[PATCH v4 0/7] commit-graph: usage fixes

A re-roll of v3 which should fix all outstanding issues & feedback. Thanks SZEDER & Taylor: https://lore.kernel.org/git/cover-0.6-00000000000-20210720T113707Z-avarab@gmail.com/

I dropped this myself because per https://lore.kernel.org/git/87im14unfd.fsf@evledraar.gmail.com/ I was under the impression that Taylor was intending to pick up these patches as part of some more generale usage() fixes of his (which also touched multi-pack-index.c), but his recent changes to fix multi-pack-index.c didn't pick this up, so here it is as a re-roll instead.

Ævar Arnfjörð Bjarmason (7):
  commit-graph: define common usage with a macro
  commit-graph: remove redundant handling of -h
  commit-graph: use parse_options_concat()
  multi-pack-index: refactor "goto usage" pattern
  commit-graph: early exit to "usage" on !argc
  commit-graph: show usage on "commit-graph [write|verify] garbage"
  commit-graph: show "unexpected subcommand" error

 builtin/commit-graph.c     | 90 +++++++++++++++++++++-----------------
 builtin/multi-pack-index.c | 11 +++--
 t/t5318-commit-graph.sh    | 19 ++++++++
 3 files changed, 74 insertions(+), 46 deletions(-)

Range-diff against v3:
1:  1b9b4703ce2 = 1:  ef37a8243c8 commit-graph: define common usage with a macro
2:  8f50750ae5e = 2:  bbed18ff193 commit-graph: remove redundant handling of -h
3:  f02da994363 = 3:  32cc0d1c7bc commit-graph: use parse_options_concat()
4:  6e9bd877866 ! 4:  087f98bbec6 multi-pack-index: refactor "goto usage" pattern
    @@ Commit message
     
         Refactor the "goto usage" pattern added in
         cd57bc41bbc (builtin/multi-pack-index.c: display usage on unrecognized
    -    command, 2021-03-30) to maintain the same brevity, but doesn't run
    -    afoul of the recommendation in CodingGuidelines about braces:
    +    command, 2021-03-30) and 88617d11f9d (multi-pack-index: fix potential
    +    segfault without sub-command, 2021-07-19) to maintain the same
    +    brevity, but in a form that doesn't run afoul of the recommendation in
    +    CodingGuidelines about braces:
     
             When there are multiple arms to a conditional and some of them
             require braces, enclose even a single line block in braces for
    @@ builtin/multi-pack-index.c: int cmd_multi_pack_index(int argc, const char **argv
      	else if (!strcmp(argv[0], "expire"))
      		return cmd_multi_pack_index_expire(argc, argv);
     -	else {
    +-		error(_("unrecognized subcommand: %s"), argv[0]);
     +
    ++	error(_("unrecognized subcommand: %s"), argv[0]);
      usage:
    --		error(_("unrecognized subcommand: %s"), argv[0]);
     -		usage_with_options(builtin_multi_pack_index_usage,
     -				   builtin_multi_pack_index_options);
     -	}
    -+	error(_("unrecognized subcommand: %s"), argv[0]);
     +	usage_with_options(builtin_multi_pack_index_usage,
     +			   builtin_multi_pack_index_options);
      }
5:  7acb4bd75ce = 5:  2983e16ba69 commit-graph: early exit to "usage" on !argc
6:  5c1694e071e ! 6:  85552a6f88c commit-graph: show usage on "commit-graph [write|verify] garbage"
    @@ Metadata
      ## Commit message ##
         commit-graph: show usage on "commit-graph [write|verify] garbage"
     
    -    Change the parse_options() invocation in the commit-graph code to make
    -    sense. We're calling it twice, once for common options parsing, and
    -    then for the sub-commands.
    +    Change the parse_options() invocation in the commit-graph code to
    +    error on unknown leftover argv elements, in addition to the existing
    +    and implicit erroring via parse_options() on unknown options.
     
    -    But we never checked if we had something leftover in argc in "write"
    -    or "verify", as a result we'd silently accept garbage in these
    -    subcommands. Let's not do that.
    +    We'd already error in cmd_commit_graph() on e.g.:
    +
    +        git commit-graph unknown verify
    +        git commit-graph --unknown verify
    +
    +    But here we're calling parse_options() twice more for the "write" and
    +    "verify" subcommands. We did not do the same checking for leftover
    +    argv elements there. As a result we'd silently accept garbage in these
    +    subcommands, let's not do that.
     
         Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## builtin/commit-graph.c ##
     @@ builtin/commit-graph.c: static int graph_verify(int argc, const char **argv)
    - 	opts.progress = isatty(2);
      	argc = parse_options(argc, argv, NULL,
      			     options,
    --			     builtin_commit_graph_verify_usage, 0);
    -+			     builtin_commit_graph_verify_usage,
    -+			     PARSE_OPT_KEEP_UNKNOWN);
    + 			     builtin_commit_graph_verify_usage, 0);
     +	if (argc)
     +		usage_with_options(builtin_commit_graph_verify_usage, options);
      
      	if (!opts.obj_dir)
      		opts.obj_dir = get_object_directory();
     @@ builtin/commit-graph.c: static int graph_write(int argc, const char **argv)
    - 
      	argc = parse_options(argc, argv, NULL,
      			     options,
    --			     builtin_commit_graph_write_usage, 0);
    -+			     builtin_commit_graph_write_usage,
    -+			     PARSE_OPT_KEEP_UNKNOWN);
    + 			     builtin_commit_graph_write_usage, 0);
     +	if (argc)
     +		usage_with_options(builtin_commit_graph_write_usage, options);
      
-:  ----------- > 7:  962521cfa17 commit-graph: show "unexpected subcommand" error