Auto link everything found in dist/klib.

Disable such behavior with -nodefaultlibs.
Omit libraries from the link stage if their packages have not been referenced.

backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2Native.kt

@@ -78,6 +78,7 @@ class K2Native : CLICompiler<K2NativeCompilerArguments>() {
         with(KonanConfigKeys) {
             with(configuration) {
 
+                put(NODEFAULTLIBS, arguments.nodefaultlibs)
                 put(NOSTDLIB, arguments.nostdlib)
                 put(NOPACK, arguments.nopack)
                 put(NOMAIN, arguments.nomain)

backend.native/cli.bc/src/org/jetbrains/kotlin/cli/bc/K2NativeCompilerArguments.kt

@@ -48,6 +48,9 @@ class K2NativeCompilerArguments : CommonCompilerArguments() {
     @Argument(value = "-nativelibrary", shortName = "-nl", valueDescription = "<path>", description = "Include the native bitcode library")
     var nativeLibraries: Array<String>? = null
 
+    @Argument(value = "-nodefaultlibs", description = "Don't link the libraries from dist/klib automatically")
+    var nodefaultlibs: Boolean = false
+
     @Argument(value = "-nomain", description = "Assume 'main' entry point to be provided by external libraries")
     var nomain: Boolean = false
 

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

@@ -75,26 +75,26 @@ class KonanConfig(val project: Project, val configuration: CompilerConfiguration
         get() = outputName
 
     private val libraryNames: List<String>
-        get() {
-            val fromCommandLine = configuration.getList(KonanConfigKeys.LIBRARY_FILES)
-            if (configuration.get(KonanConfigKeys.NOSTDLIB) ?: false) {
-                return fromCommandLine
-            }
-            return fromCommandLine + "stdlib"
-        }
+        get() = configuration.getList(KonanConfigKeys.LIBRARY_FILES)
 
     private val repositories = configuration.getList(KonanConfigKeys.REPOSITORIES)
     private val resolver = KonanLibrarySearchPathResolver(repositories, distribution.klib, distribution.localKonanDir)
-    private val librariesFound: List<File> by lazy {
-        val resolvedLibraries = libraryNames.map{it -> resolver.resolve(it)}
-        checkLibraryDuplicates(resolvedLibraries)
-        resolvedLibraries
-    }
-
-    internal val libraries: List<KonanLibraryReader> by lazy {
+    val libraries: List<KonanLibraryReader> by lazy {
         val target = targetManager.target
-        // Here we have chosen a particular KonanLibraryReader implementation.
-        librariesFound.map{it -> LibraryReaderImpl(it, currentAbiVersion, target)}
+
+        val defaultLibraries = resolver.defaultLinks(
+                configuration.getBoolean(KonanConfigKeys.NOSTDLIB),
+                configuration.getBoolean(KonanConfigKeys.NODEFAULTLIBS)
+            ) .map { LibraryReaderImpl(it, currentAbiVersion, target, isDefaultLink=true) }
+
+        val userProvidedLibraries = libraryNames
+            .map { resolver.resolve(it) }
+            .map{ LibraryReaderImpl(it, currentAbiVersion, target) }
+
+        val resolvedLibraries = defaultLibraries + userProvidedLibraries
+        checkLibraryDuplicates(resolvedLibraries.map{it.libraryFile})
+
+        resolvedLibraries
     }
 
     private val loadedDescriptors = loadLibMetadata()

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

@@ -57,6 +57,8 @@ class KonanConfigKeys {
                 = CompilerConfigurationKey.create("module kind")
         val NATIVE_LIBRARY_FILES: CompilerConfigurationKey<List<String>>
                 = CompilerConfigurationKey.create("native library file paths")
+        val NODEFAULTLIBS: CompilerConfigurationKey<Boolean>
+                = CompilerConfigurationKey.create("don't link with the default libraries")
         val NOMAIN: CompilerConfigurationKey<Boolean> 
                 = CompilerConfigurationKey.create("assume 'main' entry point to be provided by external libraries")
         val NOSTDLIB: CompilerConfigurationKey<Boolean> 

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

@@ -231,7 +231,15 @@ internal class LinkStage(val context: Context) {
     private val debug = config.get(KonanConfigKeys.DEBUG) ?: false
     private val nomain = config.get(KonanConfigKeys.NOMAIN) ?: false
     private val emitted = context.bitcodeFileName
-    private val libraries = context.config.libraries
+    private val libraries = context.config.libraries 
+        .map { 
+            if (!it.isNeededForLink) { 
+                if (!it.isDefaultLink) {
+                    context.reportCompilationWarning("The '${it.libraryName}' library has not been referenced. Omitted from the final link.")
+                }
+                null
+            } else it
+        }.filterNotNull()
 
     private fun MutableList<String>.addNonEmpty(elements: List<String>) {
         addAll(elements.filter { !it.isEmpty() })

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/library/KonanLibraryReader.kt

@@ -26,6 +26,8 @@ interface KonanLibraryReader {
     val includedPaths: List<String>
     val linkerOpts: List<String>
     val escapeAnalysis: ByteArray?
+    val isNeededForLink: Boolean get() = true
+    val isDefaultLink: Boolean get() = false
     val manifestProperties: Properties
     fun moduleDescriptor(specifics: LanguageVersionSettings): ModuleDescriptor
 }

