Re: [PATCH v2] fetch: no FETCH_HEAD display if --no-write-fetch-head

[Jonathan Nieder <jrnieder@gmail.com>]

Jonathan Tan wrote:

> 887952b8c6 ("fetch: optionally allow disabling FETCH_HEAD update",
> 2020-08-18) introduced the ability to disable writing to FETCH_HEAD
> during fetch, but did not suppress the "<source> -> FETCH_HEAD" message
> when this ability is used. This message is misleading in this case,
> because FETCH_HEAD is not written. Also, because "fetch" is used to
> lazy-fetch missing objects in a partial clone, this significantly
> clutters up the output in that case since the objects to be fetched are
> potentially numerous.
>
> Therefore, suppress this message when --no-write-fetch-head is passed
> (but not when --dry-run is set).
>
> Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
> ---
[...]
>  builtin/fetch.c          |  8 +++++++-
>  t/t0410-partial-clone.sh |  7 +++++--
>  t/t5510-fetch.sh         | 18 ++++++++++--------
>  3 files changed, 22 insertions(+), 11 deletions(-)

Thanks for fixing it, and sorry I didn't catch it during initial
review.

> diff --git a/builtin/fetch.c b/builtin/fetch.c
> index 320ba9471d..c6c4689250 100644
> --- a/builtin/fetch.c
> +++ b/builtin/fetch.c
> @@ -1023,11 +1023,17 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
>  				rc |= update_local_ref(ref, what, rm, &note,
>  						       summary_width);
>  				free(ref);
> -			} else
> +			} else if (write_fetch_head || dry_run) {
> +				/*
> +				 * Display fetches written to FETCH_HEAD (or
> +				 * would be written to FETCH_HEAD, if --dry-run

nit: to fix the parallel construction, s/would/that would/ or
s/written/that were written/

> +				 * is set).
> +				 */
>  				format_display(&note, '*',
>  					       *kind ? kind : "branch", NULL,
>  					       *what ? what : "HEAD",
>  					       "FETCH_HEAD", summary_width);
> +			}
>  			if (note.len) {
>  				if (verbosity >= 0 && !shown_url) {
>  					fprintf(stderr, _("From %.*s\n"),
> diff --git a/t/t0410-partial-clone.sh b/t/t0410-partial-clone.sh
> index d681e90640..584a039b85 100755
> --- a/t/t0410-partial-clone.sh
> +++ b/t/t0410-partial-clone.sh
> @@ -183,7 +183,7 @@ test_expect_success 'missing CLI object, but promised, passes fsck' '
>  '
>  
>  test_expect_success 'fetching of missing objects' '
> -	rm -rf repo &&
> +	rm -rf repo err &&
>  	test_create_repo server &&
>  	test_commit -C server foo &&
>  	git -C server repack -a -d --write-bitmap-index &&
> @@ -194,7 +194,10 @@ test_expect_success 'fetching of missing objects' '
>  
>  	git -C repo config core.repositoryformatversion 1 &&
>  	git -C repo config extensions.partialclone "origin" &&
> -	git -C repo cat-file -p "$HASH" &&
> +	git -C repo cat-file -p "$HASH" 2>err &&
> +
> +	# Ensure that no spurious FETCH_HEAD messages are written
> +	! grep FETCH_HEAD err &&

This test feels very specific to the bug being addressed.  That said,
since we *also* have a test below for the generic behavior I don't mind.

>  
>  	# Ensure that the .promisor file is written, and check that its
>  	# associated packfile contains the object
> diff --git a/t/t5510-fetch.sh b/t/t5510-fetch.sh
> index 2a1abe91f0..759aec9305 100755
> --- a/t/t5510-fetch.sh
> +++ b/t/t5510-fetch.sh
> @@ -543,16 +543,18 @@ test_expect_success 'fetch into the current branch with --update-head-ok' '
>  
>  '
>  
> -test_expect_success 'fetch --dry-run does not touch FETCH_HEAD' '
> -	rm -f .git/FETCH_HEAD &&
> -	git fetch --dry-run . &&
> -	! test -f .git/FETCH_HEAD
> +test_expect_success 'fetch --dry-run does not touch FETCH_HEAD, but still prints what would be written' '
> +	rm -f .git/FETCH_HEAD err &&
> +	git fetch --dry-run . 2>err &&
> +	! test -f .git/FETCH_HEAD &&
> +	grep FETCH_HEAD err
>  '
>  
> -test_expect_success '--no-write-fetch-head does not touch FETCH_HEAD' '
> -	rm -f .git/FETCH_HEAD &&
> -	git fetch --no-write-fetch-head . &&
> -	! test -f .git/FETCH_HEAD
> +test_expect_success '--no-write-fetch-head does not touch FETCH_HEAD, and does not print what would be written' '
> +	rm -f .git/FETCH_HEAD err &&
> +	git fetch --no-write-fetch-head . 2>err &&
> +	! test -f .git/FETCH_HEAD &&
> +	! grep FETCH_HEAD err

Nice.

With or without the following squashed in,
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>

diff --git i/builtin/fetch.c w/builtin/fetch.c
index c6c46892503..387eeb1ec08 100644
--- i/builtin/fetch.c
+++ w/builtin/fetch.c
@@ -1025,9 +1025,9 @@ static int store_updated_refs(const char *raw_url, const char *remote_name,
 				free(ref);
 			} else if (write_fetch_head || dry_run) {
 				/*
-				 * Display fetches written to FETCH_HEAD (or
-				 * would be written to FETCH_HEAD, if --dry-run
-				 * is set).
+				 * Display fetches that wrote to FETCH_HEAD (or,
+				 * if --dry-run is set, that would write to
+				 * FETCH_HEAD).
 				 */
 				format_display(&note, '*',
 					       *kind ? kind : "branch", NULL,