[PATCH v2] parse-options.c: use "enum parse_opt_result" for parse_nodash_opt()

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

Change the parse_nodash_opt() function to use "enum
parse_opt_result".In 352e761388b (parse-options.[ch]: consistently
use "enum parse_opt_result", 2021-10-08) its only caller
parse_options_step() started using that return type, and the
get_value() which will be called and return from it uses the same
enum.

Let's do the same here so that this function always returns an "enum
parse_opt_result" value.

We could go for either PARSE_OPT_HELP (-2) or PARSE_OPT_ERROR (-1)
here. The reason we ended up with "-2" is that in code added in
07fe54db3cd (parse-opt: do not print errors on unknown options, return
"-2" instead., 2008-06-23) we used that value in a meaningful way.

Then in 51a9949eda7 (parseopt: add PARSE_OPT_NODASH, 2009-05-07) the
use of "-2" was seemingly copy/pasted from parse_long_opt(), which was
the function immediately above the parse_nodash_opt() function added
in that commit.

Since we only care about whether the return value here is non-zero
let's use the more generic PARSE_OPT_ERROR.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---

Now with an updated commit message per the v1 discussion. I peeled off
the 1/2 patch as it's already on "master" as 06a199f38b5
(parse-options.[ch]: revert use of "enum" for parse_options(),
2021-11-09).

Range-diff against v1:
1:  057a9f81b47 < -:  ----------- parse-options.[ch]: revert use of "enum" for parse_options()
2:  aa6224b10f8 ! 1:  376f76bb44e parse-options.c: use "enum parse_opt_result" for parse_nodash_opt()
    @@ Commit message
         parse-options.c: use "enum parse_opt_result" for parse_nodash_opt()
     
         Change the parse_nodash_opt() function to use "enum
    -    parse_opt_result". In 352e761388b (parse-options.[ch]: consistently
    +    parse_opt_result".In 352e761388b (parse-options.[ch]: consistently
         use "enum parse_opt_result", 2021-10-08) its only caller
         parse_options_step() started using that return type, and the
         get_value() which will be called and return from it uses the same
    @@ Commit message
         Let's do the same here so that this function always returns an "enum
         parse_opt_result" value.
     
    +    We could go for either PARSE_OPT_HELP (-2) or PARSE_OPT_ERROR (-1)
    +    here. The reason we ended up with "-2" is that in code added in
    +    07fe54db3cd (parse-opt: do not print errors on unknown options, return
    +    "-2" instead., 2008-06-23) we used that value in a meaningful way.
    +
    +    Then in 51a9949eda7 (parseopt: add PARSE_OPT_NODASH, 2009-05-07) the
    +    use of "-2" was seemingly copy/pasted from parse_long_opt(), which was
    +    the function immediately above the parse_nodash_opt() function added
    +    in that commit.
    +
    +    Since we only care about whether the return value here is non-zero
    +    let's use the more generic PARSE_OPT_ERROR.
    +
         Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
     
      ## parse-options.c ##

 parse-options.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/parse-options.c b/parse-options.c
index fc5b43ff0b2..629e7963497 100644
--- a/parse-options.c
+++ b/parse-options.c
@@ -404,8 +404,9 @@ static enum parse_opt_result parse_long_opt(
 	return PARSE_OPT_UNKNOWN;
 }
 
-static int parse_nodash_opt(struct parse_opt_ctx_t *p, const char *arg,
-			    const struct option *options)
+static enum parse_opt_result parse_nodash_opt(struct parse_opt_ctx_t *p,
+					      const char *arg,
+					      const struct option *options)
 {
 	const struct option *all_opts = options;
 
@@ -415,7 +416,7 @@ static int parse_nodash_opt(struct parse_opt_ctx_t *p, const char *arg,
 		if (options->short_name == arg[0] && arg[1] == '\0')
 			return get_value(p, options, all_opts, OPT_SHORT);
 	}
-	return -2;
+	return PARSE_OPT_ERROR;
 }
 
 static void check_typos(const char *arg, const struct option *options)
-- 
2.34.0.rc1.741.gab7bfd97031