Re: [PATCH 2/2] format-patch: don't include --stat with --range-diff output

[Junio C Hamano]

Junio C Hamano  writes:

> Ævar Arnfjörð Bjarmason   writes:
>
>>  if (rev->rdiff1) {
>> +struct diff_options opts;
>> +memcpy(, >diffopt, sizeof(opts));
>> +opts.output_format &= ~(DIFF_FORMAT_DIFFSTAT | 
>> DIFF_FORMAT_SUMMARY);
>> +
>>  fprintf_ln(rev->diffopt.file, "%s", rev->rdiff_title);
>>  show_range_diff(rev->rdiff1, rev->rdiff2,
>> -rev->creation_factor, 1, >diffopt);
>> +rev->creation_factor, 1, );
>
> I am not quite convinced if this shallow copy is a safe thing to do.
> Quite honestly at this late in the release cycle, as a band-aid, I'd
> rather see a simpler revert than a change like this that we have to
> worry about what happens if/when show_range_diff() _thinks_ it is
> done with the opts and ends up discarding resources (e.g. "FILE *")
> that are shared with rev->diffopt that would still have to be used
> later.

Well, let's take it anyway as-is, at least for today, as I notice
show_range_diff() itself does another shallow copy, so we are not
making anything dramatically worse.

Thanks.

Re: [PATCH 2/2] format-patch: don't include --stat with --range-diff output

[Junio C Hamano]

Ævar Arnfjörð Bjarmason   writes:

>   if (rev->rdiff1) {
> + struct diff_options opts;
> + memcpy(, >diffopt, sizeof(opts));
> + opts.output_format &= ~(DIFF_FORMAT_DIFFSTAT | 
> DIFF_FORMAT_SUMMARY);
> +
>   fprintf_ln(rev->diffopt.file, "%s", rev->rdiff_title);
>   show_range_diff(rev->rdiff1, rev->rdiff2,
> - rev->creation_factor, 1, >diffopt);
> + rev->creation_factor, 1, );

I am not quite convinced if this shallow copy is a safe thing to do.
Quite honestly at this late in the release cycle, as a band-aid, I'd
rather see a simpler revert than a change like this that we have to
worry about what happens if/when show_range_diff() _thinks_ it is
done with the opts and ends up discarding resources (e.g. "FILE *")
that are shared with rev->diffopt that would still have to be used
later.

[PATCH 2/2] format-patch: don't include --stat with --range-diff output

[Ævar Arnfjörð Bjarmason]

Fix a regression introduced in my a48e12ef7a ("range-diff: make diff
option behavior (e.g. --stat) consistent", 2018-11-13). Since the
format-patch setup code implicitly sets --stat --summary by default,
we started emitting the --stat output in the cover letter's
range-diff.

As noted in df569c3f31 ("range-diff doc: add a section about output
stability", 2018-11-09) the --stat output is currently rather useless,
and just adds noise.

Perhaps we should detect if --stat or --summary were implicitly passed
to format-patch, and then pass them along, but I think fixing it this
way is fine. If our --stat output ever becomes useful in range-diff we
can revisit this.

There's still cases like e.g. --numstat triggering rather useless
range-diff output, but I think it's OK to just handle the default
case. Users are unlikely to produce a formatted patch with the likes
of --numstat, or indeed any other custom diff option except -U or
maybe -W. If they need weirder combinations of options they can always
manually produce the range-diff.

This whole situation comes about because we're assuming that when the
user passes along e.g. -U10 that they want that some 10-line context
for the range-diff as for the patches themselves. As noted in [1] I
think it's worth re-visiting this and making -U10 just apply to the
patches, and e.g. --range-diff-U10 to the range-diff. But that's left
as a topic for another series less close to a rc2.

1. https://public-inbox.org/git/87d0ri7gbs@evledraar.gmail.com/

Signed-off-by: Ævar Arnfjörð Bjarmason 
---
 builtin/log.c |  7 ++-
 t/t3206-range-diff.sh | 12 
 2 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/builtin/log.c b/builtin/log.c
index 0fe6f9ba1e..7cd2db0be9 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1094,9 +1094,13 @@ static void make_cover_letter(struct rev_info *rev, int 
use_stdout,
}
 
if (rev->rdiff1) {
+   struct diff_options opts;
+   memcpy(, >diffopt, sizeof(opts));
+   opts.output_format &= ~(DIFF_FORMAT_DIFFSTAT | 
DIFF_FORMAT_SUMMARY);
+
fprintf_ln(rev->diffopt.file, "%s", rev->rdiff_title);
show_range_diff(rev->rdiff1, rev->rdiff2,
-   rev->creation_factor, 1, >diffopt);
+   rev->creation_factor, 1, );
}
 }
 
@@ -1697,6 +1701,7 @@ int cmd_format_patch(int argc, const char **argv, const 
char *prefix)
if (!use_patch_format &&
(!rev.diffopt.output_format ||
 rev.diffopt.output_format == DIFF_FORMAT_PATCH))
+   /* Needs to be mirrored in show_range_diff() invocation */
rev.diffopt.output_format = DIFF_FORMAT_DIFFSTAT | 
DIFF_FORMAT_SUMMARY;
if (!rev.diffopt.stat_width)
rev.diffopt.stat_width = MAIL_DEFAULT_WRAP;
diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
index 0235c038be..90def330bd 100755
--- a/t/t3206-range-diff.sh
+++ b/t/t3206-range-diff.sh
@@ -252,21 +252,9 @@ do
master..unmodified >actual.raw &&
sed -e "s|^:||" -e "s|:$||" >expect <<-\EOF &&
:1:  4de457d = 1:  35b9b25 s/5/A/
-   : a => b | 0
-   : 1 file changed, 0 insertions(+), 0 deletions(-)
-   ::
:2:  fccce22 = 2:  de345ab s/4/A/
-   : a => b | 0
-   : 1 file changed, 0 insertions(+), 0 deletions(-)
-   ::
:3:  147e64e = 3:  9af6654 s/11/B/
-   : a => b | 0
-   : 1 file changed, 0 insertions(+), 0 deletions(-)
-   ::
:4:  a63e992 = 4:  2901f77 s/12/B/
-   : a => b | 0
-   : 1 file changed, 0 insertions(+), 0 deletions(-)
-   ::
:-- :
EOF
sed -ne "/^1:/,/^--/p" actual &&
-- 
2.20.0.rc0.387.gc7a69e6b6c