Invalid and incomplete instructions in README.md for using -Xasync about scala-async

[jdjohnston]

OK. I changed my build.sbt to require Scala 2.13.3 (was using 2.13.2) and scala-async 1.0.0-M1 . Also re-enabled -Xasync. Minimal project compiled & ran fine.

BTW, while the snippets of code in README.md are helpful, I found SmokeTest.scala in the test directory to be of the most help in getting started. I have some experience with concurrency & some with Scala, but little with the combination.

[SethTisue]

Scala 2.13.3 definitely accepts -Xasync, and yes it is required. I think you must be mistaken that you are actually using 2.13.3.

I fixed the scalaOptions vs scalacOptions thing in 7c494a7 — good catch, thanks.

[jdjohnston]

Strange, when I commented out the -Xasync line in my build.sbt, it ran fine

sbt:async> scalaVersion
[info] 2.13.2

(Oops, 2.13.3 was the command-line scalac, not the one sbt is using)

[SethTisue]

oh, aha, you must be using the old 0.x plugin, which doesn't use -Xasync. try it with 1.0.0-M1

@retronym mind updating the README to have appropriate advice about what version(s) to use?