Fixing shutdown routine

build.sbt

@@ -1,5 +1,9 @@
 inThisBuild(
   List(
+    version ~= { old =>
+      if (sys.env.contains("CI")) old
+      else "0.1-SNAPSHOT" // to avoid manually updating extension.js
+    },
     scalaVersion := "2.12.3",
     organization := "org.scalameta",
     licenses := Seq(

languageserver/src/main/scala/langserver/core/LanguageServer.scala

@@ -30,7 +30,7 @@ class LanguageServer(inStream: InputStream, outStream: OutputStream) extends Laz
 
       case (_, Shutdown()) =>
         shutdown()
-        ShutdownResult(0) // the value is a dummy, because Play Json needs to serialize something
+        ShutdownResult()
       case c =>
         logger.error(s"Unknown command $c")
         sys.error("Unknown command")
@@ -40,6 +40,7 @@ class LanguageServer(inStream: InputStream, outStream: OutputStream) extends Laz
   protected val documentManager = new TextDocumentManager(connection)
 
   connection.notificationHandlers += {
+    case Exit() => onExit()
     case DidOpenTextDocumentParams(td) => onOpenTextDocument(td)
     case DidChangeTextDocumentParams(td, changes) => onChangeTextDocument(td, changes)
     case DidSaveTextDocumentParams(td) => onSaveTextDocument(td)
@@ -52,6 +53,12 @@ class LanguageServer(inStream: InputStream, outStream: OutputStream) extends Laz
     connection.start()
   }
 
+  def onExit(): Unit = {
+    logger.debug("exit")
+    // TODO: should exit with success code 0 if the shutdown request has been received before; otherwise with error code 1
+    sys.exit(0)
+  }
+
   def onOpenTextDocument(td: TextDocumentItem) = {
     logger.debug(s"openTextDocuemnt $td")
   }
@@ -82,9 +89,7 @@ class LanguageServer(inStream: InputStream, outStream: OutputStream) extends Laz
     CompletionList(isIncomplete = false, Nil)
   }
 
-  def shutdown(): Unit = {
-
-  }
+  def shutdown(): Unit = {}
 
   def gotoDefinitionRequest(textDocument: TextDocumentIdentifier, position: Position): DefinitionResult = {
     DefinitionResult(Seq.empty[Location])

languageserver/src/main/scala/langserver/messages/Commands.scala

@@ -141,13 +141,13 @@ object CompletionList {
 case class InitializeResult(capabilities: ServerCapabilities) extends ResultResponse
 
 case class Shutdown() extends ServerCommand
-object Shutdown {
-  implicit val format: Format[Shutdown] = OFormat(
-    Reads(jsValue => JsSuccess(Shutdown())),
-    OWrites[Shutdown](s => Json.obj()))
-}
 
-case class ShutdownResult(dummy: Int) extends ResultResponse
+case class ShutdownResult() extends ResultResponse
+object ShutdownResult {
+  implicit val format: Format[ShutdownResult] = OFormat(
+    Reads(jsValue => JsSuccess(ShutdownResult())),
+    OWrites[ShutdownResult](s => Json.obj()))
+}
 
 case class ShowMessageRequestParams(
   /**
@@ -193,13 +193,20 @@ object ServerCommand extends CommandCompanion[ServerCommand] {
 
   override val CommandFormats = Message.MessageFormats(
     "initialize" -> Json.format[InitializeParams],
-    "shutdown" -> Shutdown.format,
     "textDocument/completion" -> valueFormat(TextDocumentCompletionRequest)(_.params),
     "textDocument/definition" -> valueFormat(TextDocumentDefinitionRequest)(_.params),
     "textDocument/hover" -> valueFormat(TextDocumentHoverRequest)(_.params),
     "textDocument/documentSymbol" -> Json.format[DocumentSymbolParams],
     "textDocument/formatting" -> valueFormat(TextDocumentFormattingRequest)(_.params)
   )
+
+  // NOTE: this is a workaround to read `shutdown` request which doesn't have parameters (scala-json-rpc requires parameters for all requests)
+  override def read(jsonRpcRequestMessage: JsonRpcRequestMessage): JsResult[_ <: ServerCommand] = {
+    jsonRpcRequestMessage.method match {
+      case "shutdown" => JsSuccess(Shutdown())
+      case _ => super.read(jsonRpcRequestMessage)
+    }
+  }
 }
 
 object ClientCommand extends CommandCompanion[ClientCommand] {
@@ -217,7 +224,8 @@ case class PublishDiagnostics(uri: String, diagnostics: Seq[Diagnostic]) extends
 
