Support reflection calls to multifile class members

#KT-11447 Fixed

compiler/testData/codegen/box/reflection/multifileClasses/callFunctionsInMultifileClass.kt

@@ -0,0 +1,32 @@
+// WITH_REFLECT
+// FILE: Test1.kt
+
+@file:kotlin.jvm.JvmName("Test")
+@file:kotlin.jvm.JvmMultifileClass
+package test
+
+import kotlin.test.assertEquals
+
+fun getX() = 1
+
+fun box(): String {
+    assertEquals("getX", ::getX.name)
+    assertEquals("getY", ::getY.name)
+    assertEquals("getZ", ::getZ.name)
+
+    assertEquals(1, ::getX.call())
+    assertEquals(239, ::getY.call())
+    assertEquals(42, ::getZ.callBy(emptyMap()))
+
+    return "OK"
+}
+
+// FILE: Test2.kt
+
+@file:kotlin.jvm.JvmName("Test")
+@file:kotlin.jvm.JvmMultifileClass
+package test
+
+fun getY() = 239
+
+fun getZ(value: Int = 42) = value

compiler/testData/codegen/box/reflection/multifileClasses/callPropertiesInMultifileClass.kt

@@ -0,0 +1,42 @@
+// KT-11447 Multifile declaration causes IAE: Method can not access a member of class
+// WITH_REFLECT
+// FILE: Test1.kt
+
+@file:kotlin.jvm.JvmName("Test")
+@file:kotlin.jvm.JvmMultifileClass
+package test
+
+import kotlin.test.assertEquals
+
+var x = 1
+
+fun box(): String {
+    assertEquals("x", ::x.name)
+    assertEquals("y", ::y.name)
+    assertEquals("MAGIC_NUMBER", ::MAGIC_NUMBER.name)
+
+    assertEquals(1, ::x.call())
+    assertEquals(1, ::x.getter.call())
+
+    assertEquals(239, ::y.call())
+    assertEquals(239, ::y.getter.call())
+
+    assertEquals(42, ::MAGIC_NUMBER.call())
+    assertEquals(42, ::MAGIC_NUMBER.getter.call())
+
+    assertEquals(Unit, ::x.setter.call(2))
+    assertEquals(2, ::x.call())
+    assertEquals(2, ::x.getter.call())
+
+    return "OK"
+}
+
+// FILE: Test2.kt
+
+@file:kotlin.jvm.JvmName("Test")
+@file:kotlin.jvm.JvmMultifileClass
+package test
+
+val y = 239
+
+const val MAGIC_NUMBER = 42

compiler/testData/codegen/box/reflection/multifileClasses/javaFieldForVarAndConstVal.kt

@@ -0,0 +1,52 @@
+// WITH_REFLECT
+// FULL_JDK
+// FILE: 1.kt
+
+@file:kotlin.jvm.JvmName("Test")
+@file:kotlin.jvm.JvmMultifileClass
+package test
+
+import kotlin.reflect.jvm.*
+import kotlin.test.assertEquals
+
+fun testX() {
+    val field = ::x.javaField ?: throw AssertionError("No java field for ${::x.name}")
+
+    try {
+        field.get(null)
+        throw AssertionError("Fail: field.get should fail because the field is private")
+    }
+    catch (e: IllegalAccessException) {
+        // OK
+    }
+
+    field.setAccessible(true)
+    assertEquals("I am x", field.get(null))
+    field.set(null, "OK")
+}
+
+fun testY() {
+    val field = ::y.javaField ?: throw AssertionError("No java field for ${::y.name}")
+
+    assertEquals("I am const y", field.get(null))
+
+    // Accessible = false should have no effect because the field is public
+    field.setAccessible(false)
+
+    assertEquals("I am const y", field.get(null))
+}
+
+fun box(): String {
+    testX()
+    testY()
+    return x
+}
+
+// FILE: 2.kt
+
+@file:kotlin.jvm.JvmName("Test")
+@file:kotlin.jvm.JvmMultifileClass
+package test
+
+var x = "I am x"
+const val y = "I am const y"

compiler/tests/org/jetbrains/kotlin/codegen/BlackBoxCodegenTestGenerated.java

@@ -11485,6 +11485,33 @@ public class BlackBoxCodegenTestGenerated extends AbstractBlackBoxCodegenTest {
             }
         }
 
