Check access rights of objects in import selectors

[hamzaremmal]

Compiler version

c4531d4

Minimized code

package bar:
  private[bar] object Bar

package foo:
  import bar.Bar   // no error
  val _ =  Bar     // error: not found (import is a no-op)
  val _ =  bar.Bar // error: access modifier

Output

-- [E006] Not Found Error: minim.scala:6:11 ------------------------------------
6 |  val _ =  Bar // error: not found (import is a no-op)
  |           ^^^
  |           Not found: Bar
  |
  | longer explanation available when compiling with `-explain`
-- [E173] Reference Error: minim.scala:7:15 ------------------------------------
7 |  val _ =  bar.Bar // error: access modifier
  |           ^^^^^^^
  |object Bar cannot be accessed as a member of bar.type from the top-level definitions in package foo.
  |  private[bar] object Bar can only be accessed from package bar.
2 errors found

Expectation

Have an error when importing an object that is not accessible from the current scope

[som-snytt]

Might be tricky without forcing the enclosing foo. But since there is a typer error, you don't get an unused import (which could do an additional check).

I often mix up that importable implies accessible (per spec); for inheritance, matching requires non-private.

[som-snytt]

Oh I forgot recent #22430