 // from client to server
 
-case class ExitNotification() extends Notification
+case class Exit() extends Notification
+
 case class DidOpenTextDocumentParams(textDocument: TextDocumentItem) extends Notification
 case class DidChangeTextDocumentParams(
   textDocument: VersionedTextDocumentIdentifier,
@@ -259,6 +267,14 @@ object Notification extends NotificationCompanion[Notification] {
     "initialized" -> Initialized.format,
     "$/cancelRequest" -> Json.format[CancelRequest]
   )
+
+  // NOTE: this is a workaround to read `exit` notification which doesn't have parameters (scala-json-rpc requires parameters for all notifications)
+  override def read(jsonRpcNotificationMessage: JsonRpcNotificationMessage): JsResult[_ <: Notification] = {
+    jsonRpcNotificationMessage.method match {
+      case "exit" => JsSuccess(Exit())
+      case _ => super.read(jsonRpcNotificationMessage)
+    }
+  }
 }
 
 case class DocumentSymbolResult(params: Seq[SymbolInformation]) extends ResultResponse
@@ -275,5 +291,6 @@ object ResultResponse extends ResponseCompanion[Any] {
     "textDocument/hover" -> Json.format[Hover],
     "textDocument/documentSymbol" -> valueFormat(DocumentSymbolResult)(_.params),
     "textDocument/formatting" -> valueFormat(DocumentFormattingResult)(_.params),
-    "shutdown" -> Json.format[ShutdownResult])
+    "shutdown" -> ShutdownResult.format
+  )
 }

metaserver/src/main/scala/scala/meta/languageserver/ScalametaLanguageServer.scala

@@ -155,27 +155,20 @@ class ScalametaLanguageServer(
       td: TextDocumentIdentifier,
       options: FormattingOptions
   ): List[TextEdit] = {
-    try {
-      val path = Uri.toPath(td.uri).get
-      val contents = buffers.read(path)
-      val fullDocumentRange = Range(
-        start = Position(0, 0),
-        end = Position(Int.MaxValue, Int.MaxValue)
-      )
-      val config = cwd.resolve(".scalafmt.conf")
-      if (Files.isRegularFile(config.toNIO)) {
-        val formattedContent =
-          scalafmt.format(contents, path.toString(), config)
-        List(TextEdit(fullDocumentRange, formattedContent))
-      } else {
-        connection.showMessage(MessageType.Info, s"Missing $config")
-        Nil
-      }
-    } catch {
-      case NonFatal(e) =>
-        connection.showMessage(MessageType.Error, e.getMessage)
-        logger.error(e.getMessage, e)
-        Nil
+    val path = Uri.toPath(td.uri).get
+    val contents = buffers.read(path)
+    val fullDocumentRange = Range(
+      start = Position(0, 0),
+      end = Position(Int.MaxValue, Int.MaxValue)
+    )
+    val config = cwd.resolve(".scalafmt.conf")
+    if (Files.isRegularFile(config.toNIO)) {
+      val formattedContent =
+        scalafmt.format(contents, path.toString(), config)
+      List(TextEdit(fullDocumentRange, formattedContent))
+    } else {
+      connection.showMessage(MessageType.Info, s"Missing $config")
+      Nil
     }
   }
 
@@ -263,27 +256,21 @@ class ScalametaLanguageServer(
       td: TextDocumentIdentifier,
       position: Position
   ): ResultResponse = {
-    try {
-      val completions = compiler.autocomplete(
-        Uri.toPath(td.uri).get,
-        position.line,
-        position.character
-      )
-      CompletionList(
-        isIncomplete = false,
-        items = completions.map {
-          case (signature, name) =>
-            CompletionItem(
-              label = name,
-              detail = Some(signature)
-            )
-        }
-      )
-    } catch {
-      case NonFatal(e) =>
-        onError(e)
-        ShutdownResult(-1)
-    }
+    val completions = compiler.autocomplete(
+      Uri.toPath(td.uri).get,
+      position.line,
+      position.character
+    )
+    CompletionList(
+      isIncomplete = false,
+      items = completions.map {
+        case (signature, name) =>
+          CompletionItem(
+            label = name,
+            detail = Some(signature)
+          )
+      }
+    )
   }
 
   override def hoverRequest(