Make findMember depend on RefinedThis level.

When doing a findMember we now look at the level of a RefinedThis instead
of its `rt` field. This required several fixes to how levels are assigned
to RefinedThis types.

1 files changed, 72 insertions, 8 deletions

diff --git a/src/dotty/tools/dotc/core/Substituters.scala b/src/dotty/tools/dotc/core/Substituters.scala
index 119aca569..9fd01ab56 100644
--- a/src/dotty/tools/dotc/core/Substituters.scala
+++ b/src/dotty/tools/dotc/core/Substituters.scala
@@ -1,6 +1,6 @@
 package dotty.tools.dotc.core
 
-import Types._, Symbols._, Contexts._
+import Types._, Symbols._, Contexts._, Names._
 
 /** Substitution operations on types. See the corresponding `subst` and
  *  `substThis` methods on class Type for an explanation.
@@ -179,7 +179,9 @@ trait Substituters { this: Context =>
           .mapOver(tp)
     }
 
-  final def substThis(tp: Type, from: RefinedType, to: Type, theMap: SubstRefinedThisMap): Type =
+  // !!! TODO remove once we are sure new RefinedThis scheme works and we drop the ref to
+  // the target type from RefinedThis.
+  final def substThis0(tp: Type, from: RefinedType, to: Type, theMap: SubstRefinedThisMap0): Type =
     tp match {
       case tp @ RefinedThis(rt, level) =>
         if (rt eq from) 
@@ -190,16 +192,39 @@ trait Substituters { this: Context =>
         else tp
       case tp: NamedType =>
         if (tp.currentSymbol.isStatic) tp
-        else tp.derivedSelect(substThis(tp.prefix, from, to, theMap))
+        else tp.derivedSelect(substThis0(tp.prefix, from, to, theMap))
       case _: ThisType | _: BoundType | NoPrefix =>
         tp
       case tp: RefinedType =>
-        tp.derivedRefinedType(substThis(tp.parent, from, to, theMap), tp.refinedName, substThis(tp.refinedInfo, from, to, theMap))
+        tp.derivedRefinedType(substThis0(tp.parent, from, to, theMap), tp.refinedName, substThis0(tp.refinedInfo, from, to, theMap))
       case tp: TypeAlias =>
-        tp.derivedTypeAlias(substThis(tp.alias, from, to, theMap))
+        tp.derivedTypeAlias(substThis0(tp.alias, from, to, theMap))
       case _ =>
-        (if (theMap != null) theMap else new SubstRefinedThisMap(from, to))
+        (if (theMap != null) theMap else new SubstRefinedThisMap0(from, to))
           .mapOver(tp)
+    }      
+      
+    final def substRefinedThis(tp: Type, level: Int, to: Type, theMap: SubstRefinedThisMap): Type =
+    tp match {
+      case tp @ RefinedThis(rt, l) if l == level =>
+        to
+      case tp: NamedType =>
+        if (tp.currentSymbol.isStatic) tp
+        else tp.derivedSelect(substRefinedThis(tp.prefix, level, to, theMap))
+      case _: ThisType | _: BoundType | NoPrefix =>
+        tp
+      case tp: RefinedType =>
+        tp.derivedRefinedType(
+            substRefinedThis(tp.parent, level, to, theMap), tp.refinedName, 
+            substRefinedThis(tp.refinedInfo, level + 1, to, theMap))
+      case tp: TypeAlias =>
+        tp.derivedTypeAlias(substRefinedThis(tp.alias, level, to, theMap))
+      case _ =>
+        val m = if (theMap != null) theMap else new SubstRefinedThisMap(to)
+        val saved = m.level
+        m.level = level
+        try m.mapOver(tp)
+        finally m.level = saved
     }
 
   final def substParam(tp: Type, from: ParamType, to: Type, theMap: SubstParamMap): Type =
@@ -271,8 +296,13 @@ trait Substituters { this: Context =>
     def apply(tp: Type): Type = substThis(tp, from, to, this)
   }
 
-  final class SubstRefinedThisMap(from: RefinedType, to: Type) extends DeepTypeMap {
-    def apply(tp: Type): Type = substThis(tp, from, to, this)
+  final class SubstRefinedThisMap0(from: RefinedType, to: Type) extends DeepTypeMap {
+    def apply(tp: Type): Type = substThis0(tp, from, to, this)
+  }
+
+  final class SubstRefinedThisMap(to: Type) extends DeepTypeMap {
+    var level: Int = 0
+    def apply(tp: Type): Type = substRefinedThis(tp, level, to, this)
   }
 
   final class SubstParamMap(from: ParamType, to: Type) extends DeepTypeMap {
@@ -282,4 +312,38 @@ trait Substituters { this: Context =>
   final class SubstParamsMap(from: BindingType, to: List[Type]) extends DeepTypeMap {
     def apply(tp: Type) = substParams(tp, from, to, this)
   }
+
+  /** Substitute every occurrence of symbol `from_i` with `RefinedThis(leve).select(to_i)`
+   *  where level represents the nesting level of the occurrence (i.e. number
+   *  of refinedInfos between substituted type and the occurrence.
+   *  TODO: Drop `rt` once it is dropped from RefinedThis
+   *  TODO: Apply to enclosing refined type instead of refined info. That way we
+   *        can optimize for types not containing any RefinedThis
+   */
+  final class SubstWithRefinedSelectMap(rt: RefinedType, from: List[Symbol], to: List[TypeName]) extends DeepTypeMap {
+    private var level = 0
+    def apply(tp: Type): Type = tp match {
+      case tp: NamedType =>
+        val sym = tp.symbol
+        var fs = from
+        var ts = to
+        while (fs.nonEmpty) {
+          if (fs.head eq sym) 
+            return RefinedThis(rt, level).select(ts.head)
+          fs = fs.tail
+          ts = ts.tail
+        }
+        if (sym.isStatic && !existsStatic(from)) tp
+        else tp.derivedSelect(apply(tp.prefix))
+      case tp: RefinedType =>
+        val parent1 = apply(tp.parent)
+        level += 1
+        try tp.derivedRefinedType(parent1, tp.refinedName, apply(tp.refinedInfo))
+        finally level -= 1
+      case tp: TypeAlias =>
+        tp.derivedTypeAlias(apply(tp.alias))
+      case _ =>
+        mapOver(tp)
+    }
+  }
 }
\ No newline at end of file