Subject: Re: [PATCH 3/5] commit-graph: use parse_options_concat()

From: Ævar Arnfjörð Bjarmason <[email-masked]>
Date: Mon, 15 Feb 2021 21:39:11 +0100

On Mon, Feb 15 2021, Taylor Blau wrote:

> On Mon, Feb 15, 2021 at 07:41:16PM +0100, Ævar Arnfjörð Bjarmason wrote:
>> Make use of the parse_options_concat() so we don't need to copy/paste
>> common options like --object-dir. This is inspired by a similar change
>> to "checkout" in 2087182272
>> (checkout: split options[] array in three pieces, 2019-03-29).
>>
>> A minor behavior change here is that now we're going to list both
>> --object-dir and --progress first, before we'd list --progress along
>> with other options.
>
> "Behavior change" referring only to the output of `git commit-graph -h`,
> no?
>
> Looking at the code (and understanding this whole situation a little bit
> better), I'd think that this wouldn't cause us to parse anything
> differently before or after this change, right?

Indeed, I just mean the "-h" or "--invalid-opt" output changed in the
order we show the options in.

>> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
>> ---
>>  builtin/commit-graph.c | 43 ++++++++++++++++++++++++------------------
>>  1 file changed, 25 insertions(+), 18 deletions(-)
>>
>> diff --git a/builtin/commit-graph.c b/builtin/commit-graph.c
>> index baead04a03..a7718b2025 100644
>> --- a/builtin/commit-graph.c
>> +++ b/builtin/commit-graph.c
>> @@ -44,6 +44,21 @@ static struct opts_commit_graph {
>>  	int enable_changed_paths;
>>  } opts;
>>
>> +static struct option *add_common_options(struct option *prevopts)
>> +{
>> +	struct option options[] = {
>> +		OPT_STRING(0, "object-dir", &opts.obj_dir,
>> +			   N_("dir"),
>> +			   N_("the object directory to store the graph")),
>> +		OPT_BOOL(0, "progress", &opts.progress,
>> +			 N_("force progress reporting")),
>> +		OPT_END()
>> +	};
>
> I'm nitpicking, but I wouldn't be sad to see this called "common"
> instead".
>
> Can't this also be declared statically?

It happens to work now to do that, but try it in builtin/checkout.c and
you'll see it blows up with a wall of "initializer element is not
constant".

Probably better to be consistent in parse_options() usage than make it
safe for that sort of use...

>> +	struct option *newopts = parse_options_concat(options, prevopts);
>> +	free(prevopts);
>> +	return newopts;
>> +}
>> +
>>  static struct object_directory *find_odb(struct repository *r,
>>  					 const char *obj_dir)
>>  {
>> @@ -75,22 +90,20 @@ static int graph_verify(int argc, const char **argv)
>>  	int fd;
>>  	struct stat st;
>>  	int flags = 0;
>> -
>> +	struct option *options = NULL;
>>  	static struct option builtin_commit_graph_verify_options[] = {
>> -		OPT_STRING(0, "object-dir", &opts.obj_dir,
>> -			   N_("dir"),
>> -			   N_("the object directory to store the graph")),
>>  		OPT_BOOL(0, "shallow", &opts.shallow,
>>  			 N_("if the commit-graph is split, only verify the tip file")),
>> -		OPT_BOOL(0, "progress", &opts.progress, N_("force progress reporting")),
>>  		OPT_END(),
>>  	};
>> +	options = parse_options_dup(builtin_commit_graph_verify_options);
>
> Another nitpick, but I'd rather see the initialization of "options" and
> its declaration be on the same line, after declaring
> builtin_commit_graph_verify_options.

As you noted in your own reply "the NULL initialization is important",
or more specifically: We're doing this dance here (and in other existing
code, e.g. checkout.c) to trampoline from the stack ot the heap.

>> +	options = add_common_options(options);
>>
>>  	trace2_cmd_mode("verify");
>>
>>  	opts.progress = isatty(2);
>>  	argc = parse_options(argc, argv, NULL,
>> -			     builtin_commit_graph_verify_options,
>> +			     options,
>>  			     builtin_commit_graph_verify_usage, 0);
>>
>>  	if (!opts.obj_dir)
>> @@ -205,11 +218,8 @@ static int graph_write(int argc, const char **argv)
>>  	int result = 0;
>>  	enum commit_graph_write_flags flags = 0;
>>  	struct progress *progress = NULL;
>> -
>> +	struct option *options = NULL;
>>  	static struct option builtin_commit_graph_write_options[] = {
>> -		OPT_STRING(0, "object-dir", &opts.obj_dir,
>> -			N_("dir"),
>> -			N_("the object directory to store the graph")),
>>  		OPT_BOOL(0, "reachable", &opts.reachable,
>>  			N_("start walk at all refs")),
>>  		OPT_BOOL(0, "stdin-packs", &opts.stdin_packs,
>> @@ -220,7 +230,6 @@ static int graph_write(int argc, const char **argv)
>>  			N_("include all commits already in the commit-graph file")),
>>  		OPT_BOOL(0, "changed-paths", &opts.enable_changed_paths,
>>  			N_("enable computation for changed paths")),
>> -		OPT_BOOL(0, "progress", &opts.progress, N_("force progress reporting")),
>>  		OPT_CALLBACK_F(0, "split", &write_opts.split_flags, NULL,
>>  			N_("allow writing an incremental commit-graph file"),
>>  			PARSE_OPT_OPTARG | PARSE_OPT_NONEG,
>> @@ -236,6 +245,8 @@ static int graph_write(int argc, const char **argv)
>>  			0, write_option_max_new_filters),
>>  		OPT_END(),
>>  	};
>> +	options = parse_options_dup(builtin_commit_graph_write_options);
>> +	options = add_common_options(options);
>>
>>  	opts.progress = isatty(2);
>>  	opts.enable_changed_paths = -1;
>> @@ -249,7 +260,7 @@ static int graph_write(int argc, const char **argv)
>>  	git_config(git_commit_graph_write_config, &opts);
>>
>>  	argc = parse_options(argc, argv, NULL,
>> -			     builtin_commit_graph_write_options,
>> +			     options,
>>  			     builtin_commit_graph_write_usage, 0);
>>
>>  	if (opts.reachable + opts.stdin_packs + opts.stdin_commits > 1)
>> @@ -312,12 +323,8 @@ static int graph_write(int argc, const char **argv)
>>
>>  int cmd_commit_graph(int argc, const char **argv, const char *prefix)
>>  {
>> -	static struct option builtin_commit_graph_options[] = {
>> -		OPT_STRING(0, "object-dir", &opts.obj_dir,
>> -			N_("dir"),
>> -			N_("the object directory to store the graph")),
>> -		OPT_END(),
>> -	};
>> +	struct option *no_options = parse_options_dup(NULL);
>
> Hmm. Why bother calling add_common_options at all here?

I assume you mean in this line just below what you quoted:

    struct option *builtin_commit_graph_options = add_common_options(no_options);

Do you mean why not do the whole thing in graph_{verify,write}() and
only show the usage if we fail here?

Yeah arguably that makes more sense, but I wanted to just focus on
refactoring existing behavior & get rid of the copy/pasted options
rather than start a bigger rewrite of "maybe we shouldn't show this
rather useless help info if we die here....".