2 files changed, 24 insertions, 7 deletions
diff --git a/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala b/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
index 348c7f688f..9e5186b731 100644
--- a/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
+++ b/src/compiler/scala/tools/nsc/symtab/SymbolLoaders.scala
@@ -97,8 +97,15 @@ abstract class SymbolLoaders {
     val clazz = enterClass(root, name, completer)
     val module = enterModule(root, name, completer)
     if (!clazz.isAnonymousClass) {
-      assert(clazz.companionModule == module, module)
-      assert(module.companionClass == clazz, clazz)
+      // Diagnostic for SI-7147
+      def msg: String = {
+        def symLocation(sym: Symbol) = if (sym == null) "null" else s"${clazz.fullLocationString} (from ${clazz.associatedFile})"
+        sm"""Inconsistent class/module symbol pair for `$name` loaded from ${symLocation(root)}.
+            |clazz = ${symLocation(clazz)}; clazz.companionModule = ${clazz.companionModule}
+            |module = ${symLocation(module)}; module.companionClass = ${module.companionClass}"""
+      }
+      assert(clazz.companionModule == module, msg)
+      assert(module.companionClass == clazz, msg)
     }
   }
 
diff --git a/src/compiler/scala/tools/nsc/util/TreeSet.scala b/src/compiler/scala/tools/nsc/util/TreeSet.scala
index 3cdbcc5110..d2e9238e8f 100644
--- a/src/compiler/scala/tools/nsc/util/TreeSet.scala
+++ b/src/compiler/scala/tools/nsc/util/TreeSet.scala
@@ -40,12 +40,22 @@ class TreeSet[T >: Null <: AnyRef](less: (T, T) => Boolean) extends Set[T] {
     tree = add(tree)
   }
 
-  def iterator = {
-    def elems(t: Tree): Iterator[T] = {
-      if (t eq null) Iterator.empty
-      else elems(t.l) ++ (Iterator single t.elem) ++ elems(t.r)
+  def iterator = toList.iterator
+
+  override def foreach[U](f: T => U) {
+    def loop(t: Tree) {
+      if (t ne null) {
+        loop(t.l)
+        f(t.elem)
+        loop(t.r)
+      }
     }
-    elems(tree)
+    loop(tree)
+  }
+  override def toList = {
+    val xs = scala.collection.mutable.ListBuffer[T]()
+    foreach(xs += _)
+    xs.toList
   }
 
   override def toString(): String = {