Add /etc/host.conf file with 'multi on' to tst-nss-files-hosts-long.root.
Ensures the entire file, and all long lines, need to be parsed for the
test.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
Since the introduction of explicit flags in the internal implementation
of the printf family of functions, the 'mode' parameter can be used to
select which format long double parameters have (with the mode flag:
PRINTF_LDBL_IS_DBL). This patch uses this feature in the implementation
of some functions in argp.h, err.h, and error.h (only those that take a
format string and positional parameters). Future patches will add
support for 'nldbl' and 'ieee128' versions of these functions.
Tested for powerpc64le and x86_64.
The configure fragment for powerpc64le contains a test for the presence
of several compiler builtins and of the __float128 type, which are
provided by GCC 6.2 for powerpc64le. Since this configure test was
added, the compiler version required to build glibc for powerpc64le was
different than that required for the other architectures.
Now that glibc requires GCC 6.2 globally (since commit ID 4dcbbc3b28),
this patch removes the powerpc64le-specific test.
Even tough the configure test checks for compiler features rather than
compiler version, the intent of the test was to stop build attempts at
early stages, if they had been configured with a too old compiler. It
was not the intention of the test to detect compiler breakage (such as
the removal of the required compiler features in future GCC versions),
and glibc is not the place to test for compiler regressions, anyway.
Tested for powerpc64le with GCC 6.2 (built with build-many-glibcs.py).
Reviewed-by: Tulio Magno Quites Machado Filho <tuliom@linux.ibm.com>
In pthread_tryjoin if pd->tid == 0 then we will not block on a
futex operation because we will immediately see the join is already
complete and return. The comment is fixed to reflect that.
Signed-off-by: Carlos O'Donell <carlos@redhat.com>
Building glibc with -Wextra shows a -Wimplicit-fallthrough warning for
SPARC64 that appears to be a real bug in glibc. The dynamic linker
handling of R_SPARC_H34 falls through to that of R_SPARC_H44, which in
the case of this code is nonsensical (it means the value computed for
R_SPARC_H34 gets overwritten by one computed with the different logic
for R_SPARC_H44). Thus, this patch adds the missing break there.
Note: I do not have a testcase to demonstrate this bug.
Tested with build-many-glibcs.py.
[BZ #24231]
* sysdeps/sparc/sparc64/dl-machine.h (elf_machine_rela): Add break
after R_SPARC_H34 case.
These variables are only used to determine if a stdio stream is
a pre-allocated stream, but it is possible to do so by comparing
a FILE * to all pre-allocated stream objects. As a result, it is
not necessary to keep those pointers in separate variables.
Behavior with symbol interposition is unchanged because _IO_stdin_,
_IO_stdout_, _IO_stderr_ are exported, and refer to objects outside of
libc if symbol interposition or copy relocations are involved. (The
removed variables _IO_stdin, _IO_stdout, _IO_stderr were not exported,
of course.)
From time to time the test misc/tst-clone3 fails with a timeout.
Then futex_wait is blocking. Usually ctid should be set to zero
due to CLONE_CHILD_CLEARTID and the futex should be waken up.
But the fail occures if the thread has already exited before
ctid is set to the return value of clone(). Then futex_wait() will
block as there will be nobody who wakes the futex up again.
This patch initializes ctid to a known value before calling clone
and the kernel is the only one who updates the value to zero after clone.
If futex_wait is called then it is either waked up due to the exited thread
or the futex syscall fails as *ctid_ptr is already zero instead of the
specified value 1.
ChangeLog:
* sysdeps/unix/sysv/linux/tst-clone3.c (do_test):
Initialize ctid with a known value and remove update of ctid
after clone.
(wait_tid): Adjust arguments and call futex_wait with ctid_val
as assumed current value of ctid_ptr.
If building on a subset of architectures only, it is easy to miss
wrapper headers which are required by other architectures because
they lack the corresponding sysdeps header. The check ensures
that every installed header which is not itself a sysdeps header
has a header under include/ (that presumably wraps the header,
and perhaps also adding declarations and definitions for !_ISOMAC).
