From: Jeff King <peff@peff.net>
To: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
Cc: git@vger.kernel.org, Junio C Hamano <gitster@pobox.com>,
"brian m . carlson" <sandals@crustytoothpaste.net>,
Derrick Stolee <stolee@gmail.com>,
Stefan Beller <sbeller@google.com>,
Eric Sunshine <sunshine@sunshineco.com>,
Duy Nguyen <pclouds@gmail.com>
Subject: Re: [PATCH v4 6/6] get_short_oid: document & warn if we ignore the type selector
Date: Thu, 10 May 2018 12:03:22 -0400 [thread overview]
Message-ID: <20180510160322.GC6462@sigill.intra.peff.net> (raw)
In-Reply-To: <20180510124303.6020-7-avarab@gmail.com>
On Thu, May 10, 2018 at 12:43:03PM +0000, Ævar Arnfjörð Bjarmason wrote:
> The SHA1 prefix 06fa currently matches no blobs in git.git. When
> disambiguating short SHA1s we've been quietly ignoring the user's type
> selector as a fallback mechanism, this was intentionally added in
> 1ffa26c461 ("get_short_sha1: list ambiguous objects on error",
> 2016-09-26).
>
> I think that behavior makes sense, it's not very useful to just show
> nothing because a preference has been expressed via core.disambiguate,
> but it's bad that we're quietly doing this. The user might thing that
> we just didn't understand what e.g 06fa^{blob} meant.
I had to read this through a few times to figure out what problem you
were solving. Possibly because you lead with 06fa, which is really just
an example (and also, I have an 06fa blob in my clone ;) ).
Maybe:
If the short-sha1 disambiguation code is told to use a particular hint
(e.g., treeish or blob) but no objects with that short-sha1 match that
hint, we end up ignoring the hint. This can result in either:
1. We choose the non-matching object if there is only one. This will
typically result in an error later up the stack (since whatever
gave us the hint is expecting a particular type).
2. We list all objects with that short-sha1, including those with
non-matching types.
This second case can be confusing to the user, who might think that we
didn't apply the hint properly (especially if the hint came from
them). For example, in git.git there is no blob with the prefix 06fa.
So the user may see:
$ git rev-parse 06fa^{blob}
hint: The candidates are:
hint: 06fa2b7c2b tag v2.1.4
hint: 06faf6ba64 tree
06fa^{blob}
fatal: ambiguous argument '06fa^{blob}': unknown revision or path not in the working tree.
Let's help them out by issuing a warning whenever the hint is ignored.
So that at least explains it in a way that makes sense to me. But now
that I've propped up my strawman, let me take a few swings...
Your patch just covers case 2, I think. And for the error case, that's
probably OK:
$ git rev-parse 06faf^{blob}
error: 06faf^{blob}: expected blob type, but the object dereferences to tree type
06faf^{blob}
error: 06faf^{blob}: expected blob type, but the object dereferences to tree type
fatal: ambiguous argument '06faf^{blob}': unknown revision or path not in the working tree.
(though there is a separate bug in showing the error twice).
But some cases _don't_ issue an error. For example, try this:
$ git log ..06faf
which returns an empty output! We return the single matching tree, even
though the ".." triggers the commit hint. The revision machinery just
queues the tree, and then later when we see we're not doing an --objects
traversal, it just gets ignored. (That's a separate issue, but it shows
that the hints are just that: hints. The code that runs after does not
necessarily require a matching type).
And that example shows another issue, which is that the user does not
necessarily feed us the hint explicitly. We're using a committish hint
there, but I'm not sure if mentioning that would confuse the user or
not. Certainly this warning:
> warning: Your hint (via core.disambiguate or peel syntax) was ignored, we fell
> back to showing all object types since no object of the requested type
> matched the provide short SHA1 06fa
is not accurate, because the hint came from neither of those places. ;)
So all that said together, I kind of wonder if we should consider
issuing the warning earlier, doing so for all cases, and being a bit
less chatty. Like:
$ git rev-parse 06fa^{blob}
warning: short object id 06fa did not match any objects of type 'blob'
If that were followed by any of:
1. error: short SHA1 06fa is ambiguous, then a bunch of non-blobs
2. error: expected blob but I got a tree
3. the command proceeds and silently ignores the matched object
I think it would be helpful. We'd need to add in an extra mapping of
GET_OID_* back to a human-readable string, but I think that should be
pretty easy.
And finally, your 06fa example for me shows behavior that's either
buggy, or I'm just confused. I get:
$ git rev-parse 06fa^{blob}
error: short SHA1 06fa is ambiguous
hint: The candidates are:
hint: 06fa2b7c2b tag v2.1.4
hint: 06faa52353 commit 2005-10-18 - 2005-10-18 midnight
hint: 06fac427af blob
hint: 06faf6ba64 tree
(That 06fac blob comes Junio's refs/notes/amlog). Shouldn't the blob
disambiguator show me just that object?
