[Gradle] Fix friendArtifactResolver for External Targets API

It was failing with ClassCastException in an attempt of using it.

Also added a test case to cover the logic with friendArtifactResolver

^KT-66431 Verification Pending

libraries/tools/kotlin-gradle-plugin-tcs-android/src/main/kotlin/org/jetbrains/kotlin/gradle/android/PrototypeAndroidCompilation.kt

@@ -7,6 +7,7 @@
 
 package org.jetbrains.kotlin.gradle.android
 
+import org.gradle.api.file.ConfigurableFileCollection
 import org.jetbrains.kotlin.gradle.dsl.KotlinCommonOptions
 import org.jetbrains.kotlin.gradle.dsl.KotlinJvmCompilerOptions
 import org.jetbrains.kotlin.gradle.dsl.KotlinJvmOptions
@@ -27,5 +28,7 @@ class PrototypeAndroidCompilation(delegate: Delegate) : DecoratedExternalKotlinC
         get() = super.compilerOptions as HasCompilerOptions<KotlinJvmCompilerOptions>
 
     var androidCompilationSpecificStuff = 10
+
+    val extraFriendPaths: ConfigurableFileCollection = project.files()
 }
 

libraries/tools/kotlin-gradle-plugin-tcs-android/src/main/kotlin/org/jetbrains/kotlin/gradle/android/createAndroidCompilation.kt

@@ -25,6 +25,10 @@ internal fun PrototypeAndroidTarget.createAndroidCompilation(name: String): Prot
         compilationFactory = CompilationFactory(::PrototypeAndroidCompilation)
         compileTaskName = camelCase("prototype", "compile", targetName, name)
 
+        friendArtifactResolver = ExternalKotlinCompilationDescriptor.FriendArtifactResolver { compilation ->
+            compilation.extraFriendPaths
+        }
+
         /*
         Replace Kotlin's compilation association (main <-> test) with noop,
         since Android goes through adding a dependency on the project itself

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/external/createExternalKotlinCompilation.kt

@@ -61,7 +61,7 @@ fun <T : DecoratedExternalKotlinCompilation> DecoratedExternalKotlinTarget.creat
                 descriptor.friendArtifactResolver?.let { declaredResolver ->
                     DefaultKotlinCompilationFriendPathsResolver.FriendArtifactResolver { compilation ->
                         @Suppress("unchecked_cast")
-                        declaredResolver.resolveFriendPaths(compilation as T)
+                        declaredResolver.resolveFriendPaths(compilation.decoratedInstance as T)
                     }
                 }
             )

libraries/tools/kotlin-gradle-plugin/src/functionalTest/kotlin/org/jetbrains/kotlin/gradle/dependencyResolutionTests/tcs/ExternalAndroidTargetPrototypeSmokeTest.kt

@@ -16,9 +16,12 @@ import org.jetbrains.kotlin.gradle.dsl.multiplatformExtension
 import org.jetbrains.kotlin.gradle.idea.testFixtures.tcs.anyDependency
 import org.jetbrains.kotlin.gradle.idea.testFixtures.tcs.assertMatches
 import org.jetbrains.kotlin.gradle.idea.testFixtures.tcs.binaryCoordinates
+import org.jetbrains.kotlin.gradle.plugin.KotlinCompilerArgumentsProducer.CreateCompilerArgumentsContext.Companion.default
 import org.jetbrains.kotlin.gradle.plugin.ide.kotlinIdeMultiplatformImport
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
 import org.jetbrains.kotlin.gradle.util.*
 import org.jetbrains.kotlin.gradle.utils.getByType
+import org.jetbrains.kotlin.util.assertDoesNotThrow
 import org.junit.Test
 import kotlin.test.BeforeTest
 import kotlin.test.assertEquals
@@ -96,4 +99,47 @@ class ExternalAndroidTargetPrototypeSmokeTest {
             anyDependency()
         )
     }
+
+    @Test
+    fun `test compile task arguments created without failures`() {
+        val project = buildProject {
+            enableDefaultStdlibDependency(false)
+            enableDependencyVerification(false)
+            applyMultiplatformPlugin()
+            repositories.mavenLocal()
+            repositories.mavenCentralCacheRedirector()
+        }
+        setAndroidSdkDirProperty(project)
+        project.androidLibrary { compileSdk = 31 }
+        val androidTargetPrototype = project.multiplatformExtension.androidTargetPrototype()
+        project.evaluate()
+
+        androidTargetPrototype.compilations.forEach { compilation ->
+            val compileTask = compilation.compileTaskProvider.get() as KotlinCompile
+            assertDoesNotThrow { compileTask.createCompilerArguments(default) }
+        }
+    }
+
+    @Test
+    fun `test extra friend-path is added correctly to compiler args`() {
+        val project = buildProject {
+            enableDefaultStdlibDependency(false)
+            enableDependencyVerification(false)
+            applyMultiplatformPlugin()
+            repositories.mavenLocal()
+            repositories.mavenCentralCacheRedirector()
+        }
+        setAndroidSdkDirProperty(project)
+        project.androidLibrary { compileSdk = 31 }
+        val androidTargetPrototype = project.multiplatformExtension.androidTargetPrototype()
+        project.evaluate()
+
+        val unitTest = androidTargetPrototype.compilations.getByName("unitTest")
+        val file = project.file("foo.jar")
+        unitTest.extraFriendPaths.from(file)
+
+        val compileTask = unitTest.compileTaskProvider.get() as KotlinCompile
+        val args = compileTask.createCompilerArguments(default)
+        if (file.absolutePath !in args.friendPaths!!) fail("File $file was not found int the friend paths ${args.friendPaths!!.toList()}")
+    }
 }