Also check for the absence of the sysdeps/generic/bits directory
removed in commit c72565e5f1, to make
accidental re-introduction more difficult.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
With a complete set of wrapper headers, it will be possible to check
for automatically for new installed headers which lack such wrappers.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
sys/procfs.h was already using this sysdeps directory.
This avoids the need for nptl-specific wrapper headers under
include/, a generic location in the source tree.
With internal fcntl64 internal (commit 06ab719d), it is possible to
consolidate lockf implementation by using the LFS fcntl interface
instead of using arch and system-specific implementations.
For Linux, the i386 implementation is used as generic implementation
by replacing the direct syscall with fcntl64 call. The LFS symbol
alias for default LFS ABI (__OFF_T_MATCHES_OFF64_T) is used to avoid
the duplicate symbol (instead of overriding the implementation with an
empty file).
For Hurd lockf64 semantic is changed: previous generic lockf64
implementation returned EOVERFLOW if LEN input is larger than 32-bit
off_t. However, Hurd fcntl64 implementation for F_GETLK64, F_SETLK64,
and F_SETLKW64 do accept off64_t inputs (__f_setlk accepts only off64_t
inputs).
Checked on i686-linux-gnu and x86_64-linux-gnu along with a i686-gnu
build.
* io/Makefile (tests): Add tst-lockf.
* io/lockf.c (lockf): Use __fcntl and only define for
!__OFF_T_MATCHES_OFF64_T.
* io/lockf64.c (__lockf64): Call __fcntl64 and alias to lockf for
__OFF_T_MATCHES_OFF64_T case.
* io/tst-lockf.c: New file.
* sysdeps/unix/sysv/linux/i386/lockf64.c: Remove file.
* sysdeps/unix/sysv/linux/arm/lockf64.c: Likewise.
* sysdeps/unix/sysv/linux/m68k/lockf64.c: Likewise.
* sysdeps/unix/sysv/linux/mips/mips32/lockf64.c: Likewise.
* sysdeps/unix/sysv/linux/mips/mips64/n32/lockf64.c: Likewise.
* sysdeps/unix/sysv/linux/powerpc/powerpc32/lockf64.c: Likewise.
* sysdeps/unix/sysv/linux/s390/s390-32/lockf64.c: Likewise.
* sysdeps/unix/sysv/linux/sh/lockf64.c: Likewise.
* sysdeps/unix/sysv/linux/sparc/sparc32/lockf64.c: Likewise.
After commit f1ac745583 ("arm: Use "nr"
constraint for Systemtap probes [BZ #24164]"), we load pd->result into
a register in the probe below:
/* Free the TCB. */
__free_tcb (pd);
}
else
pd->joinid = NULL;
LIBC_PROBE (pthread_join_ret, 3, threadid, result, pd->result);
However, at this point, the thread descriptor has been freed. If the
thread stack does not fit into the thread stack cache, the memory will
have been unmapped, and the program will crash in the probe.
Building the testsuite with -Wextra produces a warning in
sunrpc/tst-svc_register.c for a useless qualifier on a function return
type. This patch removes that qualifier.
Tested for x86_64.
* sunrpc/tst-svc_register.c (rpcbind_address): Remove qualifier
from function return type.
Building the testsuite with -Wextra (together with
-Wno-cast-function-type -Wno-clobbered -Wno-expansion-to-defined
-Wno-missing-field-initializers -Wno-old-style-declaration
-Wno-shift-negative-value -Wno-sign-compare -Wno-type-limits
-Wno-unused-parameter, which reflect the set of -Wextra warnings for
which glibc itself is not currently clean on x86_64) showed up
implicit-fallthrough warnings in tst-setjmp.c. Those warnings appear
to be false positives, arising from a function "jump" that calls
longjmp not itself being marked as noreturn; thus, this patch adds the
noreturn marking to that function to fix the warnings.
Tested for x86_64.
* setjmp/tst-setjmp.c (jump): Use __attribute__ ((__noreturn__)).
In some cases, sensitive to readline version and the user's
environment, gdb might emit escape codes while run under python's
pexpect (i.e. testing pretty printers). This patch, suggested
by Jan, helps isolate the test from the user's environment.
Tested on RHEL 7 x86_64 with DTS 7 and EPEL, which is one
magic combination of components that triggers this bug.
