Compilation with the plugin produces warning after updating to 2.x

[kubukoz]

It might be a compiler plugin issue more than an sbt plugin issue, but it seems like I can't get one without the other so I'm reporting here:

For users of https://github.com/polyvariant/better-tostring, updating scoverage to 2.x causes a warning to be emitted (with fatal warnings, that becomes an error).

For example, this Scala:

case class A(s: String, s2: String)

gets rewritten by better-tostring to something like the following:

case class A(s: String, s2: String {
  override def toString: String = "A(" + "s = " + s + ", " + "s2 = " + s2 + ")"
}

and the scoverage plugin complains:

[error] Could not instrument [Apply/method +].

Notably, this worked in sbt-scoverage 1.9.3 but doesn't work in 2.0.5. I'm using Scala 2.13.8, as it happens to be a stable version where both versions of scoverage work (as well as the latest better-tostring).

I might be able to work around this by ignoring the issue on Apply/method +, but I'm not sure what the impact would be, so wanted to report it anyway.

Reproduction

1. clone https://github.com/kubukoz/demos/tree/scoverage-change-b2s

2. in the project:

sbt
clean;coverage;compile

3. the above will fail. Switch versions of sbt-scoverage in plugins.sbt, and it starts working again.

[ckipp01]

Thanks for reporting @kubukoz. Oddly enough I still see the warning when using the older sbt-scoverage:

[info] Beginning coverage instrumentation
[info] [warn] Could not instrument [Apply/method +]. No pos.
[info] Instrumentation completed [0 statements]

But it doesn't fail anything, whereas as you pointed out, the new one does:

[info] Beginning coverage instrumentation
[error] Could not instrument [Apply/method +].
[info] Instrumentation completed [0 statements]

I'm actually not 100% sure why this is different here. It'll need some more investigation. I won't move this over yet to the actual compiler plugin because I'd want to ensure I understand where the actual issue stems from first.

[kubukoz]

Yeah, should've been more specific, that's the behavior I was seeing as well.