Merge changes from topic "fix_ui"

* changes:
  ResolveMerger: do not content-merge gitlinks on del/mod conflicts
  ResolveMerger: Adding test cases for GITLINK deletion
  ResolveMerger: choose OURS on gitlink when ignoreConflicts
  ResolveMerger: improving content merge readability
  ResolveMerger: extracting createGitLinksMergeResult method
  ResolveMerger: Adding test cases for GITLINK merge

org.eclipse.jgit.junit/src/org/eclipse/jgit/junit/RepositoryTestCase.java

@@ -34,6 +34,7 @@ import org.eclipse.jgit.dircache.DirCacheBuilder;
 import org.eclipse.jgit.dircache.DirCacheCheckout;
 import org.eclipse.jgit.dircache.DirCacheEntry;
 import org.eclipse.jgit.internal.storage.file.FileRepository;
+import org.eclipse.jgit.lib.AnyObjectId;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.ObjectId;
@@ -512,6 +513,21 @@ public abstract class RepositoryTestCase extends LocalDiskRepositoryTestCase {
 		return entry;
 	}
 
+	/**
+	 * Create <code>DirCacheEntry</code>
+	 *
+	 * @param path
+	 * @param objectId
+	 * @return the DirCacheEntry
+	 */
+	protected DirCacheEntry createGitLink(String path, AnyObjectId objectId) {
+		final DirCacheEntry entry = new DirCacheEntry(path,
+				DirCacheEntry.STAGE_0);
+		entry.setFileMode(FileMode.GITLINK);
+		entry.setObjectId(objectId);
+		return entry;
+	}
+
 	/**
 	 * Assert files are equal
 	 *

