#include <wchar.h>
#include <string.h>
#include <assert.h>
#include <stdio.h>
#include <locale.h>

static void check(char *s, int exp_ret)
{
	wchar_t res;
	size_t ret;

	ret = mbrtowc(&res, s, strlen(s) + 1, NULL);
	if (ret != exp_ret)
		fprintf(stderr, "got %d, expected %d\n", ret, exp_ret);
	assert(ret == exp_ret);
	if (ret != -1)
		printf("converted %d byte(s) at start of '%s' to %x\n", ret, s, res);
}

int main(int argc, char **argv)
{
	setlocale(LC_CTYPE, "de_DE.UTF-8");

	check("\xc3\xb6", 2);
	// this is an invalid utf-8 sequence, since it expands to
	// U+2f43580
	check("\xfa\xbd\x83\x96\x80", -1);
}