Add Scala 2.13.0-M5 support

[gslowikowski]

Waiting for dependencies:

• scalatest - publish for Scala 2.13.0-M5 scalatest/scalatest#1409
• scala-logging - Publish version for 2.13.0-M5 lightbend-labs/scala-logging#131

[SethTisue]

ScalaTest has now published, still waiting on scala-logging

[SethTisue]

scala-logging has published

[SethTisue]

has publishing happened?

(asking, in part, because this might be a blocker for cats? /cc @kailuowang)

[kailuowang]

We disabled coverage on 2.13 due to this.
related typelevel/cats#2347

[gslowikowski]

Yes, I released it yesterday.

[SethTisue]

@gslowikowski would you mind submitting a PR adding it to https://github.com/scala/make-release-notes/blob/2.13.x/projects-2.13.md ? I'm not sure exactly where/how to list it.

[gslowikowski]

Done scala/make-release-notes#286

[SethTisue]

cool, thanks

[gslowikowski]

Hi @SethTisue

Scala 2.13.0-M5 reports some warnings in scoverage build:

https://travis-ci.org/scoverage/scalac-scoverage-plugin/jobs/448599407#L519-L521
https://travis-ci.org/scoverage/scalac-scoverage-plugin/jobs/448599407#L541-L550

There are two kinds of warnings:

object DeprecatedDoubleOrdering in object Ordering is deprecated (since 2.13.0): 
There are multiple ways to order Doubles (Ordering.Double.TotalOrdering, Ordering.Double.IeeeOrdering). 
Specify one by using a local import, assigning an implicit val, or passing it explicitly. 
See the documentation for details.

class Reporter in package reporters is deprecated (since 2.13.0): Use reflect.internal.Reporter

I cannot find, how to change the code in a backward compatible way (without creating separate source files for Scala 2.13+). Can you help?

[SethTisue]

it's often not possible to cross-compile without deprecation warnings, this is normal, I'm afraid.

if you prefer to use -Xfatal-warnings, I'd suggest enabling it in 2.11 and/or 2.12 only. in 2.13, you either live with the warnings, or use silencer to suppress them. I'm sorry scalac doesn't offer better control over warning suppression.

separate source files is an option as well, I have seen some projects take that route. not duplicating massive amounts of code, just having small amounts of version specific code in version specific source directories.

[gslowikowski]

I'm not worried about warnings. I'm thinking about the moment when the deprecated classes/syntax will be removed. Will it be version 2.13.0 or later?