Small changes to reflection API to make it safe for IDE use.

* Removed `typeSymbol` and `termSymbol` from `reflect.api.base`, and pushed them down to
  `reflect.api`.
* extracted `TypeTree.symbol` to a top-level method so it can be overridden in other layers

4 files changed, 22 insertions, 16 deletions

diff --git a/src/library/scala/reflect/base/Base.scala b/src/library/scala/reflect/base/Base.scala
index 4457a6cf14..5df48307fe 100644
--- a/src/library/scala/reflect/base/Base.scala
+++ b/src/library/scala/reflect/base/Base.scala
@@ -96,8 +96,8 @@ class Base extends Universe { self =>
 
   // todo. write a decent toString that doesn't crash on recursive types
   class Type extends TypeBase {
-    def typeSymbol: Symbol = NoSymbol
     def termSymbol: Symbol = NoSymbol
+    def typeSymbol: Symbol = NoSymbol
   }
   implicit val TypeTagg = ClassTag[Type](classOf[Type])
 
diff --git a/src/library/scala/reflect/base/Types.scala b/src/library/scala/reflect/base/Types.scala
index 6e8ffc7984..28aaf2d04d 100644
--- a/src/library/scala/reflect/base/Types.scala
+++ b/src/library/scala/reflect/base/Types.scala
@@ -3,25 +3,14 @@ package base
 
 trait Types { self: Universe =>
 
-  /** The base API that all types support */
-  abstract class TypeBase {
-
-    /** The term symbol associated with the type, or `NoSymbol` for types
-     *  that do not refer to a term symbol.
-     */
-    def termSymbol: Symbol
-
-    /** The type symbol associated with the type, or `NoSymbol` for types
-     *  that do not refer to a type symbol.
-     */
-    def typeSymbol: Symbol
-  }
-
   /** The type of Scala types, and also Scala type signatures.
    *  (No difference is internally made between the two).
    */
   type Type >: Null <: TypeBase
 
+  /** The base API that all types support */
+  abstract class TypeBase
+
   /** A tag that preserves the identity of the `Type` abstract type from erasure.
    *  Can be used for pattern matching, instance tests, serialization and likes.
    */
diff --git a/src/reflect/scala/reflect/api/Types.scala b/src/reflect/scala/reflect/api/Types.scala
index 231b9b248b..01de5fa9a7 100644
--- a/src/reflect/scala/reflect/api/Types.scala
+++ b/src/reflect/scala/reflect/api/Types.scala
@@ -8,6 +8,15 @@ trait Types extends base.Types { self: Universe =>
   /** The extended API of types
    */
   abstract class TypeApi extends TypeBase {
+    /** The term symbol associated with the type, or `NoSymbol` for types
+     *  that do not refer to a term symbol.
+     */
+    def termSymbol: Symbol
+
+    /** The type symbol associated with the type, or `NoSymbol` for types
+     *  that do not refer to a type symbol.
+     */
+    def typeSymbol: Symbol
 
     /** The defined or declared members with name `name` in this type;
      *  an OverloadedSymbol if several exist, NoSymbol if none exist.
diff --git a/src/reflect/scala/reflect/internal/Trees.scala b/src/reflect/scala/reflect/internal/Trees.scala
index e92d644f4a..619e3bc170 100644
--- a/src/reflect/scala/reflect/internal/Trees.scala
+++ b/src/reflect/scala/reflect/internal/Trees.scala
@@ -469,7 +469,7 @@ trait Trees extends api.Trees { self: SymbolTable =>
     private var orig: Tree = null
     private[scala] var wasEmpty: Boolean = false
 
-    override def symbol = if (tpe == null) null else tpe.typeSymbol
+    override def symbol = typeTreeSymbol(this) // if (tpe == null) null else tpe.typeSymbol
     override def isEmpty = (tpe eq null) || tpe == NoType
 
     def original: Tree = orig
@@ -1024,6 +1024,14 @@ trait Trees extends api.Trees { self: SymbolTable =>
     }
   }
 
+    
+  /** Delegate for a TypeTree symbol. This operation is unsafe because
+   *  it may trigger type checking when forcing the type symbol of the
+   *  underlying type.
+   */
+  protected def typeTreeSymbol(tree: TypeTree): Symbol =
+    if (tree.tpe == null) null else tree.tpe.typeSymbol
+  
   // --- generic traversers and transformers
 
   override protected def itraverse(traverser: Traverser, tree: Tree): Unit = {