SBT plugin doesn't support dottydoc

[Blaisorblade]

On the example project:

sbt:dotty-example-project> doc
[info] Updating ...
[warn] Binary version (0.9.0-RC1) for dependency ch.epfl.lamp#scala-library;0.9.0-RC1
[warn] 	in dotty-example-project#dotty-example-project_0.9;0.1.0 differs from Scala binary version in project (0.9).
[warn] circular dependency found: ch.epfl.lamp#scala-library;0.9.0-RC1->ch.epfl.lamp#dotty-library_0.9;0.9.0-RC1->...
[warn] circular dependency found: ch.epfl.lamp#dotty-library_0.9;0.9.0-RC1->ch.epfl.lamp#scala-library;0.9.0-RC1->...
[info] Done updating.
[info] Main Scala API documentation to /Users/pgiarrusso/git/dotty-example-project/target/scala-0.9/api...
[info] Non-compiled module 'dotty-sbt-bridge' for Scala 0.9.0-RC1. Compiling...
[info]   Compilation completed in 6.301s.
[error] The dotty sbt-bridge currently does not support doc generation directly
[error] via sbt. Please see the dotty documentation at dotty.epfl.ch
[info] Main Scala API documentation successful.
[success] Total time: 7 s, completed Aug 20, 2018 2:09:37 PM

On Dotty (in case it's fixed later):

sbt:dotty> doc
[success] Total time: 2 s, completed Aug 20, 2018 2:07:44 PM

[Duhemm]

See #4952