This patch fixes implicit-fallthrough warnings in sunrpc/xdr.c when
building with -Wextra. A fall-through comment is added in three
places; in two other places, an existing comment is reworded so it
matches the default patterns used by -Wimplicit-fallthrough.
Tested for x86_64.
* sunrpc/xdr.c (xdr_int): Add fall-through comment.
(xdr_u_int): Likewise.
(xdr_enum): Likewise.
(xdr_bytes): Reword fall-through comment.
(xdr_string): Likewise.
Patch ce7eb0e903 ("nptl: Cleanup cancellation macros") changed the
join sequence for internal common __pthread_timedjoin_ex to use the
new macro lll_wait_tid. The idea was this macro would issue the
cancellable futex operation depending whether the timeout is used or
not. However if a timeout is used, __lll_timedwait_tid is called and
it is not a cancellable entrypoint.
This patch fixes it by simplifying the code in various ways:
- Instead of adding the cancellation handling on __lll_timedwait_tid,
it moves the generic implementation to pthread_join_common.c (called
now timedwait_tid with some fixes to use the correct type for pid).
- The llvm_wait_tid macro is removed, along with its replication on
x86_64, i686, and sparc arch-specific lowlevellock.h.
- sparc32 __lll_timedwait_tid is also removed, since the code is similar
to generic one.
- x86_64 and i386 provides arch-specific __lll_timedwait_tid which is
also removed since they are similar in functionality to generic C code
and there is no indication it is better than compiler generated code.
New tests, tst-join8 and tst-join9, are provided to check if
pthread_timedjoin_np acts as a cancellation point.
Checked on x86_64-linux-gnu, i686-linux-gnu, sparcv9-linux-gnu, and
aarch64-linux-gnu.
[BZ #24215]
* nptl/Makefile (lpthread-routines): Remove lll_timedwait_tid.
(tests): Add tst-join8 tst-join9.
* nptl/lll_timedwait_tid.c: Remove file.
* sysdeps/sparc/sparc32/lll_timedwait_tid.c: Likewise.
* sysdeps/unix/sysv/linux/i386/lll_timedwait_tid.c: Likewise.
* sysdeps/sysv/linux/x86_64/lll_timedwait_tid.c: Likewise.
* nptl/pthread_join_common.c (timedwait_tid): New function.
(__pthread_timedjoin_ex): Act as cancellation entrypoint is block
is set.
* nptl/tst-join5.c (thread_join): New function.
(tf1, tf2, do_test): Use libsupport and add pthread_timedjoin_np
check.
* nptl/tst-join8.c: New file.
* nptl/tst-join9.c: Likewise.
* sysdeps/nptl/lowlevellock-futex.h (lll_futex_wait_cancel,
lll_futex_timed_wait_cancel): Add generic macros.
* sysdeps/nptl/lowlevellock.h (__lll_timedwait_tid, lll_wait_tid):
Remove definitions.
* sysdeps/unix/sysv/linux/i386/lowlevellock.h: Likewise.
* sysdeps/unix/sysv/linux/sparc/lowlevellock.h: Likewise.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Likewise.
* sysdeps/sparc/sparc32/lowlevellock.c (__lll_timedwait_tid):
Remove function.
* sysdeps/unix/sysv/linux/i386/lowlevellock.S (__lll_timedwait_tid):
Likewise.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.S: Likewise.
* sysdeps/unix/sysv/linux/lowlevellock-futex.h
(lll_futex_timed_wait_cancel): New macro.
Add a malloc micro benchmark to enable accurate testing of the
various paths in malloc and free. The benchmark does a varying
number of allocations of a given block size, then frees them again.
It tests 3 different scenarios: single-threaded using main arena,
multi-threaded using thread-arena, main arena with SINGLE_THREAD_P
false.
* benchtests/Makefile: Add malloc-simple benchmark.
* benchtests/bench-malloc-simple.c: New benchmark.
The ORIG_SRC argument is likely a useless relic from the original
correctness tests that are not needed in the benchmarks. Remove the
argument and use S1 to point to the source to avoid confusion.
* benchtests/bench-memmove.c (do_one_test): Remove unused
ORIG_SRC.
(do_test): Adjust.
