TreeTypeMap needs to map declarations of mapped classes

... and these mappings have to be part of the applied substitutions.
Without the patch, the postCondition of FirstTransform fails for TreeInfo.scala and others,
because it selects symbols which are not defined in the mapped class.

Unrelated bugfix: JavaArray derives from Object.

3 files changed, 42 insertions, 13 deletions

diff --git a/src/dotty/tools/dotc/ast/TreeTypeMap.scala b/src/dotty/tools/dotc/ast/TreeTypeMap.scala
index 33be848c1..22428edb6 100644
--- a/src/dotty/tools/dotc/ast/TreeTypeMap.scala
+++ b/src/dotty/tools/dotc/ast/TreeTypeMap.scala
@@ -79,14 +79,25 @@ final class TreeTypeMap(
 
   override def transform(tree: tpd.Tree)(implicit ctx: Context): tpd.Tree = treeMap(tree) match {
     case impl @ Template(constr, parents, self, body) =>
-      val tmap = withMappedSyms(impl.symbol :: impl.constr.symbol :: Nil)
-      val parents1 = parents mapconserve transform
-      val (_, constr1 :: self1 :: Nil) = transformDefs(constr :: self :: Nil)
-      val body1 = tmap.transformStats(body)
-      updateDecls(constr :: body, constr1 :: body1)
-      cpy.Template(impl)(
-        constr1.asInstanceOf[DefDef], parents1, self1.asInstanceOf[ValDef], body1)
-        .withType(tmap.mapType(impl.tpe))
+      if (oldOwners contains impl.symbol.owner) {
+        val tmap = withMappedSyms(localSyms(impl :: self :: Nil))
+        cpy.Template(impl)(
+          constr = tmap.transformSub(constr),
+          parents = parents mapconserve transform,
+          self = tmap.transformSub(self),
+          body = body mapconserve tmap.transform
+        ).withType(tmap.mapType(impl.tpe))
+      }
+      else {
+        val tmap = withMappedSyms(impl.symbol :: impl.constr.symbol :: Nil)
+        val parents1 = parents mapconserve transform
+        val (_, constr1 :: self1 :: Nil) = transformDefs(constr :: self :: Nil)
+        val body1 = tmap.transformStats(body)
+        updateDecls(constr :: body, constr1 :: body1)
+        cpy.Template(impl)(
+          constr1.asInstanceOf[DefDef], parents1, self1.asInstanceOf[ValDef], body1)
+          .withType(tmap.mapType(impl.tpe))
+      }
     case tree1 =>
       tree1.withType(mapType(tree1.tpe)) match {
         case id: Ident if tpd.needsSelect(id.tpe) =>
@@ -160,8 +171,24 @@ final class TreeTypeMap(
    *  and return a treemap that contains the substitution
    *  between original and mapped symbols.
    */
-  def withMappedSyms(syms: List[Symbol]): TreeTypeMap = {
-    val mapped = ctx.mapSymbols(syms, this)
-    withSubstitution(syms, mapped)
-  }
+  def withMappedSyms(syms: List[Symbol]): TreeTypeMap =
+    withMappedSyms(syms, ctx.mapSymbols(syms, this))
+
+  /** The tree map with the substitution between originals `syms`
+   *  and mapped symbols `mapped`. Also goes into mapped classes
+   *  and substitutes their declarations.
+   */
+  def withMappedSyms(syms: List[Symbol], mapped: List[Symbol]): TreeTypeMap =
+    if (mapped eq syms) this
+    else {
+      val substMap = withSubstitution(syms, mapped)
+      val mappedClasses = mapped.filter(_.isClass)
+      (substMap /: mappedClasses) { (tmap, cls) =>
+        val origDcls = cls.decls.toList
+        val mappedDcls = ctx.mapSymbols(origDcls, tmap)
+        val tmap1 = tmap.withMappedSyms(origDcls, mappedDcls)
+        (origDcls, mappedDcls).zipped.foreach(cls.asClass.replace)
+       tmap1
+      }
+    }
 }
diff --git a/src/dotty/tools/dotc/core/Symbols.scala b/src/dotty/tools/dotc/core/Symbols.scala
index 0174f75cf..cedc0adc8 100644
--- a/src/dotty/tools/dotc/core/Symbols.scala
+++ b/src/dotty/tools/dotc/core/Symbols.scala
@@ -267,7 +267,7 @@ trait Symbols { this: Context =>
    *  Cross symbol references are brought over from originals to copies.
    *  Do not copy any symbols if all attributes of all symbols stay the same.
    */
-  def mapSymbols(originals: List[Symbol], ttmap: TreeTypeMap) =
+  def mapSymbols(originals: List[Symbol], ttmap: TreeTypeMap): List[Symbol] =
     if (originals forall (sym =>
         (ttmap.mapType(sym.info) eq sym.info) &&
         !(ttmap.oldOwners contains sym.owner)))
diff --git a/src/dotty/tools/dotc/core/Types.scala b/src/dotty/tools/dotc/core/Types.scala
index d93e4eb09..33ce71ad3 100644
--- a/src/dotty/tools/dotc/core/Types.scala
+++ b/src/dotty/tools/dotc/core/Types.scala
@@ -116,6 +116,8 @@ object Types {
         tp.tp1.derivesFrom(cls) || tp.tp2.derivesFrom(cls)
       case tp: OrType =>
         tp.tp1.derivesFrom(cls) && tp.tp2.derivesFrom(cls)
+      case tp: JavaArrayType =>
+        cls == defn.ObjectClass
       case _ =>
         false
     }