[PATCH v3/GSoC/MICRO] revision: forbid combining --graph and --no-walk

[Dongcan Jiang <dongcan.jiang@gmail.com>]

Because "--graph" is about connected history while --no-walk
is about discrete points, it does not make sense to allow
giving these two options at the same time. [1]

This change allows git-show to have such options' combination
as a special case, because git-show itself has underlying
--no-walk option, while "git show --graph" is a legal and
useful operation which is tested in t4052. [2,3]

2 testcases have been added to test this patch.

[1]: http://article.gmane.org/gmane.comp.version-control.git/216083
[2]: http://article.gmane.org/gmane.comp.version-control.git/264950
[3]: http://article.gmane.org/gmane.comp.version-control.git/265107

Helped-By: Eric Sunshine <sunshine@sunshineco.com>
Helped-By: René Scharfe <l.s.r@web.de>
Helped-By: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Dongcan Jiang <dongcan.jiang@gmail.com>
---
 Documentation/rev-list-options.txt | 2 ++
 builtin/log.c                      | 1 +
 revision.c                         | 4 ++++
 revision.h                         | 3 +++
 t/t4202-log.sh                     | 4 ++++
 t/t6014-rev-list-all.sh            | 4 ++++
 6 files changed, 18 insertions(+)

diff --git a/Documentation/rev-list-options.txt b/Documentation/rev-list-options.txt
index 4ed8587..136abdf 100644
--- a/Documentation/rev-list-options.txt
+++ b/Documentation/rev-list-options.txt
@@ -679,6 +679,7 @@ endif::git-rev-list[]
 	given on the command line. Otherwise (if `sorted` or no argument
 	was given), the commits are shown in reverse chronological order
 	by commit time.
+	Cannot be combined with `--graph`.
 
 --do-walk::
 	Overrides a previous `--no-walk`.
@@ -781,6 +782,7 @@ you would get an output like this:
 	on the left hand side of the output.  This may cause extra lines
 	to be printed in between commits, in order for the graph history
 	to be drawn properly.
+	Cannot be combined with `--no-walk`.
 +
 This enables parent rewriting, see 'History Simplification' below.
 +
diff --git a/builtin/log.c b/builtin/log.c
index dd8f3fc..5b5d028 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -524,6 +524,7 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 
 	memset(&match_all, 0, sizeof(match_all));
 	init_revisions(&rev, prefix);
+	rev.cmd_is_show = 1;
 	rev.diff = 1;
 	rev.always_show_header = 1;
 	rev.no_walk = REVISION_WALK_NO_WALK_SORTED;
diff --git a/revision.c b/revision.c
index 66520c6..5d6fbef 100644
--- a/revision.c
+++ b/revision.c
@@ -1399,6 +1399,8 @@ void init_revisions(struct rev_info *revs, const char *prefix)
 
 	revs->commit_format = CMIT_FMT_DEFAULT;
 
+	revs->cmd_is_show = 0;
+
 	init_grep_defaults();
 	grep_init(&revs->grep_filter, prefix);
 	revs->grep_filter.status_only = 1;
@@ -2339,6 +2341,8 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
 
 	if (revs->reflog_info && revs->graph)
 		die("cannot combine --walk-reflogs with --graph");
+	if (!revs->cmd_is_show && revs->no_walk && revs->graph)
+		die("cannot combine --no-walk with --graph");
 	if (!revs->reflog_info && revs->grep_filter.use_reflog_filter)
 		die("cannot use --grep-reflog without --walk-reflogs");
 
diff --git a/revision.h b/revision.h
index 0ea8b4e..378c3bf 100644
--- a/revision.h
+++ b/revision.h
@@ -146,6 +146,9 @@ struct rev_info {
 			track_first_time:1,
 			linear:1;
 
+	/* cmd type */
+	unsigned int  cmd_is_show:1;
+
 	enum date_mode date_mode;
 
 	unsigned int	abbrev;
diff --git a/t/t4202-log.sh b/t/t4202-log.sh
index 5f2b290..f111705 100755
--- a/t/t4202-log.sh
+++ b/t/t4202-log.sh
@@ -887,4 +887,8 @@ test_expect_success GPG 'log --graph --show-signature for merged tag' '
 	grep "^| | gpg: Good signature" actual
 '
 
+test_expect_success 'log --graph --no-walk is forbidden' '
+	test_must_fail git log --graph --no-walk
+'
+
 test_done
diff --git a/t/t6014-rev-list-all.sh b/t/t6014-rev-list-all.sh
index 991ab4a..c9bedd2 100755
--- a/t/t6014-rev-list-all.sh
+++ b/t/t6014-rev-list-all.sh
@@ -35,4 +35,8 @@ test_expect_success 'repack does not lose detached HEAD' '
 
 '
 
+test_expect_success 'rev-list --graph --no-walk is forbidden' '
+	test_must_fail git rev-list --graph --no-walk HEAD
+'
+
 test_done
-- 
2.3.1.252.ge67f612