* benchtests/bench-memmove-large.c (do_one_test): Remove unused
ORIG_SRC.
(do_test): Adjust.
The clone.S patch fixes 2 elfutils testsuite unwind failures, where the
backtrace gets stuck repeating __thread_start until we hit the backtrace
limit. This was confirmed by building and installing a patched glibc and
then building elfutils and running its testsuite.
Unfortunately, the testcase isn't working as expected and I don't know why.
The testcase passes even when my clone.S patch is not installed. The testcase
looks logically similarly to the elfutils testcases that are failing. Maybe
there is a subtle difference in how the glibc unwinding works versus the
elfutils unwinding? I don't have good gdb pthread support yet, so I haven't
found a way to debug this. Anyways, I don't know if the testcase is useful or
not. If the testcase isn't useful then maybe the clone.S patch is OK without
a testcase?
Jim
[BZ #24040]
* elf/Makefile (CFLAGS-tst-unwind-main.c): Add -DUSE_PTHREADS=0.
* elf/tst-unwind-main.c: If USE_PTHEADS, include pthread.h and error.h
(func): New.
(main): If USE_PTHREADS, call pthread_create to run func. Otherwise
call func directly.
* nptl/Makefile (tests): Add tst-unwind-thread.
(CFLAGS-tst-unwind-thread.c): Define.
* nptl/tst-unwind-thread.c: New file.
* sysdeps/unix/sysv/linux/riscv/clone.S (__thread_start): Mark ra
as undefined.
In two places in glibc, -Wextra produces implicit-fallthrough warnings
where there are comments about the fall-through but their wording
doesn't match one of the forms expected by the default
implicit-fallthrough level. This patch adjusts those two places to
have a comment in a form that is accepted, so avoiding the warning
(this seems preferable to only being able to use a looser level of the
warning that allows any comment at all as evidence of deliberate
fall-through).
Tested for x86_64.
* iconvdata/cns11643.h (ucs4_to_cns11643): Adjust fall-through
comment wording.
* nis/nis_call.c (__do_niscall3): Likewise.
One group of warnings seen building glibc with -Wextra is -Wempty-body
warnings about an 'if' body (or in one case an 'else' body) that is
just a semicolon, "warning: suggest braces around empty body in an
'if' statement [-Wempty-body]" - I think the point of the warning
being to make it more visible whether an 'if' body is actually present
or not.
This patch fixes such warnings in glibc. There's one place, with a
semicolon at the end of a comment, where this is clearly making the
presence of an 'else' body more visible. The other cases involve
macro definitions expanding to nothing. While there's no issue there
with visibility at the call sites, I think it's still cleaner to have
a macro that expands to something nonempty appropriate for the context
- so do {} while (0) if it's only intended to be usable as a
statement, or ((void) 0) where the macro definition is an alternative
to a call to a function returning void, so this patch makes those
changes.
Tested for x86_64.
* catgets/gencat.c (normalize_line): Use braces around empty
'else' body.
* include/stap-probe.h [!USE_STAP_PROBE && !__ASSEMBLER__]
(STAP_PROBE0): Use do {} while (0) for do-nothing definition.
[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE1): Likewise.
[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE2): Likewise.
[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE3): Likewise.
[!USE_STAP_PROBE && !__ASSEMBLER__] (STAP_PROBE4): Likewise.
* libio/libio.h (_IO_funlockfile): Use ((void) 0) for do-nothing
definition.
One of the implicit-fallthrough warnings from compiling glibc with
-Wextra appears to indicate an actual bug: the test-container code
could fall through inappropriately if execlp returns (which only
occurs on error). This patch adds appropriate error handling in this
case to avoid that fall-through.
Tested for x86_64.
* support/test-container.c (recursive_remove): Use FAIL_EXIT1 if
execlp returns.
This change moves the audit module loading and early notification into
separate functions out of dl_main.
It restores the bug fix from commit
8e889c5da3 ("elf: Fix LD_AUDIT for
modules with invalid version (BZ#24122)") which was reverted in commit
83e6b59625 ("[elf] Revert 8e889c5da3
(BZ#24122)").
