git-bisect(1) next after finding the commit
Hi!
Is there a plumbing command for retrieving the bisected commit after a git-bisect(1) session has successfully found it (and of course before resetting the session)?
I expected git bisect next would bring me to it, and then I'd rev-list HEAD -1, but it doesn't bring me to it.
Have a lovely day!
Alex
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<https://www.alejandro-colomar.es>
Quoted 6 lines · Alejandro Colomar
Is there a plumbing command for retrieving the bisected commit after a git-bisect(1) session has successfully found it (and of course before resetting the session)?
I expected
git bisect nextwould bring me to it, and then I'd rev-list HEAD -1, but it doesn't bring me to it.
I'm not 100% sure, but I think "git show bisect/bad" should work.
As the bisection progresses, we advance a single refs/bisect/bad from the bottom of the range (the top is multiple refs/bisect/good-* refs). So at the end, it should point to the blamed commit.
-Peff
Quoted 6 lines · Jeff King
Quoted 4 lines · Alejandro Colomar
Is there a plumbing command for retrieving the bisected commit after a git-bisect(1) session has successfully found it (and of course before resetting the session)?
Quoted 8 lines
Quoted 2 lines
I expected
git bisect nextwould bring me to it, and then I'd rev-list HEAD -1, but it doesn't bring me to it.I'm not 100% sure, but I think "git show bisect/bad" should work.
As the bisection progresses, we advance a single refs/bisect/bad from the bottom of the range (the top is multiple refs/bisect/good-* refs). So at the end, it should point to the blamed commit.
The only code that gives "is the first .* commit" message is this bit in bisect.c:
if (oideq(bisect_rev, current_bad_oid)) {
res = error_if_skipped_commits(tried, current_bad_oid);
if (res)
goto cleanup;
printf("%s is the first '%s' commit\n", oid_to_hex(bisect_rev),
term_bad);it is fed bisect_rev only when it is the same as current_bad_oid, which was read from "refs/bisect/bad". So I think you are right.
[Footnote]
There is a last-step optimization that made me double check the code, but the optimization is about not bothering to move HEAD and not moving refs/bisect/bad pointer.
We have a three-topic branch X, X is at the tip, X~1 at the middle and X-2 at the bottom. X~3 is on the mainline.
----- X~3 ---- X~2 ---- X~1 ---- X
We found X~2 to be good. X is bad.
$ git bisect start X X~2
We are asked to test X~1.
* It turns out to be bad. We move bisect/bad to X~1. And then we report that X~1 is the first bad commit.
* Or it turns out to be good. Then we report that X is the first bad commit. But we do not move HEAD and checkout X.
Hi Junio,
Quoted 30 lines
Date: 2026-10-02 15:32:13-0700
From: Junio C Hamano <[email protected]>Quoted 6 lines · Jeff King
Quoted 4 lines · Alejandro Colomar
Is there a plumbing command for retrieving the bisected commit after a git-bisect(1) session has successfully found it (and of course before resetting the session)?
Quoted 8 lines
Quoted 2 lines
I expected
git bisect nextwould bring me to it, and then I'd rev-list HEAD -1, but it doesn't bring me to it.I'm not 100% sure, but I think "git show bisect/bad" should work.
As the bisection progresses, we advance a single refs/bisect/bad from the bottom of the range (the top is multiple refs/bisect/good-* refs). So at the end, it should point to the blamed commit.
The only code that gives "is the first .* commit" message is this bit in
bisect.c:if (oideq(bisect_rev, current_bad_oid)) { res = error_if_skipped_commits(tried, current_bad_oid); if (res) goto cleanup; printf("%s is the first '%s' commit\n", oid_to_hex(bisect_rev), term_bad);
Quoted 2 lines
it is fed
bisect_revonly when it is the same ascurrent_bad_oid, which was read from "refs/bisect/bad". So I think you are right.
Thanks for confirming! It certainly works for me (I've tested it).
Quoted 15 lines
[Footnote]
There is a last-step optimization that made me double check the code, but the optimization is about not bothering to move HEAD and not moving refs/bisect/bad pointer.
We have a three-topic branch X, X is at the tip, X~1 at the middle and X-2 at the bottom. X~3 is on the mainline.
----- X~3 ---- X~2 ---- X~1 ---- X
We found X~2 to be good. X is bad.
$ git bisect start X X~2
Quoted 7 lines
We are asked to test X~1.
* It turns out to be bad. We move bisect/bad to X~1. And then we report that X~1 is the first bad commit.
* Or it turns out to be good. Then we report that X is the first bad commit. But we do not move HEAD and checkout X.
Indeed, this optimization is what surprised me. I expected it would move the HEAD as with every other git-bisect(1) step, but the last one didn't move it. I can live with it, FWIW, since bisect/bad contains all the information I need (and anyway, I will move the HEAD myself, so I don't need the HEAD in any specific position). It was just surprising.
:)
Have a lovely day!
Alex
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Hi Jeff,
Quoted 5 lines
Date: 2026-10-02 18:11:54-0400
From: Jeff King <[email protected]>On Fri, Oct 02, 2026 at 11:49:01PM +0200, Alejandro Colomar wrote:
Quoted 8 lines
Quoted 6 lines
Is there a plumbing command for retrieving the bisected commit after a git-bisect(1) session has successfully found it (and of course before resetting the session)?
I expected
git bisect nextwould bring me to it, and then I'd rev-list HEAD -1, but it doesn't bring me to it.I'm not 100% sure, but I think "git show bisect/bad" should work.
Thanks! It works.
I guess the plumbing version of it would be
git rev-list -1 bisect/bad
right?
Quoted 5 lines
As the bisection progresses, we advance a single refs/bisect/bad from the bottom of the range (the top is multiple refs/bisect/good-* refs). So at the end, it should point to the blamed commit.
-Peff
Have a lovely day!
Alex
Signature · 1 line
<https://www.alejandro-colomar.es>
Quoted 7 lines · Alejandro Colomar
Quoted 1 line
I'm not 100% sure, but I think "git show bisect/bad" should work.
Thanks! It works.
I guess the plumbing version of it would be
git rev-list -1 bisect/bad
right?
Yeah. Or even just "git rev-parse bisect/bad" (maybe with --verify if appropriate).
-Peff
Hi Jeff,
Quoted 7 lines
Date: 2026-10-04 23:23:48-0400
From: Jeff King <[email protected]>Quoted 2 lines · Alejandro Colomar
Quoted 1 line
I'm not 100% sure, but I think "git show bisect/bad" should work.
Quoted 8 lines
Quoted 5 lines
Thanks! It works.
I guess the plumbing version of it would be
git rev-list -1 bisect/bad
right?Yeah. Or even just "git rev-parse bisect/bad" (maybe with --verify if appropriate).
Oh, thanks! I've changed the rev-list -1 calls to do rev-parse.
Have a lovely day!
Alex
Quoted 1 line
-Peff
Signature · 1 line
<https://www.alejandro-colomar.es>