line-log: suppress diff output with "-s"

Commit Message

Jeff King Feb. 25, 2019, 5:32 p.m. UTC

On Mon, Feb 25, 2019 at 12:18:17PM -0500, Jeff King wrote:

> > git log docs suggest it should not do this:
> > 
> >        -s, --no-patch
> >            Suppress diff output. Useful for commands like git show
> > that show the patch by default, or to cancel
> >            the effect of --patch.
> > 
> > Couldn't find anything in a search of the archives of this mailing
> > list, although that's obviously far from conclusive. Seems to be
> > longstanding, as it was mentioned on StackOverflow back in 2015:
> 
> I think the issue is just that "-L" follows a very different code path
> than the normal diff generator. Perhaps something like this helps?

Here it is with a test and a commit message (I don't think any doc
update is necessary; as you noted, the docs already imply this is what
should happen).

-- >8 --
Subject: [PATCH] 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 <[e-mail]>
---
This punts completely on the larger question of what should happen with
other formats like "--stat", "--raw", etc. They'll continue to be
ignored entirely and we'll generate the line-log patch. Possibly we
should detect and complain?

 line-log.c          | 3 ++-
 t/t4211-line-log.sh | 7 +++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

Comments

SZEDER Gábor Feb. 25, 2019, 5:59 p.m. UTC | #1

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.

>  	show_log(rev);
> -	dump_diff_hacky(rev, range);
> +	if (!(rev->diffopt.output_format & DIFF_FORMAT_NO_OUTPUT))
> +		dump_diff_hacky(rev, range);
>  	return 1;
>  }
>

Jeff King Feb. 25, 2019, 6:55 p.m. UTC | #2

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 <[e-mail]>
---
 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

Patch

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);
 
 	show_log(rev);
-	dump_diff_hacky(rev, range);
+	if (!(rev->diffopt.output_format & DIFF_FORMAT_NO_OUTPUT))
+		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