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/library/SearchPathResolver.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.konan.file.File
 interface SearchPathResolver {
     val searchRoots: List<File>
     fun resolve(givenPath: String): File
+    fun defaultLinks(nostdlib: Boolean, noDefaultLibs: Boolean): List<File>
 }
 
 class KonanLibrarySearchPathResolver(repositories: List<String>,
@@ -72,5 +73,19 @@ class KonanLibrarySearchPathResolver(repositories: List<String>,
 
     private val File.klib
         get() = File(this, "klib")
+
+    // The libraries from the default root are linked autimatically.
+    val defaultRoot: File?
+        get() = if (distHead?.exists ?: false) distHead else null
+
+    override fun defaultLinks(nostdlib: Boolean, noDefaultLibs: Boolean): List<File> {
+        val defaultLibs = defaultRoot?.listFiles.orEmpty()
+            .filterNot { it.name.removeSuffixIfPresent(".klib") == "stdlib" }
+            .map { File(it.absolutePath) }
+        val result = mutableListOf<File>()
+        if (!nostdlib) result.add(resolve("stdlib"))
+        if (!noDefaultLibs) result.addAll(defaultLibs)
+        return result
+    }
 }
 

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/library/impl/KonanLibraryReaderImpl.kt

@@ -18,13 +18,16 @@ package org.jetbrains.kotlin.backend.konan.library.impl
 
 import org.jetbrains.kotlin.backend.konan.library.KonanLibraryReader
 import org.jetbrains.kotlin.backend.konan.createInteropLibrary
+import org.jetbrains.kotlin.backend.konan.serialization.emptyPackages
 import org.jetbrains.kotlin.backend.konan.serialization.deserializeModule
 import org.jetbrains.kotlin.konan.file.File
 import org.jetbrains.kotlin.konan.properties.*
 import org.jetbrains.kotlin.config.LanguageVersionSettings
 import org.jetbrains.kotlin.konan.target.KonanTarget
 
-class LibraryReaderImpl(var libraryFile: File, val currentAbiVersion: Int, val target: KonanTarget? = null) : KonanLibraryReader {
+class LibraryReaderImpl(var libraryFile: File, val currentAbiVersion: Int,
+    val target: KonanTarget? = null, override val isDefaultLink: Boolean = false)
+    : KonanLibraryReader {
 
     // For the zipped libraries inPlace gives files from zip file system
     // whereas realFiles extracts them to /tmp.
@@ -66,8 +69,22 @@ class LibraryReaderImpl(var libraryFile: File, val currentAbiVersion: Int, val t
         reader.loadSerializedModule()
     }
 
-    fun packageMetadata(fqName: String): ByteArray =
-        reader.loadSerializedPackageFragment(fqName)
+    override val isNeededForLink: Boolean
+        get() {
+            packagesAccessed.forEach {
+                if (!emptyPackages(moduleHeaderData).contains(it)) {
+                    return true
+                }
+            }
+            return false
+        }
+
+    val packagesAccessed = mutableSetOf<String>()
+
+    fun packageMetadata(fqName: String): ByteArray {
+        packagesAccessed.add(fqName)
+        return reader.loadSerializedPackageFragment(fqName)
+    }
 
     override fun moduleDescriptor(specifics: LanguageVersionSettings) 
         = deserializeModule(specifics, {packageMetadata(it)}, moduleHeaderData, createInteropLibrary(this))

backend.native/compiler/ir/backend.native/src/org/jetbrains/kotlin/backend/konan/serialization/KonanLinkData.proto

@@ -76,6 +76,7 @@ message PackageFragment {
     required string fq_name = 1;
     required Package package = 4;
     required Classes classes = 5;
+    required bool is_empty = 6;
 
     // To construct name resolver
     required QualifiedNameTable name_table = 2;
@@ -91,5 +92,6 @@ message Classes {
 message Library {
     required string module_name = 1;
     repeated string package_fragment_name = 2;
+    repeated string empty_package = 3;
 }
 

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

@@ -119,6 +119,9 @@ public fun parseModuleHeader(libraryData: ByteArray): Library =
     Library.parseFrom(libraryData, 
         KonanSerializerProtocol.extensionRegistry)
 
+public fun emptyPackages(libraryData: ByteArray) 
+    = parseModuleHeader(libraryData).emptyPackageList
+
 internal fun deserializeModule(languageVersionSettings: LanguageVersionSettings,
                                packageLoader:(String)->ByteArray, library: ByteArray,
                                interopLibrary: InteropLibrary?): ModuleDescriptorImpl {
@@ -220,6 +223,7 @@ internal class KonanSerializationUtil(val context: Context) {
         val strings = serializerExtension.stringTable
         val (stringTableProto, nameTableProto) = strings.buildProto()
 
+        val isEmpty = members.isEmpty() && classifierDescriptors.isEmpty()
         val fragmentBuilder = KonanLinkData.PackageFragment.newBuilder()
 
         val fragmentProto = fragmentBuilder
@@ -228,6 +232,7 @@ internal class KonanSerializationUtil(val context: Context) {
             .setClasses(classesProto)
             .setStringTable(stringTableProto)
             .setNameTable(nameTableProto)
+            .setIsEmpty(isEmpty)
             .build()
 
         return fragmentProto
@@ -251,6 +256,7 @@ internal class KonanSerializationUtil(val context: Context) {
             }
         }
     }
+
     internal fun serializeModule(moduleDescriptor: ModuleDescriptor): LinkData {
         val libraryProto = KonanLinkData.Library.newBuilder()
         libraryProto.moduleName = moduleDescriptor.name.asString()
@@ -262,6 +268,9 @@ internal class KonanSerializationUtil(val context: Context) {
             if (packageProto == null) return@iteration
 
             libraryProto.addPackageFragmentName(it.asString())
+            if (packageProto.isEmpty) {
+                libraryProto.addEmptyPackage(it.asString())
+            }
             fragments.add(packageProto.toByteArray())
             fragmentNames.add(it.asString())
         }