Hi!
On gcc112 which has glibc 2.17 I've noticed
FAIL: 17_intro/names.cc (test for excess errors)
FAIL: experimental/names.cc (test for excess errors)
These are because glibc < 2.19 used __unused as field member of various structs,
including mcontext_t in sys/ucontext.h on ppc64le.
This was changed in glibc with
https://gcc.gnu.org/pipermail/libc-alpha/2013-November/045766.html
names.cc even has
#ifdef __GLIBC_PREREQ
#if ! __GLIBC_PREREQ(2, 19)
// Glibc defines this prior to 2.19
#undef __unused
#endif
#endif
for it, but it doesn't work. The reason is that __GLIBC_PREREQ is defined in
<features.h> but nothing included that header before this spot (it is included
later
from bits/stdc++.h).
The following patch on Linux/Hurd conditionally includes features.h to get
the needed macros before deciding if __unused should be undefined or not.
If needed, I could use __GLIBC_PREREQ then but would need to check if it is
defined and between 1996 and 1999 it wasn't.
Tested on powerpc64le-linux with glibc 2.17 (where it fixes the
regressions), on x86_64-linux with glibc 2.35 (where it still PASSes),
plus on the latter with -E -dD on the test to verify __unused is just
defined and not undefined later on, ok for trunk?
2023-01-27 Jakub Jelinek <ja...@redhat.com>
PR libstdc++/108568
* testsuite/17_intro/names.cc (__unused): For linux or GNU hurd
include features.h if present and then check __GLIBC__ and
__GLIBC_MINOR__ macros for glibc prior to 2.19, instead of testing
__GLIBC_PREREQ which isn't defined yet.
--- libstdc++-v3/testsuite/17_intro/names.cc.jj 2023-01-16 23:19:06.292716661
+0100
+++ libstdc++-v3/testsuite/17_intro/names.cc 2023-01-27 10:20:20.787645823
+0100
@@ -252,12 +252,15 @@
#undef y
#endif
-#ifdef __GLIBC_PREREQ
-#if ! __GLIBC_PREREQ(2, 19)
+#if defined (__linux__) || defined (__gnu_hurd__)
+#if __has_include(<features.h>)
+#include <features.h>
+#if __GLIBC__ == 2 && __GLIBC_MINOR__ < 19
// Glibc defines this prior to 2.19
#undef __unused
#endif
#endif
+#endif
#if __has_include(<newlib.h>)
// newlib's <sys/cdefs.h> defines these as macros.
Jakub