org.eclipse.jgit.test/tst/org/eclipse/jgit/merge/GitlinkMergeTest.java

@@ -0,0 +1,368 @@
+/*
+ * Copyright (c) 2020, Google LLC  and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+package org.eclipse.jgit.merge;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+
+import org.eclipse.jgit.annotations.Nullable;
+import org.eclipse.jgit.dircache.DirCache;
+import org.eclipse.jgit.dircache.DirCacheBuilder;
+import org.eclipse.jgit.dircache.DirCacheEntry;
+import org.eclipse.jgit.lib.CommitBuilder;
+import org.eclipse.jgit.lib.FileMode;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.ObjectInserter;
+import org.eclipse.jgit.lib.PersonIdent;
+import org.eclipse.jgit.test.resources.SampleDataRepositoryTestCase;
+import org.eclipse.jgit.treewalk.TreeWalk;
+import org.junit.Test;
+
+public class GitlinkMergeTest extends SampleDataRepositoryTestCase {
+	private static final String LINK_ID1 = "DEADBEEFDEADBEEFBABEDEADBEEFDEADBEEFBABE";
+	private static final String LINK_ID2 = "DEADDEADDEADDEADDEADDEADDEADDEADDEADDEAD";
+	private static final String LINK_ID3 = "BEEFBEEFBEEFBEEFBEEFBEEFBEEFBEEFBEEFBEEF";
+
+	private static final String SUBMODULE_PATH = "submodule.link";
+
+	@Test
+	public void testGitLinkMerging_AddNew() throws Exception {
+		assertGitLinkValue(
+				testGitLink(null, null, LINK_ID3, newResolveMerger(), true),
+				LINK_ID3);
+	}
+
+	@Test
+	public void testGitLinkMerging_Delete() throws Exception {
+		assertGitLinkDoesntExist(testGitLink(LINK_ID1, LINK_ID1, null,
+				newResolveMerger(), true));
+	}
+
+	@Test
+	public void testGitLinkMerging_UpdateDelete() throws Exception {
+		testGitLink(LINK_ID1, LINK_ID2, null, newResolveMerger(), false);
+	}
+
+	@Test
+	public void testGitLinkMerging_DeleteUpdate() throws Exception {
+		testGitLink(LINK_ID1, null, LINK_ID3, newResolveMerger(), false);
+	}
+
+	@Test
+	public void testGitLinkMerging_UpdateUpdate() throws Exception {
+		testGitLink(LINK_ID1, LINK_ID2, LINK_ID3, newResolveMerger(), false);
+	}
+
+	@Test
+	public void testGitLinkMerging_bothAddedSameLink() throws Exception {
+		assertGitLinkValue(
+				testGitLink(null, LINK_ID2, LINK_ID2, newResolveMerger(), true),
+				LINK_ID2);
+	}
+
+	@Test
+	public void testGitLinkMerging_bothAddedDifferentLink() throws Exception {
+		testGitLink(null, LINK_ID2, LINK_ID3, newResolveMerger(), false);
+	}
+
+	@Test
+	public void testGitLinkMerging_AddNew_ignoreConflicts() throws Exception {
+		assertGitLinkValue(
+				testGitLink(null, null, LINK_ID3, newIgnoreConflictMerger(),
+						true),
+				LINK_ID3);
+	}
+
+	@Test
+	public void testGitLinkMerging_Delete_ignoreConflicts() throws Exception {
+		assertGitLinkDoesntExist(testGitLink(LINK_ID1, LINK_ID1, null,
+				newIgnoreConflictMerger(), true));
+	}
+
+	@Test
+	public void testGitLinkMerging_UpdateDelete_ignoreConflicts()
+			throws Exception {
+		assertGitLinkValue(testGitLink(LINK_ID1, LINK_ID2, null,
+				newIgnoreConflictMerger(), true), LINK_ID2);
+	}
+
+	@Test
+	public void testGitLinkMerging_DeleteUpdate_ignoreConflicts()
+			throws Exception {
+		assertGitLinkDoesntExist(testGitLink(LINK_ID1, null, LINK_ID3,
+				newIgnoreConflictMerger(), true));
+	}
+
+	@Test
+	public void testGitLinkMerging_UpdateUpdate_ignoreConflicts()
+			throws Exception {
+		assertGitLinkValue(testGitLink(LINK_ID1, LINK_ID2, LINK_ID3,
+				newIgnoreConflictMerger(), true), LINK_ID2);
+	}
+
+	@Test
+	public void testGitLinkMerging_bothAddedSameLink_ignoreConflicts()
+			throws Exception {
+		assertGitLinkValue(testGitLink(null, LINK_ID2, LINK_ID2,
+				newIgnoreConflictMerger(), true), LINK_ID2);
+	}
+
+	@Test
+	public void testGitLinkMerging_bothAddedDifferentLink_ignoreConflicts()
+			throws Exception {
+		assertGitLinkValue(testGitLink(null, LINK_ID2, LINK_ID3,
+				newIgnoreConflictMerger(), true), LINK_ID2);
+	}
+
