Added substSym method and dropped NoPrefix requirement.

Substituters now work on arbitrary NamedTypes, even if the prefix is different from NoPrefix.

1 files changed, 43 insertions, 18 deletions

diff --git a/src/dotty/tools/dotc/core/Substituters.scala b/src/dotty/tools/dotc/core/Substituters.scala
index a63465f2c..33dd14b8e 100644
--- a/src/dotty/tools/dotc/core/Substituters.scala
+++ b/src/dotty/tools/dotc/core/Substituters.scala
@@ -27,10 +27,8 @@ trait Substituters { this: Context =>
     tp match {
       case tp: NamedType =>
         val sym = tp.symbol
-        if (tp.prefix eq NoPrefix) {
-          if (sym eq from) return to
-        }
-        if (sym.isStatic) tp
+        if (sym eq from) return to
+        if (sym.isStatic && !from.isStatic) tp
         else tp.derivedNamedType(subst1(tp.prefix, from, to, map), tp.name)
       case _: ThisType | _: BoundType | NoPrefix =>
         tp
@@ -46,11 +44,9 @@ trait Substituters { this: Context =>
     tp match {
       case tp: NamedType =>
         val sym = tp.symbol
-        if (tp.prefix eq NoPrefix) {
-          if (sym eq from1) return to1
-          if (sym eq from2) return to2
-        }
-        if (sym.isStatic) tp
+        if (sym eq from1) return to1
+        if (sym eq from2) return to2
+        if (sym.isStatic && !from1.isStatic && !from2.isStatic) tp
         else tp.derivedNamedType(subst2(tp.prefix, from1, to1, from2, to2, map), tp.name)
       case _: ThisType | _: BoundType | NoPrefix =>
         tp
@@ -66,16 +62,14 @@ trait Substituters { this: Context =>
     tp match {
       case tp: NamedType =>
         val sym = tp.symbol
-        if (tp.prefix eq NoPrefix) {
-          var fs = from
-          var ts = to
-          while (fs.nonEmpty) {
-            if (fs.head eq sym) return ts.head
-            fs = fs.tail
-            ts = ts.tail
-          }
+        var fs = from
+        var ts = to
+        while (fs.nonEmpty) {
+          if (fs.head eq sym) return ts.head
+          fs = fs.tail
+          ts = ts.tail
         }
-        if (sym.isStatic) tp
+        if (sym.isStatic && !existsStatic(from)) tp
         else tp.derivedNamedType(subst(tp.prefix, from, to, map), tp.name)
       case _: ThisType | _: BoundType | NoPrefix =>
         tp
@@ -87,6 +81,28 @@ trait Substituters { this: Context =>
     }
   }
 
+  final def substSym(tp: Type, from: List[Symbol], to: List[Symbol], map: SubstSymMap): 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 NamedType(tp.prefix, ts.head)
+          fs = fs.tail
+          ts = ts.tail
+        }
+        if (sym.isStatic && !existsStatic(from)) tp
+        else tp.derivedNamedType(substSym(tp.prefix, from, to, map), tp.name)
+      case _: ThisType | _: BoundType | NoPrefix =>
+        tp
+      case tp: RefinedType =>
+        tp.derivedRefinedType(substSym(tp.parent, from, to, map), tp.name, substSym(tp.info, from, to, map))
+      case _ =>
+        (if (map != null) map else new SubstSymMap(from, to))
+          .mapOver(tp)
+    }
+
   final def substThis(tp: Type, from: ClassSymbol, to: Type, map: SubstThisMap): Type =
     tp match {
       case tp @ ThisType(clazz) =>
@@ -119,6 +135,11 @@ trait Substituters { this: Context =>
           .mapOver(tp)
     }
 
+  private def existsStatic(syms: List[Symbol]): Boolean = syms match {
+    case sym :: syms1 => sym.isStatic || existsStatic(syms1)
+    case nil => false
+  }
+
   final class SubstBindingMap(from: BindingType, to: BindingType) extends TypeMap {
     def apply(tp: Type) = subst(tp, from, to, this)
   }
@@ -135,6 +156,10 @@ trait Substituters { this: Context =>
     def apply(tp: Type): Type = subst(tp, from, to, this)
   }
 
+  final class SubstSymMap(from: List[Symbol], to: List[Symbol]) extends TypeMap {
+    def apply(tp: Type): Type = substSym(tp, from, to, this)
+  }
+
   final class SubstThisMap(from: ClassSymbol, to: Type) extends TypeMap {
     def apply(tp: Type): Type = substThis(tp, from, to, this)
   }