akka/akka-core

Scala 3 type inference issue with ActorSystemSetups#get

Open

#29,990 opened on Feb 1, 2021

View on GitHub
 (0 comments) (0 reactions) (0 assignees)Scala (3,547 forks)batch import
1 - triagedhelp wantedt:coret:scala-3

Repository metrics

Stars
 (13,277 stars)
PR merge metrics
 (Avg merge 8d 19h) (10 merged PRs in 30d)

Description

Investigate and see if it surfaces in user code or just some curiosity in the tests/interaction with Scalatest.

Needing that extra type ascription is curious, but only about some weirdness with Scalatest === in Scala 3 right?

(The signature of get is ActorSystemSetups#get[T <: Setup: ClassTag]: Option[T] and we explicitly give it the T, so get here returns Option[DummySetup] and setup is DummySetup so Some(setup) should be Some[DummySetup] which extends Option[DummySetup])

Originally posted by @johanandren in https://github.com/akka/akka/pull/29956#discussion_r565905744

Contributor guide

Research direction
Check if the type inference issue reproduces in a standalone Scala 3 project without Scalatest.
Tech stack
scala
Domain
backend
Issue type
Bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
ScalaGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70