Load definitions of symbols from .kotlin_metadata files

Extract AbstractDeserializedPackageFragmentProvider out of
JvmBuiltInsPackageFragmentProvider and implement it a little bit differently in
MetadataPackageFragmentProvider. The main difference is in how the package
fragment scope is constructed: for built-ins, it's just a single scope that
loads everything from one protobuf message. For metadata, package scope can
consist of many files, some of which store information about classes and others
are similar to package parts on JVM, so a ChainedMemberScope instance is
created.

Introduce a bunch of interfaces/methods to deliver the needed behavior to the
'deserialization' module which is not JVM-specific and does not depend on the
compiler code: MetadataFinderFactory,
PackagePartProvider#findMetadataPackageParts, KotlinMetadataFinder#findMetadata.
Note that these declarations are currently only implemented in the compiler; no
metadata package parts/fragments will be found in IDE or reflection

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/JvmCliVirtualFileFinder.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.load.kotlin.VirtualFileKotlinClassFinder
 import org.jetbrains.kotlin.name.ClassId
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
+import org.jetbrains.kotlin.serialization.deserialization.MetadataPackageFragment
 import org.jetbrains.kotlin.utils.addToStdlib.check
 import java.io.InputStream
 
@@ -35,6 +36,12 @@ class JvmCliVirtualFileFinder(
     override fun findVirtualFileWithHeader(classId: ClassId): VirtualFile? =
             findBinaryClass(classId, classId.relativeClassName.asString().replace('.', '$') + ".class")
 
+    override fun findMetadata(classId: ClassId): InputStream? {
+        assert(!classId.isNestedClass) { "Nested classes are not supported here: $classId" }
+
+        return findBinaryClass(classId, classId.shortClassName.asString() + MetadataPackageFragment.METADATA_FILE_EXTENSION)?.inputStream
+    }
+
     override fun findBuiltInsData(packageFqName: FqName): InputStream? {
         // "<builtins-metadata>" is just a made-up name
         // JvmDependenciesIndex requires the ClassId of the class which we're searching for, to cache the last request+result

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/JvmPackagePartProvider.kt

@@ -22,6 +22,7 @@ import org.jetbrains.kotlin.cli.jvm.config.JvmClasspathRoot
 import org.jetbrains.kotlin.config.JVMConfigurationKeys
 import org.jetbrains.kotlin.descriptors.PackagePartProvider
 import org.jetbrains.kotlin.load.kotlin.ModuleMapping
+import org.jetbrains.kotlin.load.kotlin.PackageParts
 import java.io.EOFException
 
 class JvmPackagePartProvider(
@@ -38,11 +39,16 @@ class JvmPackagePartProvider(
 
     private val loadedModules: MutableList<ModuleMapping> = SmartList()
 
-    @Synchronized
-    override fun findPackageParts(packageFqName: String): List<String> {
-        processNotLoadedRelevantRoots(packageFqName)
+    override fun findPackageParts(packageFqName: String): List<String> =
+            getPackageParts(packageFqName).flatMap(PackageParts::parts).distinct()
 
-        return loadedModules.flatMap { it.findPackageParts(packageFqName)?.parts ?: emptySet<String>() }.distinct()
+    override fun findMetadataPackageParts(packageFqName: String): List<String> =
+            getPackageParts(packageFqName).flatMap(PackageParts::metadataParts).distinct()
+
+    @Synchronized
+    private fun getPackageParts(packageFqName: String): List<PackageParts> {
+        processNotLoadedRelevantRoots(packageFqName)
+        return loadedModules.mapNotNull { it.findPackageParts(packageFqName) }
     }
 
     private fun processNotLoadedRelevantRoots(packageFqName: String) {

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/compiler/KotlinCoreEnvironment.kt

@@ -86,6 +86,7 @@ import org.jetbrains.kotlin.extensions.StorageComponentContainerContributor
 import org.jetbrains.kotlin.idea.KotlinFileType
 import org.jetbrains.kotlin.load.kotlin.JvmVirtualFileFinderFactory
 import org.jetbrains.kotlin.load.kotlin.KotlinBinaryClassCache
+import org.jetbrains.kotlin.load.kotlin.MetadataFinderFactory
 import org.jetbrains.kotlin.load.kotlin.ModuleVisibilityManager
 import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.isValidJavaFqName
@@ -160,7 +161,9 @@ class KotlinCoreEnvironment private constructor(
         (ServiceManager.getService(project, CoreJavaFileManager::class.java)
                 as KotlinCliJavaFileManagerImpl).initIndex(rootsIndex)
 
-        project.registerService(JvmVirtualFileFinderFactory::class.java, JvmCliVirtualFileFinderFactory(rootsIndex))
+        val finderFactory = JvmCliVirtualFileFinderFactory(rootsIndex)
+        project.registerService(MetadataFinderFactory::class.java, finderFactory)
+        project.registerService(JvmVirtualFileFinderFactory::class.java, finderFactory)
 
         ExpressionCodegenExtension.registerExtensionPoint(project)
         ClassBuilderInterceptorExtension.registerExtensionPoint(project)