Alphanumeric infix warning - behavior with -source future

[OndrejSpanel]

I wrote in: @infix to unlock operator notation is, in fact, controversial! - #19 by OndrejSpanel (deleted by accident now, when trying to quote it, unable to restore):

@OndrejSpanel

@lihaoyi

it forces them to list out those methods in their build file, and enforces that only the methods they intend to be infix can be used as infix methods.

At the moment I use following string in my scalacOptions:

  "-Wconf:msg=Alphanumeric method .* is not declared infix:s",

This silences all warnings about infix methods.

Using this in SBT makes infix acceptable in my project anytime anyone sees fit.

As long as this work, I have no real problems with this feature, as I am not forced to use it. I would prefer the silencing to be less drastic (more similar to using other optional language features, like dynamics), but practically speaking this works fine.

(I hope this post will nor result in further tightening of ropes, which would really require me to list methods one by one or something like that).

When I have tried compiling my sources with 3.4.0 - 3.6.2 and source future, I discovered the warning is promoted to error and you can no longer silence it.

Is this intentional? If it is, is it documented somewhere? Or is it just how source future works?

Repro:

scalaVersion := "3.6.2"

name := "Sandbox"
scalacOptions ++= Seq(
  "-source", "future",
  "-Wconf:msg=Alphanumeric method .* is not declared infix:s",
)

object Main {
  extension (a: String) def concat(b: String): String = a + b
  def main(args: Array[String]): Unit = {
    println("Hello " concat "world")
  }
}

Scastie - An interactive playground for Scala.

[som-snytt]

I don’t know about policy, but I see there is a handy table.

scala/scala3/blob/main/compiler/src/dotty/tools/dotc/config/MigrationVersion.scala#L21

[WojciechMazur]

Well, that’s the expected behavior. ‘-source:feature’ basically means ‘I’d like to use the bleading edge, I accept feature/syntax deprecations that might be removed at some unspecified time in the future’.

If you don’t need it don’t use it. Typically you should rather aim to use exploit minor version which might keep you project source backward compatible with newer version of compiler (best effort), or the next minor version, eg.Scala 3.6 allows to specify ‘-source:3.7’. You can also not specify it at all.

[MateuszKowalewski]

@OndrejSpanel

(deleted by accident now, when trying to quote it, unable to restore)

Did you cut it instead of copying it?

If so, just edit it once more and copy it back from here. Should work, I think.

[OndrejSpanel]

@MateuszKowalewski

If so, just edit it once more and copy it back from here

I wanted to quote. I think I pressed … and then again at the same place, which is delete.

Unfortunately there is no edit action available now.

@WojciechMazur

Typically you should rather aim to use exploit minor version which might keep you project source backward compatible with newer version of compiler (best effort), or the next minor version, eg.Scala 3.6 allows to specify ‘-source:3.7’

Thanks, source 3.7 works quite well for me - I do not intend to use it on regular basis, I just want to be confident I am ready for the next version, but without warning me about stuff which is too far away.

That said, I think perhaps Source Compatibility would deserve some maintenance, so that one does not have to hunt through discussions and github issues to get the complete picture?

[spamegg1]

@OndrejSpanel

Unfortunately there is no edit action available now.

I noticed that too, the Edit option goes away after a while.
Some kind of “edit spam protection”?
Not sure what the time limit is.
It’s available at least for the next few minutes after posting (because I do edit often right after posting).
There is discussion here, apparently the default is 2 months.