the @switch cases in the codebase but only 2.
In those cases the switch doesn't have enough cases and is not going to be optimized, Scala 2 silently accept the code while Scala 3 emits an error.

I added a comment with a note for the future, hope is enough.

patriknw · 2021-01-09T14:13:55Z

project/Dependencies.scala

@@ -32,7 +32,7 @@ object Dependencies {

  val sslConfigVersion = "0.4.2"

-  val scalaTestVersion = "3.1.4"
+  val scalaTestVersion = "3.2.3"


can we use a different version of ScalaTest for Scala 3?

akka-ci · 2021-01-09T18:30:59Z

Test PASSed.

akka-ci · 2021-01-11T11:21:00Z

Test PASSed.

patriknw · 2021-01-25T12:08:18Z

Superseded by #29956, I assume

andreaTP added 9 commits January 6, 2021 07:38

Remove @switch when it doesn't take effect

3c34377

Use ActorRef.noSender

553d960

Minor tweaks to SchedulerSpec

ed07adf

Disambiguate TypedActor for Scala 3

ef8538f

Bump ScalaTest to a version compatible with Scala 3

8f19ac1

Bump ScalaCheck

6f6277d

Disambiguate Event in SupervisorHierarchySpec

4d3579b

Scala 3 compatible EventBusSpec

5810bb3

Prevent private unused variables to be erased by Scala 3

d639f8d

probot-autolabeler bot added the dependency-change label Jan 6, 2021

raboof reviewed Jan 6, 2021

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Bump mockito

c74f59d

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scalafmt

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andreaTP mentioned this pull request Jan 9, 2021

[WIP] Cross-compile Akka with Scala 3 #29929

Closed

patriknw reviewed Jan 9, 2021

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Reminder to re add switch annotation in case

614a626

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andreaTP added 2 commits January 11, 2021 09:24

revert bump of scalatest and scalacheck

7bc5bf0

Merge branch 'scala3-1' of github.com:andreaTP/akka into scala3-1

0fcfe24

akka-ci added validating PR is currently being validated by Jenkins tested PR that was successfully built and tested by Jenkins and removed tested PR that was successfully built and tested by Jenkins validating PR is currently being validated by Jenkins labels Jan 11, 2021

patriknw closed this Jan 25, 2021

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Scala3 support patch 1 #29930

Scala3 support patch 1 #29930

andreaTP commented Jan 6, 2021

akka-ci commented Jan 6, 2021

raboof Jan 6, 2021

raboof Jan 6, 2021

andreaTP Jan 6, 2021

patriknw Jan 9, 2021

andreaTP Jan 9, 2021

patriknw Jan 9, 2021

andreaTP Jan 9, 2021 •

edited

patriknw Jan 11, 2021

andreaTP Jan 11, 2021

raboof commented Jan 6, 2021

akka-ci commented Jan 6, 2021

akka-ci commented Jan 6, 2021

patriknw Jan 9, 2021

andreaTP Jan 9, 2021

patriknw Jan 9, 2021

andreaTP Jan 9, 2021

patriknw Jan 9, 2021

akka-ci commented Jan 9, 2021

akka-ci commented Jan 11, 2021

patriknw commented Jan 25, 2021

Scala3 support patch 1 #29930

Scala3 support patch 1 #29930

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andreaTP commented Jan 6, 2021

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andreaTP Jan 9, 2021 • edited

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raboof commented Jan 6, 2021

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akka-ci commented Jan 9, 2021

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patriknw commented Jan 25, 2021

andreaTP Jan 9, 2021 •

edited