Merge branch 'js/merge-tree-3-trees'

"git merge-tree" has learned that the three trees involved in the
3-way merge only need to be trees, not necessarily commits.

* js/merge-tree-3-trees:
  fill_tree_descriptor(): mark error message for translation
  cache-tree: avoid an unnecessary check
  Always check `parse_tree*()`'s return value
  t4301: verify that merge-tree fails on missing blob objects
  merge-ort: do check `parse_tree()`'s return value
  merge-tree: fail with a non-zero exit code on missing tree objects
  merge-tree: accept 3 trees as arguments

Author: gitster

Documentation/git-merge-tree.txt

@@ -64,10 +64,13 @@ OPTIONS
 	share no common history.  This flag can be given to override that
 	check and make the merge proceed anyway.
 
---merge-base=<commit>::
+--merge-base=<tree-ish>::
 	Instead of finding the merge-bases for <branch1> and <branch2>,
 	specify a merge-base for the merge, and specifying multiple bases is
 	currently not supported. This option is incompatible with `--stdin`.
++
+As the merge-base is provided directly, <branch1> and <branch2> do not need
+to specify commits; trees are enough.
 
 [[OUTPUT]]
 OUTPUT

builtin/checkout.c

@@ -704,7 +704,8 @@ static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 	init_checkout_metadata(&opts.meta, info->refname,
 			       info->commit ? &info->commit->object.oid : null_oid(),
 			       NULL);
-	parse_tree(tree);
+	if (parse_tree(tree) < 0)
+		return 128;
 	init_tree_desc(&tree_desc, tree->buffer, tree->size);
 	switch (unpack_trees(1, &tree_desc, &opts)) {
 	case -2:
@@ -783,9 +784,15 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		if (new_branch_info->commit)
 			BUG("'switch --orphan' should never accept a commit as starting point");
 		new_tree = parse_tree_indirect(the_hash_algo->empty_tree);
-	} else
+		if (!new_tree)
+			BUG("unable to read empty tree");
+	} else {
 		new_tree = repo_get_commit_tree(the_repository,
 						new_branch_info->commit);
+		if (!new_tree)
+			return error(_("unable to read tree (%s)"),
+				     oid_to_hex(&new_branch_info->commit->object.oid));
+	}
 	if (opts->discard_changes) {
 		ret = reset_tree(new_tree, opts, 1, writeout_error, new_branch_info);
 		if (ret)
@@ -820,7 +827,8 @@ static int merge_working_tree(const struct checkout_opts *opts,
 				oid_to_hex(old_commit_oid));
 
 		init_tree_desc(&trees[0], tree->buffer, tree->size);
-		parse_tree(new_tree);
+		if (parse_tree(new_tree) < 0)
+			exit(128);
 		tree = new_tree;
 		init_tree_desc(&trees[1], tree->buffer, tree->size);
 
@@ -1240,10 +1248,15 @@ static void setup_new_branch_info_and_source_tree(
 	if (!new_branch_info->commit) {
 		/* not a commit */
 		*source_tree = parse_tree_indirect(rev);
+		if (!*source_tree)
+			die(_("unable to read tree (%s)"), oid_to_hex(rev));
 	} else {
 		parse_commit_or_die(new_branch_info->commit);
 		*source_tree = repo_get_commit_tree(the_repository,
 						    new_branch_info->commit);
+		if (!*source_tree)
+			die(_("unable to read tree (%s)"),
+			    oid_to_hex(&new_branch_info->commit->object.oid));
 	}
 }
 

builtin/clone.c

@@ -738,7 +738,8 @@ static int checkout(int submodule_progress, int filter_submodules)
 	tree = parse_tree_indirect(&oid);
 	if (!tree)
 		die(_("unable to parse commit %s"), oid_to_hex(&oid));
-	parse_tree(tree);
+	if (parse_tree(tree) < 0)
+		exit(128);
 	init_tree_desc(&t, tree->buffer, tree->size);
 	if (unpack_trees(1, &t, &opts) < 0)
 		die(_("unable to checkout working tree"));

builtin/commit.c

@@ -331,7 +331,8 @@ static void create_base_index(const struct commit *current_head)
 	tree = parse_tree_indirect(&current_head->object.oid);
 	if (!tree)
 		die(_("failed to unpack HEAD tree object"));
-	parse_tree(tree);
+	if (parse_tree(tree) < 0)
+		exit(128);
 	init_tree_desc(&t, tree->buffer, tree->size);
 	if (unpack_trees(1, &t, &opts))
 		exit(128); /* We've already reported the error, finish dying */

builtin/merge-tree.c

@@ -429,35 +429,49 @@ static int real_merge(struct merge_tree_options *o,
 	struct merge_options opt;
 
 	copy_merge_options(&opt, &o->merge_options);
-	parent1 = get_merge_parent(branch1);
-	if (!parent1)
-		help_unknown_ref(branch1, "merge-tree",
-				 _("not something we can merge"));
-
-	parent2 = get_merge_parent(branch2);
-	if (!parent2)
-		help_unknown_ref(branch2, "merge-tree",
-				 _("not something we can merge"));
-
 	opt.show_rename_progress = 0;
 
 	opt.branch1 = branch1;
 	opt.branch2 = branch2;
 
 	if (merge_base) {
-		struct commit *base_commit;
 		struct tree *base_tree, *parent1_tree, *parent2_tree;
 
