selftests/nolibc: avoid passing NULL to printf("%s")

Clang on higher optimization levels detects that NULL is passed to
printf("%s") and warns about it.
While printf() from nolibc gracefully handles that NULL,
it is undefined behavior as per POSIX, so the warning is reasonable.
Avoid the warning by transforming NULL into a non-NULL placeholder.

Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Acked-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/r/20240807-nolibc-llvm-v2-8-c20f2f5fc7c2@weissschuh.net
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>

diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index 0800b10fc3f761ff70612d35244cc4aeeb01ede1..6fba7025c5e3c002085862fdf6fa950da6000d6c 100644 (file)
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -542,7 +542,7 @@ int expect_strzr(const char *expr, int llen)
 {
        int ret = 0;
 
-       llen += printf(" = <%s> ", expr);
+       llen += printf(" = <%s> ", expr ? expr : "(null)");
        if (expr) {
                ret = 1;
                result(llen, FAIL);
@@ -561,7 +561,7 @@ int expect_strnz(const char *expr, int llen)
 {
        int ret = 0;
 
-       llen += printf(" = <%s> ", expr);
+       llen += printf(" = <%s> ", expr ? expr : "(null)");
        if (!expr) {
                ret = 1;
                result(llen, FAIL);