unchecked TypeRef match in interpreter/TypeStrings

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The following warning is generated during compilation of scalac (locker and quick):

src/compiler/scala/tools/nsc/interpreter/TypeStrings.scala:215: warning: abstract type reflect.runtime.universe.TypeRef in type pattern reflect.runtime.universe.TypeRef is unchecked since it is eliminated by erasure
    def typeArguments: List[ru.Type] = ru.typeOf[T] match { case ru.TypeRef(_, _, args) => args; case _ => Nil }
                                                                           ^

It is likely a valid warning that results from ru.TypeRefTag not being visible for the pattern match. It should be straightforward to fix this particular warning, but in general, this is a problem with selective imports from Universe in reflection. I remember this general problem being discussed elsewhere (and Eugene wanting to be able to have XXTag imported whenever XX is imported), but I couldn't find an internals thread or bug report to link to.

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Imported From: https://issues.scala-lang.org/browse/SI-6338?orig=1
Reporter: @harrah
Affected Versions: 2.10.0-RC3

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@paulp said:
I'm not really working on 2.10 anymore, but if anyone wants it, this warning and other issues are handled here: https://github.com/paulp/scala/tree/topic/210-quieter-warnings

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@harrah said:
This warning is the valid one. The spurious warning is #6275. I've copied the comment there.

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@paulp said:
Pretty sure this warning is eliminated in that patch (by importing ru._.)

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@paulp said:
... and I haven't fixed 6275 yet.

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@harrah said:
I see. Sorry about that.

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@paulp said:
That's okay, it's refreshing to see you blunder once in a while.

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@paulp said:
Apparently this will be the world's most exciting trivial fix, because attempting to include it with two of my pull requests caused both to fail. You can suppress the warning with import ru._, and then the rangepos test blows up on an unpositioned tree. https://scala-webapps.epfl.ch/jenkins/job/pr-rangepos/582/console

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@xeno-by said:
#6754

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@adriaanm said:
(Pushing reflection bugs to 2.11 to aid scheduling -- as it's experimental in 2.10.x, it shouldn't influence 2.10's schedule. They may be fixed earlier, of course.)

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@retronym said:
Appears we forgot to close this for 2.10.1