+	protected Merger testGitLink(@Nullable String baseLink,
+			@Nullable String oursLink, @Nullable String theirsLink,
+			Merger merger, boolean shouldMerge)
+			throws Exception {
+		DirCache treeB = db.readDirCache();
+		DirCache treeO = db.readDirCache();
+		DirCache treeT = db.readDirCache();
+
+		DirCacheBuilder bTreeBuilder = treeB.builder();
+		DirCacheBuilder oTreeBuilder = treeO.builder();
+		DirCacheBuilder tTreeBuilder = treeT.builder();
+
+		maybeAddLink(bTreeBuilder, baseLink);
+		maybeAddLink(oTreeBuilder, oursLink);
+		maybeAddLink(tTreeBuilder, theirsLink);
+
+		bTreeBuilder.finish();
+		oTreeBuilder.finish();
+		tTreeBuilder.finish();
+
+		ObjectInserter ow = db.newObjectInserter();
+		ObjectId b = commit(ow, treeB, new ObjectId[] {});
+		ObjectId o = commit(ow, treeO, new ObjectId[] { b });
+		ObjectId t = commit(ow, treeT, new ObjectId[] { b });
+
+		boolean merge = merger.merge(new ObjectId[] { o, t });
+		assertEquals(shouldMerge, merge);
+
+		return merger;
+	}
+
+	private Merger newResolveMerger() {
+		return MergeStrategy.RESOLVE.newMerger(db, true);
+	}
+
+	private Merger newIgnoreConflictMerger() {
+		return new ResolveMerger(db, true) {
+			@Override
+			protected boolean mergeImpl() throws IOException {
+				// emulate call with ignore conflicts.
+				return mergeTrees(mergeBase(), sourceTrees[0], sourceTrees[1],
+						true);
+			}
+		};
+	}
+
+	@Test
+	public void testGitLinkMerging_blobWithLink() throws Exception {
+		DirCache treeB = db.readDirCache();
+		DirCache treeO = db.readDirCache();
+		DirCache treeT = db.readDirCache();
+
+		DirCacheBuilder bTreeBuilder = treeB.builder();
+		DirCacheBuilder oTreeBuilder = treeO.builder();
+		DirCacheBuilder tTreeBuilder = treeT.builder();
+
+		bTreeBuilder.add(
+				createEntry(SUBMODULE_PATH, FileMode.REGULAR_FILE, "blob"));
+		oTreeBuilder.add(
+				createEntry(SUBMODULE_PATH, FileMode.REGULAR_FILE, "blob 2"));
+
+		maybeAddLink(tTreeBuilder, LINK_ID3);
+
+		bTreeBuilder.finish();
+		oTreeBuilder.finish();
+		tTreeBuilder.finish();
+
+		ObjectInserter ow = db.newObjectInserter();
+		ObjectId b = commit(ow, treeB, new ObjectId[] {});
+		ObjectId o = commit(ow, treeO, new ObjectId[] { b });
+		ObjectId t = commit(ow, treeT, new ObjectId[] { b });
+
+		Merger resolveMerger = MergeStrategy.RESOLVE.newMerger(db);
+		boolean merge = resolveMerger.merge(new ObjectId[] { o, t });
+		assertFalse(merge);
+	}
+
+	@Test
+	public void testGitLinkMerging_linkWithBlob() throws Exception {
+		DirCache treeB = db.readDirCache();
+		DirCache treeO = db.readDirCache();
+		DirCache treeT = db.readDirCache();
+
+		DirCacheBuilder bTreeBuilder = treeB.builder();
+		DirCacheBuilder oTreeBuilder = treeO.builder();
+		DirCacheBuilder tTreeBuilder = treeT.builder();
+
+		maybeAddLink(bTreeBuilder, LINK_ID1);
+		maybeAddLink(oTreeBuilder, LINK_ID2);
+		tTreeBuilder.add(
+				createEntry(SUBMODULE_PATH, FileMode.REGULAR_FILE, "blob 3"));
+
+		bTreeBuilder.finish();
+		oTreeBuilder.finish();
+		tTreeBuilder.finish();
+
+		ObjectInserter ow = db.newObjectInserter();
+		ObjectId b = commit(ow, treeB, new ObjectId[] {});
+		ObjectId o = commit(ow, treeO, new ObjectId[] { b });
+		ObjectId t = commit(ow, treeT, new ObjectId[] { b });
+
+		Merger resolveMerger = MergeStrategy.RESOLVE.newMerger(db);
+		boolean merge = resolveMerger.merge(new ObjectId[] { o, t });
+		assertFalse(merge);
+	}
+
+	@Test
+	public void testGitLinkMerging_linkWithLink() throws Exception {
+		DirCache treeB = db.readDirCache();
+		DirCache treeO = db.readDirCache();
+		DirCache treeT = db.readDirCache();
+
+		DirCacheBuilder bTreeBuilder = treeB.builder();
+		DirCacheBuilder oTreeBuilder = treeO.builder();
+		DirCacheBuilder tTreeBuilder = treeT.builder();
+
+		bTreeBuilder.add(
+				createEntry(SUBMODULE_PATH, FileMode.REGULAR_FILE, "blob"));
+		maybeAddLink(oTreeBuilder, LINK_ID2);
