New failure on aarch64 in Fedora Rawhide.

[Carlos O'Donell <codonell at redhat dot com>]

Szabolcs,

https://kojipkgs.fedoraproject.org//work/tasks/2880/34082880/build.log

BUILDSTDERR: In file included from ../sysdeps/aarch64/sysdep.h:22,
BUILDSTDERR:                  from ../sysdeps/unix/sysv/linux/aarch64/sysdep.h:26,
BUILDSTDERR:                  from ../sysdeps/aarch64/nptl/tls.h:37,
BUILDSTDERR:                  from ../include/errno.h:25,
BUILDSTDERR:                  from ../sysdeps/unix/sysv/linux/netlink_assert_response.c:19:
BUILDSTDERR: ../sysdeps/generic/sysdep.h:81: error: "CFI_RESTORE" redefined [-Werror]
BUILDSTDERR:    81 | # define CFI_RESTORE(reg) \
BUILDSTDERR:       |
BUILDSTDERR: In file included from ../sysdeps/unix/sysdep.h:18,
BUILDSTDERR:                  from ../sysdeps/unix/sysv/linux/aarch64/sysdep.h:25,
BUILDSTDERR:                  from ../sysdeps/aarch64/nptl/tls.h:37,
BUILDSTDERR:                  from ../include/errno.h:25,
BUILDSTDERR:                  from ../sysdeps/unix/sysv/linux/netlink_assert_response.c:19:
BUILDSTDERR: ../sysdeps/generic/sysdep.h:81: note: this is the location of the previous definition
BUILDSTDERR:    81 | # define CFI_RESTORE(reg) \
BUILDSTDERR:       |
BUILDSTDERR: cc1: all warnings being treated as errors

This just came up in Fedora Rawhide.

We have no guards on systeps/generic/sysdep.h, I assume we want to include it multiple
times with different macro API settings.

Note the difference in include path is:

sysdeps/aarch64/sysdep.h vs. sysdeps/unix/sysdep.h

In sysdeps/unix/sysv/linux/aarch64/sysdep.h we include both:

 25 #include <sysdeps/unix/sysdep.h>
 26 #include <sysdeps/aarch64/sysdep.h>

Then in sysdeps/aarch64/sysdep.h we include:

 22 #include <sysdeps/generic/sysdep.h>

Then in sysdeps/unix/sysdeps.h we include:

 18 #include <sysdeps/generic/sysdep.h>

So we get two copies.

In general the project rule has been "Include the headers you need."

Guarding the macros with ifndef could lead to defaults being used incorrectly
(macro API issues), and was the reason we enabled -Wundef, so doing that makes
things less robust.

It would be really nice if we could just include what we needed once.

I would like to get to something like this:
diff --git a/sysdeps/unix/sysv/linux/aarch64/sysdep.h b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
index 935c507f8cb36b2a..35f3dd65b3397001 100644
--- a/sysdeps/unix/sysv/linux/aarch64/sysdep.h
+++ b/sysdeps/unix/sysv/linux/aarch64/sysdep.h
@@ -22,9 +22,8 @@
 /* Always enable vsyscalls on aarch64 */
 #define ALWAYS_USE_VSYSCALL 1
 
-#include <sysdeps/unix/sysdep.h>
-#include <sysdeps/aarch64/sysdep.h>
 #include <sysdeps/unix/sysv/linux/generic/sysdep.h>
+#include <sysdeps/aarch64/sysdep.h>
 
 /* Defines RTLD_PRIVATE_ERRNO and USE_DL_SYSINFO.  */
 #include <dl-sysdep.h>
---
We include the aarch64 sysdep.h, and then the Linux version, and we're done.
This avoids the double inclusion, and appears to work just fine, matching
what other arches do.

Thoughts?

--
Cheers,
Carlos.