parse-options: add precision handling for PARSE_OPT_CMDMODE

Build on 09705696f7 (parse-options: introduce precision handling for
`OPTION_INTEGER`, 2025-04-17) to support value variables of different
sizes for PARSE_OPT_CMDMODE options.  Do that by requiring their
"precision" to be set and casting their "value" pointer accordingly.

Call the function that does the raw casting do_get_int_value() to
reserve the name get_int_value() for a more friendly wrapper we're
going to introduce in one of the next patches.

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

builtin/am.c

@@ -2406,6 +2406,7 @@ int cmd_am(int argc,
 			.type = OPTION_CALLBACK,
 			.long_name = "show-current-patch",
 			.value = &resume_mode,
+			.precision = sizeof(resume_mode),
 			.argh = "(diff|raw)",
 			.help = N_("show the patch being applied"),
 			.flags = PARSE_OPT_CMDMODE | PARSE_OPT_OPTARG | PARSE_OPT_NONEG | PARSE_OPT_LITERAL_ARGHELP,

parse-options.c

@@ -68,6 +68,26 @@ static char *fix_filename(const char *prefix, const char *file)
 		return prefix_filename_except_for_dash(prefix, file);
 }
 
+static int do_get_int_value(const void *value, size_t precision, intmax_t *ret)
+{
+	switch (precision) {
+	case sizeof(int8_t):
+		*ret = *(int8_t *)value;
+		return 0;
+	case sizeof(int16_t):
+		*ret = *(int16_t *)value;
+		return 0;
+	case sizeof(int32_t):
+		*ret = *(int32_t *)value;
+		return 0;
+	case sizeof(int64_t):
+		*ret = *(int64_t *)value;
+		return 0;
+	default:
+		return -1;
+	}
+}
+
 static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 					  const struct option *opt,
 					  enum opt_parsed flags,
@@ -266,7 +286,9 @@ static enum parse_opt_result do_get_value(struct parse_opt_ctx_t *p,
 }
 
 struct parse_opt_cmdmode_list {
-	int value, *value_ptr;
+	intmax_t value;
+	void *value_ptr;
+	size_t precision;
 	const struct option *opt;
 	const char *arg;
 	enum opt_parsed flags;
@@ -280,7 +302,7 @@ static void build_cmdmode_list(struct parse_opt_ctx_t *ctx,
 
 	for (; opts->type != OPTION_END; opts++) {
 		struct parse_opt_cmdmode_list *elem = ctx->cmdmode_list;
-		int *value_ptr = opts->value;
+		void *value_ptr = opts->value;
 
 		if (!(opts->flags & PARSE_OPT_CMDMODE) || !value_ptr)
 			continue;
@@ -292,10 +314,13 @@ static void build_cmdmode_list(struct parse_opt_ctx_t *ctx,
 
 		CALLOC_ARRAY(elem, 1);
 		elem->value_ptr = value_ptr;
-		elem->value = *value_ptr;
+		elem->precision = opts->precision;
+		if (do_get_int_value(value_ptr, opts->precision, &elem->value))
+			optbug(opts, "has invalid precision");
 		elem->next = ctx->cmdmode_list;
 		ctx->cmdmode_list = elem;
 	}
+	BUG_if_bug("invalid 'struct option'");
 }
 
 static char *optnamearg(const struct option *opt, const char *arg,
@@ -317,7 +342,13 @@ static enum parse_opt_result get_value(struct parse_opt_ctx_t *p,
 	char *opt_name, *other_opt_name;
 
 	for (; elem; elem = elem->next) {
-		if (*elem->value_ptr == elem->value)
+		intmax_t new_value;
+
+		if (do_get_int_value(elem->value_ptr, elem->precision,
+				     &new_value))
+			BUG("impossible: invalid precision");
+
+		if (new_value == elem->value)
 			continue;
 
 		if (elem->opt &&
@@ -327,7 +358,7 @@ static enum parse_opt_result get_value(struct parse_opt_ctx_t *p,
 		elem->opt = opt;
 		elem->arg = arg;
 		elem->flags = flags;
-		elem->value = *elem->value_ptr;
+		elem->value = new_value;
 	}
 
 	if (result || !elem)

parse-options.h

@@ -269,6 +269,7 @@ struct option {
 	.short_name = (s), \
 	.long_name = (l), \
 	.value = (v), \
+	.precision = sizeof(*v), \
 	.help = (h), \
 	.flags = PARSE_OPT_CMDMODE|PARSE_OPT_NOARG|PARSE_OPT_NONEG | (f), \
 	.defval = (i), \

t/helper/test-parse-options.c

@@ -148,9 +148,16 @@ int cmd__parse_options(int argc, const char **argv)
 		OPT_SET_INT(0, "set23", &integer, "set integer to 23", 23),
 		OPT_CMDMODE(0, "mode1", &integer, "set integer to 1 (cmdmode option)", 1),
 		OPT_CMDMODE(0, "mode2", &integer, "set integer to 2 (cmdmode option)", 2),
-		OPT_CALLBACK_F(0, "mode34", &integer, "(3|4)",
-			"set integer to 3 or 4 (cmdmode option)",
-			PARSE_OPT_CMDMODE, mode34_callback),
+		{
+			.type = OPTION_CALLBACK,
+			.long_name = "mode34",
+			.value = &integer,
+			.precision = sizeof(integer),
+			.argh = "(3|4)",
+			.help = "set integer to 3 or 4 (cmdmode option)",
+			.flags = PARSE_OPT_CMDMODE,
+			.callback = mode34_callback,
+		},
 		OPT_CALLBACK('L', "length", &integer, "str",
 			"get length of <str>", length_callback),
 		OPT_FILENAME('F', "file", &file, "set file to <file>"),