+        @TestMetadata("compiler/testData/codegen/box/reflection/multifileClasses")
+        @TestDataPath("$PROJECT_ROOT")
+        @RunWith(JUnit3RunnerWithInners.class)
+        public static class MultifileClasses extends AbstractBlackBoxCodegenTest {
+            public void testAllFilesPresentInMultifileClasses() throws Exception {
+                KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("compiler/testData/codegen/box/reflection/multifileClasses"), Pattern.compile("^(.+)\\.kt$"), true);
+            }
+
+            @TestMetadata("callFunctionsInMultifileClass.kt")
+            public void testCallFunctionsInMultifileClass() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/multifileClasses/callFunctionsInMultifileClass.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("callPropertiesInMultifileClass.kt")
+            public void testCallPropertiesInMultifileClass() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/multifileClasses/callPropertiesInMultifileClass.kt");
+                doTest(fileName);
+            }
+
+            @TestMetadata("javaFieldForVarAndConstVal.kt")
+            public void testJavaFieldForVarAndConstVal() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("compiler/testData/codegen/box/reflection/multifileClasses/javaFieldForVarAndConstVal.kt");
+                doTest(fileName);
+            }
+        }
+
         @TestMetadata("compiler/testData/codegen/box/reflection/noReflectAtRuntime")
         @TestDataPath("$PROJECT_ROOT")
         @RunWith(JUnit3RunnerWithInners.class)

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KDeclarationContainerImpl.kt

@@ -39,6 +39,9 @@ internal abstract class KDeclarationContainerImpl : ClassBasedDeclarationContain
     val moduleData: RuntimeModuleData
         get() = moduleData_()
 
+    protected open val methodOwner: Class<*>
+        get() = jClass
+
     abstract val constructorDescriptors: Collection<ConstructorDescriptor>
 
     abstract fun getProperties(name: Name): Collection<PropertyDescriptor>
@@ -175,9 +178,7 @@ internal abstract class KDeclarationContainerImpl : ClassBasedDeclarationContain
     fun findMethodBySignature(name: String, desc: String, declared: Boolean): Method? {
         if (name == "<init>") return null
 
-        // Method for a top level function should be the one from the package facade.
+        return methodOwner.tryGetMethod(name, loadParameterTypes(desc), declared)
-        // This is likely to change after the package part reform.
-        return jClass.tryGetMethod(name, loadParameterTypes(desc), declared)
     }
 
     fun findDefaultMethod(name: String, desc: String, isMember: Boolean, declared: Boolean): Method? {
@@ -189,7 +190,7 @@ internal abstract class KDeclarationContainerImpl : ClassBasedDeclarationContain
         }
         addParametersAndMasks(parameterTypes, desc, false)
 
-        return jClass.tryGetMethod(name + JvmAbi.DEFAULT_PARAMS_IMPL_SUFFIX, parameterTypes, declared)
+        return methodOwner.tryGetMethod(name + JvmAbi.DEFAULT_PARAMS_IMPL_SUFFIX, parameterTypes, declared)
     }
 
     fun findConstructorBySignature(desc: String, declared: Boolean): Constructor<*>? {

core/reflection.jvm/src/kotlin/reflect/jvm/internal/KPackageImpl.kt

@@ -38,6 +38,19 @@ internal class KPackageImpl(override val jClass: Class<*>, val moduleName: Strin
         }
     }
 
+    override val methodOwner: Class<*> by lazy(LazyThreadSafetyMode.PUBLICATION) {
+        val facadeName = ReflectKotlinClass.create(jClass)?.classHeader?.multifileClassName
+        // We need to check isNotEmpty because this is the value read from the annotation which cannot be null.
+        // The default value for 'xs' is empty string, as declared in kotlin.Metadata
+        // TODO: do not read ReflectKotlinClass multiple times, obtain facade name from descriptor
+        if (facadeName != null && facadeName.isNotEmpty()) {
+            jClass.classLoader.loadClass(facadeName.replace('/', '.'))
+        }
+        else {
+            jClass
+        }
+    }
+
     internal val scope: MemberScope get() = descriptor().memberScope
 
     override val members: Collection<KCallable<*>>