Do not add JDK .jar roots if the JDK is modular (9+)

Files like ant-javafx.jar, deploy.jar, java.jnlp.jar, javafx-swt.jar etc
should not be added to the classpath if JDK home points to a JDK 9
distribution

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/K2JVMCompiler.kt

@@ -34,6 +34,7 @@ import org.jetbrains.kotlin.cli.jvm.config.JvmModulePathRoot
 import org.jetbrains.kotlin.cli.jvm.config.addJavaSourceRoot
 import org.jetbrains.kotlin.cli.jvm.config.addJvmClasspathRoots
 import org.jetbrains.kotlin.cli.jvm.config.jvmClasspathRoots
+import org.jetbrains.kotlin.cli.jvm.modules.CoreJrtFileSystem
 import org.jetbrains.kotlin.cli.jvm.plugins.PluginCliParser
 import org.jetbrains.kotlin.cli.jvm.repl.ReplFromTerminal
 import org.jetbrains.kotlin.codegen.CompilationException
@@ -404,22 +405,24 @@ class K2JVMCompiler : CLICompiler<K2JVMCompilerArguments>() {
                     return OK
                 }
 
-                if (arguments.jdkHome != null) {
+                val (jdkHome, classesRoots) = if (arguments.jdkHome != null) {
                     val jdkHome = File(arguments.jdkHome)
-                    configuration.put(JVMConfigurationKeys.JDK_HOME, jdkHome)
-                    val classesRoots = PathUtil.getJdkClassesRoots(jdkHome)
-                    configuration.addJvmClasspathRoots(classesRoots)
-
                     messageCollector.report(LOGGING, "Using JDK home directory $jdkHome")
+                    jdkHome to PathUtil.getJdkClassesRoots(jdkHome)
+                }
+                else {
+                    File(System.getProperty("java.home")) to PathUtil.getJdkClassesRootsFromCurrentJre()
+                }
+
+                configuration.put(JVMConfigurationKeys.JDK_HOME, jdkHome)
+
+                if (!CoreJrtFileSystem.isModularJdk(jdkHome)) {
+                    configuration.addJvmClasspathRoots(classesRoots)
                     if (classesRoots.isEmpty()) {
                         messageCollector.report(ERROR, "No class roots are found in the JDK path: $jdkHome")
                         return COMPILATION_ERROR
                     }
                 }
-                else {
-                    configuration.put(JVMConfigurationKeys.JDK_HOME, File(System.getProperty("java.home")))
-                    configuration.addJvmClasspathRoots(PathUtil.getJdkClassesRootsFromCurrentJre())
-                }
             }
             catch (t: Throwable) {
                 MessageCollectorUtil.reportException(messageCollector, t)

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/modules/CoreJrtFileSystem.kt

@@ -50,13 +50,17 @@ class CoreJrtFileSystem(private val fileSystem: FileSystem) : DeprecatedVirtualF
                         FileSystems.newFileSystem(rootUri, mapOf("java.home" to jdkHome.absolutePath))
                     }
                     else {
-                        val jrtFsJar = File(jdkHome, "lib/jrt-fs.jar")
-                        if (!jrtFsJar.exists()) return null
-
+                        val jrtFsJar = loadJrtFsJar(jdkHome) ?: return null
                         val classLoader = URLClassLoader(arrayOf(jrtFsJar.toURI().toURL()), null)
                         FileSystems.newFileSystem(rootUri, emptyMap<String, Nothing>(), classLoader)
                     }
             return CoreJrtFileSystem(fileSystem)
         }
+
+        private fun loadJrtFsJar(jdkHome: File): File? =
+                File(jdkHome, "lib/jrt-fs.jar").takeIf(File::exists)
+
+        fun isModularJdk(jdkHome: File): Boolean =
+                loadJrtFsJar(jdkHome) != null
     }
 }