Support friend modules in native mpp

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinCompilationFactory.kt

@@ -86,6 +86,7 @@ class KotlinNativeCompilationFactory(
     override fun create(name: String): KotlinNativeCompilation =
         KotlinNativeCompilation(target, name, target.createCompilationOutput(name)).apply {
             if (name == KotlinCompilation.TEST_COMPILATION_NAME) {
+                friendCompilationName = KotlinCompilation.MAIN_COMPILATION_NAME
                 outputKinds = mutableListOf(NativeOutputKind.EXECUTABLE)
                 buildTypes = mutableListOf(NativeBuildType.DEBUG)
                 isTestCompilation = true

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/kotlinCompilations.kt

@@ -281,6 +281,13 @@ class KotlinNativeCompilation(
 
     var isTestCompilation = false
 
+    var friendCompilationName: String? = null
+
+    internal val friendCompilation: KotlinNativeCompilation?
+        get() = friendCompilationName?.let {
+            target.compilations.getByName(it)
+        }
+
     // Native-specific DSL.
     val extraOpts = mutableListOf<String>()
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/tasks/KotlinNativeTasks.kt

@@ -42,6 +42,10 @@ open class KotlinNativeCompile : DefaultTask() {
     val libraries: FileCollection
         @InputFiles get() = compilation.compileDependencyFiles
 
+    val friendModule: FileCollection?
+        // It's already taken into account in libraries
+        @Internal get() = compilation.friendCompilation?.output
+
     @Input
     var optimized = false
     @Input
@@ -138,6 +142,11 @@ open class KotlinNativeCompile : DefaultTask() {
                 addArg("-l", library.nameWithoutExtension)
             }
 
+            val friends = friendModule?.files
+            if (friends != null && friends.isNotEmpty()) {
+                addArg("-friend-modules", friends.map { it.absolutePath }.joinToString(File.pathSeparator))
+            }
+
             // TODO: Filter only kt files?
             addAll(sources.files.map { it.absolutePath })
         }