Remove hacky PluginURLClassLoader

It was once needed for the compiler plugins bundled straight into the compiler (read: kapt1). Since there are no bundled plugins anymore, the parent-last plugin classloader itself is not needed anymore.

.idea/dictionaries/yan.xml

@@ -3,6 +3,7 @@
     <words>
       <w>debuggee</w>
       <w>deserializes</w>
+      <w>hacky</w>
       <w>impls</w>
       <w>kapt</w>
       <w>parceler</w>

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/plugins/PluginCliParser.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.cli.common.messages.MessageCollectorUtil
 import org.jetbrains.kotlin.compiler.plugin.*
 import org.jetbrains.kotlin.config.CompilerConfiguration
 import java.io.File
+import java.net.URLClassLoader
 import java.util.*
 
 object PluginCliParser {
@@ -58,7 +59,7 @@ object PluginCliParser {
 
     @JvmStatic
     fun loadPlugins(pluginClasspaths: Iterable<String>?, pluginOptions: Iterable<String>?, configuration: CompilerConfiguration) {
-        val classLoader = PluginURLClassLoader(
+        val classLoader = URLClassLoader(
             pluginClasspaths
                 ?.map { File(it).toURI().toURL() }
                 ?.toTypedArray()

compiler/cli/src/org/jetbrains/kotlin/cli/jvm/plugins/PluginURLClassLoader.kt

@@ -1,52 +0,0 @@
-/*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.jetbrains.kotlin.cli.jvm.plugins
-
-import java.net.URL
-import java.net.URLClassLoader
-import java.util.*
-
-internal class PluginURLClassLoader(urls: Array<URL>, parent: ClassLoader) : ClassLoader(Thread.currentThread().contextClassLoader) {
-    private val childClassLoader: SelfThenParentURLClassLoader = SelfThenParentURLClassLoader(urls, parent)
-
-    @Synchronized
-    override fun loadClass(name: String, resolve: Boolean): Class<*> {
-        return try {
-            childClassLoader.findClass(name)
-        } catch (e: ClassNotFoundException) {
-            super.loadClass(name, resolve)
-        }
-    }
-
-    override fun getResources(name: String): Enumeration<URL> = childClassLoader.getResources(name)
-
-    private class SelfThenParentURLClassLoader(urls: Array<URL>, private val onFail: ClassLoader) : URLClassLoader(urls, null) {
-
-        public override fun findClass(name: String): Class<*> {
-            val loaded = findLoadedClass(name)
-            if (loaded != null) {
-                return loaded
-            }
-
-            return try {
-                super.findClass(name)
-            } catch (e: ClassNotFoundException) {
-                onFail.loadClass(name)
-            }
-        }
-    }
-}