Re: [PATCH 2/2] format-patch: allow for independent diff & range-diff options

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

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Hi Ævar,

On Wed, 28 Nov 2018, Ævar Arnfjörð Bjarmason wrote:

> Change the semantics of the "--range-diff" option so that the regular
> diff options can be provided separately for the range-diff and the
> patch. This allows for supplying e.g. --range-diff-U0 and -U1 to
> "format-patch" to provide different context for the range-diff and the
> patch. This wasn't possible before.

I really, really dislike the `--range-diff-<random-thing>`. We have
precedent for passing optional arguments that are passed to some other
command, so a much more logical and consistent convention would be to use
`--range-diff[=<diff-option>..]`, allowing all of the diff options that
you might want to pass to the outer diff in one go rather than having a
lengthy string of `--range-diff-this` and `--range-diff-that` options.

I only had time to skim the patch, and I have to wonder why you pass
around full-blown `rev_info` structs for range diff (and with that really
awful name `rd_rev`) rather than just the `diff_options` that you
*actually* care about?

Ciao,
Dscho

> 
> Ever since the "--range-diff" option was added in
> 31e2617a5f ("format-patch: add --range-diff option to embed diff in
> cover letter", 2018-07-22) the "rev->diffopt" we pass down to the diff
> machinery has been the one we get from "format-patch"'s own
> setup_revisions().
> 
> This sort of thing is unique among the log-like commands in
> builtin/log.c, no command than format-patch will embed the output of
> another log-like command. Since the "rev->diffopt" is reused we need
> to munge it before we pass it to show_range_diff(). See
> 43dafc4172 ("format-patch: don't include --stat with --range-diff
> output", 2018-11-22) for a related regression fix which is being
> mostly reverted here.
> 
> Implementation notes: 1) We're not bothering with the full teardown
> around die() and will leak memory, but it's too much boilerplate to do
> all the frees with/without the die() and not worth it. 2) We call
> repo_init_revisions() for "rd_rev" even though we could get away with
> a shallow copy like the code we're replacing (and which
> show_range_diff() itself does). This is to make this code more easily
> understood.
> 
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> ---
>  Documentation/git-format-patch.txt | 10 ++++++-
>  builtin/log.c                      | 42 +++++++++++++++++++++++-------
>  t/t3206-range-diff.sh              | 41 +++++++++++++++++++++++++++++
>  3 files changed, 82 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
> index aba4c5febe..6c048f415f 100644
> --- a/Documentation/git-format-patch.txt
> +++ b/Documentation/git-format-patch.txt
> @@ -24,7 +24,8 @@ SYNOPSIS
>  		   [--to=<email>] [--cc=<email>]
>  		   [--[no-]cover-letter] [--quiet] [--notes[=<ref>]]
>  		   [--interdiff=<previous>]
> -		   [--range-diff=<previous> [--creation-factor=<percent>]]
> +		   [--range-diff=<previous> [--creation-factor=<percent>]
> +		      [--range-diff<common diff option>]]
>  		   [--progress]
>  		   [<common diff options>]
>  		   [ <since> | <revision range> ]
> @@ -257,6 +258,13 @@ feeding the result to `git send-email`.
>  	creation/deletion cost fudge factor. See linkgit:git-range-diff[1])
>  	for details.
>  
> +--range-diff<common diff option>::
> +	Other options prefixed with `--range-diff` are stripped of
> +	that prefix and passed as-is to the diff machinery used to
> +	generate the range-diff, e.g. `--range-diff-U0` and
> +	`--range-diff--no-color`. This allows for adjusting the format
> +	of the range-diff independently from the patch itself.
> +
>  --notes[=<ref>]::
>  	Append the notes (see linkgit:git-notes[1]) for the commit
>  	after the three-dash line.
> diff --git a/builtin/log.c b/builtin/log.c
> index 02d88fa233..7658e56ecc 100644
> --- a/builtin/log.c
> +++ b/builtin/log.c
> @@ -1023,7 +1023,8 @@ static void show_diffstat(struct rev_info *rev,
>  	fprintf(rev->diffopt.file, "\n");
>  }
>  
> -static void make_cover_letter(struct rev_info *rev, int use_stdout,
> +static void make_cover_letter(struct rev_info *rev, struct rev_info *rd_rev,
> +			      int use_stdout,
>  			      struct commit *origin,
>  			      int nr, struct commit **list,
>  			      const char *branch_name,
