From a12538b69f28b5de8dd2d05e820f52f28090fb85 Mon Sep 17 00:00:00 2001
From: Georgi Krastev <joro.kr.21@gmail.com>
Date: Fri, 11 Feb 2022 07:04:23 +0100
Subject: [PATCH] Merge pull request #1238 from joroKr21/default-access

Access nested defaults through this to avoid stack overflow
---
 core/src/main/scala/shapeless/default.scala | 21 ++++++++++++---------
 core/src/test/scala/shapeless/default.scala | 10 ++++++++++
 2 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/core/src/main/scala/shapeless/default.scala b/core/src/main/scala/shapeless/default.scala
index 0d06b3c4b..8de95db9f 100644
--- a/core/src/main/scala/shapeless/default.scala
+++ b/core/src/main/scala/shapeless/default.scala
@@ -240,15 +240,18 @@ class DefaultMacros(val c: whitebox.Context) extends CaseClassMacros {
         alt => alt.isMethod && hasDefaultParams(alt.asMethod)
       }
 
-    def defaultsFor(fields: List[(TermName, Type)]) = for {
-      ((_, argTpe), i) <- fields.zipWithIndex
-      default = tpe.companion.member(TermName(s"apply$$default$$${i + 1}")) orElse
-        altCompanion.member(TermName(s"$$lessinit$$greater$$default$$${i + 1}"))
-    } yield if (default.isTerm) {
-      val defaultTpe = appliedType(someTpe, devarargify(argTpe))
-      val defaultVal = some(q"$companion.$default")
-      (defaultTpe, defaultVal)
-    } else (noneTpe, none)
+    def defaultsFor(fields: List[(TermName, Type)]) = {
+      lazy val enclosing = ownerChain(c.internal.enclosingOwner)
+      for (((_, argTpe), i) <- fields.zipWithIndex) yield {
+        val default = tpe.companion.member(TermName(s"apply$$default$$${i + 1}")) orElse
+          altCompanion.member(TermName(s"$$lessinit$$greater$$default$$${i + 1}"))
+        if (default.isTerm) {
+          val owner = default.owner
+          val qualifier = if (!owner.isStatic && enclosing.contains(owner)) This(owner) else companion
+          (appliedType(someTpe, devarargify(argTpe)), some(q"$qualifier.$default"))
+        } else (noneTpe, none)
+      }
+    }
 
     def mkDefault(defaults: List[(Type, Tree)]) = {
       val (types, values) = defaults.unzip
diff --git a/core/src/test/scala/shapeless/default.scala b/core/src/test/scala/shapeless/default.scala
index f1de92fd5..2d7075389 100644
--- a/core/src/test/scala/shapeless/default.scala
+++ b/core/src/test/scala/shapeless/default.scala
@@ -240,4 +240,14 @@ class DefaultTests {
     }
     assert(thrownException, "Expected DefaultRun to be thrown")
   }
+
+  @Test
+  def testInCompanion: Unit =
+    assertEquals(InCompanion.default, Some(9) :: HNil)
+
+  // Note: this has to be inside a class, not an object
+  case class InCompanion(a: Int = 9)
+  object InCompanion {
+    val default = Default[InCompanion].apply()
+  }
 }