+		maybeAddLink(tTreeBuilder, LINK_ID3);
+
+		bTreeBuilder.finish();
+		oTreeBuilder.finish();
+		tTreeBuilder.finish();
+
+		ObjectInserter ow = db.newObjectInserter();
+		ObjectId b = commit(ow, treeB, new ObjectId[] {});
+		ObjectId o = commit(ow, treeO, new ObjectId[] { b });
+		ObjectId t = commit(ow, treeT, new ObjectId[] { b });
+
+		Merger resolveMerger = MergeStrategy.RESOLVE.newMerger(db);
+		boolean merge = resolveMerger.merge(new ObjectId[] { o, t });
+		assertFalse(merge);
+	}
+
+	@Test
+	public void testGitLinkMerging_blobWithBlobFromLink() throws Exception {
+		DirCache treeB = db.readDirCache();
+		DirCache treeO = db.readDirCache();
+		DirCache treeT = db.readDirCache();
+
+		DirCacheBuilder bTreeBuilder = treeB.builder();
+		DirCacheBuilder oTreeBuilder = treeO.builder();
+		DirCacheBuilder tTreeBuilder = treeT.builder();
+
+		maybeAddLink(bTreeBuilder, LINK_ID1);
+		oTreeBuilder.add(
+				createEntry(SUBMODULE_PATH, FileMode.REGULAR_FILE, "blob 2"));
+		tTreeBuilder.add(
+				createEntry(SUBMODULE_PATH, FileMode.REGULAR_FILE, "blob 3"));
+
+		bTreeBuilder.finish();
+		oTreeBuilder.finish();
+		tTreeBuilder.finish();
+
+		ObjectInserter ow = db.newObjectInserter();
+		ObjectId b = commit(ow, treeB, new ObjectId[] {});
+		ObjectId o = commit(ow, treeO, new ObjectId[] { b });
+		ObjectId t = commit(ow, treeT, new ObjectId[] { b });
+
+		Merger resolveMerger = MergeStrategy.RESOLVE.newMerger(db);
+		boolean merge = resolveMerger.merge(new ObjectId[] { o, t });
+		assertFalse(merge);
+	}
+
+	@Test
+	public void testGitLinkMerging_linkBlobDeleted() throws Exception {
+		// We changed a link to a blob, others has deleted this link.
+		DirCache treeB = db.readDirCache();
+		DirCache treeO = db.readDirCache();
+		DirCache treeT = db.readDirCache();
+
+		DirCacheBuilder bTreeBuilder = treeB.builder();
+		DirCacheBuilder oTreeBuilder = treeO.builder();
+		DirCacheBuilder tTreeBuilder = treeT.builder();
+
+		maybeAddLink(bTreeBuilder, LINK_ID1);
+		oTreeBuilder.add(
+				createEntry(SUBMODULE_PATH, FileMode.REGULAR_FILE, "blob 2"));
+
+		bTreeBuilder.finish();
+		oTreeBuilder.finish();
+		tTreeBuilder.finish();
+
+		ObjectInserter ow = db.newObjectInserter();
+		ObjectId b = commit(ow, treeB, new ObjectId[] {});
+		ObjectId o = commit(ow, treeO, new ObjectId[] { b });
+		ObjectId t = commit(ow, treeT, new ObjectId[] { b });
+
+		Merger resolveMerger = MergeStrategy.RESOLVE.newMerger(db);
+		boolean merge = resolveMerger.merge(new ObjectId[] { o, t });
+		assertFalse(merge);
+	}
+
+	private void maybeAddLink(DirCacheBuilder builder,
+			@Nullable String linkId) {
+		if (linkId == null) {
+			return;
+		}
+		DirCacheEntry newLink = createGitLink(SUBMODULE_PATH,
+				ObjectId.fromString(linkId));
+		builder.add(newLink);
+	}
+
+	private void assertGitLinkValue(Merger resolveMerger, String expectedValue)
+			throws Exception {
+		try (TreeWalk tw = new TreeWalk(db)) {
+			tw.setRecursive(true);
+			tw.reset(resolveMerger.getResultTreeId());
+
+			assertTrue(tw.next());
+			assertEquals(SUBMODULE_PATH, tw.getPathString());
+			assertEquals(ObjectId.fromString(expectedValue), tw.getObjectId(0));
+
+			assertFalse(tw.next());
+		}
+	}
+
+	private void assertGitLinkDoesntExist(Merger resolveMerger)
+			throws Exception {
+		try (TreeWalk tw = new TreeWalk(db)) {
+			tw.setRecursive(true);
+			tw.reset(resolveMerger.getResultTreeId());
+
+			assertFalse(tw.next());
+		}
+	}
+
+	private static ObjectId commit(ObjectInserter odi, DirCache treeB,
+			ObjectId[] parentIds) throws Exception {
+		CommitBuilder c = new CommitBuilder();
+		c.setTreeId(treeB.writeTree(odi));
+		c.setAuthor(new PersonIdent("A U Thor", "a.u.thor", 1L, 0));
+		c.setCommitter(c.getAuthor());
+		c.setParentIds(parentIds);
+		c.setMessage("Tree " + c.getTreeId().name());
+		ObjectId id = odi.insert(c);
+		odi.flush();
+		return id;
+	}
+}

