[glibc] posix: Fix macro expansion producing 'defined' has undefined behavior

[glibc] posix: Fix macro expansion producing 'defined' has undefined behavior

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=ddcf5a9170a0db5055259118f3090debab248126

commit ddcf5a9170a0db5055259118f3090debab248126
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Wed Mar 9 18:22:46 2022 -0300

    posix: Fix macro expansion producing 'defined' has undefined behavior
    
    The NEED_CHECK_SPEC is defined as:
    
      #define NEED_CHECK_SPEC \
        (!defined _XBS5_ILP32_OFF32 || !defined _XBS5_ILP32_OFFBIG \
         || !defined _XBS5_LP64_OFF64 || !defined _XBS5_LPBIG_OFFBIG \
         || !defined _POSIX_V6_ILP32_OFF32 || !defined _POSIX_V6_ILP32_OFFBIG \
         || !defined _POSIX_V6_LP64_OFF64 || !defined _POSIX_V6_LPBIG_OFFBIG \
         || !defined _POSIX_V7_ILP32_OFF32 || !defined _POSIX_V7_ILP32_OFFBIG \
         || !defined _POSIX_V7_LP64_OFF64 || !defined _POSIX_V7_LPBIG_OFFBIG)
    
    Which is undefined behavior accordingly to C Standard (Preprocessing
    directives, p4).
    
    Checked on x86_64-linux-gnu.

Diff:
---
 sysdeps/posix/sysconf.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/sysdeps/posix/sysconf.c b/sysdeps/posix/sysconf.c
index f760bf4e2b..c29b70ad80 100644
--- a/sysdeps/posix/sysconf.c
+++ b/sysdeps/posix/sysconf.c
@@ -37,13 +37,17 @@
 #define NEED_SPEC_ARRAY 0
 #include <posix-conf-vars.h>
 
-#define NEED_CHECK_SPEC \
-  (!defined _XBS5_ILP32_OFF32 || !defined _XBS5_ILP32_OFFBIG \
+#if !defined _XBS5_ILP32_OFF32 || !defined _XBS5_ILP32_OFFBIG \
    || !defined _XBS5_LP64_OFF64 || !defined _XBS5_LPBIG_OFFBIG \
    || !defined _POSIX_V6_ILP32_OFF32 || !defined _POSIX_V6_ILP32_OFFBIG \
    || !defined _POSIX_V6_LP64_OFF64 || !defined _POSIX_V6_LPBIG_OFFBIG \
    || !defined _POSIX_V7_ILP32_OFF32 || !defined _POSIX_V7_ILP32_OFFBIG \
-   || !defined _POSIX_V7_LP64_OFF64 || !defined _POSIX_V7_LPBIG_OFFBIG)
+   || !defined _POSIX_V7_LP64_OFF64 || !defined _POSIX_V7_LPBIG_OFFBIG
+# define NEED_CHECK_SPEC 1
+#else
+# define NEED_CHECK_SPEC 0
+#endif
+
 #if NEED_CHECK_SPEC
 static long int __sysconf_check_spec (const char *spec);
 #endif