> @@ -1095,13 +1096,9 @@ static void make_cover_letter(struct rev_info *rev, int use_stdout,
>  	}
>  
>  	if (rev->rdiff1) {
> -		struct diff_options opts;
> -		memcpy(&opts, &rev->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, &opts);
> +				rev->creation_factor, 1, &rd_rev->diffopt);
>  	}
>  }
>  
> @@ -1485,6 +1482,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
>  	struct commit *commit;
>  	struct commit **list = NULL;
>  	struct rev_info rev;
> +	struct rev_info rd_rev;
>  	struct setup_revision_opt s_r_opt;
>  	int nr = 0, total, i;
>  	int use_stdout = 0;
> @@ -1603,6 +1601,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
>  	init_log_defaults();
>  	git_config(git_format_config, NULL);
>  	repo_init_revisions(the_repository, &rev, prefix);
> +	repo_init_revisions(the_repository, &rd_rev, prefix);
>  	rev.commit_format = CMIT_FMT_EMAIL;
>  	rev.expand_tabs_in_log_default = 0;
>  	rev.verbose_header = 1;
> @@ -1689,8 +1688,32 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
>  	rev.preserve_subject = keep_subject;
>  
>  	argc = setup_revisions(argc, argv, &rev, &s_r_opt);
> -	if (argc > 1)
> -		die(_("unrecognized argument: %s"), argv[1]);
> +	if (argc > 1) {
> +		struct argv_array args = ARGV_ARRAY_INIT;
> +		const char *prefix = "--range-diff";
> +		int have_prefix = 0;
> +
> +		for (i = 0; i < argc; i++) {
> +			struct strbuf sb = STRBUF_INIT;
> +			char *str;
> +
> +			strbuf_addstr(&sb, argv[i]);
> +			if (starts_with(argv[i], prefix)) {
> +				have_prefix = 1;
> +				strbuf_remove(&sb, 0, strlen(prefix));
> +			}
> +			str = strbuf_detach(&sb, NULL);
> +			strbuf_release(&sb);
> +
> +			argv_array_push(&args, str);
> +		}
> +
> +		if (!have_prefix)
> +			die(_("unrecognized argument: %s"), argv[1]);
> +		argc = setup_revisions(args.argc, args.argv, &rd_rev, NULL);
> +		if (argc > 1)
> +			die(_("unrecognized argument: %s"), argv[1]);
> +	}
>  
>  	if (rev.diffopt.output_format & DIFF_FORMAT_NAME)
>  		die(_("--name-only does not make sense"));
> @@ -1702,7 +1725,6 @@ 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;
> @@ -1877,7 +1899,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
>  	if (cover_letter) {
>  		if (thread)
>  			gen_message_id(&rev, "cover");
> -		make_cover_letter(&rev, use_stdout,
> +		make_cover_letter(&rev, &rd_rev, use_stdout,
>  				  origin, nr, list, branch_name, quiet);
>  		print_bases(&bases, rev.diffopt.file);
>  		print_signature(rev.diffopt.file);
> diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
> index bc5facc1cd..6916103888 100755
> --- a/t/t3206-range-diff.sh
> +++ b/t/t3206-range-diff.sh
> @@ -308,6 +308,35 @@ test_expect_success 'format-patch with <common diff option>' '
>  		--range-diff=topic~..topic changed~..changed >actual.raw &&
>  	sed -ne "/^1:/,/^--/p" <actual.raw >actual.range-diff &&
>  	sed -e "s|:$||" >expect <<-\EOF &&
> +	1:  a63e992 ! 1:  d966c5c s/12/B/
> +	    @@ -8,7 +8,7 @@
> +	     @@
> +	      9
> +	      10
> +	    - B
> +	    + BB
> +	     -12
> +	     +B
> +	      13
> +	-- :
> +	EOF
> +	test_cmp expect actual.range-diff &&
> +	sed -ne "/^--- /,/^--/p" <actual.raw >actual.diff &&
> +	sed -e "s|:$||" >expect <<-\EOF &&
> +	--- a/file
> +	+++ b/file
> +	@@ -12 +12 @@ BB
> +	-12
> +	+B
> +	-- :
> +	EOF
> +	test_cmp expect actual.diff &&
> +
> +	# -U0 & --range-diff-U0
> +	git format-patch --cover-letter --stdout -U0 --range-diff-U0 \
> +		--range-diff=topic~..topic changed~..changed >actual.raw &&
> +	sed -ne "/^1:/,/^--/p" <actual.raw >actual.range-diff &&
> +	sed -e "s|:$||" >expect <<-\EOF &&
>  	1:  a63e992 ! 1:  d966c5c s/12/B/
>  	    @@ -11 +11 @@
>  	    - B
> @@ -327,4 +356,16 @@ test_expect_success 'format-patch with <common diff option>' '
>  	test_cmp expect actual.diff
>  '
>  
> +test_expect_success 'format-patch option parsing with --range-diff-*' '
> +	test_must_fail git format-patch --stdout --unknown \
> +		master..unmodified 2>stderr &&
> +	test_i18ngrep "unrecognized argument: --unknown" stderr &&
> +	test_must_fail git format-patch --stdout --range-diff-unknown \
> +		master..unmodified 2>stderr &&
> +	test_i18ngrep "unrecognized argument: --range-diff-unknown" stderr &&
> +	test_must_fail git format-patch --stdout --unknown --range-diff-unknown \
> +		master..unmodified 2>stderr &&
> +	test_i18ngrep "unrecognized argument: --unknown" stderr
> +'
> +
>  test_done
> -- 
> 2.20.0.rc1.387.gf8505762e3
> 
>