Workbench restart is unavailable if '--launcher.noRestart' is used.

bundles/org.eclipse.e4.ui.workbench/src/org/eclipse/e4/ui/internal/workbench/E4Workbench.java

@@ -20,6 +20,7 @@
 import java.util.Hashtable;
 import java.util.List;
 import java.util.UUID;
+import org.eclipse.core.runtime.ILog;
 import org.eclipse.e4.core.commands.ExpressionContext;
 import org.eclipse.e4.core.contexts.ContextInjectionFactory;
 import org.eclipse.e4.core.contexts.EclipseContextFactory;
@@ -201,6 +202,12 @@ public boolean close() {
 
 	@Override
 	public boolean restart() {
+		if (!canRestart()) {
+			String message = "Can't restart the workbench. This application was started with the '--launcher.noRestart' argument. Shutdown and start again manually."; //$NON-NLS-1$
+			ILog.get().error(message);
+			return false;
+		}
+
 		this.restart = true;
 		return close();
 	}
@@ -212,6 +219,22 @@ public boolean isRestart() {
 		return restart;
 	}
 
+	/**
+	 * Returns whether the workbench can be {@link #restart() restarted}.
+	 *
+	 * <p>
+	 * It can not be restarted if the <code>--launcher.noRestart</code> argument is
+	 * given.
+	 * </p>
+	 *
+	 * @return <code>true</code> if the workbench can be restarted.
+	 */
+	public static boolean canRestart() {
+		String commands = System.getProperty("eclipse.commands", ""); //$NON-NLS-1$ //$NON-NLS-2$
+		String NO_RESTART_ARGUMENT = "--launcher.noRestart"; //$NON-NLS-1$
+		return commands.lines().map(String::strip).noneMatch(NO_RESTART_ARGUMENT::equals);
+	}
+
 	/**
 	 * @return a context that can be used to lookup OSGi services
 	 */

bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/Workbench.java

@@ -1404,6 +1404,11 @@ public boolean close() {
 	 */
 	/* package */
 	boolean close(int returnCode, final boolean force) {
+		if (returnCode == PlatformUI.RETURN_RESTART && !E4Workbench.canRestart()) {
+			informNoRestart();
+			return false;
+		}
+
 		this.returnCode = returnCode;
 		final boolean[] ret = new boolean[1];
 		BusyIndicator.showWhile(null, () -> ret[0] = busyClose(force));
@@ -2555,11 +2560,21 @@ public WorkbenchWindow openWorkbenchWindow(IAdaptable input, IPerspectiveDescrip
 
 	@Override
 	public boolean restart() {
+		if (!E4Workbench.canRestart()) {
+			informNoRestart();
+			return false;
+		}
+
 		return close(PlatformUI.RETURN_RESTART, false);
 	}
 
 	@Override
 	public boolean restart(boolean useCurrrentWorkspace) {
+		if (!E4Workbench.canRestart()) {
+			informNoRestart();
+			return false;
+		}
+
 		if (Platform.inDevelopmentMode()) {
 			// In development mode, command line parameters cannot be changed and restart
 			// will always be EXIT_RESTART. Also see setRestartArguments method
@@ -2583,6 +2598,18 @@ public boolean restart(boolean useCurrrentWorkspace) {
 		return close(PlatformUI.RETURN_RESTART, false);
 	}
 
+	/**
+	 * Inform the user that the workbench can't be restarted. If the workbench UI is
+	 * not available, this method does nothing.
+	 */
+	public void informNoRestart() {
+		final Display display = getDisplay();
+		if (display != null && !display.isDisposed()) {
+			MessageDialog.openError(null, WorkbenchMessages.Workbench_CantRestart_Title,
+					WorkbenchMessages.Workbench_CantRestart_Message);
+		}
+	}
+
 	/**
 	 * Create and return a string with command line options for eclipse.exe that
 	 * will launch a new workbench that is the same as the currently running one,

bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/WorkbenchMessages.java

@@ -586,6 +586,9 @@ public class WorkbenchMessages extends NLS {
 	public static String Workbench_NeedsClose_Title;
 	public static String Workbench_NeedsClose_Message;
 
+	public static String Workbench_CantRestart_Title;
+	public static String Workbench_CantRestart_Message;
+
 	public static String ErrorPreferencePage_errorMessage;
 
 	public static String ListSelection_title;

bundles/org.eclipse.ui.workbench/Eclipse UI/org/eclipse/ui/internal/messages.properties

@@ -554,6 +554,10 @@ InstallationDialog_ShellTitle={0} Installation Details
 Workbench_NeedsClose_Title = Restart Needed
 Workbench_NeedsClose_Message = A required plug-in is no longer available and the Workbench needs to be restarted. You will be prompted to save if there is any unsaved work.
 
+Workbench_CantRestart_Title = Restart unavailable
+Workbench_CantRestart_Message = Can't restart the workbench. This application was started with the '--launcher.noRestart' argument.\n\
+Shutdown and start again manually.
+
 ErrorPreferencePage_errorMessage = An error has occurred when creating this preference page.
 
 ListSelection_title = Selection Needed