replace warning with error

Author: halotukozak

core/src/test/scala/com/avsystem/commons/serialization/NotUsedTransientDefault.scala

@@ -3,13 +3,14 @@ package com.avsystem.commons.serialization
 import org.scalatest.funsuite.AnyFunSuite
 
 final class NotUsedTransientDefault extends AnyFunSuite {
+  case class Valid(@transientDefault a: String = "default")
+  case class Invalid(@transientDefault a: String)
 
   test("no warnings when @transientDefault is used properly") {
     assertCompiles(
       //language=Scala
       s"""
-         |case class X(@transientDefault a: String = "default")
-         |val codec = GenCodec.materialize[X]
+         |GenCodec.materialize[Valid]
          |""".stripMargin
     )
   }
@@ -18,8 +19,7 @@ final class NotUsedTransientDefault extends AnyFunSuite {
     assertDoesNotCompile(
       //language=Scala
       s"""
-         |case class X(@transientDefault a: String)
-         |val codec = GenCodec.materialize[X]
+         |GenCodec.materialize[Invalid]
          |""".stripMargin
     )
   }

macros/src/main/scala/com/avsystem/commons/macros/serialization/GenCodecMacros.scala

@@ -134,7 +134,7 @@ class GenCodecMacros(ctx: blackbox.Context) extends CodecMacroCommons(ctx) with
   def isTransientDefault(param: ApplyParam, warnIfDefaultNotProvided: Boolean = false): Boolean =
     (hasAnnotation(param.sym, TransientDefaultAnnotType), param.defaultValue.nonEmpty, warnIfDefaultNotProvided) match {
       case (true, false, true) =>
-        warning(s"@transientDefault has no effect on parameter ${param.sym.name} because it has no default value")
+        error(s"@transientDefault has no effect on parameter ${param.sym.name} because it has no default value")
         false
       case (hasAnnotation, noDefaultValue, _) => hasAnnotation && noDefaultValue
     }