org.eclipse.jgit/src/org/eclipse/jgit/merge/ResolveMerger.java

@@ -588,7 +588,8 @@ public class ResolveMerger extends ThreeWayMerger {
 		final int modeO = tw.getRawMode(T_OURS);
 		final int modeT = tw.getRawMode(T_THEIRS);
 		final int modeB = tw.getRawMode(T_BASE);
-
+		boolean gitLinkMerging = isGitLink(modeO) || isGitLink(modeT)
+				|| isGitLink(modeB);
 		if (modeO == 0 && modeT == 0 && modeB == 0)
 			// File is either untracked or new, staged but uncommitted
 			return true;
@@ -737,31 +738,28 @@ public class ResolveMerger extends ThreeWayMerger {
 				return false;
 			}
 
-			boolean gitlinkConflict = isGitLink(modeO) || isGitLink(modeT);
-			// Don't attempt to resolve submodule link conflicts
-			if (gitlinkConflict || !attributes.canBeContentMerged()) {
+			if (gitLinkMerging && ignoreConflicts) {
+				// Always select 'ours' in case of GITLINK merge failures so
+				// a caller can use virtual commit.
+				add(tw.getRawPath(), ours, DirCacheEntry.STAGE_0, EPOCH, 0);
+				return true;
+			} else if (gitLinkMerging) {
+				add(tw.getRawPath(), base, DirCacheEntry.STAGE_1, EPOCH, 0);
+				add(tw.getRawPath(), ours, DirCacheEntry.STAGE_2, EPOCH, 0);
+				add(tw.getRawPath(), theirs, DirCacheEntry.STAGE_3, EPOCH, 0);
+				MergeResult<SubmoduleConflict> result = createGitLinksMergeResult(
+						base, ours, theirs);
+				result.setContainsConflicts(true);
+				mergeResults.put(tw.getPathString(), result);
+				unmergedPaths.add(tw.getPathString());
+				return true;
+			} else if (!attributes.canBeContentMerged()) {
 				add(tw.getRawPath(), base, DirCacheEntry.STAGE_1, EPOCH, 0);
 				add(tw.getRawPath(), ours, DirCacheEntry.STAGE_2, EPOCH, 0);
 				add(tw.getRawPath(), theirs, DirCacheEntry.STAGE_3, EPOCH, 0);
 
-				if (gitlinkConflict) {
-					MergeResult<SubmoduleConflict> result = new MergeResult<>(
-							Arrays.asList(
-									new SubmoduleConflict(base == null ? null
-											: base.getEntryObjectId()),
-									new SubmoduleConflict(ours == null ? null
-											: ours.getEntryObjectId()),
-									new SubmoduleConflict(theirs == null ? null
-											: theirs.getEntryObjectId())));
-					result.setContainsConflicts(true);
-					mergeResults.put(tw.getPathString(), result);
-					if (!ignoreConflicts) {
-						unmergedPaths.add(tw.getPathString());
-					}
-				} else {
-					// attribute merge issues are conflicts but not failures
-					unmergedPaths.add(tw.getPathString());
-				}
+				// attribute merge issues are conflicts but not failures
+				unmergedPaths.add(tw.getPathString());
 				return true;
 			}
 