-		base_commit = lookup_commit_reference_by_name(merge_base);
-		if (!base_commit)
-			die(_("could not lookup commit '%s'"), merge_base);
+		/*
+		 * We actually only need the trees because we already
+		 * have a merge base.
+		 */
+		struct object_id base_oid, head_oid, merge_oid;
+
+		if (repo_get_oid_treeish(the_repository, merge_base, &base_oid))
+			die(_("could not parse as tree '%s'"), merge_base);
+		base_tree = parse_tree_indirect(&base_oid);
+		if (!base_tree)
+			die(_("unable to read tree (%s)"), oid_to_hex(&base_oid));
+		if (repo_get_oid_treeish(the_repository, branch1, &head_oid))
+			die(_("could not parse as tree '%s'"), branch1);
+		parent1_tree = parse_tree_indirect(&head_oid);
+		if (!parent1_tree)
+			die(_("unable to read tree (%s)"), oid_to_hex(&head_oid));
+		if (repo_get_oid_treeish(the_repository, branch2, &merge_oid))
+			die(_("could not parse as tree '%s'"), branch2);
+		parent2_tree = parse_tree_indirect(&merge_oid);
+		if (!parent2_tree)
+			die(_("unable to read tree (%s)"), oid_to_hex(&merge_oid));
 
 		opt.ancestor = merge_base;
-		base_tree = repo_get_commit_tree(the_repository, base_commit);
-		parent1_tree = repo_get_commit_tree(the_repository, parent1);
-		parent2_tree = repo_get_commit_tree(the_repository, parent2);
 		merge_incore_nonrecursive(&opt, base_tree, parent1_tree, parent2_tree, &result);
 	} else {
+		parent1 = get_merge_parent(branch1);
+		if (!parent1)
+			help_unknown_ref(branch1, "merge-tree",
+					 _("not something we can merge"));
+
+		parent2 = get_merge_parent(branch2);
+		if (!parent2)
+			help_unknown_ref(branch2, "merge-tree",
+					 _("not something we can merge"));
+
 		/*
 		 * Get the merge bases, in reverse order; see comment above
 		 * merge_incore_recursive in merge-ort.h

builtin/read-tree.c

@@ -261,7 +261,8 @@ int cmd_read_tree(int argc, const char **argv, const char *cmd_prefix)
 	cache_tree_free(&the_index.cache_tree);
 	for (i = 0; i < nr_trees; i++) {
 		struct tree *tree = trees[i];
-		parse_tree(tree);
+		if (parse_tree(tree) < 0)
+			return 128;
 		init_tree_desc(t+i, tree->buffer, tree->size);
 	}
 	if (unpack_trees(nr_trees, t, &opts))

builtin/reset.c

@@ -116,6 +116,10 @@ static int reset_index(const char *ref, const struct object_id *oid, int reset_t
 
 	if (reset_type == MIXED || reset_type == HARD) {
 		tree = parse_tree_indirect(oid);
+		if (!tree) {
+			error(_("unable to read tree (%s)"), oid_to_hex(oid));
+			goto out;
+		}
 		prime_cache_tree(the_repository, the_repository->index, tree);
 	}
 

cache-tree.c

@@ -778,8 +778,8 @@ static void prime_cache_tree_rec(struct repository *r,
 			struct cache_tree_sub *sub;
 			struct tree *subtree = lookup_tree(r, &entry.oid);
 
-			if (!subtree->object.parsed)
-				parse_tree(subtree);
+			if (parse_tree(subtree) < 0)
+				exit(128);
 			sub = cache_tree_sub(it, entry.path);
 			sub->cache_tree = cache_tree();
 

merge-ort.c

@@ -1658,9 +1658,10 @@ static int collect_merge_info(struct merge_options *opt,
 	info.data = opt;
 	info.show_all_errors = 1;
 
-	parse_tree(merge_base);
-	parse_tree(side1);
-	parse_tree(side2);
+	if (parse_tree(merge_base) < 0 ||
+	    parse_tree(side1) < 0 ||
+	    parse_tree(side2) < 0)
+		return -1;
 	init_tree_desc(t + 0, merge_base->buffer, merge_base->size);
 	init_tree_desc(t + 1, side1->buffer, side1->size);
 	init_tree_desc(t + 2, side2->buffer, side2->size);
@@ -4377,9 +4378,11 @@ static int checkout(struct merge_options *opt,
 	unpack_opts.verbose_update = (opt->verbosity > 2);
 	unpack_opts.fn = twoway_merge;
 	unpack_opts.preserve_ignored = 0; /* FIXME: !opts->overwrite_ignore */
-	parse_tree(prev);
+	if (parse_tree(prev) < 0)
+		return -1;
 	init_tree_desc(&trees[0], prev->buffer, prev->size);
-	parse_tree(next);
+	if (parse_tree(next) < 0)
+		return -1;
 	init_tree_desc(&trees[1], next->buffer, next->size);
 
 	ret = unpack_trees(2, trees, &unpack_opts);
@@ -4983,6 +4986,9 @@ static void merge_ort_nonrecursive_internal(struct merge_options *opt,
 
 	if (result->clean >= 0) {
 		result->tree = parse_tree_indirect(&working_tree_oid);
+		if (!result->tree)
+			die(_("unable to read tree (%s)"),
+			    oid_to_hex(&working_tree_oid));
 		/* existence of conflicted entries implies unclean */
 		result->clean &= strmap_empty(&opt->priv->conflicted);
 	}

merge-recursive.c

@@ -405,7 +405,8 @@ static inline int merge_detect_rename(struct merge_options *opt)
 
 static void init_tree_desc_from_tree(struct tree_desc *desc, struct tree *tree)
 {
-	parse_tree(tree);
+	if (parse_tree(tree) < 0)
+		exit(128);
 	init_tree_desc(desc, tree->buffer, tree->size);
 }