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Inconsistent root package name #9728

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scabug opened this issue Mar 31, 2016 · 3 comments
Closed

Inconsistent root package name #9728

scabug opened this issue Mar 31, 2016 · 3 comments
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@scabug
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scabug commented Mar 31, 2016 

Welcome to Scala 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_77).
Type in expressions for evaluation. Or try :help.

scala> import scala.reflect.runtime.universe._
import scala.reflect.runtime.universe._

scala> import scala.reflect.runtime.currentMirror
import scala.reflect.runtime.currentMirror

scala> currentMirror.moduleSymbol(None.getClass).owner.owner.name
res0: reflect.runtime.universe.Symbol#NameType = <root>

scala> termNames.ROOTPKG
res1: reflect.runtime.universe.termNames.NameType = _root_

scala> currentMirror.moduleSymbol(None.getClass).owner.owner.name == termNames.ROOTPKG
res2: Boolean = false
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scabug commented Mar 31, 2016

Imported From: https://issues.scala-lang.org/browse/SI-9728?orig=1
Reporter: @Atry
Affected Versions: 2.11.8

@scabug
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scabug commented Apr 3, 2016

@retronym said:

scala> currentMirror.RootPackage
res12: reflect.runtime.universe.ModuleSymbol = package _root_

scala> currentMirror.RootClass
res13: reflect.runtime.universe.ClassSymbol = package <root>

scala> currentMirror.RootClass.asClass.module
res14: reflect.runtime.universe.Symbol = package _root_

This is certainly confusing, but I don't think it is a bug. When you navigate .owner.owner, you get to the package class of the root package, not the root package itself. The package class is named TypeName("<root>"), whereas the root package is named TermName("_root_"). The term is the only one of these name that is designed to be referenced from user code, so it used underscores rather than <..>.

@scabug scabug closed this as completed Apr 3, 2016
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scabug commented Apr 3, 2016

@Atry said (edited on Apr 3, 2016 5:31:43 PM UTC):
I found that there is a ROOT constant and Symbol.isRoot method in scala-compiler, however there is not such a constant or method in scala-reflect. How could a macro writer determine if a TermName is root without internal APIs?

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