Re: [PATCH 04/10] parse-options.c: use exhaustive "case" arms for "enum parse_opt_type"

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 29, 2021, 15:14 UTC
Message-ID: <xmqq7dezfm7m.fsf@gitster.g>
In-Reply-To: <87tui3vk8y.fsf@evledraar.gmail.com>

Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:

> I think listing the remaining enum arms is a small price to pay for
> having that all moved to compile-time.

I can sympathize with that point of view, since I used to think the same way, but I am not yet convinced. An example like this from your postimage, which doubles the size of a switch statement with empty case arms, demonstrates that it is not a "small" price.

Admittedly, the original switch statement is particularly bad, though ;-)

 		switch (opts->type) {
 		case OPTION_STRING:
 		case OPTION_FILENAME:
 		case OPTION_INTEGER:
 		case OPTION_MAGNITUDE:
 		case OPTION_CALLBACK:
 		case OPTION_BIT:
 		case OPTION_NEGBIT:
 		case OPTION_COUNTUP:
 		case OPTION_SET_INT:
 			has_unset_form = 1;
 			break;
-		default:
+		/* special types */
+		case OPTION_END:
+		case OPTION_GROUP:
+		case OPTION_NUMBER:
+		case OPTION_ALIAS:
+		/* options with no arguments */
+		case OPTION_BITOP:
+		/* options with arguments (usually) */
+		case OPTION_LOWLEVEL_CALLBACK:
 			break;
 		}