Merge branch 'js/am-3-merge-recursive-direct'

"git am -3" calls "git merge-recursive" when it needs to fall back
to a three-way merge; this call has been turned into an internal
subroutine call instead of spawning a separate subprocess.

* js/am-3-merge-recursive-direct:
  merge-recursive: flush output buffer even when erroring out
  merge_trees(): ensure that the callers release output buffer
  merge-recursive: offer an option to retain the output in 'obuf'
  merge-recursive: write the commit title in one go
  merge-recursive: flush output buffer before printing error messages
  am -3: use merge_recursive() directly again
  merge-recursive: switch to returning errors instead of dying
  merge-recursive: handle return values indicating errors
  merge-recursive: allow write_tree_from_memory() to error out
  merge-recursive: avoid returning a wholesale struct
  merge_recursive: abort properly upon errors
  prepare the builtins for a libified merge_recursive()
  merge-recursive: clarify code in was_tracked()
  die(_("BUG")): avoid translating bug messages
  die("bug"): report bugs consistently
  t5520: verify that `pull --rebase` shows the helpful advice when failing

5 files changed, 31 insertions, 43 deletions

diff --git a/builtin/am.c b/builtin/am.c
index 8aa9b5b93..739b34dcf 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -1579,47 +1579,18 @@ static int build_fake_ancestor(const struct am_state *state, const char *index_f
 }
 
 /**
- * Do the three-way merge using fake ancestor, their tree constructed
- * from the fake ancestor and the postimage of the patch, and our
- * state.
- */
-static int run_fallback_merge_recursive(const struct am_state *state,
-					unsigned char *orig_tree,
-					unsigned char *our_tree,
-					unsigned char *their_tree)
-{
-	struct child_process cp = CHILD_PROCESS_INIT;
-	int status;
-
-	cp.git_cmd = 1;
-
-	argv_array_pushf(&cp.env_array, "GITHEAD_%s=%.*s",
-			 sha1_to_hex(their_tree), linelen(state->msg), state->msg);
-	if (state->quiet)
-		argv_array_push(&cp.env_array, "GIT_MERGE_VERBOSITY=0");
-
-	argv_array_push(&cp.args, "merge-recursive");
-	argv_array_push(&cp.args, sha1_to_hex(orig_tree));
-	argv_array_push(&cp.args, "--");
-	argv_array_push(&cp.args, sha1_to_hex(our_tree));
-	argv_array_push(&cp.args, sha1_to_hex(their_tree));
-
-	status = run_command(&cp) ? (-1) : 0;
-	discard_cache();
-	read_cache();
-	return status;
-}
-
-/**
  * Attempt a threeway merge, using index_path as the temporary index.
  */
 static int fall_back_threeway(const struct am_state *state, const char *index_path)
 {
-	unsigned char orig_tree[GIT_SHA1_RAWSZ], their_tree[GIT_SHA1_RAWSZ],
-		      our_tree[GIT_SHA1_RAWSZ];
+	struct object_id orig_tree, their_tree, our_tree;
+	const struct object_id *bases[1] = { &orig_tree };
+	struct merge_options o;
+	struct commit *result;
+	char *their_tree_name;
 
-	if (get_sha1("HEAD", our_tree) < 0)
-		hashcpy(our_tree, EMPTY_TREE_SHA1_BIN);
+	if (get_oid("HEAD", &our_tree) < 0)
+		hashcpy(our_tree.hash, EMPTY_TREE_SHA1_BIN);
 
 	if (build_fake_ancestor(state, index_path))
 		return error("could not build fake ancestor");
@@ -1627,7 +1598,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	discard_cache();
 	read_cache_from(index_path);
 
