New method on scopes: openForMutations

Replaces `asInstanceOf[MutableScope]` calls.

1 files changed, 7 insertions, 3 deletions

diff --git a/src/dotty/tools/dotc/core/Scopes.scala b/src/dotty/tools/dotc/core/Scopes.scala
index cd1eacc91..70bcbdee6 100644
--- a/src/dotty/tools/dotc/core/Scopes.scala
+++ b/src/dotty/tools/dotc/core/Scopes.scala
@@ -93,7 +93,7 @@ object Scopes {
 
     /** Lookup next entry with same name as this one */
     def lookupNextEntry(entry: ScopeEntry)(implicit ctx: Context): ScopeEntry
-
+    
     /** Lookup a symbol */
     final def lookup(name: Name)(implicit ctx: Context): Symbol = {
       val e = lookupEntry(name)
@@ -138,7 +138,9 @@ object Scopes {
     }
 
     def implicitDecls(implicit ctx: Context): List[TermRef] = Nil
-
+    
+    def openForMutations: MutableScope = unsupported("openForMutations")
+    
     final def toText(printer: Printer): Text = printer.toText(this)
   }
 
@@ -374,6 +376,8 @@ object Scopes {
       }
       syms
     }
+    
+    override def openForMutations: MutableScope = this
   }
 
   /** Create a new scope */
@@ -404,7 +408,7 @@ object Scopes {
   /** The empty scope (immutable).
    */
   object EmptyScope extends Scope {
-    override def lastEntry = null
+    override private[dotc] def lastEntry = null
     override def size = 0
     override def nestingLevel = 0
     override def toList = Nil