threads / patch / 66648

patchbuiltin/reflog: say "would prune" for named refs with --dry-run

Subject: [PATCH] builtin/reflog: say "would prune" for named refs with --dry-run

## tl;dr

A one-line fix for a wrong "prune" label has led to a suggestion to restructure the loops that caused the bug. Read the story.

replies: 4people: 3as markdown or json

Laveesh Bansal· Oct 24, 2026, 01:38 UTC · lore

With --dry-run --verbose, "git reflog expire --all" reports the entries it would remove as "would prune", but when refs are named on the command line it reports them as "prune", which looks as if they were removed:

    $ git reflog expire --dry-run --verbose --expire=now HEAD
    prune commit (initial): first

Nothing is removed in either case, only the label is wrong. This was reported at [1].

fcd2c3d9d8 (reflog + refs-backend: move "verbose" out of the backend, 2021-12-22) added dry_run to struct expire_reflog_policy_cb and set it in the --all loop, but not in the loop for named refs. Set it there too.

Add tests for named refs and --all. No test checked the keep/prune wording before.

[1] https://lore.kernel.org/git/b46cbce8-d2bb-46d2-bdd3-545422813d6b@tngtech.com/
Reported-by: Sven Weiland <sven.weiland@tngtech.com>
Assisted-by: Claude Sonnet 5.5
Signed-off-by: Laveesh Bansal <laveeshb@laveeshbansal.com>
---
Notes:
    The dry_run bit just duplicates what is already in flags, so every
    caller has to copy it, and one got missed. Dropping it would mean
    changing the callback signature, so I left that alone.
 builtin/reflog.c  |  5 ++++-
 t/t1410-reflog.sh | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+), 1 deletion(-)
Show changes to 2 files +38 −1

builtin/reflog.c, t/t1410-reflog.sh

diff --git a/builtin/reflog.c b/builtin/reflog.c
index 1211c58fa4..49e5453dd9 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -279,7 +279,10 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix,
 
 	for (i = 0; i < argc; i++) {
 		char *ref;
-		struct expire_reflog_policy_cb cb = { .opts = opts };
+		struct expire_reflog_policy_cb cb = {
+			.opts = opts,
+			.dry_run = !!(flags & EXPIRE_REFLOGS_DRY_RUN),
+		};
 
 		if (!repo_dwim_log(the_repository, argv[i], strlen(argv[i]), NULL, &ref)) {
 			status |= error(_("reflog could not be found: '%s'"), argv[i]);
diff --git a/t/t1410-reflog.sh b/t/t1410-reflog.sh
index 93b5b49e1d..998a7e8667 100755
--- a/t/t1410-reflog.sh
+++ b/t/t1410-reflog.sh
@@ -240,6 +240,40 @@ test_expect_success 'reflog expire --dry-run should not touch reflog' '
 	check_fsck "missing blob $F"
 '
 
+# A dry run only ever says "keep" or "would prune".
+check_dry_run_output () {
+	test_grep "^would prune " "$1" &&
+	sed -e "/^keep /d" -e "/^would prune /d" \
+		-e "/^Marking reachable objects/d" "$1" >unexpected &&
+	test_must_be_empty unexpected
+}
+
+test_expect_success 'reflog expire --dry-run --verbose with a named ref' '
+	git reflog refs/heads/main >before &&
+	git reflog expire --dry-run --verbose \
+		--expire=$(($test_tick - 10000)) \
+		--expire-unreachable=$(($test_tick - 10000)) \
+		--stale-fix \
+		refs/heads/main >output &&
+	check_dry_run_output output &&
+
+	git reflog refs/heads/main >after &&
+	test_cmp before after
+'
+
+test_expect_success 'reflog expire --dry-run --verbose --all' '
+	git reflog refs/heads/main >before &&
+	git reflog expire --dry-run --verbose \
+		--expire=$(($test_tick - 10000)) \
+		--expire-unreachable=$(($test_tick - 10000)) \
+		--stale-fix \
+		--all >output &&
+	check_dry_run_output output &&
+
+	git reflog refs/heads/main >after &&
+	test_cmp before after
+'
+
 test_expect_success 'reflog expire' '
 