The actual bug fix is the separate error message for the case when
la_version returns zero. The dynamic linker error message (which is
NULL in this case) is no longer used. Based on the intended use of
version zero (ignore this module due to explicit request), the message
is only printed if debugging is enabled.
This patch adds fall-through comments in some cases where -Wextra
produces implicit-fallthrough warnings.
The patch is non-exhaustive. Apart from architecture-specific code
for non-x86_64 architectures, it does not change sunrpc/xdr.c (legacy
code, probably should have such changes, but left to be dealt with
separately), or places that already had comments about the
fall-through but not matching the form expected by
-Wimplicit-fallthrough=3 (the default level with -Wextra; my
inclination is to adjust those comments to match rather than
downgrading to -Wimplicit-fallthrough=1 to allow any comment), or one
place where I thought the implicit fallthrough was not correct and so
should be handled separately as a bug fix. I think the key thing to
consider in review of this patch is whether the fall-through is indeed
intended and correct in each place where such a comment is added.
Tested for x86_64.
* elf/dl-exception.c (_dl_exception_create_format): Add
fall-through comments.
* elf/ldconfig.c (parse_conf_include): Likewise.
* elf/rtld.c (print_statistics): Likewise.
* locale/programs/charmap.c (parse_charmap): Likewise.
* misc/mntent_r.c (__getmntent_r): Likewise.
* posix/wordexp.c (parse_arith): Likewise.
(parse_backtick): Likewise.
* resolv/ns_ttl.c (ns_parse_ttl): Likewise.
* sysdeps/x86/cpu-features.c (init_cpu_features): Likewise.
* sysdeps/x86_64/dl-machine.h (elf_machine_rela): Likewise.
The type used within e_sqrt.c(__slow_ieee754_sqrtf) was, unnecessarily and
likely inadvertently, double. float is not only appropriate, but also
more efficient, avoiding the need for the compiler to emit a
round-to-single-precision instruction.
This is the difference in compiled code:
0000000000000000 <__ieee754_sqrtf>:
0: 2c 08 20 ec fsqrts f1,f1
- 4: 18 08 20 fc frsp f1,f1
- 8: 20 00 80 4e blr
+ 4: 20 00 80 4e blr
(Found by Anton Blanchard.)
Having checked the arrangement of whitespace in time/strftime_l.c
using "unexpand" and "unexpand -a" command, three inconsistencies are
detected. So fix them for consistency.
ChangeLog:
* time/strftime_l.c: Fix a few whitespace arrangement inconsistencies.
Continuing the process of moving away from having bits/mathinline.h
headers in glibc, leaving the compiler to inline functions as
appropriate depending on the options passed to it, this patch removes
the header for powerpc.
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88558> is the
corresponding GCC bug for adding replacements for these powerpc
(32-bit-only) lrint / lrintf inlines.
Tested with build-many-glibcs.py for its powerpc configurations.
* sysdeps/powerpc/bits/mathinline.h: Remove.
sysdeps/ia64/fpu/bits/math-finite.h exists and will be installed on
ia64, but during the build, the default math/bits/math-finite.h file
is used, which is wrong.
Fixes commit 0ac5ae2335 ("Optimize
libm").
No functional change; the previous path worked as well, but it
re-added the obsolete sysdeps/generic/bits directory, which was
removed (for the first time) in commit
c72565e5f1.
Fixes commit e47d82c99a ("Provide
<bits/unistd_ext.h> as a sysdeps header exclusively").
When the /etc/hosts file has a line longer than 1028
characters getent ahostsv4 and ahostsv6 will fail.
This test performs a getent call on a /etc/hosts file that contains
a very long line (greater than 1028) using the test-in-container
framework.
Non-sysdeps headers cannot be overriden by sysdeps headers across the
entire build, so it is necessary to turn such extension headers into
sysdeps headers themselves. The approach here follows the existing
<bits/shm.h> header (although it uses sysdeps/gnu instead of
sysdeps/generic).
Fixes commit 1d0fc21382 ("Linux: Add
gettid system call wrapper [BZ #6399]") and commit
8f89ab216f ("posix: Fix missing wrapper
header for <bits/unistd_ext.h>").
