get_sha1: don't die() on bogus search stringsnd/dwim-wildcards-as-pathspecs

The get_sha1() function generally returns an error code
rather than dying, and we sometimes speculatively call it
with something that may be a revision or a pathspec, in
order to see which one it might be.

If it sees a bogus ":/" search string, though, it complains,
without giving the caller the opportunity to recover. We can
demonstrate this in t6133 by looking for ":/*.t", which
should mean "*.t at the root of the tree", but instead dies
because of the invalid regex (the "*" has nothing to operate
on).

We can fix this by returning an error rather than calling
die(). Unfortunately, the tradeoff is that the error message
is slightly worse in cases where we _do_ know we have a rev.
E.g., running "git log ':/*.t' --" before yielded:

  fatal: Invalid search pattern: *.t

and now we get only:

  fatal: bad revision ':/*.t'

There's not a simple way to fix this short of passing a
"quiet" flag all the way through the get_sha1() stack.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 12 insertions, 2 deletions

diff --git a/sha1_name.c b/sha1_name.c
index 6d10f052b5..6a2195fcc1 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -858,12 +858,12 @@ static int get_sha1_oneline(const char *prefix, unsigned char *sha1,
 
 	if (prefix[0] == '!') {
 		if (prefix[1] != '!')
-			die ("Invalid search pattern: %s", prefix);
+			return -1;
 		prefix++;
 	}
 
 	if (regcomp(&regex, prefix, REG_EXTENDED))
-		die("Invalid search pattern: %s", prefix);
+		return -1;
 
 	for (l = list; l; l = l->next) {
 		l->item->object.flags |= ONELINE_SEEN;
diff --git a/t/t6133-pathspec-rev-dwim.sh b/t/t6133-pathspec-rev-dwim.sh
index 8e5b338633..a290ffca0d 100755
--- a/t/t6133-pathspec-rev-dwim.sh
+++ b/t/t6133-pathspec-rev-dwim.sh
@@ -35,4 +35,14 @@ test_expect_success '@{foo} with metacharacters dwims to rev' '
 	test_cmp expect actual
 '
 
+test_expect_success ':/*.t from a subdir dwims to a pathspec' '
+	mkdir subdir &&
+	(
+		cd subdir &&
+		git log -- ":/*.t" >expect &&
+		git log    ":/*.t" >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done