Add diagnostics for plugin classpath problems

plugins/scripting/scripting-compiler/src/org/jetbrains/kotlin/scripting/compiler/plugin/pluginRegisrar.kt

@@ -10,6 +10,8 @@ import org.jetbrains.kotlin.cli.common.CLIConfigurationKeys
 import org.jetbrains.kotlin.cli.common.extensions.ReplFactoryExtension
 import org.jetbrains.kotlin.cli.common.extensions.ScriptEvaluationExtension
 import org.jetbrains.kotlin.cli.common.extensions.ShellExtension
+import org.jetbrains.kotlin.cli.common.messages.CompilerMessageSeverity
+import org.jetbrains.kotlin.cli.common.messages.MessageCollector
 import org.jetbrains.kotlin.compiler.plugin.ComponentRegistrar
 import org.jetbrains.kotlin.config.CompilerConfiguration
 import org.jetbrains.kotlin.extensions.CollectAdditionalSourcesExtension
@@ -24,6 +26,7 @@ import org.jetbrains.kotlin.scripting.definitions.ScriptDefinitionProvider
 import org.jetbrains.kotlin.scripting.definitions.ScriptDependenciesProvider
 import org.jetbrains.kotlin.scripting.extensions.*
 import org.jetbrains.kotlin.scripting.resolve.ScriptReportSink
+import java.net.URLClassLoader
 
 private fun <T> ProjectExtensionDescriptor<T>.registerExtensionIfRequired(project: MockProject, extension: T) {
     try {
@@ -35,6 +38,8 @@ private fun <T> ProjectExtensionDescriptor<T>.registerExtensionIfRequired(projec
 
 class ScriptingCompilerConfigurationComponentRegistrar : ComponentRegistrar {
     override fun registerProjectComponents(project: MockProject, configuration: CompilerConfiguration) {
+        val messageCollector = configuration.get(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY)
+        withClassloadingProblemsReporting(messageCollector) {
             CompilerConfigurationExtension.registerExtension(project, ScriptingCompilerConfigurationExtension(project))
             CollectAdditionalSourcesExtension.registerExtension(project, ScriptingCollectAdditionalSourcesExtension(project))
             ScriptEvaluationExtension.registerExtensionIfRequired(project, JvmCliScriptEvaluationExtension())
@@ -48,11 +53,8 @@ class ScriptingCompilerConfigurationComponentRegistrar : ComponentRegistrar {
                 CliScriptDependenciesProvider(project)
             )
             SyntheticResolveExtension.registerExtension(project, ScriptingResolveExtension())
-        ExtraImportsProviderExtension.registerExtension(project,
+            ExtraImportsProviderExtension.registerExtension(project, ScriptExtraImportsProviderExtension())
-                                                        ScriptExtraImportsProviderExtension()
-        )
 
-        val messageCollector = configuration.get(CLIConfigurationKeys.MESSAGE_COLLECTOR_KEY)
             if (messageCollector != null) {
                 project.registerService(
                     ScriptReportSink::class.java,
@@ -60,4 +62,24 @@ class ScriptingCompilerConfigurationComponentRegistrar : ComponentRegistrar {
                 )
             }
         }
+    }
+}
+
+private inline fun withClassloadingProblemsReporting(messageCollector: MessageCollector?, body: () -> Unit) {
+    try {
+        body()
+        null
+    } catch (e: ClassNotFoundException) {
+        e
+    } catch (e: NoClassDefFoundError) {
+        e
+    }?.also { e ->
+        val classpath = (ScriptingCompilerConfigurationComponentRegistrar::class.java.classLoader as? URLClassLoader)?.urLs?.map { it.path }
+        val msg = "Error registering scripting services: $e\n  current classpath:\n    ${classpath?.joinToString("\n    ")}"
+        if (messageCollector != null) {
+            messageCollector.report(CompilerMessageSeverity.STRONG_WARNING, msg)
+        } else {
+            System.err.println(msg)
+        }
+    }
 }