On Mon, May 29, 2023 at 09:00:01PM +0800, Zhangjin Wu wrote:
Compiling nolibc-test.c with gcc on x86_64 got such warning:
tools/testing/selftests/nolibc/nolibc-test.c: In function 'expect_eq': tools/testing/selftests/nolibc/nolibc-test.c:177:24: warning: format '%lld' expects argument of type 'long long int', but argument 2 has type 'uint64_t' {aka 'long unsigned int'} [-Wformat=] 177 | llen += printf(" = %lld ", expr); | ~~~^ ~~~~ | | | | | uint64_t {aka long unsigned int} | long long int | %ld
It because that glibc defines uint64_t as "unsigned long int" when word size (means sizeof(long)) is 64bit (see include/bits/types.h), but nolibc directly use the 64bit "unsigned long long" (see tools/include/nolibc/stdint.h), which is simpler, seems kernel uses it too (include/uapi/asm-generic/int-ll64.h).
It is able to do like glibc, defining __WORDSIZE for all of platforms and using "unsigned long int" to define uint64_t when __WORDSIZE is 64bits, but here uses a simpler solution: nolibc always requires %lld to match "unsigned long long", for others, only require %lld when word size is 32bit.
Signed-off-by: Zhangjin Wu falcon@tinylab.org
tools/testing/selftests/nolibc/nolibc-test.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c index d417ca5d976f..7f9b716fd9b1 100644 --- a/tools/testing/selftests/nolibc/nolibc-test.c +++ b/tools/testing/selftests/nolibc/nolibc-test.c @@ -174,7 +174,11 @@ static int expect_eq(uint64_t expr, int llen, uint64_t val) { int ret = !(expr == val); +#if __SIZEOF_LONG__ == 4 || defined(NOLIBC) llen += printf(" = %lld ", expr); +#else
- llen += printf(" = %ld ", expr);
+#endif pad_spc(llen, 64, ret ? "[FAIL]\n" : " [OK]\n"); return ret; }
Please don't proceed like this. There's much easier to do here for a printf, just cast the expression to the type printf expects:
- llen += printf(" = %lld ", expr);
- llen += printf(" = %lld ", (long long)expr);
Yes, this conversion is better, my method make things more complex ;-)
Thanks, Zhangjin
Willy