[PATCH v3] checkout: add --progress option

[Edmundo Carmona Antoranz <eantoranz@gmail.com>]

Under normal circumstances, and like other git commands,
git checkout will write progress info to stderr if
attached to a terminal. This option allows progress
to be forced even if not using a terminal. Also,
progress can be skipped if using option --no-progress.
---
 Documentation/git-checkout.txt |  6 ++++++
 builtin/checkout.c             | 26 ++++++++++++++++++++++++--
 2 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index e269fb1..93ba35a 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -107,6 +107,12 @@ OPTIONS
 --quiet::
 	Quiet, suppress feedback messages.
 
+--progress::
+	Progress status is reported on the standard error stream
+	by default when it is attached to a terminal, unless -q
+	is specified. This flag forces progress status even if the
+	standard error stream is not directed to a terminal.
+
 -f::
 --force::
 	When switching branches, proceed even if the index or the
diff --git a/builtin/checkout.c b/builtin/checkout.c
index bc703c0..1bc4efe 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -37,6 +37,7 @@ struct checkout_opts {
 	int overwrite_ignore;
 	int ignore_skipworktree;
 	int ignore_other_worktrees;
+	int show_progress;
 
 	const char *new_branch;
 	const char *new_branch_force;
@@ -417,7 +418,7 @@ static int reset_tree(struct tree *tree, const struct checkout_opts *o,
 	opts.reset = 1;
 	opts.merge = 1;
 	opts.fn = oneway_merge;
-	opts.verbose_update = !o->quiet && isatty(2);
+	opts.verbose_update = o->show_progress;
 	opts.src_index = &the_index;
 	opts.dst_index = &the_index;
 	parse_tree(tree);
@@ -501,7 +502,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 		topts.update = 1;
 		topts.merge = 1;
 		topts.gently = opts->merge && old->commit;
-		topts.verbose_update = !opts->quiet && isatty(2);
+		topts.verbose_update = opts->show_progress;
 		topts.fn = twoway_merge;
 		if (opts->overwrite_ignore) {
 			topts.dir = xcalloc(1, sizeof(*topts.dir));
@@ -1156,6 +1157,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 				N_("second guess 'git checkout <no-such-branch>'")),
 		OPT_BOOL(0, "ignore-other-worktrees", &opts.ignore_other_worktrees,
 			 N_("do not check if another worktree is holding the given ref")),
+		OPT_BOOL(0, "progress", &opts.show_progress, N_("force progress reporting")),
 		OPT_END(),
 	};
 
@@ -1163,6 +1165,7 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	memset(&new, 0, sizeof(new));
 	opts.overwrite_ignore = 1;
 	opts.prefix = prefix;
+	opts.show_progress = -1;
 
 	gitmodules_config();
 	git_config(git_checkout_config, &opts);
@@ -1172,6 +1175,25 @@ int cmd_checkout(int argc, const char **argv, const char *prefix)
 	argc = parse_options(argc, argv, prefix, options, checkout_usage,
 			     PARSE_OPT_KEEP_DASHDASH);
 
+	/*
+	 * Final processing of show_progress
+	 * - User selected --progress: show progress
+	 * - user selected --no-progress: skip progress
+	 * - User didn't specify:
+	 *     (check rules in order till finding the first matching one)
+	 *     - user selected --quiet: skip progress
+	 *     - stderr is connected to a terminal: show progress
+	 *     - fallback: skip progress
+	 */
+	if (opts.show_progress < 0) {
+		/* user selected --progress or didn't specify */
+		if (opts.quiet) {
+			opts.show_progress = 0;
+		} else {
+			opts.show_progress = isatty(2);
+		}
+	}
+
 	if (conflict_style) {
 		opts.merge = 1; /* implied */
 		git_xmerge_config("merge.conflictstyle", conflict_style, NULL);
-- 
2.6.1