[PATCH v2 0/5] help: fix usage nits & bugs, completion shellscript->C

This series fixes various bugs & edge cases in the "git help" command, and improves and splits the internal-only "--completion-for-config" option into two, and as a result can get rid of an awk/sort -u pipeline in the bash completion.

For v1, see : https://lore.kernel.org/git/cover-0.6-00000000000-20210908T151949Z-avarab@gmail.com/

This should address all the feedback on v1 and more. I dropped the 4/6 refactoring change, we now also specifically say what option combinations are bad before emitting usage info, as requested by Eric Sunshine.

Ævar Arnfjörð Bjarmason (5):
  help: correct the usage string in -h and documentation
  help: correct usage & behavior of "git help --guides"
  help tests: add test for --config output
  help: correct logic error in combining --all and --config
  help / completion: make "git help" do the hard work

 Documentation/git-help.txt             |   9 +-
 builtin/help.c                         | 110 ++++++++++++++++++-------
 contrib/completion/git-completion.bash |  21 +++--
 t/t0012-help.sh                        |  46 +++++++++++
 4 files changed, 140 insertions(+), 46 deletions(-)

Range-diff against v1:
1:  b5c79d87847 = 1:  b10bfd21f14 help: correct the usage string in -h and documentation
2:  1ebd443e43c ! 2:  039639a0dd3 help: correct usage string for "git help --guides"
    @@ Metadata
     Author: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## Commit message ##
    -    help: correct usage string for "git help --guides"
    +    help: correct usage & behavior of "git help --guides"
     
         As noted in 65f98358c0c (builtin/help.c: add --guide option,
         2013-04-02) and a133737b809 (doc: include --guide option description
    @@ Commit message
         argument we'll now error out.
     
         The comment being removed was added in 15f7d494380 (builtin/help.c:
    -    split "-a" processing into two, 2013-04-02) and is no longer
    -    applicable as explained above.
    +    split "-a" processing into two, 2013-04-02). The "Ignore any remaining
    +    args" part of it is now no longer applicable as explained above, let's
    +    just remove it entirely, it's rather obvious that if we're returning
    +    we're done.
     
         Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
    @@ builtin/help.c: static struct option builtin_help_options[] = {
      };
      
     @@ builtin/help.c: int cmd_help(int argc, const char **argv, const char *prefix)
    - 	int nongit;
    - 	enum help_format parsed_help_format;
    - 	const char *page;
    -+	int standalone = 0;
    - 
    - 	argc = parse_options(argc, argv, prefix, builtin_help_options,
      			builtin_help_usage, 0);
      	parsed_help_format = help_format;
      
     +	/* Options that take no further arguments */
    -+	standalone = show_config || show_guides;
    -+	if (standalone && argc)
    -+		usage_with_options(builtin_help_usage, builtin_help_options);
    ++	if (argc && show_guides)
    ++		usage_msg_opt(_("--guides cannot be combined with other options"),
    ++			      builtin_help_usage, builtin_help_options);
     +
      	if (show_all) {
      		git_config(git_help_config, NULL);
      		if (verbose) {
     @@ builtin/help.c: int cmd_help(int argc, const char **argv, const char *prefix)
    - 	if (show_guides)
    - 		list_guides_help();
      
    --	if (show_all || show_guides) {
    -+	if (show_all || standalone) {
    + 	if (show_all || show_guides) {
      		printf("%s\n", _(git_more_info_string));
     -		/*
     -		* We're done. Ignore any remaining args
    @@ t/t0012-help.sh: test_expect_success 'basic help commands' '
      '
      
     +test_expect_success 'invalid usage' '
    -+	test_expect_code 129 git help -c git-add &&
     +	test_expect_code 129 git help -g git-add
     +'
     +
3:  d0a8045c9ed = 3:  258282095de help tests: add test for --config output
4:  e4bc7e57a6d < -:  ----------- help: refactor "for_human" control flow in cmd_help()
5:  bcc640d32a1 ! 4:  32d73d5273c help: correct logic error in combining --all and --config
    @@ builtin/help.c: static const char * const builtin_help_usage[] = {
      };
      
