parse-options: add precision handling for OPTION_BITOP

Similar to 0970569 (parse-options: introduce precision handling for
`OPTION_INTEGER`, 2025-04-17) support value variables of different sizes
for OPTION_BITOP.  Do that by requiring their "precision" to be set,
casting their "value" pointer accordingly and checking whether the value
fits.

Check if "devfal" fits into an integer variable with the given
"precision", but don't check "extra", as its value is only used to clear
bits, so cannot lead to an overflow.  Not checking continues to allow
e.g., using -1 to clear all bits even if the value variable has a
narrower type than intptr_t.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: rscharfe

parse-options.c

@@ -167,11 +167,14 @@ static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 	}
 
 	case OPTION_BITOP:
+	{
+		intmax_t value = get_int_value(opt, flags);
 		if (unset)
 			BUG("BITOP can't have unset form");
-		*(int *)opt->value &= ~opt->extra;
-		*(int *)opt->value |= opt->defval;
-		return 0;
+		value &= ~opt->extra;
+		value |= opt->defval;
+		return set_int_value(opt, flags, value);
+	}
 
 	case OPTION_COUNTUP:
 		if (*(int *)opt->value < 0)
@@ -647,12 +650,12 @@ static void parse_options_check(const struct option *opts)
 		case OPTION_SET_INT:
 		case OPTION_BIT:
 		case OPTION_NEGBIT:
+		case OPTION_BITOP:
 			if (!signed_int_fits(opts->defval, opts->precision))
 				optbug(opts, "has invalid defval");
 			/* fallthru */
 		case OPTION_COUNTUP:
 		case OPTION_NUMBER:
-		case OPTION_BITOP:
 			if ((opts->flags & PARSE_OPT_OPTARG) ||
 			    !(opts->flags & PARSE_OPT_NOARG))
 				optbug(opts, "should not accept an argument");

parse-options.h

@@ -240,6 +240,7 @@ struct option {
 	.short_name = (s), \
 	.long_name = (l), \
 	.value = (v), \
+	.precision = sizeof(*v), \
 	.help = (h), \
 	.flags = PARSE_OPT_NOARG|PARSE_OPT_NONEG, \
 	.defval = (set), \