Merge pull request #6717 from herrerog/fix-rename-detection

merge: fix incorrect rename detection for empty files.

src/libgit2/merge.c

@@ -1225,6 +1225,13 @@ static int merge_diff_mark_similarity_exact(
 		if (!GIT_MERGE_INDEX_ENTRY_EXISTS(conflict_src->ancestor_entry))
 			continue;
 
+		/*
+		 * Ignore empty files because it has always the same blob sha1
+		 * and will lead to incorrect matches between all entries.
+		 */
+		if (git_oid_equal(&conflict_src->ancestor_entry.id, &git_oid__empty_blob_sha1))
+			continue;
+
 		if (!GIT_MERGE_INDEX_ENTRY_EXISTS(conflict_src->our_entry)) {
 			error = deletes_by_oid_enqueue(ours_deletes_by_oid, &diff_list->pool, &conflict_src->ancestor_entry.id, i);
 			if (error < 0)

tests/libgit2/merge/trees/renames.c

@@ -350,3 +350,22 @@ void test_merge_trees_renames__cache_recomputation(void)
 	git_tree_free(our_tree);
 	git__free(data);
 }
+
+void test_merge_trees_renames__emptyfile_renames(void)
+{
+	git_index *index;
+	git_merge_options *opts = NULL;
+
+	struct merge_index_entry merge_index_entries[] = {
+		{ 0100644, "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391", 1, "bar" },
+		{ 0100644, "60b12be2d2f57977ce83d8dfd32e2394ac1ba1a2", 3, "bar" },
+		{ 0100644, "e69de29bb2d1d6434b8b29ae775ad8c2e48c5391", 0, "boo" },
+		{ 0100644, "e50a49f9558d09d4d3bfc108363bb24c127ed263", 0, "foo" },
+	};
+
+	cl_git_pass(merge_trees_from_branches(&index, repo,
+		"emptyfile_renames", "emptyfile_renames-branch",
+		opts));
+	cl_assert(merge_test_index(index, merge_index_entries, 4));
+	git_index_free(index);
+}

tests/resources/merge-resolve/.gitted/objects/54/c9d15687fb4f56e08252662962d6d1dbc09d9d

@@ -0,0 +1,3 @@
+x
¥NI
+1ôœWô]<5D>žì
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+­q6YØâ€î8ÛåÏÅ3­W<C2AD>^áBM½
ùiQ†

tests/resources/merge-resolve/.gitted/objects/cd/edf9760406dc79e0c6a8899ce9f180ec2a23a0

@@ -0,0 +1,2 @@
+x
<01><>A
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tests/resources/merge-resolve/.gitted/objects/ea/789495e0a72efadcd0f86a48f4c9ed435bb8a3

@@ -0,0 +1,3 @@
+x
¥OIj1ÌY¯è»!´¶‘Áøâä­V‹ÉA£ Ëøû–M~<7E>:ÕE÷Ö~&o>æ<10>ÌZ;§uB[‹¡JärN9z)ÚVÄb¼ú¥!Ç.Rj
+:Ü
+‡$ÈŘKª:¢°!c	ÝçÞ\˃F<C692>ï½·[?àK–ûbyê“{;ƒ<18>õÞ œpA-w<><77>òϵ–S[_iÀì<C380>{WOG‰Rï

tests/resources/merge-resolve/.gitted/refs/heads/emptyfile_renames

@@ -0,0 +1 @@
+ea789495e0a72efadcd0f86a48f4c9ed435bb8a3

tests/resources/merge-resolve/.gitted/refs/heads/emptyfile_renames-branch

@@ -0,0 +1 @@
+ab347abd8cda4a0e3b8bb42bb620c0c72c7df779