-Peff
next prev parent reply other threads:[~2018-05-10 16:03 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-30 22:07 [PATCH 0/9] get_short_oid UI improvements Ævar Arnfjörð Bjarmason
2018-04-30 22:07 ` [PATCH 1/9] sha1-name.c: remove stray newline Ævar Arnfjörð Bjarmason
2018-04-30 22:07 ` [PATCH 2/9] sha1-array.h: align function arguments Ævar Arnfjörð Bjarmason
2018-04-30 22:07 ` [PATCH 3/9] sha1-name.c: move around the collect_ambiguous() function Ævar Arnfjörð Bjarmason
2018-04-30 22:07 ` [PATCH 4/9] get_short_oid: sort ambiguous objects by type, then SHA-1 Ævar Arnfjörð Bjarmason
2018-05-01 11:11 ` Derrick Stolee
2018-05-01 11:27 ` Ævar Arnfjörð Bjarmason
2018-05-01 12:26 ` Derrick Stolee
2018-05-01 12:36 ` Ævar Arnfjörð Bjarmason
2018-05-01 13:05 ` Derrick Stolee
2018-04-30 22:07 ` [PATCH 5/9] get_short_oid: learn to disambiguate by ^{tag} Ævar Arnfjörð Bjarmason
2018-04-30 22:07 ` [PATCH 6/9] get_short_oid: learn to disambiguate by ^{blob} Ævar Arnfjörð Bjarmason
2018-04-30 22:07 ` [PATCH 7/9] get_short_oid / peel_onion: ^{tree} should mean tree, not treeish Ævar Arnfjörð Bjarmason
2018-05-01 1:13 ` brian m. carlson
2018-04-30 22:07 ` [PATCH 8/9] get_short_oid / peel_onion: ^{tree} should mean commit, not commitish Ævar Arnfjörð Bjarmason
2018-04-30 23:22 ` Eric Sunshine
2018-04-30 22:07 ` [PATCH 9/9] config doc: document core.disambiguate Ævar Arnfjörð Bjarmason
2018-04-30 22:34 ` [PATCH 0/9] get_short_oid UI improvements Stefan Beller
2018-05-01 1:27 ` brian m. carlson
2018-05-01 11:16 ` Derrick Stolee
2018-05-01 12:06 ` [PATCH v2 00/12] " Ævar Arnfjörð Bjarmason
2018-05-01 13:03 ` [PATCH v2 06/11] get_short_oid: sort ambiguous objects by type, then SHA-1 Derrick Stolee
2018-05-01 13:39 ` Ævar Arnfjörð Bjarmason
2018-05-01 13:44 ` Derrick Stolee
2018-05-01 14:10 ` Ævar Arnfjörð Bjarmason
2018-05-01 14:15 ` Derrick Stolee
2018-05-01 18:40 ` [PATCH v3 00/12] get_short_oid UI improvements Ævar Arnfjörð Bjarmason
2018-05-02 12:42 ` Derrick Stolee
2018-05-02 13:45 ` Derrick Stolee
2018-05-03 6:43 ` Jacob Keller
2018-05-01 18:40 ` [PATCH v3 01/12] sha1-name.c: remove stray newline Ævar Arnfjörð Bjarmason
2018-05-01 18:40 ` [PATCH v3 02/12] sha1-array.h: align function arguments Ævar Arnfjörð Bjarmason
2018-05-01 18:40 ` [PATCH v3 03/12] git-p4: change "commitish" typo to "committish" Ævar Arnfjörð Bjarmason
2018-05-01 18:40 ` [PATCH v3 04/12] cache.h: add comment explaining the order in object_type Ævar Arnfjörð Bjarmason
2018-05-03 5:05 ` Junio C Hamano
2018-05-08 15:35 ` Duy Nguyen
2018-05-08 15:56 ` [PATCH] pack-format.txt: more details on pack file format Nguyễn Thái Ngọc Duy
2018-05-08 17:23 ` Stefan Beller
2018-05-08 18:22 ` Duy Nguyen
2018-05-08 18:58 ` Stefan Beller
2018-05-08 18:21 ` Ævar Arnfjörð Bjarmason
2018-05-08 18:24 ` Duy Nguyen
2018-05-10 15:09 ` [PATCH v2] " Nguyễn Thái Ngọc Duy
2018-05-10 17:06 ` Stefan Beller
2018-05-11 6:41 ` Duy Nguyen
2018-05-11 3:54 ` Junio C Hamano
2018-05-11 6:55 ` [PATCH v3] " Nguyễn Thái Ngọc Duy
2018-05-01 18:40 ` [PATCH v3 05/12] sha1-name.c: move around the collect_ambiguous() function Ævar Arnfjörð Bjarmason
2018-05-01 18:40 ` [PATCH v3 06/12] get_short_oid: sort ambiguous objects by type, then SHA-1 Ævar Arnfjörð Bjarmason
2018-05-03 5:13 ` Junio C Hamano
2018-05-08 14:44 ` Jeff King
2018-05-01 18:40 ` [PATCH v3 07/12] get_short_oid: learn to disambiguate by ^{tag} Ævar Arnfjörð Bjarmason
