From 3ec0b67f9d4150937cb233adabd23f0edd95887c Mon Sep 17 00:00:00 2001
From: Martin Odersky <odersky@gmail.com>
Date: Mon, 1 Jan 2018 12:19:47 +0100
Subject: [PATCH] Fix #3585: Add missing changeOwner when building lazy
 implicits

---
 .../src/dotty/tools/dotc/typer/Implicits.scala   |  4 +++-
 tests/pos/i3585.scala                            | 16 ++++++++++++++++
 2 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 tests/pos/i3585.scala

diff --git a/compiler/src/dotty/tools/dotc/typer/Implicits.scala b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
index d35852a2b2e8..bc846b96053b 100644
--- a/compiler/src/dotty/tools/dotc/typer/Implicits.scala
+++ b/compiler/src/dotty/tools/dotc/typer/Implicits.scala
@@ -635,7 +635,9 @@ trait Implicits { self: Typer =>
           case _ => false
         }
         if (lazyImplicit.exists && refersToLazyImplicit)
-          Block(ValDef(lazyImplicit.asTerm, arg).withPos(pos) :: Nil, ref(lazyImplicit))
+          Block(
+            ValDef(lazyImplicit.asTerm, arg.changeOwner(ctx.owner, lazyImplicit)).withPos(pos) :: Nil,
+            ref(lazyImplicit))
         else
           arg
       case fail @ SearchFailure(tree) =>
diff --git a/tests/pos/i3585.scala b/tests/pos/i3585.scala
new file mode 100644
index 000000000000..01660a64e38e
--- /dev/null
+++ b/tests/pos/i3585.scala
@@ -0,0 +1,16 @@
+trait Foo[T]
+
+object Foo {
+  implicit def pair[T, U]
+    (implicit
+      fooT: => Foo[(T, U)],
+      fooU: => Foo[(U, T)]
+    ): Foo[(T, U)] = ???
+
+  implicit def int: Foo[Int] = ???
+  implicit def string: Foo[String] = ???
+}
+
+object Test extends App {
+  implicitly[Foo[(Int, String)]]
+}