linux-kernel - [PATCH v2 3/7] selftests/nolibc: fix up compile warning with glibc on x86

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Message-Id: <aeb48b9cf6fc4674f7560166f22c7dc87d02302d.1685362482.git.falcon@tinylab.org>
Date:   Mon, 29 May 2023 21:00:01 +0800
From:   Zhangjin Wu <falcon@...ylab.org>
To:     w@....eu
Cc:     arnd@...db.de, falcon@...ylab.org, linux-kernel@...r.kernel.org,
        linux-kselftest@...r.kernel.org, linux-riscv@...ts.infradead.org,
        thomas@...ch.de
Subject: [PATCH v2 3/7] selftests/nolibc: fix up compile warning with glibc on x86_64

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@...ylab.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;
 }
-- 
2.25.1