SI-3832 Extract tracking of under-construction classes to a mixin

In order to reduce the noise in OuterPathTransformer.

2 files changed, 21 insertions, 15 deletions

diff --git a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
index d6a6e027cb..8af95afdec 100644
--- a/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
+++ b/src/compiler/scala/tools/nsc/transform/ExplicitOuter.scala
@@ -216,7 +216,7 @@ abstract class ExplicitOuter extends InfoTransform
    *  values for outer parameters of constructors.
    *  The class provides methods for referencing via outer.
    */
-  abstract class OuterPathTransformer(unit: CompilationUnit) extends TypingTransformer(unit) {
+  abstract class OuterPathTransformer(unit: CompilationUnit) extends TypingTransformer(unit) with UnderConstructionTransformer {
     /** The directly enclosing outer parameter, if we are in a constructor */
     protected var outerParam: Symbol = NoSymbol
 
@@ -276,16 +276,6 @@ abstract class ExplicitOuter extends InfoTransform
     }
 
 
-    /** The stack of class symbols in which a call to this() or to the super
-      * constructor, or early definition is active
-      */
-    protected def isUnderConstruction(clazz: Symbol) = selfOrSuperCalls contains clazz
-    protected val selfOrSuperCalls = mutable.Stack[Symbol]()
-    @inline protected def inSelfOrSuperCall[A](sym: Symbol)(a: => A) = {
-      selfOrSuperCalls push sym
-      try a finally selfOrSuperCalls.pop()
-    }
-
     override def transform(tree: Tree): Tree = {
       val savedOuterParam = outerParam
       try {
@@ -299,10 +289,7 @@ abstract class ExplicitOuter extends InfoTransform
             }
           case _ =>
         }
-        if ((treeInfo isSelfOrSuperConstrCall tree) || (treeInfo isEarlyDef tree))
-          inSelfOrSuperCall(currentOwner.owner)(super.transform(tree))
-        else
-          super.transform(tree)
+        super.transform(tree)
       }
       finally outerParam = savedOuterParam
     }
diff --git a/src/reflect/scala/reflect/internal/Trees.scala b/src/reflect/scala/reflect/internal/Trees.scala
index 84818a6f42..e784d704d6 100644
--- a/src/reflect/scala/reflect/internal/Trees.scala
+++ b/src/reflect/scala/reflect/internal/Trees.scala
@@ -1617,6 +1617,25 @@ trait Trees extends api.Trees { self: SymbolTable =>
     }
   }
 
+  /** Tracks the classes currently under construction during a transform */
+  trait UnderConstructionTransformer extends Transformer {
+    import collection.mutable
+
+    protected def isUnderConstruction(clazz: Symbol) = selfOrSuperCalls contains clazz
+
+    /** The stack of class symbols in which a call to this() or to the super
+      * constructor, or early definition is active */
+    private val selfOrSuperCalls = mutable.Stack[Symbol]()
+
+    abstract override def transform(tree: Tree) = {
+      if ((treeInfo isSelfOrSuperConstrCall tree) || (treeInfo isEarlyDef tree)) {
+        selfOrSuperCalls push currentOwner.owner
+        try super.transform(tree)
+        finally selfOrSuperCalls.pop()
+      } else super.transform(tree)
+    }
+  }
+
   def duplicateAndKeepPositions(tree: Tree) = new Duplicator(focusPositions = false) transform tree
 
   // ------ copiers -------------------------------------------