 	git reflog expire --verbose \

-- 
2.54.0
Junio C Hamano· Oct 25, 2026, 18:07 UTC · re: Laveesh Bansal · lore

Re: [PATCH] builtin/reflog: say "would prune" for named refs with --dry-run

Laveesh Bansal <laveeshb@laveeshbansal.com> writes:
Show 28 quoted lines
> With --dry-run --verbose, "git reflog expire --all" reports the entries
> it would remove as "would prune", but when refs are named on the command
> line it reports them as "prune", which looks as if they were removed:
>
>     $ git reflog expire --dry-run --verbose --expire=now HEAD
>     prune commit (initial): first
>
> Nothing is removed in either case, only the label is wrong. This was
> reported at [1].
>
> fcd2c3d9d8 (reflog + refs-backend: move "verbose" out of the backend,
> 2021-12-22) added dry_run to struct expire_reflog_policy_cb and set it
> in the --all loop, but not in the loop for named refs. Set it there
> too.
> ...
> diff --git a/builtin/reflog.c b/builtin/reflog.c
> index 1211c58fa4..49e5453dd9 100644
> --- a/builtin/reflog.c
> +++ b/builtin/reflog.c
> @@ -279,7 +279,10 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix,
>  
>  	for (i = 0; i < argc; i++) {
>  		char *ref;
> -		struct expire_reflog_policy_cb cb = { .opts = opts };
> +		struct expire_reflog_policy_cb cb = {
> +			.opts = opts,
> +			.dry_run = !!(flags & EXPIRE_REFLOGS_DRY_RUN),
> +		};
This obviously mimics what happens in the "if (do_all)" side.

But I have to wonder why nobody finds it disgusting that what happens inside the "for_each_string_list_item()" and the later "for (i = 0; i < rgc; i++)" loop have striking similarity between them.

Would it make sense to retructure the code flow to
	if (do_all) {
		collect "all" to a strvec or string list
	}
	foreach arg in argv[]) {
		add arg to the same strvec or string list
	}
	foreach ref in collected {
		do the expiration of ref's reflog
	}

That will help prevent a similar bug from ever happening again, as there would be only a single place that sets up how the expiration is called, instead of two we currently have.

Laveesh Bansal· Oct 25, 2026, 19:15 UTC · re: Junio C Hamano · lore

Re: [PATCH] builtin/reflog: say "would prune" for named refs with --dry-run

Junio C Hamano <gitster@pobox.com> writes:
> That will help prevent a similar bug from ever happening again, as
> there would be only a single place that sets up how the expiration
> is called, instead of two we currently have.
Agreed, and I think the consolidation is doable.

I suggest keeping this patch as it is, since it fixes the reported bug. I'll look into what you describe as a separate patch after this one, and the tests added here would stay useful for that patch too.

Junio C Hamano· Oct 26, 2026, 01:16 UTC · re: Laveesh Bansal · lore

Re: [PATCH] builtin/reflog: say "would prune" for named refs with --dry-run

Laveesh Bansal <laveeshb@laveeshbansal.com> writes:
Show 11 quoted lines
> Junio C Hamano <gitster@pobox.com> writes:
>
>> That will help prevent a similar bug from ever happening again, as
>> there would be only a single place that sets up how the expiration
>> is called, instead of two we currently have.
>
> Agreed, and I think the consolidation is doable.
>
> I suggest keeping this patch as it is, since it fixes the reported
> bug. I'll look into what you describe as a separate patch after this
> one, and the tests added here would stay useful for that patch too.
Sounds like a good plan to me.
Patrick Steinhardt· Oct 29, 2026, 12:18 UTC · re: Laveesh Bansal · lore

Re: [PATCH] builtin/reflog: say "would prune" for named refs with --dry-run

On Fri, Oct 23, 2026 at 06:38:50PM -0700, Laveesh Bansal wrote:
Show 14 quoted lines
> With --dry-run --verbose, "git reflog expire --all" reports the entries
> it would remove as "would prune", but when refs are named on the command
> line it reports them as "prune", which looks as if they were removed:
> 
>     $ git reflog expire --dry-run --verbose --expire=now HEAD
>     prune commit (initial): first
> 
> Nothing is removed in either case, only the label is wrong. This was
> reported at [1].
> 
> fcd2c3d9d8 (reflog + refs-backend: move "verbose" out of the backend,
> 2021-12-22) added dry_run to struct expire_reflog_policy_cb and set it
> in the --all loop, but not in the loop for named refs. Set it there
> too.

Phew, kind of lucky that it's only the message and not us accidentally pruning stuff.

> Add tests for named refs and --all. No test checked the keep/prune
> wording before.

Tiny nit, not worth a reroll: this paragraph doesn't really add a ton of value, as it's self-evident from the patch.

Show 15 quoted lines
> diff --git a/t/t1410-reflog.sh b/t/t1410-reflog.sh
> index 93b5b49e1d..998a7e8667 100755
> --- a/t/t1410-reflog.sh
> +++ b/t/t1410-reflog.sh
> @@ -240,6 +240,40 @@ test_expect_success 'reflog expire --dry-run should not touch reflog' '
>  	check_fsck "missing blob $F"
>  '
>  
> +# A dry run only ever says "keep" or "would prune".
> +check_dry_run_output () {
> +	test_grep "^would prune " "$1" &&
> +	sed -e "/^keep /d" -e "/^would prune /d" \
> +		-e "/^Marking reachable objects/d" "$1" >unexpected &&
> +	test_must_be_empty unexpected
> +}

Okay, this is quite defensive in that it both checks that we print "would prune" but none of the other lines. We could have made it even more defensive by filtering out "would prune" lines and then testing that the result is empty. But this here is certainly good enough, I'd say.

So overall this looks good to me as-is, thanks!
Patrick

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