[PATCH 3/3] string: Fix tester with fortify enabled

[Adhemerval Zanella]

If fortify is enabled, the truncated output warning is issued by
the wrapper itself:

In function ‘strncpy’,
    inlined from ‘test_strncpy’ at tester.c:505:10:
../string/bits/string_fortified.h:95:10: error: ‘__builtin_strncpy’
destination unchanged after copying no bytes from a string of length 3
[-Werror=stringop-truncation]
   95 |   return __builtin___strncpy_chk (__dest, __src, __len,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   96 |                                   __glibc_objsize (__dest));
      |                                   ~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ../include/bits/string_fortified.h:1,
                 from ../string/string.h:548,
                 from ../include/string.h:60,
                 from tester.c:33,
                 from inl-tester.c:6:
In function ‘strncpy’,
    inlined from ‘test_strncpy’ at tester.c:505:10:

Checked on x86_64-linux-gnu.
---
 string/tester.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/string/tester.c b/string/tester.c
index 8de70ad3ce..da42c72141 100644
--- a/string/tester.c
+++ b/string/tester.c
@@ -26,6 +26,14 @@
 #undef __USE_STRING_INLINES
 #endif
 
+#include <sys/cdefs.h>
+#include <libc-diag.h>
+
+/* Triggered by strncpy fortify wrapper when it is enabled.  */
+#if __GNUC_PREREQ (8, 0)
+DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
+#endif
+
 #include <errno.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -33,7 +41,6 @@
 #include <string.h>
 #include <strings.h>
 #include <fcntl.h>
-#include <libc-diag.h>
 
 /* This file tests a range of corner cases of string functions,
    including cases where truncation occurs or where sizes specified
@@ -45,9 +52,6 @@ DIAG_IGNORE_NEEDS_COMMENT (5.0, "-Wmemset-transposed-args");
 DIAG_IGNORE_NEEDS_COMMENT (9, "-Wrestrict");
 DIAG_IGNORE_NEEDS_COMMENT (7, "-Wstringop-overflow=");
 #endif
-#if __GNUC_PREREQ (8, 0)
-DIAG_IGNORE_NEEDS_COMMENT (8, "-Wstringop-truncation");
-#endif
 #if __GNUC_PREREQ (11, 0)
 DIAG_IGNORE_NEEDS_COMMENT (11, "-Wstringop-overread");
 #endif
-- 
2.34.1