Subject: Re: [PATCH] line-log: suppress diff output with "-s"

From: Jeff King <[email-masked]>
Date: Mon, 25 Feb 2019 13:55:19 -0500

On Mon, Feb 25, 2019 at 06:59:18PM +0100, SZEDER Gábor wrote:

> On Mon, Feb 25, 2019 at 12:32:49PM -0500, Jeff King wrote:
> > diff --git a/line-log.c b/line-log.c
> > index 24e21731c4..863f5cbe0f 100644
> > --- a/line-log.c
> > +++ b/line-log.c
> > @@ -1106,7 +1106,8 @@ int line_log_print(struct rev_info *rev, struct commit *commit)
> >  	struct line_log_data *range = lookup_line_range(rev, commit);
> 
> Note that the result of this lookup_line_range() call is only used
> when we do show the diff below; if we don't, there is no use calling
> it.

Thanks. I think sometimes we can depend on an optimizing compiler to
delay the initialization until use, but in this case the function call
is much too complex to be reordered. Here's a v2 which bumps it down.

-- >8 --
Subject: [PATCH v2] line-log: suppress diff output with "-s"

When "-L" is in use, we ignore any diff output format that the user
provides to us, and just always print a patch (with extra context lines
covering the whole area of interest). It's not entirely clear what we
should do with all formats (e.g., should "--stat" show just the diffstat
of the touched lines, or the stat for the whole file?).

But "-s" is pretty clear: the user probably wants to see just the
commits that touched those lines, without any diff at all. Let's at
least make that work.

Signed-off-by: Jeff King <[email-masked]>
---
 line-log.c          | 6 ++++--
 t/t4211-line-log.sh | 7 +++++++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/line-log.c b/line-log.c
index 24e21731c4..59248e37cc 100644
--- a/line-log.c
+++ b/line-log.c
@@ -1103,10 +1103,12 @@ static int process_all_files(struct line_log_data **range_out,
 
 int line_log_print(struct rev_info *rev, struct commit *commit)
 {
-	struct line_log_data *range = lookup_line_range(rev, commit);
 
 	show_log(rev);
-	dump_diff_hacky(rev, range);
+	if (!(rev->diffopt.output_format & DIFF_FORMAT_NO_OUTPUT)) {
+		struct line_log_data *range = lookup_line_range(rev, commit);
+		dump_diff_hacky(rev, range);
+	}
 	return 1;
 }
 
diff --git a/t/t4211-line-log.sh b/t/t4211-line-log.sh
index bd5fe4d148..c9f2036f68 100755
--- a/t/t4211-line-log.sh
+++ b/t/t4211-line-log.sh
@@ -115,4 +115,11 @@ test_expect_success 'range_set_union' '
 	git log $(for x in $(test_seq 200); do echo -L $((2*x)),+1:c.c; done)
 '
 
+test_expect_success '-s shows only line-log commits' '
+	git log --format="commit %s" -L1,24:b.c >expect.raw &&
+	grep ^commit expect.raw >expect &&
+	git log --format="commit %s" -L1,24:b.c -s >actual &&
+	test_cmp expect actual
+'
+
 test_done
-- 
2.21.0.674.ga8a7ac9a24