From d8864d36e07e1343fc623250b72fdd590c84e732 Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Wed, 18 Jun 2014 19:15:41 +0200
Subject: Add cloneScope method and handle versioning of ClassInfo#decls

This is done to streamline changing class denotations in new phases
by adding to (or otherwise modifying) their decls scope.
---
 src/dotty/tools/dotc/core/Scopes.scala            | 9 +++++----
 src/dotty/tools/dotc/core/Types.scala             | 6 +++---
 src/dotty/tools/dotc/core/transform/Erasure.scala | 2 +-
 3 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/src/dotty/tools/dotc/core/Scopes.scala b/src/dotty/tools/dotc/core/Scopes.scala
index 367713d11..919e35a7e 100644
--- a/src/dotty/tools/dotc/core/Scopes.scala
+++ b/src/dotty/tools/dotc/core/Scopes.scala
@@ -18,6 +18,7 @@ import SymDenotations._
 import printing.Texts._
 import printing.Printer
 import util.common._
+import util.DotClass
 import SymDenotations.NoDenotation
 import collection.mutable.ListBuffer
 
@@ -55,7 +56,7 @@ object Scopes {
    *  or to delete them. These methods are provided by subclass
    *  MutableScope.
    */
-  abstract class Scope extends printing.Showable with Iterable[Symbol] {
+  abstract class Scope extends DotClass with printing.Showable with Iterable[Symbol] {
 
     /** The last scope-entry from which all others are reachable via `prev` */
     private[dotc] def lastEntry: ScopeEntry
@@ -77,8 +78,8 @@ object Scopes {
      */
     def iterator: Iterator[Symbol] = toList.iterator
 
-    /** Returns a new scope with the same content as this one. */
-    def cloneScope(implicit ctx: Context): Scope
+    /** Returns a new mutable scope with the same content as this one. */
+    def cloneScope(implicit ctx: Context): MutableScope
 
     /** Is the scope empty? */
     override def isEmpty: Boolean = lastEntry eq null
@@ -354,7 +355,7 @@ object Scopes {
     override def size = 0
     override def nestingLevel = 0
     override def toList = Nil
-    override def cloneScope(implicit ctx: Context): Scope = this
+    override def cloneScope(implicit ctx: Context): MutableScope = unsupported("cloneScope")
     override def lookupEntry(name: Name)(implicit ctx: Context): ScopeEntry = null
     override def lookupNextEntry(entry: ScopeEntry)(implicit ctx: Context): ScopeEntry = null
   }
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index 4885b30d8..dad88bc60 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -2077,8 +2077,8 @@ object Types {
       if (prefix eq this.prefix) this
       else ClassInfo(prefix, cls, classParents, decls, selfInfo)
 
-    def derivedClassInfo(prefix: Type = this.prefix, classParents: List[TypeRef] = classParents, selfInfo: DotClass = this.selfInfo)(implicit ctx: Context) =
-      if ((prefix eq this.prefix) && (classParents eq this.classParents) && (selfInfo eq this.selfInfo)) this
+    def derivedClassInfo(prefix: Type = this.prefix, classParents: List[TypeRef] = classParents, decls: Scope = this.decls, selfInfo: DotClass = this.selfInfo)(implicit ctx: Context) =
+      if ((prefix eq this.prefix) && (classParents eq this.classParents) && (decls eq this.decls) && (selfInfo eq this.selfInfo)) this
       else ClassInfo(prefix, cls, classParents, decls, selfInfo)
 
     override def computeHash = doHash(cls, prefix)
@@ -2431,7 +2431,7 @@ object Types {
         case self: Type => this(self)
         case _ => tp.self
       }
-      tp.derivedClassInfo(prefix1, parents1, self1)
+      tp.derivedClassInfo(prefix1, parents1, tp.decls, self1)
     }
   }
 
diff --git a/src/dotty/tools/dotc/core/transform/Erasure.scala b/src/dotty/tools/dotc/core/transform/Erasure.scala
index da14f72d1..e35cdd128 100644
--- a/src/dotty/tools/dotc/core/transform/Erasure.scala
+++ b/src/dotty/tools/dotc/core/transform/Erasure.scala
@@ -146,7 +146,7 @@ class Erasure(isJava: Boolean, isSemi: Boolean, isConstructor: Boolean, wildcard
         if ((cls eq defn.ObjectClass) || cls.isPrimitiveValueClass) Nil
         else if (cls eq defn.ArrayClass) defn.ObjectClass.typeRef :: Nil
         else removeLaterObjects(classParents.mapConserve(eraseTypeRef))
-      tp.derivedClassInfo(this(pre), parents, this(tp.selfType))
+      tp.derivedClassInfo(this(pre), parents, decls, this(tp.selfType))
     case NoType | NoPrefix | ErrorType =>
       tp
     case tp: WildcardType if wildcardOK =>
-- 
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