     @@ builtin/help.c: int cmd_help(int argc, const char **argv, const char *prefix)
    + 	int nongit;
      	enum help_format parsed_help_format;
      	const char *page;
    - 	int standalone = 0;
     +	int need_config = 0;
      
      	argc = parse_options(argc, argv, prefix, builtin_help_options,
    @@ builtin/help.c: int cmd_help(int argc, const char **argv, const char *prefix)
      	parsed_help_format = help_format;
      
     +	/* Incompatible options */
    -+	if (show_all + !!show_config + show_guides > 1)
    -+		usage_with_options(builtin_help_usage, builtin_help_options);
    ++	if (show_all && show_config)
    ++		usage_msg_opt(_("--config and --all cannot be combined"),
    ++			      builtin_help_usage, builtin_help_options);
    ++
    ++	if (show_config && show_guides)
    ++		usage_msg_opt(_("--config and --guides cannot be combined"),
    ++			      builtin_help_usage, builtin_help_options);
     +
      	/* Options that take no further arguments */
    - 	standalone = show_config || show_guides;
    - 	if (standalone && argc)
    - 		usage_with_options(builtin_help_usage, builtin_help_options);
    ++	if (argc && show_config)
    ++		usage_msg_opt(_("--config cannot be combined with command or guide names"),
    ++			      builtin_help_usage, builtin_help_options);
    + 	if (argc && show_guides)
    +-		usage_msg_opt(_("--guides cannot be combined with other options"),
    ++		usage_msg_opt(_("--guides cannot be combined with command or guide names"),
    + 			      builtin_help_usage, builtin_help_options);
      
     -	if (show_all) {
     +	need_config = show_all || show_config;
    @@ builtin/help.c: int cmd_help(int argc, const char **argv, const char *prefix)
     -	if (show_guides)
     -		list_guides_help();
     -
    --	if (show_all || standalone) {
    +-	if (show_all || show_guides) {
     -		printf("%s\n", _(git_more_info_string));
     -		return 0;
     -	}
    @@ builtin/help.c: int cmd_help(int argc, const char **argv, const char *prefix)
     
      ## t/t0012-help.sh ##
     @@ t/t0012-help.sh: test_expect_success 'basic help commands' '
    + '
      
      test_expect_success 'invalid usage' '
    - 	test_expect_code 129 git help -c git-add &&
     -	test_expect_code 129 git help -g git-add
     +	test_expect_code 129 git help -g git-add &&
    ++	test_expect_code 129 git help -c git-add &&
    ++	test_expect_code 129 git help -g git-add &&
     +
     +	test_expect_code 129 git help -a -c &&
     +	test_expect_code 129 git help -g -c
6:  940061e84d1 ! 5:  e995a42cb8d help / completion: make "git help" do the hard work
    @@ builtin/help.c: int cmd_help(int argc, const char **argv, const char *prefix)
      
     -	if (show_config) {
     -		int for_human = show_config == 1;
    --
    --		if (for_human)
    --			setup_pager();
    --		list_config_help(for_human);
    --		if (for_human)
     +	switch (show_config) {
     +	case SHOW_CONFIG_UNSET:
     +		break;
    -+	case SHOW_CONFIG_HUMAN:
    -+		setup_pager();
    -+		/* fallthrough */
     +	case SHOW_CONFIG_VARS:
     +	case SHOW_CONFIG_SECTIONS:
     +		list_config_help(show_config);
    -+		if (show_config == SHOW_CONFIG_HUMAN)
    - 			printf("\n%s\n", _("'git help config' for more information"));
      
    +-		if (!for_human) {
    +-			list_config_help(for_human);
    +-			return 0;
    +-		}
    ++		return 0;
    ++	case SHOW_CONFIG_HUMAN:
    + 		setup_pager();
    +-		list_config_help(for_human);
    ++		list_config_help(show_config);
    + 		printf("\n%s\n", _("'git help config' for more information"));
    ++
      		return 0;
    + 	}
    + 
     
      ## contrib/completion/git-completion.bash ##
     @@ contrib/completion/git-completion.bash: __git_config_vars=