cli: use designated initializers for opt desc

Several changes at once, just to not have to change the same lines
several times over:

- Use designated initializers to initialize opt desc arrays.

- Only initialize the needed fields.

- Remove arg_id (short options) as unused.

- Replace opt_type and output_var with several type safe output
  variables, where the output variable being non-NULL determines the
  type. Introduce checks to ensure only one is set. The downside is
  some waste of const space per argument; this could be saved by
  retaining opt_type and using a union, but that's still pretty
  verbose.

- Fix some variables due to the type safety. Mostly a good thing, but
  leads to some enums being changed to ints. This is pedantically
  correct, but somewhat annoying. We could also cast, but that defeats
  the purpose a bit.

- Terminate the opt desc arrays using {}.

The output variable type safety and the ability to add new fields for
just some output types or arguments are the big wins. For example, if
we wanted to add a variable to set when the argument is present, we
could do so for just the arguments that need it.

Beauty is in the eye of the beholder, but I think this looks nice when
defining the arguments, and reduces some of the verbosity we have
there.

1 files changed, 5 insertions, 5 deletions

diff --git a/test/hex-xcode.c b/test/hex-xcode.c
index 65d49564..bc2df713 100644
--- a/test/hex-xcode.c
+++ b/test/hex-xcode.c
@@ -44,17 +44,17 @@ int
 main (int argc, char **argv)
 {
 
-    enum direction dir = DECODE;
+    int dir = DECODE;
     int omit_newline = FALSE;
 
     notmuch_opt_desc_t options[] = {
-	{ NOTMUCH_OPT_KEYWORD, &dir, "direction", 'd',
+	{ .opt_keyword = &dir, .name = "direction", .keywords =
 	  (notmuch_keyword_t []){ { "encode", ENCODE },
 				  { "decode", DECODE },
 				  { 0, 0 } } },
-	{ NOTMUCH_OPT_BOOLEAN, &omit_newline, "omit-newline", 'n', 0 },
-	{ NOTMUCH_OPT_BOOLEAN, &inplace, "in-place", 'i', 0 },
-	{ 0, 0, 0, 0, 0 }
+	{ .opt_bool = &omit_newline, .name = "omit-newline" },
+	{ .opt_bool = &inplace, .name = "in-place" },
+	{ }
     };
 
     int opt_index = parse_arguments (argc, argv, options, 1);