Spin off src/library/scala/xml to src/xml/scala/xml.

Summary:
  - Remove the last vestiges of xml from Predef and Contexts.
  - Change build to compile scala.xml to scala-xml.jar.
  - Deploy scala-xml module to maven.
  - Update partest accordingly.

Note:
An older compiler cannot use the new standard library to
compile projects that use XML. Thus, skipping locker will
break the build until we use 2.11.0-M4 for STARR.

In the future build process, where we drop locker,
we would have to release a milestone that supports the old
and the new approach to xml. As soon as we'd be using that
new milestone for starr, we could drop support for the old approach.

1 files changed, 6 insertions, 15 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
index 1f4ff7cc2d..1f8f13ae02 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Contexts.scala
@@ -99,22 +99,13 @@ trait Contexts { self: Analyzer =>
 
     // there must be a scala.xml package when xml literals were parsed in this unit
     if (unit.hasXml && ScalaXmlPackage == NoSymbol)
-      unit.error(unit.firstXmlPos, "XML literals may only be used if the package scala.xml is present in the compilation classpath.")
-
-    // TODO: remove the def below and drop `|| predefDefinesDollarScope` in the condition for `contextWithXML`
-    // as soon as 2.11.0-M4 is released and used as STARR (and $scope is no longer defined in Predef)
-    // Until then, to allow compiling quick with pre-2.11.0-M4 STARR,
-    // which relied on Predef defining `val $scope`, we've left it in place.
-    // Since the new scheme also imports $scope (as an alias for scala.xml.TopScope),
-    // we must check whether it is still there and not import the alias to avoid ambiguity.
-    // (All of this is only necessary to compile the full quick stage with STARR.
-    //  if using locker, Predef.$scope is no longer needed.)
-    def predefDefinesDollarScope = definitions.getMemberIfDefined(PredefModule, nme.dollarScope) != NoSymbol
-
-    // hack for the old xml library (detected by looking for scala.xml.TopScope, which needs to be in scope as $scope)
-    // import scala.xml.{TopScope => $scope}
+      unit.error(unit.firstXmlPos, "To compile XML syntax, the scala.xml package must be on the classpath.\nPlease see https://github.com/scala/scala/wiki/Scala-2.11#xml.")
+
+    // scala-xml needs `scala.xml.TopScope` to be in scope globally as `$scope`
+    // We detect `scala-xml` by looking for `scala.xml.TopScope` and
+    // inject the equivalent of `import scala.xml.{TopScope => $scope}`
     val contextWithXML =
-      if (!unit.hasXml || ScalaXmlTopScope == NoSymbol || predefDefinesDollarScope) rootImportsContext
+      if (!unit.hasXml || ScalaXmlTopScope == NoSymbol) rootImportsContext
       else rootImportsContext.make(gen.mkImport(ScalaXmlPackage, nme.TopScope, nme.dollarScope))
 
     val c = contextWithXML.make(tree, unit = unit)