Implement -Xframework-import-header compiler flag (#2952)

To be used to add imports to framework header
to workaround missing imports issues.

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

@@ -194,6 +194,7 @@ class K2Native : CLICompiler<K2NativeCompilerArguments>() {
                     put(FRIEND_MODULES, arguments.friendModules!!.split(File.pathSeparator).filterNot(String::isEmpty))
 
                 put(EXPORTED_LIBRARIES, selectExportedLibraries(configuration, arguments, outputKind))
+                put(FRAMEWORK_IMPORT_HEADERS, arguments.frameworkImportHeaders.toNonNullList())
 
                 put(BITCODE_EMBEDDING_MODE, selectBitcodeEmbeddingMode(this, arguments, outputKind))
                 put(DEBUG_INFO_VERSION, arguments.debugInfoFormatVersion.toInt())

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

@@ -119,6 +119,13 @@ class K2NativeCompilerArguments : CommonCompilerArguments() {
     )
     var exportedLibraries: Array<String>? = null
 
+    @Argument(
+            value = "-Xframework-import-header",
+            valueDescription = "<header>",
+            description = "Add additional header import to framework header"
+    )
+    var frameworkImportHeaders: Array<String>? = null
+
     @Argument(value = "-Xprint-bitcode", deprecatedName = "--print_bitcode", description = "Print llvm bitcode")
     var printBitCode: Boolean = false
 

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

@@ -30,6 +30,8 @@ class KonanConfigKeys {
                 = CompilerConfigurationKey.create("fully qualified main() name")
         val EXPORTED_LIBRARIES: CompilerConfigurationKey<List<String>>
                 = CompilerConfigurationKey.create<List<String>>("libraries included into produced framework API")
+        val FRAMEWORK_IMPORT_HEADERS: CompilerConfigurationKey<List<String>>
+                = CompilerConfigurationKey.create<List<String>>("headers imported to framework header")
         val FRIEND_MODULES: CompilerConfigurationKey<List<String>>
                 = CompilerConfigurationKey.create<List<String>>("friend module paths")
         val GENERATE_TEST_RUNNER: CompilerConfigurationKey<TestRunnerKind>

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

@@ -715,6 +715,9 @@ abstract class ObjCExportHeaderGenerator internal constructor(
         add("#import <Foundation/NSSet.h>")
         add("#import <Foundation/NSString.h>")
         add("#import <Foundation/NSValue.h>")
+        getAdditionalImports().forEach {
+            add("#import <$it>")
+        }
         add("")
 
         if (classForwardDeclarations.isNotEmpty()) {
@@ -747,6 +750,8 @@ abstract class ObjCExportHeaderGenerator internal constructor(
 
     protected abstract fun reportWarning(method: FunctionDescriptor, text: String)
 
+    protected open fun getAdditionalImports(): List<String> = emptyList()
+
 
     fun translateModule(): List<Stub<*>> {
         // TODO: make the translation order stable

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

@@ -6,6 +6,7 @@
 package org.jetbrains.kotlin.backend.konan.objcexport
 
 import org.jetbrains.kotlin.backend.konan.Context
+import org.jetbrains.kotlin.backend.konan.KonanConfigKeys
 import org.jetbrains.kotlin.backend.konan.reportCompilationWarning
 import org.jetbrains.kotlin.cli.common.messages.CompilerMessageSeverity
 import org.jetbrains.kotlin.cli.common.messages.MessageUtil
@@ -36,4 +37,7 @@ internal class ObjCExportHeaderGeneratorImpl(
 
         context.messageCollector.report(CompilerMessageSeverity.WARNING, text, location)
     }
+
+    override fun getAdditionalImports(): List<String> =
+            context.config.configuration.getNotNull(KonanConfigKeys.FRAMEWORK_IMPORT_HEADERS)
 }