From 81b88c9e54b2b39441be616d1b70cef3bfa5ef4f Mon Sep 17 00:00:00 2001
From: rubenporras <Ruben.PorrasCampo@avaloq.com>
Date: Tue, 15 Feb 2022 09:45:37 +0100
Subject: [PATCH] Fix NPE if there is no resource provider for an URI

Fix NPE if there is no resource provider for an URI by checking for null
and defaulting to false if null, the null check is equivalent to the one
already present in getDeltasForDeletedResources. In addition mark the
URI for removal.

The resource provider can be null in our development environments or if
a persisted index is being reused after some language was de-installed.
---
 .../src/org/eclipse/xtext/build/Indexer.java  | 48 ++++++++++++++-----
 1 file changed, 35 insertions(+), 13 deletions(-)

diff --git a/org.eclipse.xtext/src/org/eclipse/xtext/build/Indexer.java b/org.eclipse.xtext/src/org/eclipse/xtext/build/Indexer.java
index ffb3380a4..4e31d6479 100644
--- a/org.eclipse.xtext/src/org/eclipse/xtext/build/Indexer.java
+++ b/org.eclipse.xtext/src/org/eclipse/xtext/build/Indexer.java
@@ -198,10 +198,18 @@ public class Indexer {
 				.transform(IResourceDescription::getURI).copyInto(new HashSet<>());
 		remainingURIs.removeAll(FluentIterable.from(deltas).transform(Delta::getUri).toSet());
 		List<URI> allAffected = FluentIterable.from(remainingURIs).filter(it -> {
-			IResourceDescription.Manager manager = context.getResourceServiceProvider(it)
-					.getResourceDescriptionManager();
-			IResourceDescription resourceDescription = previousIndex.getResourceDescription(it);
-			return isAffected(resourceDescription, manager, allDeltas, allDeltas, newIndex);
+			IResourceServiceProvider resourceServiceProvider = context.getResourceServiceProvider(it);
+			if (resourceServiceProvider != null) {
+				IResourceDescription.Manager manager = resourceServiceProvider.getResourceDescriptionManager();
+				IResourceDescription resourceDescription = previousIndex.getResourceDescription(it);
+				return isAffected(resourceDescription, manager, allDeltas, allDeltas, newIndex);
+			} else {
+				IResourceDescription.Delta delta = getDeltaForDeletedResource(it, previousIndex);
+				if (delta != null) {
+					deltas.add(delta);
+				}
+				return false;
+			}
 		}).toList();
 		deltas.addAll(getDeltasForChangedResources(allAffected, previousIndex, context));
 		return new Indexer.IndexResult(deltas, newIndex);
@@ -213,21 +221,35 @@ public class Indexer {
 	protected List<IResourceDescription.Delta> getDeltasForDeletedResources(BuildRequest request,
 			ResourceDescriptionsData oldIndex, BuildContext context) {
 		List<IResourceDescription.Delta> deltas = new ArrayList<>();
-		for (URI deleted : request.getDeletedFiles()) {
-			IResourceServiceProvider resourceServiceProvider = context.getResourceServiceProvider(deleted);
-			if (resourceServiceProvider != null) {
-				operationCanceledManager.checkCanceled(context.getCancelIndicator());
-				IResourceDescription oldDescription = oldIndex != null ? oldIndex.getResourceDescription(deleted)
-						: null;
-				if (oldDescription != null) {
-					DefaultResourceDescriptionDelta delta = new DefaultResourceDescriptionDelta(oldDescription, null);
-					deltas.add(delta);
+		if (oldIndex != null) {
+			for (URI deleted : request.getDeletedFiles()) {
+				IResourceServiceProvider resourceServiceProvider = context.getResourceServiceProvider(deleted);
+				if (resourceServiceProvider != null) {
+					operationCanceledManager.checkCanceled(context.getCancelIndicator());
+					IResourceDescription.Delta delta = getDeltaForDeletedResource(deleted, oldIndex);
+					if (delta != null) {
+						deltas.add(delta);
+					}
 				}
 			}
 		}
 		return deltas;
 	}
 
+	/**
+	 * Gets a delta for a resource that shall be deleted.
+	 *
+	 * @since 2.26
+	 *
+	 */
+	protected IResourceDescription.Delta getDeltaForDeletedResource(URI uri, ResourceDescriptionsData oldIndex) {
+		IResourceDescription oldDescription = oldIndex.getResourceDescription(uri);
+		if (oldDescription != null) {
+			return new DefaultResourceDescriptionDelta(oldDescription, null);
+		}
+		return null;
+	}
+
 	/**
 	 * Process the changed resources.
 	 */