Kotlin 2.1 and friends (#1966)

* Kotlin 2.1 and friends

* fix kotlin 2.1 aliases nullability (#1982)

---------

Co-authored-by: Florian LE FICHER <florian.leficher@gmail.com>

moshi-kotlin-tests/build.gradle.kts

@@ -35,8 +35,9 @@ tasks.withType<Test>().configureEach {
 tasks.withType<KotlinCompile>().configureEach {
   compilerOptions {
     allWarningsAsErrors.set(true)
-    freeCompilerArgs.add(
+    freeCompilerArgs.addAll(
       "-opt-in=kotlin.ExperimentalStdlibApi",
+      "-Xannotation-default-target=param-property",
     )
   }
 }

moshi-kotlin-tests/codegen-only/build.gradle.kts

@@ -36,8 +36,9 @@ tasks.withType<Test>().configureEach {
 tasks.withType<KotlinCompile>().configureEach {
   compilerOptions {
     allWarningsAsErrors.set(true)
-    freeCompilerArgs.add(
+    freeCompilerArgs.addAll(
       "-opt-in=kotlin.ExperimentalStdlibApi",
+      "-Xannotation-default-target=param-property",
     )
   }
 }

moshi-kotlin-tests/src/test/kotlin/com/squareup/moshi/kotlin/DualKotlinTest.kt

@@ -487,7 +487,7 @@ class DualKotlinTest {
     val parameterized: GenericClass<TypeAlias>,
     val wildcardIn: GenericClass<in TypeAlias>,
     val wildcardOut: GenericClass<out TypeAlias>,
-    val complex: GenericClass<GenericTypeAlias>?,
+    val complex: GenericClass<GenericTypeAlias?>?,
   )
 
   // Regression test for https://github.com/square/moshi/issues/991