Fix incorrect type variance being applied on generated adapters (#1010)

* Fix: force object type for type arguments

* Add outDeclaration regression test for #1009

* Create mapTypesUtility for reusing recursive type mapping

* Strip typevar variance where appropriate

Resolves #1009

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

@@ -522,6 +522,24 @@ class DualKotlinTest(useReflection: Boolean) {
       val convolutedMultiNullableShouldBeNullable: NullableB?,
       val deepNestedNullableShouldBeNullable: E
   )
+
+  // Regression test for https://github.com/square/moshi/issues/1009
+  @Test fun outDeclaration() {
+    val adapter = moshi.adapter<OutDeclaration<Int>>()
+
+    @Language("JSON")
+    val testJson = """{"input":3}"""
+
+    val instance = OutDeclaration(3)
+    assertThat(adapter.serializeNulls().toJson(instance))
+        .isEqualTo(testJson)
+
+    val result = adapter.fromJson(testJson)!!
+    assertThat(result).isEqualTo(instance)
+  }
+
+  @JsonClass(generateAdapter = true)
+  data class OutDeclaration<out T>(val input: T)
 }
 
 typealias TypeAlias = Int

kotlin/tests/src/test/kotlin/com/squareup/moshi/kotlin/reflect/-MoshiKotlinExtensions.kt

@@ -57,12 +57,16 @@ fun <T> Moshi.adapter(ktype: KType): JsonAdapter<T> {
 }
 
 @PublishedApi
-internal fun KType.toType(): Type {
+internal fun KType.toType(allowPrimitives: Boolean = true): Type {
   classifier?.let {
     when (it) {
       is KTypeParameter -> throw IllegalArgumentException("Type parameters are not supported")
       is KClass<*> -> {
-        val javaType = it.java
+        val javaType = if (allowPrimitives) {
+          it.java
+        } else {
+          it.javaObjectType
+        }
         if (javaType.isArray) {
           return Types.arrayOf(javaType.componentType)
         }
@@ -88,7 +92,7 @@ internal fun KType.toType(): Type {
 }
 
 internal fun KTypeProjection.toType(): Type {
-  val javaType = type?.toType() ?: return Any::class.java
+  val javaType = type?.toType(allowPrimitives = false) ?: return Any::class.java
   return when (variance) {
     null -> Any::class.java
     KVariance.INVARIANT -> javaType