akka/akka-core

Scala 3 type inference issue with ActorSystemSetups#get

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#29,990 建立於 2021年2月1日

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1 - triagedhelp wantedt:coret:scala-3

描述

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

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backend
議題類型
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前置要求
Scala 3 type systemAkka core basicsScalatest
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研究方向
Investigate if the type inference issue is specific to Scalatest's `===` operator or appears in general user code. Refer to the discussion in PR #29956 (https://github.com/akka/akka/pull/29956) for context. Check the source file for ActorSystemSetups#get to understand the generic type constraints. Reproduce the issue in a simple Scala 3 project with and without Scalatest to determine the scope.