From 84717c796918236b71492827a88a1bfc095b5fa5 Mon Sep 17 00:00:00 2001
From: lgoubet <laurent.goubet@obeo.fr>
Date: Thu, 14 Oct 2021 16:29:11 +0200
Subject: [PATCH] Cannot merge added/deleted resources

If one of the comparison sides is empty (we're comparing only addition
or deletion of resources with no other resource existing on the
opposite side), EMF Compare is unable to merge the change because
there are no MatchResource allowing us to "find" the opposite
ResourceSet. This is a legacy of the early implementation in which
the comparison scope was no longer available once the comparison was
computed.

Change-Id: Ic1404c984dc651a2d70f53c1f628f673efe629d5
---
 .../merge/ResourceAttachmentChangeMerger.java      | 36 +++++++++++++++++-----
 1 file changed, 28 insertions(+), 8 deletions(-)

diff --git a/plugins/org.eclipse.emf.compare/src/org/eclipse/emf/compare/merge/ResourceAttachmentChangeMerger.java b/plugins/org.eclipse.emf.compare/src/org/eclipse/emf/compare/merge/ResourceAttachmentChangeMerger.java
index 9984bfafe..5066828b5 100644
--- a/plugins/org.eclipse.emf.compare/src/org/eclipse/emf/compare/merge/ResourceAttachmentChangeMerger.java
+++ b/plugins/org.eclipse.emf.compare/src/org/eclipse/emf/compare/merge/ResourceAttachmentChangeMerger.java
@@ -18,6 +18,7 @@ import java.util.Collections;
 import java.util.List;
 
 import org.apache.log4j.Logger;
+import org.eclipse.emf.common.notify.Notifier;
 import org.eclipse.emf.common.util.URI;
 import org.eclipse.emf.compare.Comparison;
 import org.eclipse.emf.compare.Diff;
@@ -27,10 +28,12 @@ import org.eclipse.emf.compare.Match;
 import org.eclipse.emf.compare.MatchResource;
 import org.eclipse.emf.compare.ResourceAttachmentChange;
 import org.eclipse.emf.compare.internal.utils.DiffUtil;
+import org.eclipse.emf.compare.scope.IComparisonScope;
 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.emf.ecore.InternalEObject;
 import org.eclipse.emf.ecore.resource.Resource;
 import org.eclipse.emf.ecore.resource.ResourceSet;
+import org.eclipse.emf.ecore.util.EcoreUtil;
 import org.eclipse.emf.ecore.xmi.XMIResource;
 
 /**
@@ -354,15 +357,32 @@ public class ResourceAttachmentChangeMerger extends AbstractMerger {
 						+ sourceRes.getURI());
 			}
 
-			final List<MatchResource> matchedResources = comparison.getMatchedResources();
-			final int size = matchedResources.size();
 			ResourceSet targetSet = null;
-			for (int i = 0; i < size && targetSet == null; i++) {
-				final MatchResource matchRes = matchedResources.get(i);
-				if (rightToLeft && matchRes.getLeft() != null) {
-					targetSet = matchRes.getLeft().getResourceSet();
-				} else if (!rightToLeft && matchRes.getRight() != null) {
-					targetSet = matchRes.getRight().getResourceSet();
+			IComparisonScope scope = (IComparisonScope)EcoreUtil.getAdapter(comparison.eAdapters(),
+					IComparisonScope.class);
+			if (rightToLeft) {
+				Notifier left = scope.getLeft();
+				if (left instanceof ResourceSet) {
+					targetSet = (ResourceSet)left;
+				} else if (left instanceof Resource) {
+					targetSet = ((Resource)left).getResourceSet();
+				} else if (left instanceof EObject) {
+					Resource res = ((EObject)left).eResource();
+					if (res != null) {
+						targetSet = res.getResourceSet();
+					}
+				}
+			} else {
+				Notifier right = scope.getRight();
+				if (right instanceof ResourceSet) {
+					targetSet = (ResourceSet)right;
+				} else if (right instanceof Resource) {
+					targetSet = ((Resource)right).getResourceSet();
+				} else if (right instanceof EObject) {
+					Resource res = ((EObject)right).eResource();
+					if (res != null) {
+						targetSet = res.getResourceSet();
+					}
 				}
 			}
 
-- 
2.11.4.GIT