[PATCH v2 3/3] rev-parse: diagnose ambiguous revision/filename arguments

[Jeff King <peff@peff.net>]

If you have both a file and a branch named "foo", running:

  git log foo

will complain. We should do the same in rev-parse, and
demand that it be disambiguated with:

  git rev-parse foo --

or

  git rev-parse -- foo

Signed-off-by: Jeff King <peff@peff.net>
---
 builtin/rev-parse.c            | 12 ++++++++----
 t/t1506-rev-parse-diagnosis.sh | 22 ++++++++++++++++++++++
 2 files changed, 30 insertions(+), 4 deletions(-)

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index a60fcd3..a3a58bf 100644
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -781,10 +781,11 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 		}
 
 		/* Not a flag argument */
-		if (try_difference(arg))
-			continue;
-		if (try_parent_shorthands(arg))
+		if (try_difference(arg) || try_parent_shorthands(arg)) {
+			if (!has_dashdash)
+				verify_non_filename(prefix, arg);
 			continue;
+		}
 		name = arg;
 		type = NORMAL;
 		if (*arg == '^') {
@@ -794,8 +795,11 @@ int cmd_rev_parse(int argc, const char **argv, const char *prefix)
 		if (!get_sha1(name, sha1)) {
 			if (verify)
 				revs_count++;
-			else
+			else {
 				show_rev(type, sha1, name);
+				if (!has_dashdash)
+					verify_non_filename(prefix, arg);
+			}
 			continue;
 		}
 		if (verify)
diff --git a/t/t1506-rev-parse-diagnosis.sh b/t/t1506-rev-parse-diagnosis.sh
index 613d9bf..dc1f1dc 100755
--- a/t/t1506-rev-parse-diagnosis.sh
+++ b/t/t1506-rev-parse-diagnosis.sh
@@ -220,4 +220,26 @@ test_expect_success 'arg before dashdash must be a revision (ambiguous)' '
 	test_cmp expect actual
 '
 
+test_expect_success 'ambiguous arg without dashdash (normal)' '
+	>foobar &&
+	git update-ref refs/heads/foobar HEAD &&
+	test_must_fail git rev-parse foobar 2>stderr &&
+	test_i18ngrep ambiguous stderr
+'
+
+test_expect_success 'ambiguous arg without dashdash (difference)' '
+	>one..two &&
+	git update-ref refs/heads/one HEAD &&
+	git update-ref refs/heads/two HEAD &&
+	test_must_fail git rev-parse one..two 2>stderr &&
+	test_i18ngrep ambiguous stderr
+'
+
+test_expect_success 'ambiguous arg without dashdash (parents)' '
+	>"foobar^@" &&
+	git update-ref refs/heads/foobar HEAD &&
+	test_must_fail git rev-parse foobar^@ 2>stderr &&
+	test_i18ngrep ambiguous stderr
+'
+
 test_done
-- 
1.8.5.524.g6743da6