Commit 27761a1042 ("Refactor atfork
handlers") introduced a lock, atfork_lock, around fork handler list
accesses. It turns out that this lock occasionally results in
self-deadlocks in malloc/tst-mallocfork2:
(gdb) bt
#0 __lll_lock_wait_private ()
at ../sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:63
#1 0x00007f160c6f927a in __run_fork_handlers (who=(unknown: 209394016),
who@entry=atfork_run_prepare) at register-atfork.c:116
#2 0x00007f160c6b7897 in __libc_fork () at ../sysdeps/nptl/fork.c:58
#3 0x00000000004027d6 in sigusr1_handler (signo=<optimized out>)
at tst-mallocfork2.c:80
#4 sigusr1_handler (signo=<optimized out>) at tst-mallocfork2.c:64
#5 <signal handler called>
#6 0x00007f160c6f92e4 in __run_fork_handlers (who=who@entry=atfork_run_parent)
at register-atfork.c:136
#7 0x00007f160c6b79a2 in __libc_fork () at ../sysdeps/nptl/fork.c:152
#8 0x0000000000402567 in do_test () at tst-mallocfork2.c:156
#9 0x0000000000402dd2 in support_test_main (argc=1, argv=0x7ffc81ef1ab0,
config=config@entry=0x7ffc81ef1970) at support_test_main.c:350
#10 0x0000000000402362 in main (argc=<optimized out>, argv=<optimized out>)
at ../support/test-driver.c:168
If no locking happens in the single-threaded case (where fork is
expected to be async-signal-safe), this deadlock is avoided.
(pthread_atfork is not required to be async-signal-safe, so a fork
call from a signal handler interrupting pthread_atfork is not
a problem.)
This commit adds gettid to <unistd.h> on Linux, and not to the
kernel-independent GNU API.
gettid is now supportable on Linux because too many things assume a
1:1 mapping between libpthread threads and kernel threads.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
As the result of commit 6e6249d0b4
("BZ#14743: Move clock_* symbols from librt to libc."), in glibc 2.17,
clock_gettime, clock_getres, clock_settime, clock_getcpuclockid,
clock_nanosleep were added to libc, and the file rt/clock-compat.c
was added with forwarders to the actual implementations in libc.
These forwarders were wrapped in
#if SHLIB_COMPAT (librt, GLIBC_2_2, GLIBC_2_17)
so that they are not present for newer architectures (such as
powerpc64le) with a 2.17 or later ABI baseline. But the forwarders
were not marked as compatibility symbols. As a result, on older
architectures, historic configure checks such as
AC_CHECK_LIB(rt, clock_gettime)
still cause linking against librt, even though this is completely
unnecessary. It also creates a needless porting hazard because
architectures behave differently when it comes to symbol availability.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
While debugging a kernel warning, Thomas Gleixner, Sebastian Sewior and
Heiko Carstens found a bug in pthread_mutex_trylock due to misordered
instructions:
140: a5 1b 00 01 oill %r1,1
144: e5 48 a0 f0 00 00 mvghi 240(%r10),0 <--- THREAD_SETMEM (THREAD_SELF, robust_head.list_op_pending, NULL);
14a: e3 10 a0 e0 00 24 stg %r1,224(%r10) <--- last THREAD_SETMEM of ENQUEUE_MUTEX_PI
vs (with compiler barriers):
140: a5 1b 00 01 oill %r1,1
144: e3 10 a0 e0 00 24 stg %r1,224(%r10)
14a: e5 48 a0 f0 00 00 mvghi 240(%r10),0
Please have a look at the discussion:
"Re: WARN_ON_ONCE(!new_owner) within wake_futex_pi() triggerede"
(https://lore.kernel.org/lkml/20190202112006.GB3381@osiris/)
This patch is introducing the same compiler barriers and comments
for pthread_mutex_trylock as introduced for pthread_mutex_lock and
pthread_mutex_timedlock by commit 8f9450a0b7
"Add compiler barriers around modifications of the robust mutex list."
ChangeLog:
[BZ #24180]
* nptl/pthread_mutex_trylock.c (__pthread_mutex_trylock):
Do not use a statement expression in array_length, so that
array_length can be used at file scope and as a constant expression.
Instead, put the _Static_assert into a struct (as a declaration),
and nest this in the expression using a sizeof expression.
