revision: forbid combining --graph and --no-walk

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

This change makes a few calls to "show --graph" fail in t4052, but
asking to show one commit with graph is a nonsensical thing to do.
Thus, tests on "show --graph" in t4052 have been removed [2,3].
Same tests on "show" without --graph option have already been tested
in 4052.

3 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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/rev-list-options.txt

@@ -673,6 +673,7 @@ These options are mostly targeted for packing of Git repositories.
 	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`.
@@ -775,6 +776,7 @@ 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.
 +

revision.c

@@ -2337,6 +2337,8 @@ 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->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");
 

t/t4052-stat-output.sh

@@ -99,7 +99,7 @@ do
 		test_cmp "$expect" actual
 	'
 
-	test "$cmd" != diff || continue
+	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success "$cmd --graph $verb COLUMNS (big change)" '
 		COLUMNS=200 git $cmd $args --graph >output
@@ -127,7 +127,7 @@ do
 		test_cmp "$expect" actual
 	'
 
-	test "$cmd" != diff || continue
+	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success "$cmd --graph $verb not enough COLUMNS (big change)" '
 		COLUMNS=40 git $cmd $args --graph >output
@@ -155,7 +155,7 @@ do
 		test_cmp "$expect" actual
 	'
 
-	test "$cmd" != diff || continue
+	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success "$cmd --graph $verb statGraphWidth config" '
 		git -c diff.statGraphWidth=26 $cmd $args --graph >output
@@ -196,7 +196,7 @@ do
 		test_cmp expect actual
 	'
 
-	test "$cmd" != diff || continue
+	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success "$cmd --stat-width=width --graph with big change" '
 		git $cmd $args --stat-width=40 --graph >output
@@ -236,7 +236,7 @@ do
 		test_cmp expect actual
 	'
 
-	test "$cmd" != diff || continue
+	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success "$cmd --stat=width --graph with big change is balanced" '
 		git $cmd $args --stat-width=60 --graph >output &&
@@ -270,7 +270,7 @@ do
 		test_cmp "$expect" actual
 	'
 
-	test "$cmd" != diff || continue
+	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success "$cmd --graph $verb COLUMNS (long filename)" '
 		COLUMNS=200 git $cmd $args --graph >output
@@ -299,7 +299,7 @@ do
 		test_cmp "$expect" actual
 	'
 
-	test "$cmd" != diff || continue
+	case "$cmd" in diff|show) continue;; esac
 
 	test_expect_success COLUMNS_CAN_BE_1 \
 		"$cmd --graph $verb prefix greater than COLUMNS (big change)" '

t/t4202-log.sh

@@ -872,4 +872,8 @@ 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

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

t/t7007-show.sh

@@ -124,4 +124,8 @@ test_expect_success '--quiet suppresses diff' '
 	test_cmp expect actual
 '
 
+test_expect_success 'show --graph is forbidden' '
+  test_must_fail git show --graph HEAD
+'
+
 test_done