Re: [PATCH v2] sha1-name.c: for ":/", find detached HEAD commits

[Junio C Hamano <gitster@pobox.com>]

William Chargin <wchargin@gmail.com> writes:

>> As we discussed during the review on v1, ":/<substring in commit>"
>> is *NOT* pathspec (that is why having these tests in t4208 is wrong
>> but we are following existing mistakes).
>
> Ah, I understand the terminology better now. Thanks. I'll change the
> commit message wording to use "extended SHA-1s" instead of "pathspecs".
>
>> Now you have Peff's sign-off for the one-liner code change, the last
>> one is redundant.
>
> Okay: I'll remove the "Based-on-patch-by" line.
>
>> Other than the above two nits, the patch looks good.  I would have
>> broken the line after "including HEAD.", but the slightly-long line
>> is also OK.
>
> Happy to change this while making the above edits. :-)

Let's save a round-trip.  Here is what I'd queue for now, and you
can just say "looks good" if you agree with the result, or send an
updated version ;-).

Thanks for working on this.

-- >8 --
From: William Chargin <wchargin@gmail.com>
Date: Wed, 11 Jul 2018 22:49:09 -0700
Subject: [PATCH] sha1-name.c: for ":/", find detached HEAD commits

This patch broadens the set of commits matched by ":/<pattern>" to
include commits reachable from HEAD but not any named ref. This avoids
surprising behavior when working with a detached HEAD and trying to
refer to a commit that was recently created and only exists within the
detached state.

If multiple worktrees exist, only the current worktree's HEAD is
considered reachable. This is consistent with the existing behavior for
other per-worktree refs: e.g., bisect refs are considered reachable, but
only within the relevant worktree.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: William Chargin <wchargin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 Documentation/revisions.txt   |  3 ++-
 sha1_name.c                   |  1 +
 t/t4208-log-magic-pathspec.sh | 26 ++++++++++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/Documentation/revisions.txt b/Documentation/revisions.txt
index dfcc49c72c..0845c3f590 100644
--- a/Documentation/revisions.txt
+++ b/Documentation/revisions.txt
@@ -180,7 +180,8 @@ existing tag object.
   A colon, followed by a slash, followed by a text, names
   a commit whose commit message matches the specified regular expression.
   This name returns the youngest matching commit which is
-  reachable from any ref. The regular expression can match any part of the
+  reachable from any ref, including HEAD.
+  The regular expression can match any part of the
   commit message. To match messages starting with a string, one can use
   e.g. ':/^foo'. The special sequence ':/!' is reserved for modifiers to what
   is matched. ':/!-foo' performs a negative match, while ':/!!foo' matches a
diff --git a/sha1_name.c b/sha1_name.c
index 611c7d24dd..19f66713e1 100644
--- a/sha1_name.c
+++ b/sha1_name.c
@@ -1649,6 +1649,7 @@ static int get_oid_with_context_1(const char *name,
 			struct commit_list *list = NULL;
 
 			for_each_ref(handle_one_ref, &list);
+			head_ref(handle_one_ref, &list);
 			commit_list_sort_by_date(&list);
 			return get_oid_oneline(name + 2, oid, list);
 		}
diff --git a/t/t4208-log-magic-pathspec.sh b/t/t4208-log-magic-pathspec.sh
index a1705f70cf..69643d101d 100755
--- a/t/t4208-log-magic-pathspec.sh
+++ b/t/t4208-log-magic-pathspec.sh
@@ -25,6 +25,32 @@ test_expect_success '"git log :/a -- " should not be ambiguous' '
 	git log :/a --
 '
 
+test_expect_success '"git log :/detached -- " should find a commit only in HEAD' '
+	test_when_finished "git checkout master" &&
+	git checkout --detach &&
+	# Must manually call `test_tick` instead of using `test_commit`,
+	# because the latter additionally creates a tag, which would make
+	# the commit reachable not only via HEAD.
+	test_tick &&
+	git commit --allow-empty -m detached &&
+	test_tick &&
+	git commit --allow-empty -m something-else &&
+	git log :/detached --
+'
+
+test_expect_success '"git log :/detached -- " should not find an orphaned commit' '
+	test_must_fail git log :/detached --
+'
+
+test_expect_success '"git log :/detached -- " should find HEAD only of own worktree' '
+	git worktree add other-tree HEAD &&
+	git -C other-tree checkout --detach &&
+	test_tick &&
+	git -C other-tree commit --allow-empty -m other-detached &&
+	git -C other-tree log :/other-detached -- &&
+	test_must_fail git log :/other-detached --
+'
+
 test_expect_success '"git log -- :/a" should not be ambiguous' '
 	git log -- :/a
 '
-- 
2.18.0-129-ge3331758f1