log: add a --no-graph option

It's useful to be able to countermand a previous --graph option, for
example if `git log --graph` is run via an alias.

Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/blame.c

@@ -934,6 +934,7 @@ int cmd_blame(int argc, const char **argv, const char *prefix)
 		parse_revision_opt(&revs, &ctx, options, blame_opt_usage);
 	}
 parse_done:
+	revision_opts_finish(&revs);
 	no_whole_file_rename = !revs.diffopt.flags.follow_renames;
 	xdl_opts |= revs.diffopt.xdl_opts & XDF_INDENT_HEURISTIC;
 	revs.diffopt.flags.follow_renames = 0;

builtin/shortlog.c

@@ -388,6 +388,7 @@ int cmd_shortlog(int argc, const char **argv, const char *prefix)
 		parse_revision_opt(&rev, &ctx, options, shortlog_usage);
 	}
 parse_done:
+	revision_opts_finish(&rev);
 	argc = parse_options_end(&ctx);
 
 	if (nongit && argc > 1) {

revision.c

@@ -2424,10 +2424,11 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 		revs->pretty_given = 1;
 		revs->abbrev_commit = 1;
 	} else if (!strcmp(arg, "--graph")) {
-		revs->topo_order = 1;
-		revs->rewrite_parents = 1;
 		graph_clear(revs->graph);
 		revs->graph = graph_init(revs);
+	} else if (!strcmp(arg, "--no-graph")) {
+		graph_clear(revs->graph);
+		revs->graph = NULL;
 	} else if (!strcmp(arg, "--encode-email-headers")) {
 		revs->encode_email_headers = 1;
 	} else if (!strcmp(arg, "--no-encode-email-headers")) {
@@ -2524,8 +2525,6 @@ static int handle_revision_opt(struct rev_info *revs, int argc, const char **arg
 			unkv[(*unkc)++] = arg;
 		return opts;
 	}
-	if (revs->graph && revs->track_linear)
-		die(_("options '%s' and '%s' cannot be used together"), "--show-linear-break", "--graph");
 
 	return 1;
 }
@@ -2544,6 +2543,17 @@ void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
 	ctx->argc -= n;
 }
 
+void revision_opts_finish(struct rev_info *revs)
+{
+	if (revs->graph && revs->track_linear)
+		die(_("options '%s' and '%s' cannot be used together"), "--show-linear-break", "--graph");
+
+	if (revs->graph) {
+		revs->topo_order = 1;
+		revs->rewrite_parents = 1;
+	}
+}
+
 static int for_each_bisect_ref(struct ref_store *refs, each_ref_fn fn,
 			       void *cb_data, const char *term)
 {
@@ -2786,6 +2796,7 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
 			break;
 		}
 	}
+	revision_opts_finish(revs);
 
 	if (prune_data.nr) {
 		/*

revision.h

@@ -372,6 +372,7 @@ void parse_revision_opt(struct rev_info *revs, struct parse_opt_ctx_t *ctx,
 #define REVARG_COMMITTISH 02
 int handle_revision_arg(const char *arg, struct rev_info *revs,
 			int flags, unsigned revarg_opt);
+void revision_opts_finish(struct rev_info *revs);
 
 /**
  * Reset the flags used by the revision walking api. You can use this to do

t/t4202-log.sh

@@ -1671,6 +1671,75 @@ test_expect_success 'log --graph with --name-only' '
 	test_cmp_graph --name-only tangle..reach
 '
 
+test_expect_success '--no-graph countermands --graph' '
+	git log >expect &&
+	git log --graph --no-graph >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--graph countermands --no-graph' '
+	git log --graph >expect &&
+	git log --no-graph --graph >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--no-graph does not unset --topo-order' '
+	git log --topo-order >expect &&
+	git log --topo-order --no-graph >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--no-graph does not unset --parents' '
+	git log --parents >expect &&
+	git log --parents --no-graph >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--reverse and --graph conflict' '
+	test_must_fail git log --reverse --graph 2>stderr &&
+	test_i18ngrep "cannot be used together" stderr
+'
+
+test_expect_success '--reverse --graph --no-graph works' '
+	git log --reverse >expect &&
+	git log --reverse --graph --no-graph >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--show-linear-break and --graph conflict' '
+	test_must_fail git log --show-linear-break --graph 2>stderr &&
+	test_i18ngrep "cannot be used together" stderr
+'
+
+test_expect_success '--show-linear-break --graph --no-graph works' '
+	git log --show-linear-break >expect &&
+	git log --show-linear-break --graph --no-graph >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--no-walk and --graph conflict' '
+	test_must_fail git log --no-walk --graph 2>stderr &&
+	test_i18ngrep "cannot be used together" stderr
+'
+
+test_expect_success '--no-walk --graph --no-graph works' '
+	git log --no-walk >expect &&
+	git log --no-walk --graph --no-graph >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--walk-reflogs and --graph conflict' '
+	test_must_fail git log --walk-reflogs --graph 2>stderr &&
+	(test_i18ngrep "cannot combine" stderr ||
+		test_i18ngrep "cannot be used together" stderr)
+'
+
+test_expect_success '--walk-reflogs --graph --no-graph works' '
+	git log --walk-reflogs >expect &&
+	git log --walk-reflogs --graph --no-graph >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'dotdot is a parent directory' '
 	mkdir -p a/b &&
 	( echo sixth && echo fifth ) >expect &&