Avoid hanging external functions. (#2265)

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

@@ -460,13 +460,4 @@ typealias CArrayPointerVar<T> = CPointerVar<T>
 /**
  * The C function.
  */
-class CFunction<T : Function<*>>(rawPtr: NativePtr) : CPointed(rawPtr)
-
-/**
- * Returns a pointer to C function which calls given Kotlin *static* function.
- *
- * @param function must be *static*, i.e. an (unbound) reference to a Kotlin function or
- * a closure which doesn't capture any variable
- */
-@Deprecated("The function type is too general. Supply argument with known arity.", level = DeprecationLevel.ERROR)
-external fun <F : Function<*>> staticCFunction(function: F): CPointer<CFunction<F>>
+class CFunction<T : Function<*>>(rawPtr: NativePtr) : CPointed(rawPtr)

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

@@ -602,7 +602,7 @@ class StubGenerator(
                 } else {
                     sequenceOf(
                             annotationForUnableToImport,
-                            "external $header"
+                            "$header = throw UnsupportedOperationException()"
                     )
                 }
 

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/llvm/BinaryInterface.kt

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.backend.konan.llvm
 
 import llvm.LLVMTypeRef
+import org.jetbrains.kotlin.backend.common.ir.ir2string
 import org.jetbrains.kotlin.backend.konan.descriptors.isAbstract
 import org.jetbrains.kotlin.backend.konan.irasdescriptors.*
 import org.jetbrains.kotlin.backend.konan.isInlined
@@ -104,6 +105,9 @@ internal tailrec fun DeclarationDescriptor.isExported(): Boolean {
 
 private val symbolNameAnnotation = FqName("kotlin.native.SymbolName")
 
+private val intrinsicAnnotation = FqName("kotlin.native.internal.Intrinsic")
+private val objCMethodAnnotation = FqName("kotlinx.cinterop.ObjCMethod")
+
 private val cnameAnnotation = FqName("kotlin.native.CName")
 
 private val exportForCppRuntimeAnnotation = FqName("kotlin.native.internal.ExportForCppRuntime")
@@ -205,13 +209,17 @@ internal val FunctionDescriptor.symbolName: String
         if (!this.isExported()) {
             throw AssertionError(this.descriptor.toString())
         }
-        this.descriptor.annotations.findAnnotation(symbolNameAnnotation)?.let {
-            if (this.isExternal) {
+
+        if (isExternal) {
+            this.descriptor.annotations.findAnnotation(symbolNameAnnotation)?.let {
                 return getStringValue(it)!!
-            } else {
-                // ignore; TODO: report compile error
+            }
+            if (!this.descriptor.annotations.hasAnnotation(intrinsicAnnotation) &&
+                    !this.descriptor.annotations.hasAnnotation(objCMethodAnnotation)) {
+                throw Error("external function ${this.descriptor} must have @SymbolName, @Intrinsic or @ObjCMethod annotation")
             }
         }
+
         this.descriptor.annotations.findAnnotation(exportForCppRuntimeAnnotation)?.let {
             val name = getStringValue(it) ?: this.name.asString()
             return name // no wrapping currently required

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

@@ -24,7 +24,9 @@ import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameSafe
 import org.jetbrains.kotlin.types.TypeUtils
 import org.jetbrains.kotlin.utils.addToStdlib.ifNotEmpty
 
-internal fun DeclarationDescriptor.symbolName(): String = when (this) {
+
+// TODO: merge with FunctionDescriptor.symbolName in BinaryInterface.kt.
+internal val DeclarationDescriptor.symbolName: String get() = when (this) {
     is FunctionDescriptor 
         -> this.uniqueName
     is PropertyDescriptor 
@@ -35,7 +37,7 @@ internal fun DeclarationDescriptor.symbolName(): String = when (this) {
 }
 
 internal val DeclarationDescriptor.uniqId 
-    get() = this.symbolName().localHash.value
+    get() = this.symbolName.localHash.value
 
 internal val DeclarationDescriptor.isSerializableExpectClass: Boolean
     get() = this is ClassDescriptor && ExpectedActualDeclarationChecker.shouldGenerateExpectClass(this)
@@ -154,6 +156,8 @@ internal tailrec fun DeclarationDescriptor.isExported(): Boolean {
 
 private val symbolNameAnnotation = FqName("kotlin.native.SymbolName")
 
+private val intrinsicAnnotation = FqName("kotlin.native.internal.Intrinsic")
+
 private val exportForCppRuntimeAnnotation = FqName("kotlin.native.internal.ExportForCppRuntime")
 
 private val cnameAnnotation = FqName("kotlin.native.internal.CName")
@@ -244,13 +248,16 @@ private val FunctionDescriptor.uniqueName: String
             throw AssertionError(this.toString())
         }
 
-        this.annotations.findAnnotation(symbolNameAnnotation)?.let {
-            if (this.isExternal) {
+        if (this.isExternal) {
+            this.annotations.findAnnotation(symbolNameAnnotation)?.let {
                 return getStringValue(it)!!
-            } else {
-                // ignore; TODO: report compile error
+            }
+            if (!annotations.hasAnnotation(intrinsicAnnotation)) {
+                throw Error("external function $this must have @SymbolName annotation")
             }
         }
+        // TODO: check that only external function has @SymbolName.
+
 
         this.annotations.findAnnotation(exportForCppRuntimeAnnotation)?.let {
             val name = getStringValue(it) ?: this.name.asString()

runtime/src/launcher/kotlin/konan/start.kt

@@ -2,13 +2,14 @@
  * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
  * that can be found in the LICENSE file.
  */
+
 import kotlin.native.internal.ExportForCppRuntime
 
 // This function is produced by the code generator given
 // the '-entry foo.bar.main' flag. 
 // It calls the requested entry point.
 // The default is main(Array<String>):Unit in the root package.
-@ExportForCppRuntime
+@SymbolName("EntryPointSelector")
 external fun EntryPointSelector(args: Array<String>)
 
 @ExportForCppRuntime