2018-05-01 18:40 ` [PATCH v3 08/12] get_short_oid: learn to disambiguate by ^{blob} Ævar Arnfjörð Bjarmason
2018-05-01 18:40 ` [PATCH v3 09/12] get_short_oid / peel_onion: ^{tree} should be tree, not treeish Ævar Arnfjörð Bjarmason
2018-05-03 5:28 ` Junio C Hamano
2018-05-03 7:28 ` Ævar Arnfjörð Bjarmason
2018-05-04 2:19 ` Junio C Hamano
2018-05-04 8:42 ` Ævar Arnfjörð Bjarmason
2018-05-07 4:08 ` Junio C Hamano
2018-05-08 14:34 ` Jeff King
2018-05-08 18:53 ` Ævar Arnfjörð Bjarmason
2018-05-09 7:56 ` Jeff King
2018-05-09 10:48 ` Ævar Arnfjörð Bjarmason
2018-05-10 4:21 ` Junio C Hamano
2018-05-10 6:50 ` Jeff King
2018-05-10 12:42 ` [PATCH v4 0/6] get_short_oid UI improvements Ævar Arnfjörð Bjarmason
2018-05-10 16:04 ` Jeff King
2018-05-10 12:42 ` [PATCH v4 1/6] sha1-name.c: remove stray newline Ævar Arnfjörð Bjarmason
2018-05-10 12:42 ` [PATCH v4 2/6] sha1-array.h: align function arguments Ævar Arnfjörð Bjarmason
2018-05-10 15:06 ` Jeff King
2018-05-11 3:07 ` Junio C Hamano
2018-05-11 3:09 ` Junio C Hamano
2018-05-10 12:43 ` [PATCH v4 3/6] git-p4: change "commitish" typo to "committish" Ævar Arnfjörð Bjarmason
2018-05-10 15:00 ` Luke Diamand
2018-05-10 12:43 ` [PATCH v4 4/6] sha1-name.c: move around the collect_ambiguous() function Ævar Arnfjörð Bjarmason
2018-05-10 12:43 ` [PATCH v4 5/6] get_short_oid: sort ambiguous objects by type, then SHA-1 Ævar Arnfjörð Bjarmason
2018-05-10 15:22 ` Jeff King
2018-05-11 5:36 ` Junio C Hamano
2018-05-10 12:43 ` [PATCH v4 6/6] get_short_oid: document & warn if we ignore the type selector Ævar Arnfjörð Bjarmason
2018-05-10 13:15 ` Martin Ågren
2018-05-10 16:03 ` Jeff King [this message]
2018-05-10 16:10 ` Jeff King
2018-05-10 16:15 ` Jeff King
2018-05-01 18:40 ` [PATCH v3 10/12] get_short_oid / peel_onion: ^{commit} should be commit, not committish Ævar Arnfjörð Bjarmason
2018-05-01 18:40 ` [PATCH v3 11/12] config doc: document core.disambiguate Ævar Arnfjörð Bjarmason
2018-05-08 14:41 ` Jeff King
2018-05-01 18:40 ` [PATCH v3 12/12] get_short_oid: document & warn if we ignore the type selector Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 01/12] sha1-name.c: remove stray newline Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 02/12] sha1-array.h: align function arguments Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 03/12] git-p4: change "commitish" typo to "committish" Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 04/12] cache.h: add comment explaining the order in object_type Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 05/12] sha1-name.c: move around the collect_ambiguous() function Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 06/12] get_short_oid: sort ambiguous objects by type, then SHA-1 Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 07/12] get_short_oid: learn to disambiguate by ^{tag} Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 08/12] get_short_oid: learn to disambiguate by ^{blob} Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 09/12] get_short_oid / peel_onion: ^{tree} should be tree, not treeish Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 10/12] get_short_oid / peel_onion: ^{commit} should be commit, not committish Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 11/12] config doc: document core.disambiguate Ævar Arnfjörð Bjarmason
2018-05-01 12:06 ` [PATCH v2 12/12] get_short_oid: document & warn if we ignore the type selector Ævar Arnfjörð Bjarmason
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