Don't serialize expect declaration descriptors (#1307)

Thus fix producing .klib from multi-platform sources

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/serialization/KonanSerializationUtil.kt

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.backend.konan.serialization
 import org.jetbrains.kotlin.backend.konan.*
 import org.jetbrains.kotlin.backend.konan.descriptors.DeserializedKonanModule
 import org.jetbrains.kotlin.backend.konan.descriptors.createKonanModuleDescriptor
+import org.jetbrains.kotlin.backend.konan.descriptors.isExpectMember
 import org.jetbrains.kotlin.backend.konan.library.KonanLibraryReader
 import org.jetbrains.kotlin.backend.konan.library.LinkData
 import org.jetbrains.kotlin.backend.konan.llvm.base64Decode
@@ -206,12 +207,12 @@ internal class KonanSerializationUtil(val context: Context) {
         val classifierDescriptors = KonanDescriptorSerializer.sort(
                 fragments.flatMap {
                     it.getMemberScope().getContributedDescriptors(DescriptorKindFilter.CLASSIFIERS)
-                }
+                }.filter { !it.isExpectMember }
         )
 
         val members = fragments.flatMap { fragment ->
             DescriptorUtils.getAllDescriptors(fragment.getMemberScope())
-        }
+        }.filter { !it.isExpectMember }
 
         val classesBuilder = KonanLinkData.Classes.newBuilder()
 

backend.native/tests/build.gradle

@@ -1959,6 +1959,13 @@ task mpp1(type: RunStandaloneKonanTest) {
     flags = ['-tr', '-Xmulti-platform']
 }
 
+task mpp2(type: LinkKonanTest) {
+    goldValue = "C(arg=42)\ntrue\n1\nh\n"
+    source = "codegen/mpp/mpp2.kt"
+    lib = "codegen/mpp/libmpp2.kt"
+    flags = ['-Xmulti-platform']
+}
+
 task unit1(type: RunKonanTest) {
     goldValue = "First\nkotlin.Unit\n"
     source = "codegen/basics/unit1.kt"

backend.native/tests/codegen/mpp/libmpp2.kt

@@ -0,0 +1,16 @@
+expect class C {
+    constructor(arg: Any?)
+}
+
+actual data class C actual constructor(val arg: Any?) {
+
+}
+
+expect class T
+actual typealias T = C
+
+expect fun f(arg: Int): Int
+actual fun f(arg: Int) = arg
+
+expect var p: String
+actual var p: String = "p"

backend.native/tests/codegen/mpp/mpp2.kt

@@ -0,0 +1,8 @@
+fun main(args: Array<String>) {
+    println(C(42))
+    println(C(42) is T)
+    println(f(1))
+
+    p = "h"
+    println(p)
+}