@@ -786,45 +784,73 @@ public class ResolveMerger extends ThreeWayMerger {
 			// OURS or THEIRS has been deleted
 			if (((modeO != 0 && !tw.idEqual(T_BASE, T_OURS)) || (modeT != 0 && !tw
 					.idEqual(T_BASE, T_THEIRS)))) {
-				MergeResult<RawText> result = contentMerge(base, ours, theirs,
-						attributes);
-
-				if (ignoreConflicts) {
-					// In case a conflict is detected the working tree file is
-					// again filled with new content (containing conflict
-					// markers). But also stage 0 of the index is filled with
-					// that content.
-					result.setContainsConflicts(false);
-					updateIndex(base, ours, theirs, result, attributes);
-				} else {
+				if (gitLinkMerging && ignoreConflicts) {
+					add(tw.getRawPath(), ours, DirCacheEntry.STAGE_0, EPOCH, 0);
+				} else if (gitLinkMerging) {
 					add(tw.getRawPath(), base, DirCacheEntry.STAGE_1, EPOCH, 0);
 					add(tw.getRawPath(), ours, DirCacheEntry.STAGE_2, EPOCH, 0);
-					DirCacheEntry e = add(tw.getRawPath(), theirs,
-							DirCacheEntry.STAGE_3, EPOCH, 0);
-
-					// OURS was deleted checkout THEIRS
-					if (modeO == 0) {
-						// Check worktree before checking out THEIRS
-						if (isWorktreeDirty(work, ourDce)) {
-							return false;
-						}
-						if (nonTree(modeT)) {
-							if (e != null) {
-								addToCheckout(tw.getPathString(), e, attributes);
+					add(tw.getRawPath(), theirs, DirCacheEntry.STAGE_3, EPOCH, 0);
+					MergeResult<SubmoduleConflict> result = createGitLinksMergeResult(
+							base, ours, theirs);
+					result.setContainsConflicts(true);
+					mergeResults.put(tw.getPathString(), result);
+					unmergedPaths.add(tw.getPathString());
+				} else {
+					MergeResult<RawText> result = contentMerge(base, ours,
+							theirs, attributes);
+
+					if (ignoreConflicts) {
+						// In case a conflict is detected the working tree file
+						// is again filled with new content (containing conflict
+						// markers). But also stage 0 of the index is filled
+						// with that content.
+						result.setContainsConflicts(false);
+						updateIndex(base, ours, theirs, result, attributes);
+					} else {
+						add(tw.getRawPath(), base, DirCacheEntry.STAGE_1, EPOCH,
+								0);
+						add(tw.getRawPath(), ours, DirCacheEntry.STAGE_2, EPOCH,
+								0);
+						DirCacheEntry e = add(tw.getRawPath(), theirs,
+								DirCacheEntry.STAGE_3, EPOCH, 0);
+
+						// OURS was deleted checkout THEIRS
+						if (modeO == 0) {
+							// Check worktree before checking out THEIRS
+							if (isWorktreeDirty(work, ourDce)) {
+								return false;
+							}
+							if (nonTree(modeT)) {
+								if (e != null) {
+									addToCheckout(tw.getPathString(), e,
+											attributes);
+								}
 							}
 						}
-					}
 
-					unmergedPaths.add(tw.getPathString());
+						unmergedPaths.add(tw.getPathString());
 
-					// generate a MergeResult for the deleted file
-					mergeResults.put(tw.getPathString(), result);
+						// generate a MergeResult for the deleted file
+						mergeResults.put(tw.getPathString(), result);
+					}
 				}
 			}
 		}
 		return true;
 	}
 
+	private static MergeResult<SubmoduleConflict> createGitLinksMergeResult(
+			CanonicalTreeParser base, CanonicalTreeParser ours,
+			CanonicalTreeParser theirs) {
+		return new MergeResult<>(Arrays.asList(
+				new SubmoduleConflict(
+						base == null ? null : base.getEntryObjectId()),
+				new SubmoduleConflict(
+						ours == null ? null : ours.getEntryObjectId()),
+				new SubmoduleConflict(
+						theirs == null ? null : theirs.getEntryObjectId())));
+	}
+
 	/**
 	 * Does the content merge. The three texts base, ours and theirs are
 	 * specified with {@link CanonicalTreeParser}. If any of the parsers is