No summary feature warning under sbt

[som-snytt]

Compiler version

3.1.1

Minimized code

Observed on forum which links to a trivial project that incurs a feature warning.

Output

[success] Total time: 1 s, completed Feb 27, 2022, 1:44:03 PM

under -feature

[warn] -- Feature Warning: /home/.../test-scala3/src/main/scala/p/Writer.scala:5:15
[warn] 5 |  implicit def cv(t: T): String = t.toString
[warn]   |               ^
[warn]   |Definition of implicit conversion method cv should be enabled
[warn]   |by adding the import clause 'import scala.language.implicitConversions'
[warn]   |or by setting the compiler option -language:implicitConversions.
[warn]   |See the Scala docs for value scala.language.implicitConversions for a discussion
[warn]   |why the feature should be explicitly enabled.
[warn] one warning found
[warn] one warning found
[success] Total time: 0 s, completed Feb 27, 2022, 1:46:29 PM

Expectation

[warn] 1 feature warning; re-run with -feature for details
[warn] one warning found
[success] Total time: 2 s, completed Feb 27, 2022, 1:40:48 PM

as in Scala 2.

The doubled output [warn] one warning found is also suspicious.

Summary is correct from command line:

✗ scalac -source:future -d /tmp $(finds)
there were 2 feature warning(s); re-run with -feature for details

[griggt]

The doubled output [warn] one warning found is also suspicious.

This doubled output has already been fixed in 3.1.2-RC1 by #13843