-	if (write_index_as_tree(orig_tree, &the_index, index_path, 0, NULL))
+	if (write_index_as_tree(orig_tree.hash, &the_index, index_path, 0, NULL))
 		return error(_("Repository lacks necessary blobs to fall back on 3-way merge."));
 
 	say(state, stdout, _("Using index info to reconstruct a base tree..."));
@@ -1643,7 +1614,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 		init_revisions(&rev_info, NULL);
 		rev_info.diffopt.output_format = DIFF_FORMAT_NAME_STATUS;
 		diff_opt_parse(&rev_info.diffopt, &diff_filter_str, 1, rev_info.prefix);
-		add_pending_sha1(&rev_info, "HEAD", our_tree, 0);
+		add_pending_sha1(&rev_info, "HEAD", our_tree.hash, 0);
 		diff_setup_done(&rev_info.diffopt);
 		run_diff_index(&rev_info, 1);
 	}
@@ -1652,7 +1623,7 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 		return error(_("Did you hand edit your patch?\n"
 				"It does not apply to blobs recorded in its index."));
 
-	if (write_index_as_tree(their_tree, &the_index, index_path, 0, NULL))
+	if (write_index_as_tree(their_tree.hash, &the_index, index_path, 0, NULL))
 		return error("could not write tree");
 
 	say(state, stdout, _("Falling back to patching base and 3-way merge..."));
@@ -1668,11 +1639,22 @@ static int fall_back_threeway(const struct am_state *state, const char *index_pa
 	 * changes.
 	 */
 
-	if (run_fallback_merge_recursive(state, orig_tree, our_tree, their_tree)) {
+	init_merge_options(&o);
+
+	o.branch1 = "HEAD";
+	their_tree_name = xstrfmt("%.*s", linelen(state->msg), state->msg);
+	o.branch2 = their_tree_name;
+
+	if (state->quiet)
+		o.verbosity = 0;
+
+	if (merge_recursive_generic(&o, &our_tree, &their_tree, 1, bases, &result)) {
 		rerere(state->allow_rerere_autoupdate);
+		free(their_tree_name);
 		return error(_("Failed to merge in the changes."));
 	}
 
+	free(their_tree_name);
 	return 0;
 }
 
diff --git a/builtin/checkout.c b/builtin/checkout.c
index 27c1a0524..8d852d458 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -567,10 +567,13 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			o.ancestor = old->name;
 			o.branch1 = new->name;
 			o.branch2 = "local";
-			merge_trees(&o, new->commit->tree, work,
+			ret = merge_trees(&o, new->commit->tree, work,
 				old->commit->tree, &result);
+			if (ret < 0)
+				exit(128);
 			ret = reset_tree(new->commit->tree, opts, 0,
 					 writeout_error);
+			strbuf_release(&o.obuf);
 			if (ret)
 				return ret;
 		}
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index f02e3d23b..00ea91aae 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -118,7 +118,8 @@ static void show_killed_files(struct dir_struct *dir)
 				 */
 				pos = cache_name_pos(ent->name, ent->len);
 				if (0 <= pos)
-					die("bug in show-killed-files");
+					die("BUG: killed-file %.*s not found",
+						ent->len, ent->name);
 				pos = -pos - 1;
 				while (pos < active_nr &&
 				       ce_stage(active_cache[pos]))
diff --git a/builtin/merge.c b/builtin/merge.c
index 19b3bc2f2..148a9a51b 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -673,6 +673,8 @@ static int try_merge_strategy(const char *strategy, struct commit_list *common,
 		hold_locked_index(&lock, 1);
 		clean = merge_recursive(&o, head,
 				remoteheads->item, reversed, &result);
+		if (clean < 0)
+			exit(128);
 		if (active_cache_changed &&
 		    write_locked_index(&the_index, &lock, COMMIT_LOCK))
 			die (_("unable to write %s"), get_index_file());
diff --git a/builtin/update-index.c b/builtin/update-index.c
index 6cdfd5f73..ba04b197d 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -1146,7 +1146,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 		report(_("Untracked cache enabled for '%s'"), get_git_work_tree());
 		break;
 	default:
-		die("Bug: bad untracked_cache value: %d", untracked_cache);
+		die("BUG: bad untracked_cache value: %d", untracked_cache);
 	}
 
 	if (active_cache_changed) {