sbt + Scala 3 prints error summary twice

[reibitto]

steps

• Create a Scala 3 project with sbt new scala/scala3.g8
• Intentionally introduce a compile error, like trying to call a method that doesn't exist.

problem

[error] one error found gets printed twice. Example output:

[info] compiling 1 Scala source to C:\reference\scala-3-project-template\target\scala-3.0.2\classes ...
[error] -- [E006] Not Found Error: C:\reference\scala-3-project-template\src\main\scala\Main.scala:4:2
[error] 4 |  someMethodThatDoesNotExist
[error]   |  ^^^^^^^^^^^^^^^^^^^^^^^^^^
[error]   |  Not found: someMethodThatDoesNotExist
[error] one error found
[error] one error found
[error] (Compile / compileIncremental) Compilation failed
[error] Total time: 0 s, completed Oct 9, 2021, 1:28:55 AM

expectation

The error summary should only be printed once

notes

I confirmed that using the same project with Scala 2 does not have this problem.

[er1c]

Confirmed this still happens in 1.6.0-M1

[adpi2]

The root cause of this issue is in the dotty repo, printSummary is called twice:

• https://github.com/lampepfl/dotty/blob/29f03741b9668c5052ec2b9502d061b7ecd614df/compiler/src/dotty/tools/dotc/Driver.scala#L53
• https://github.com/lampepfl/dotty/blob/29f03741b9668c5052ec2b9502d061b7ecd614df/sbt-bridge/src/dotty/tools/xsbt/CompilerBridgeDriver.java#L96

[eed3si9n]

Could someone report to lampepfl/dotty as well plz?