Fix warnings in compiler and interop

Interop/Runtime/build.gradle

@@ -74,7 +74,7 @@ sourceSets.main.kotlin.srcDirs += "src/jvm/kotlin"
 
 compileKotlin {
     kotlinOptions {
-        freeCompilerArgs = ['-Xuse-experimental=kotlin.ExperimentalUnsignedTypes']
+        freeCompilerArgs = ['-Xuse-experimental=kotlin.ExperimentalUnsignedTypes', "-XXLanguage:+InlineClasses"]
     }
 }
 

Interop/Runtime/src/main/kotlin/kotlinx/cinterop/StableRef.kt

@@ -73,5 +73,4 @@ public inline class StableRef<out T : Any> @PublishedApi internal constructor(
 /**
  * Converts to [StableRef] this opaque pointer produced by [StableRef.asCPointer].
  */
-inline fun <reified T : Any> CPointer<*>.asStableRef(): StableRef<T> = StableRef<T>(this)
-        .also { it.get() as T }
+inline fun <reified T : Any> CPointer<*>.asStableRef(): StableRef<T> = StableRef<T>(this).also { it.get() }

Interop/StubGenerator/src/main/kotlin/org/jetbrains/kotlin/native/interop/gen/ObjCStubs.kt

@@ -398,6 +398,7 @@ private val ObjCClassOrProtocol.superTypes: Sequence<ObjCClassOrProtocol>
 private fun ObjCClassOrProtocol.declaredMethods(isClass: Boolean): Sequence<ObjCMethod> =
         this.methods.asSequence().filter { it.isClass == isClass }
 
+@Suppress("UNUSED_PARAMETER")
 private fun Sequence<ObjCMethod>.inheritedTo(container: ObjCClassOrProtocol, isMeta: Boolean): Sequence<ObjCMethod> =
         this // TODO: exclude methods that are marked as unavailable in [container].