Merge branch 'nd/checkout-m'

"git checkout -m <other>" was about carrying the differences
between HEAD and the working-tree files forward while checking out
another branch, and ignored the differences between HEAD and the
index.  The command has been taught to abort when the index and the
HEAD are different.

* nd/checkout-m:
  checkout: prevent losing staged changes with --merge
  read-tree: add --quiet
  unpack-trees: rename "gently" flag to "quiet"
  unpack-trees: keep gently check inside add_rejected_path

Documentation/git-read-tree.txt

@@ -129,6 +129,10 @@ OPTIONS
 	Instead of reading tree object(s) into the index, just empty
 	it.
 
+-q::
+--quiet::
+	Quiet, suppress feedback messages.
+
 <tree-ish#>::
 	The id of the tree object(s) to be read/merged.
 

builtin/checkout.c

@@ -700,7 +700,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		topts.initial_checkout = is_cache_unborn();
 		topts.update = 1;
 		topts.merge = 1;
-		topts.gently = opts->merge && old_branch_info->commit;
+		topts.quiet = opts->merge && old_branch_info->commit;
 		topts.verbose_update = opts->show_progress;
 		topts.fn = twoway_merge;
 		if (opts->overwrite_ignore) {
@@ -725,6 +725,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			 */
 			struct tree *result;
 			struct tree *work;
+			struct tree *old_tree;
 			struct merge_options o;
 			struct strbuf sb = STRBUF_INIT;
 
@@ -737,6 +738,12 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			 */
 			if (!old_branch_info->commit)
 				return 1;
+			old_tree = get_commit_tree(old_branch_info->commit);
+
+			if (repo_index_has_changes(the_repository, old_tree, &sb))
+				die(_("cannot continue with staged changes in "
+				      "the following files:\n%s"), sb.buf);
+			strbuf_release(&sb);
 
 			if (repo_index_has_changes(the_repository,
 						   get_commit_tree(old_branch_info->commit),
@@ -781,7 +788,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			ret = merge_trees(&o,
 					  get_commit_tree(new_branch_info->commit),
 					  work,
-					  get_commit_tree(old_branch_info->commit),
+					  old_tree,
 					  &result);
 			if (ret < 0)
 				exit(128);

builtin/read-tree.c

@@ -154,6 +154,7 @@ int cmd_read_tree(int argc, const char **argv, const char *unused_prefix)
 		{ OPTION_CALLBACK, 0, "recurse-submodules", NULL,
 			    "checkout", "control recursive updating of submodules",
 			    PARSE_OPT_OPTARG, option_parse_recurse_submodules_worktree_updater },
+		OPT__QUIET(&opts.quiet, N_("suppress feedback messages")),
 		OPT_END()
 	};
 

t/t7201-co.sh

@@ -223,13 +223,8 @@ test_expect_success 'switch to another branch while carrying a deletion' '
 	test_must_fail git checkout simple 2>errs &&
 	test_i18ngrep overwritten errs &&
 
-	git checkout --merge simple 2>errs &&
-	test_i18ngrep ! overwritten errs &&
-	git ls-files -u &&
-	test_must_fail git cat-file -t :0:two &&
-	test "$(git cat-file -t :1:two)" = blob &&
-	test "$(git cat-file -t :2:two)" = blob &&
-	test_must_fail git cat-file -t :3:two
+	test_must_fail git read-tree --quiet -m -u HEAD simple 2>errs &&
+	test_must_be_empty errs
 '
 
 test_expect_success 'checkout to detach HEAD (with advice declined)' '

unpack-trees.c

@@ -219,6 +219,9 @@ static int add_rejected_path(struct unpack_trees_options *o,
 			     enum unpack_trees_error_types e,
 			     const char *path)
 {
+	if (o->quiet)
+		return -1;
+
 	if (!o->show_all_errors)
 		return error(ERRORMSG(o, e), super_prefixed(path));
 
@@ -268,8 +271,7 @@ static int check_submodule_move_head(const struct cache_entry *ce,
 		flags |= SUBMODULE_MOVE_HEAD_FORCE;
 
 	if (submodule_move_head(ce->name, old_id, new_id, flags))
-		return o->gently ? -1 :
-				   add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
+		return add_rejected_path(o, ERROR_WOULD_LOSE_SUBMODULE, ce->name);
 	return 0;
 }
 
@@ -1039,7 +1041,7 @@ static int unpack_nondirectories(int n, unsigned long mask,
 static int unpack_failed(struct unpack_trees_options *o, const char *message)
 {
 	discard_index(&o->result);
-	if (!o->gently && !o->exiting_early) {
+	if (!o->quiet && !o->exiting_early) {
 		if (message)
 			return error("%s", message);
 		return -1;
@@ -1646,8 +1648,7 @@ return_failed:
 static int reject_merge(const struct cache_entry *ce,
 			struct unpack_trees_options *o)
 {
-	return o->gently ? -1 :
-		add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
+	return add_rejected_path(o, ERROR_WOULD_OVERWRITE, ce->name);
 }
 
 static int same(const struct cache_entry *a, const struct cache_entry *b)
@@ -1694,8 +1695,7 @@ static int verify_uptodate_1(const struct cache_entry *ce,
 			int r = check_submodule_move_head(ce,
 				"HEAD", oid_to_hex(&ce->oid), o);
 			if (r)
-				return o->gently ? -1 :
-					add_rejected_path(o, error_type, ce->name);
+				return add_rejected_path(o, error_type, ce->name);
 			return 0;
 		}
 
@@ -1713,8 +1713,7 @@ static int verify_uptodate_1(const struct cache_entry *ce,
 	}
 	if (errno == ENOENT)
 		return 0;
-	return o->gently ? -1 :
-		add_rejected_path(o, error_type, ce->name);
+	return add_rejected_path(o, error_type, ce->name);
 }
 
 int verify_uptodate(const struct cache_entry *ce,
@@ -1834,8 +1833,7 @@ static int verify_clean_subdirectory(const struct cache_entry *ce,
 		d.exclude_per_dir = o->dir->exclude_per_dir;
 	i = read_directory(&d, o->src_index, pathbuf, namelen+1, NULL);
 	if (i)
-		return o->gently ? -1 :
-			add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
+		return add_rejected_path(o, ERROR_NOT_UPTODATE_DIR, ce->name);
 	free(pathbuf);
 	return cnt;
 }
@@ -1904,8 +1902,7 @@ static int check_ok_to_remove(const char *name, int len, int dtype,
 			return 0;
 	}
 
-	return o->gently ? -1 :
-		add_rejected_path(o, error_type, name);
+	return add_rejected_path(o, error_type, name);
 }
 
 /*
@@ -2345,7 +2342,7 @@ int bind_merge(const struct cache_entry * const *src,
 		return error("Cannot do a bind merge of %d trees",
 			     o->merge_size);
 	if (a && old)
-		return o->gently ? -1 :
+		return o->quiet ? -1 :
 			error(ERRORMSG(o, ERROR_BIND_OVERLAP),
 			      super_prefixed(a->name),
 			      super_prefixed(old->name));

unpack-trees.h

@@ -56,7 +56,7 @@ struct unpack_trees_options {
 		     diff_index_cached,
 		     debug_unpack,
 		     skip_sparse_checkout,
-		     gently,
+		     quiet,
 		     exiting_early,
 		     show_all_errors,
 		     dry_run;