`@unchecked` fails to compile when annotation.unchecked package imported

[allanrenucci]

import annotation.unchecked

@unchecked
class Test

Compiles with scalac but not with dotty

-- Error: tests/tmp/Test.scala -------------------------------------------------
3 |@unchecked
  |^^^^^^^^^^
  |annotation.unchecked does not have a constructor

Removing the import fixes the problem

[smarter]

To clarify what's going on here: @unchecked should refer to scala.unchecked, scala.annotation.unchecked is an unrelated package.

Even when the scala.annotation.unchecked package is imported, scalac seems to be able to determine that we want @unchecked to refer to scala.unchecked but dotty doesn't.

[amanjpro]

I like the dotty behavior more. An annotation is technically a class, and when you explicitly import a name, it should take precedence over the the default imports.

If we "fix" this, we should also make import scala.collection.mutable.Map not hide the immutable counterpart.