[Interop][Linker] Full support for metadata-only interop

Add support for IdSignatures to interop declarations from metadata-only libraries.

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

@@ -0,0 +1,66 @@
+/*
+ * Copyright 2010-2020 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.
+ */
+package org.jetbrains.kotlin.backend.konan.serialization
+
+import org.jetbrains.kotlin.descriptors.*
+import org.jetbrains.kotlin.ir.util.IdSignature
+
+// The code here is intentionally copy-pasted from DeclarationStubGenerator with
+// minor changes.
+// "Find descriptor by IdSignature" task appears to be common and should be unified later.
+class DescriptorByIdSignatureFinder(
+        private val moduleDescriptor: ModuleDescriptor
+) {
+    fun findDescriptorBySignature(signature: IdSignature): DeclarationDescriptor? = when (signature) {
+        is IdSignature.AccessorSignature -> findDescriptorForAccessorSignature(signature)
+        is IdSignature.PublicSignature -> findDescriptorForPublicSignature(signature)
+        else -> error("only PublicSignature or AccessorSignature should reach this point, got $signature")
+    }
+
+    private fun findDescriptorForAccessorSignature(signature: IdSignature.AccessorSignature): DeclarationDescriptor? {
+        val propertyDescriptor = findDescriptorBySignature(signature.propertySignature) as? PropertyDescriptor
+                ?: return null
+        return propertyDescriptor.accessors.singleOrNull {
+            it.name == signature.accessorSignature.declarationFqn.shortName()
+        }
+    }
+
+    private fun findDescriptorForPublicSignature(signature: IdSignature.PublicSignature): DeclarationDescriptor? {
+        val packageDescriptor = moduleDescriptor.getPackage(signature.packageFqName())
+        val pathSegments = signature.declarationFqn.pathSegments()
+        val toplevelDescriptors = packageDescriptor.memberScope.getContributedDescriptors { name -> name == pathSegments.first() }
+                .filter { it.name == pathSegments.first() }
+        val candidates = pathSegments.drop(1).fold(toplevelDescriptors) { acc, current ->
+            acc.flatMap { container ->
+                val classDescriptor = container as? ClassDescriptor
+                        ?: return@flatMap emptyList<DeclarationDescriptor>()
+                val nextStepCandidates = classDescriptor.constructors +
+                        classDescriptor.unsubstitutedMemberScope.getContributedDescriptors { name -> name == current } +
+                        // Static scope is required only for Enum.values() and Enum.valueOf().
+                        classDescriptor.staticScope.getContributedDescriptors { name -> name == current }
+                nextStepCandidates.filter { it.name == current }
+            }
+        }
+
+        return when (candidates.size) {
+            1 -> candidates.first()
+            else -> {
+                findDescriptorByHash(candidates, signature.id)
+                        ?: error("No descriptor found for $signature")
+            }
+        }
+    }
+
+    private fun findDescriptorByHash(candidates: List<DeclarationDescriptor>, id: Long?): DeclarationDescriptor? =
+        candidates.firstOrNull { candidate ->
+            if (id == null) {
+                // We don't compute id for typealiases and classes.
+                candidate is ClassDescriptor || candidate is TypeAliasDescriptor
+            } else {
+                val candidateHash = with(KonanManglerDesc) { candidate.signatureMangle }
+                candidateHash == id
+            }
+        }
+}

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

@@ -1,12 +1,31 @@
 package org.jetbrains.kotlin.backend.konan.serialization
 
+import org.jetbrains.kotlin.backend.common.serialization.DeclarationTable
 import org.jetbrains.kotlin.backend.common.serialization.GlobalDeclarationTable
+import org.jetbrains.kotlin.backend.common.serialization.signature.DescToIrIdSignatureComputer
 import org.jetbrains.kotlin.backend.common.serialization.signature.IdSignatureSerializer
+import org.jetbrains.kotlin.backend.konan.descriptors.isFromInteropLibrary
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 
 import org.jetbrains.kotlin.ir.descriptors.IrBuiltIns
+import org.jetbrains.kotlin.ir.util.IdSignature
+import org.jetbrains.kotlin.resolve.descriptorUtil.module
 
 class KonanGlobalDeclarationTable(signatureSerializer: IdSignatureSerializer, builtIns: IrBuiltIns) : GlobalDeclarationTable(signatureSerializer, KonanManglerIr) {
     init {
         loadKnownBuiltins(builtIns)
     }
+}
+
+class KonanDeclarationTable(
+        globalDeclarationTable: GlobalDeclarationTable
+) : DeclarationTable(globalDeclarationTable) {
+
+    private val signatureIdComposer = DescToIrIdSignatureComputer(KonanIdSignaturer(KonanManglerDesc))
+
+    // TODO: We should get rid of this extension point in favor of proper support in IR-based mangler.
+    override fun tryComputeBackendSpecificSignature(declaration: IrDeclaration): IdSignature? =
+            if (declaration.descriptor.module.isFromInteropLibrary()) {
+                signatureIdComposer.computeSignature(declaration)
+            } else null
 }

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

@@ -29,5 +29,5 @@ class KonanIrModuleSerializer(
             file.fileEntry.name != IrProviderForCEnumAndCStructStubs.cTypeDefinitionsFileName
 
     override fun createSerializerForFile(file: IrFile): KonanIrFileSerializer =
-            KonanIrFileSerializer(logger, DeclarationTable(globalDeclarationTable), expectDescriptorToSymbol, skipExpects = skipExpects)
+            KonanIrFileSerializer(logger, KonanDeclarationTable(globalDeclarationTable), expectDescriptorToSymbol, skipExpects = skipExpects)
 }

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

@@ -48,6 +48,8 @@ class KonanIrLinker(
     exportedDependencies: List<ModuleDescriptor>
 ) : KotlinIrLinker(logger, builtIns, symbolTable, exportedDependencies, forwardModuleDescriptor) {
 
+    private val descriptorByIdSignatureFinder = DescriptorByIdSignatureFinder(currentModule)
+
     override fun reader(moduleDescriptor: ModuleDescriptor, fileIndex: Int, idSigIndex: Int) =
             moduleDescriptor.konanLibrary!!.irDeclaration(idSigIndex, fileIndex)
 
@@ -93,6 +95,9 @@ class KonanIrLinker(
     }
 
     override fun resolvePlatformDescriptor(idSig: IdSignature): DeclarationDescriptor? {
+        if (idSig.isInteropSignature()) {
+            return descriptorByIdSignatureFinder.findDescriptorBySignature(idSig)
+        }
         if (!idSig.isForwardDeclarationSignature()) return null
 
         val fwdModule = forwardModuleDescriptor ?: error("Forward declaration module should not be null")