Fixed error that ocurred when the companion object of a case class has alternative apply methods

3 files changed, 24 insertions, 2 deletions

diff --git a/.gitignore b/.gitignore
index e7f1455..63d54ec 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@ target
 .jvm
 .js
 .native
+.idea
diff --git a/core/shared/src/main/scala/magnolia.scala b/core/shared/src/main/scala/magnolia.scala
index 6400002..337edc7 100644
--- a/core/shared/src/main/scala/magnolia.scala
+++ b/core/shared/src/main/scala/magnolia.scala
@@ -279,9 +279,15 @@ object Magnolia {
 
         val defaults = if (!isValueClass) {
           val caseClassCompanion = genericType.companion
-          val constructorMethod = caseClassCompanion.decl(TermName("apply")).asMethod
+          // If a companion object is defined with alternative apply methods
+          // it is needed get all the alternatives
+          val constructorMethod =
+          caseClassCompanion.decl(TermName("apply")).alternatives.map(_.asMethod)
+
+          // The last apply method in the alternatives is the one that belongs
+          // to the case class, not the user defined companion object
           val indexedConstructorParams =
-            constructorMethod.paramLists.head.map(_.asTerm).zipWithIndex
+          constructorMethod.last.paramLists.head.map(_.asTerm).zipWithIndex
 
           indexedConstructorParams.map {
             case (p, idx) =>
diff --git a/tests/src/main/scala/tests.scala b/tests/src/main/scala/tests.scala
index e453502..52dc1d0 100644
--- a/tests/src/main/scala/tests.scala
+++ b/tests/src/main/scala/tests.scala
@@ -37,11 +37,26 @@ case object Blue extends Color
 
 case class `%%`(`/`: Int, `#`: String)
 
+case class Param(a: String, b: String)
+case class Test(param: Param)
+object Test {
+  def apply(): Test = Test(Param("", ""))
+
+  def apply(a: String)(implicit b: Int): Test = Test(Param(a, b.toString))
+
+  def apply(a: String, b: String): Test = Test(Param(a, b))
+}
+
 object Tests extends TestApp {
 
   def tests() = for (i <- 1 to 1000) {
     import examples._
 
+    test("construct a Show product instance with alternative apply functions") {
+      import examples._
+      Show.gen[Test].show(Test("a", "b"))
+    }.assert(_ == """Test(param=Param(a=a,b=b))""")
+
     test("construct a Show product instance") {
       import examples._
       Show.gen[Person].show(Person("John Smith", 34))