Inform clients when Preview support enabled for an incompatible version.

Signed-off-by: Roland Grunberg <[email protected]>

Author: rgrunber

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/EventType.java

@@ -40,7 +40,12 @@ public enum EventType {
 	/**
 	 * Source attachments have been updated for some jar libraries.
 	 */
-	SourceInvalidated(500);
+	SourceInvalidated(500),
+
+	/**
+	 * Incompatibility between release version and preview features
+	 */
+	PreviewFeaturesNotAllowed(600);
 
 	private final int value;
 

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/handlers/BuildWorkspaceHandler.java

@@ -80,6 +80,7 @@ public BuildWorkspaceStatus buildWorkspace(boolean forceReBuild, IProgressMonito
 			if (errors.isEmpty()) {
 				return BuildWorkspaceStatus.SUCCEED;
 			} else {
+				WorkspaceDiagnosticsHandler.checkPreviewFeatureValidity(problemMarkers);
 				// for default project, problem markers aren't sent. Add logs here for trouble shooting.
 				String newline = System.getProperty("line.separator");
 				logError("Error occured while building workspace. Details: " + newline + String.join(newline, errors));

org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/handlers/WorkspaceDiagnosticsHandler.java

@@ -44,6 +44,8 @@
 import org.eclipse.jdt.core.JavaCore;
 import org.eclipse.jdt.core.JavaModelException;
 import org.eclipse.jdt.core.compiler.IProblem;
+import org.eclipse.jdt.ls.core.internal.EventNotification;
+import org.eclipse.jdt.ls.core.internal.EventType;
 import org.eclipse.jdt.ls.core.internal.JDTUtils;
 import org.eclipse.jdt.ls.core.internal.JavaClientConnection;
 import org.eclipse.jdt.ls.core.internal.JavaLanguageServerPlugin;
@@ -62,6 +64,9 @@
 import org.eclipse.m2e.core.internal.IMavenConstants;
 import org.eclipse.m2e.core.internal.Messages;
 
+import com.google.gson.JsonArray;
+import com.google.gson.JsonObject;
+
 /**
  * Listens to the resource change events and converts {@link IMarker}s to {@link Diagnostic}s.
  *
@@ -342,6 +347,31 @@ private void publishDiagnostics(List<IMarker> markers) {
 				connection.publishDiagnostics(new PublishDiagnosticsParams(ResourceUtils.toClientUri(uri), diagnostics));
 			}
 		}
+
+		checkPreviewFeatureValidity(markers);
+	}
+
+	public static void checkPreviewFeatureValidity(List<IMarker> problemMarkers) {
+		// Preview feature support enabled on incompatible release version
+		List<IMarker> previewFeatureMarkers = problemMarkers.stream().filter(m -> m.getAttribute(IJavaModelMarker.ID, 0) == IProblem.PreviewFeaturesNotAllowed).collect(Collectors.toList());
+		JsonArray errorList = new JsonArray();
+		if (!previewFeatureMarkers.isEmpty()) {
+			for (IMarker marker : previewFeatureMarkers) {
+				// error message mentions invalid release level, and the supported level
+				String errorMessage = ResourceUtils.getMessage(marker);
+				String projectUri = JDTUtils.getFileURI(marker.getResource().getProject());
+				JsonObject entry = new JsonObject();
+				entry.addProperty("uri", projectUri);
+				entry.addProperty("message", errorMessage);
+				if (!errorList.contains(entry)) {
+					errorList.add(entry);
+				}
+			}
+			if (JavaLanguageServerPlugin.getProjectsManager().getConnection() != null) {
+				EventNotification prevFeatNotAllowedNotification = new EventNotification().withType(EventType.PreviewFeaturesNotAllowed).withData(errorList);
+				JavaLanguageServerPlugin.getProjectsManager().getConnection().sendEventNotification(prevFeatNotAllowedNotification);
+			}
+		}
 	}
 
 	@Deprecated