[Serialization] Ensure that KT-57770 is fixed

^KT-57770 Fixed

plugins/kotlinx-serialization/testData/boxIr/serializableFromAnotherModule_multipleFields.kt

@@ -0,0 +1,42 @@
+// TARGET_BACKEND: JVM_IR
+// WITH_STDLIB
+// ISSUE: KT-57626
+
+// MODULE: lib
+import kotlinx.serialization.*
+
+@Serializable
+open class Base(
+    val c: Int = 1,
+    val b: String = "hello",
+    val a: List<String> = listOf("a")
+)
+
+// MODULE: main(lib)
+import kotlinx.serialization.*
+import kotlinx.serialization.json.*
+
+@Serializable
+class Derived(val d: Long = 1000000000000) : Base(2, "world", listOf("b", "c")) {
+    override fun equals(other: Any?): Boolean {
+        if (other !is Derived) return false
+        return a == other.a && b == other.b && c == other.c && d == other.d
+    }
+
+    override fun toString(): String {
+        return "a: $a, b: $b, c: $c, d: $d"
+    }
+}
+
+fun box(): String {
+    val expected = Derived(12)
+    val result = Json.encodeToString(Derived.serializer(), expected)
+    if (result != """{"c":2,"b":"world","a":["b","c"],"d":12}""") {
+        return "Fail: $result"
+    }
+    val actual = Json.decodeFromString(Derived.serializer(), result)
+    if (expected != actual) {
+        return "Fail: expected: $expected\nactual: $actual"
+    }
+    return "OK"
+}