REPL ImportHandler is not tracking importedNames and importedSymbols correctly

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Under current implementation, both fields are mostly empty. An immediate consequence is :imports doesn't report anything. Also it causes problems to other components that rely on these fields, such as when defining classes in REPL with -Yrepl-class-based enabled. See issue [SI-9880].

There seem to be a few issues here:

• sym.thisType on a module symbol always returns NoPrefix. Should probably use sym.typeOfThis instead.
• It doesn't handle renames because it won't be able to find the renames in importable members.
• importableMembers may not always be able to return complete list (the case I encountered was with scala.reflect.runtime.universe which has a type of scala.reflect.api.JavaUniverse). Thus we probably should not restrict importedNames to only importableMembers for non-wildcard imports.
• This is caused by typeOfExpression inadvertently changing phase to jvm.

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Imported From: https://issues.scala-lang.org/browse/SI-9881?orig=1
Reporter: @jasonxh
Affected Versions: 2.11.8, 2.12.0-M5
See #9880
Duplicates #7953

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@som-snytt said (edited on Aug 7, 2016 5:59:03 PM UTC):
I took a look, too, with the same conclusion. I didn't notice #2 about renames but verified it. #3 I'm not sure. There's a related ticket for handling imported implicits, which is why I looked at it. Were you planning a PR?

Showing failure on rename. Works on regular module import. Also the failure on package import from the other ticket.

$ scala -Yrepl-class-based
Welcome to Scala 2.12.0-M5 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_92).
Type in expressions for evaluation. Or try :help.

scala> object X { def x = 42 }
defined object X

scala> import X.{x => y}
import X.{x=>y}

scala> class C(i: Int = y)
<console>:11: error: not found: value y
       class C(i: Int = y)
                        ^

scala> class C ; y
<console>:13: error: not found: value y
        y
        ^

scala> import X.x
import X.x

scala> class C(i: Int = x)
defined class C

scala> import concurrent.Future
import concurrent.Future

scala> class C(f: Future[Int])
<console>:11: error: not found: type Future
       class C(f: Future[Int])
                  ^

scala> def f: Future[Int] = ???
f: scala.concurrent.Future[Int]

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@jasonxh said:
@A. P. Marki Yes I'm working on a PR.

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@SethTisue said:
assigning a fix version of 2.11.9 because if :imports doesn't work at all we should at least remove it from the help. at bare minimum. obviously an actual fix would be much better

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@jasonxh said:
Opened PR at scala/scala#5326

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@som-snytt said (edited on Aug 13, 2016 7:04:31 AM UTC):
Sorry I didn't remember this.

Apparently, I started looking at it but then forgot about it.

scala/scala#4698

retronym's link to WIP is probably still relevant.

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@som-snytt said:
scala/scala#5640