Fix playframework#971 – "Exception occurred while executing macro exp…

…ansion."
sgodbillon · Mar 4, 2024 · ead441a · ead441a
1 parent 10a8ae1
commit ead441a
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Showing 2 changed files with 32 additions and 1 deletion.
diff --git a/play-json/shared/src/main/scala-3/play/api/libs/json/JsMacroImpl.scala b/play-json/shared/src/main/scala-3/play/api/libs/json/JsMacroImpl.scala
@@ -329,7 +329,13 @@ object JsMacroImpl { // TODO: debug
               val default: Option[Expr[t]] =
                 compCls.declaredMethod(f"$$lessinit$$greater$$default$$" + (i + 1)).headOption.collect {
                   case defaultSym if sym.flags.is(Flags.HasDefault) =>
-                    Ref(tpr.typeSymbol.companionModule).select(defaultSym).asExprOf[t]
+                    val select = Ref(tpr.typeSymbol.companionModule).select(defaultSym)
+                    val tree =
+                      TypeRepr.of[T].typeArgs match {
+                        case Nil      => select
+                        case typeArgs => select.appliedToTypes(typeArgs)
+                      }
+                    tree.asExprOf[t]
                 }
 
               ReadableField(sym, i, pt, default)

diff --git a/play-json/shared/src/test/scala/play/api/libs/json/MacroSpec.scala b/play-json/shared/src/test/scala/play/api/libs/json/MacroSpec.scala
@@ -518,6 +518,26 @@ class MacroSpec extends AnyWordSpec with Matchers with org.scalatestplus.scalach
 
       nesting.Test.format.reads(expectedJson).mustEqual(JsSuccess(expected))
     }
+
+    "handle case class with generic type and default field" in {
+      implicit val format: Format[GenericCaseClassWithDefault[Int]] = Json.format[GenericCaseClassWithDefault[Int]]
+
+      val expected     = GenericCaseClassWithDefault(3)
+      val expectedJson = Json.obj("data" -> 3, "descr" -> "something")
+
+      Json.toJson(GenericCaseClassWithDefault(3)).mustEqual(expectedJson)
+      Json.fromJson(expectedJson).mustEqual(JsSuccess(expected))
+    }
+
+    "handle case class with generic type and overridden default field" in {
+      implicit val format: Format[GenericCaseClassWithDefault[Int]] = Json.format[GenericCaseClassWithDefault[Int]]
+
+      val expected     = GenericCaseClassWithDefault(3, "foo")
+      val expectedJson = Json.obj("data" -> 3, "descr" -> "foo")
+
+      Json.toJson(GenericCaseClassWithDefault(3, "foo")).mustEqual(expectedJson)
+      Json.fromJson(expectedJson).mustEqual(JsSuccess(expected))
+    }
   }
 }
 
@@ -624,4 +644,9 @@ object MacroSpec {
         Json.format[Test]
     }
   }
+
+  case class GenericCaseClassWithDefault[A](
+      data: A,
+      descr: String = "something"
+  )
 }