Added a -Y option to resolve namespace collisio...

Added a -Y option to resolve namespace collisions between package and
object. It's a blunt instrument: if people have lots of these conflicts
they need to resolve in individually nuanced fashion, they'll probably
remain out of luck. But now people can use YourKit probes without a
custom hacked compiler. Let's say this closes #2089. Review by odersky.

2 files changed, 28 insertions, 3 deletions

diff --git a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
index 3dab85f77c..70f6ea0b89 100644
--- a/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
+++ b/src/compiler/scala/tools/nsc/settings/ScalaSettings.scala
@@ -109,6 +109,8 @@ trait ScalaSettings extends AbsScalaSettings with StandardScalaSettings {
   val Xdce          = BooleanSetting    ("-Ydead-code", "Perform dead code elimination.")
   val debug         = BooleanSetting    ("-Ydebug", "Increase the quantity of debugging output.")
   // val doc           = BooleanSetting    ("-Ydoc", "Generate documentation")
+  val termConflict  = ChoiceSetting     ("-Yresolve-term-conflict", "strategy", "Resolve term conflicts",
+    List("package", "object", "error"), "error")
   val inline        = BooleanSetting    ("-Yinline", "Perform inlining when possible.")
   val Xlinearizer   = ChoiceSetting     ("-Ylinearizer", "which", "Linearizer to use", List("normal", "dfs", "rpo", "dump"), "rpo")
   val log           = PhasesSetting     ("-Ylog", "Log operations during")
diff --git a/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala b/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
index ff54613d47..83b6168c03 100644
--- a/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
+++ b/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
@@ -151,9 +151,32 @@ abstract class SymbolLoaders {
 
     def enterPackage(root: Symbol, name: String, completer: SymbolLoader) {
       val preExisting = root.info.decls.lookup(newTermName(name))
-      if (preExisting != NoSymbol)
-        throw new TypeError(
-          root+" contains object and package with same name: "+name+"\none of them needs to be removed from classpath")
+      if (preExisting != NoSymbol) {
+        // Some jars (often, obfuscated ones) include a package and
+        // object with the same name. Rather than render them unusable,
+        // offer a setting to resolve the conflict one way or the other.
+        // This was motivated by the desire to use YourKit probes, which
+        // require yjp.jar at runtime. See SI-2089.
+        if (settings.termConflict.isDefault)
+          throw new TypeError(
+            root+" contains object and package with same name: "+
+            name+"\none of them needs to be removed from classpath"
+          )
+        else if (settings.termConflict.value == "package") {
+          global.warning(
+            "Resolving package/object name conflict in favor of package " +
+            preExisting.fullName + ".  The object will be inaccessible."
+          )
+          root.info.decls.unlink(preExisting)
+        }
+        else {
+          global.warning(
+            "Resolving package/object name conflict in favor of object " +
+            preExisting.fullName + ".  The package will be inaccessible."
+          )
+          return
+        }
+      }
       val pkg = root.newPackage(NoPosition, newTermName(name))
       pkg.moduleClass.setInfo(completer)
       pkg.setInfo(pkg.moduleClass.tpe)