[RFC v1 2/2] Makeconfig: Compile glibc with -fno-delete-null-pointer-checks

[Alejandro Colomar <alx@kernel.org>]

Don't undefine __nonnull to prevent compiler optimizations.  Instead,
tell the compiler to not optimize based on the attribute, via the
appropriate flag.

Link: <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110617>
Reported-by: Florian Weimer <fweimer@redhat.com>
Cc: Xi Ruoyao <xry111@xry111.site>
Cc: Sam James <sam@gentoo.org>
Cc: Richard Biener <rguenth@gcc.gnu.org>
Cc: Andrew Pinski <apinski@marvell.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
---
 Makeconfig          | 1 +
 include/sys/cdefs.h | 6 ------
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/Makeconfig b/Makeconfig
index 369a596e79..ecbe30e53f 100644
--- a/Makeconfig
+++ b/Makeconfig
@@ -1045,6 +1045,7 @@ CPPFLAGS = $(config-extra-cppflags) $(CPPFLAGS-config) \
 
 override CFLAGS	= -std=gnu11 \
 		  -fgnu89-inline \
+		  -fno-delete-null-pointer-checks \
 		  $(config-extra-cflags) \
 		  $(filter-out %frame-pointer,$(+cflags)) \
 		  $(+gccwarn-c) \
diff --git a/include/sys/cdefs.h b/include/sys/cdefs.h
index b84ad34a70..e4a8dd7844 100644
--- a/include/sys/cdefs.h
+++ b/include/sys/cdefs.h
@@ -10,12 +10,6 @@
 #include <misc/sys/cdefs.h>
 
 #ifndef _ISOMAC
-/* The compiler will optimize based on the knowledge the parameter is
-   not NULL.  This will omit tests.  A robust implementation cannot allow
-   this so when compiling glibc itself we ignore this attribute.  */
-# undef __nonnull
-# define __nonnull(params)
-
 extern void __chk_fail (void) __attribute__ ((__noreturn__));
 libc_hidden_proto (__chk_fail)
 rtld_hidden_proto (__chk_fail)
-- 
2.40.1