Merge pull request scala#5767 from milessabin/topic/i5766

Correct owner chains when mixing byname implicits and inlining

Author: milessabin

compiler/src/dotty/tools/dotc/ast/tpd.scala

@@ -10,7 +10,7 @@ import core._
 import util.Spans._, Types._, Contexts._, Constants._, Names._, Flags._, NameOps._
 import Symbols._, StdNames._, Annotations._, Trees._, Symbols._
 import Decorators._, DenotTransformers._
-import collection.mutable
+import collection.{immutable, mutable}
 import util.{Property, SourceFile, NoSource}
 import NameKinds.{TempResultName, OuterSelectName}
 import typer.ConstFold
@@ -730,6 +730,25 @@ object tpd extends Trees.Instance[Type] with TypedTreeInfo {
       if (from == to) tree else loop(from, Nil, to :: Nil)
     }
 
+    /**
+     * Set the owner of every definition in this tree which is not itself contained in this
+     * tree to be `newowner`
+     */
+    def changeNonLocalOwners(newOwner: Symbol)(implicit ctx: Context): Tree = {
+      val ownerAcc = new TreeAccumulator[immutable.Set[Symbol]] {
+        def apply(ss: immutable.Set[Symbol], tree: Tree)(implicit ctx: Context) = tree match {
+          case tree: DefTree =>
+            if (tree.symbol.exists) ss + tree.symbol.owner
+            else ss
+          case _ =>
+            foldOver(ss, tree)
+        }
+      }
+      val owners = ownerAcc(immutable.Set.empty[Symbol], tree).toList
+      val newOwners = List.fill(owners.size)(newOwner)
+      new TreeTypeMap(oldOwners = owners, newOwners = newOwners).apply(tree)
+    }
+
     /** After phase `trans`, set the owner of every definition in this tree that was formerly
      *  owner by `from` to `to`.
      */

compiler/src/dotty/tools/dotc/typer/Implicits.scala

@@ -1577,7 +1577,7 @@ final class SearchRoot extends SearchHistory {
             val nrhss = rhss.map(rhsMap(_))
 
             val vdefs = (nsyms zip nrhss) map {
-              case (nsym, nrhs) => ValDef(nsym.asTerm, nrhs)
+              case (nsym, nrhs) => ValDef(nsym.asTerm, nrhs.changeNonLocalOwners(nsym))
             }
 
             val constr = ctx.newConstructor(classSym, Synthetic, Nil, Nil).entered

tests/pos/i5766.scala

@@ -0,0 +1,32 @@
+object Test1 {
+  trait Foo { def next: Foo }
+
+  inline implicit def foo(implicit loop: => Foo): Foo = new Foo { def next = loop }
+
+  def summon(implicit f: Foo) = ()
+  summon
+}
+
+object Test2 {
+  trait Foo { def next: Bar }
+  trait Bar { def next: Foo }
+
+  implicit def foo(implicit loop: => Bar): Foo = new Foo { def next = loop }
+  inline implicit def bar(implicit loop: Foo): Bar = new Bar { def next = loop }
+
+  def summon(implicit f: Foo) = ()
+  summon
+}
+
+object Test3 {
+  trait Foo { def next: Bar }
+  trait Bar { def next: Baz }
+  trait Baz { def next: Foo }
+
+  implicit def foo(implicit loop: Bar): Foo = new Foo { def next = loop }
+  inline implicit def bar(implicit loop: Baz): Bar = new Bar { def next = loop }
+  inline implicit def baz(implicit loop: => Foo): Baz = new Baz { def next = loop }
+
+  def summon(implicit f: Foo) = ()
+  summon
+}