The definition of once_flag conflicts with std::once_flag in
if “using namespace std;” is active.

Updates commit a7ddbf456d97ac8d1aa7afd735e196a1488bd874
("Add once_flag, ONCE_FLAG_INIT and call_once to stdlib.h for C23").

Suggested-by: Jonathan Wakely <jwakely@redhat.com>
Reviewed-by: Collin Funk <collin.funk1@gmail.com>

C23 adds once_flag, ONCE_FLAG_INIT and call_once to stdlib.h (in C11
they were only in threads.h, in C23 they are in both headers; this
change came from N2840).  Implement this change, with a
bits/types/once_flag.h header for the common type and initializer
definitions.

Note that there's an omnibus bug (bug 33001) that covers more than
just these missing definitions.

This doesn't seem a significant enough feature to be worth mentioning
in NEWS.

ISO C is not concerned with whether functions are in libc or
libpthread, but POSIX links this to what header they are declared in,
so functions declared in stdlib.h are supposed to be in libc.
However, the current edition of POSIX is based on C17; hopefully Hurd
glibc will have completed the merge of libpthread into libc (in
particular, moving call_once) well before a future edition of POSIX
based on C23 (or a later version of ISO C) is released.

Tested for x86_64 and x86.

Add stubs and partial docs for many undocumented pthreads functions.
While neither exhaustive nor complete, gives minimal usage docs
for many functions and expands the pthreads chapters, making it
easier to continue improving this section in the future.

Reviewed-by: Collin Funk <collin.funk1@gmail.com>

Here is a patch updating the documentation to mention GNU and BSD
extensions that were adopted by POSIX.1-2024.

* manual/llio.texi (Memory-mapped I/O): Add that MAP_ANON and
MAP_ANONYMOUS were added by POSIX.1-2024.
* manual/memory.texi (Changing Block Size): Mention that reallocarray
was added by POSIX.1-2024.
* manual/message.texi (Message Translation): Adjust wording to match
standardization.
(Translation with gettext): Mention the gettext family of functions were
added by POSIX.1-2024.
* manual/pattern.texi (Wildcard Matching): Mention that FNM_CASEFOLD was
added by POSIX.1-2024.
* manual/process.texi (Creating a Process): Mention that _Fork and
WCOREDUMP were added by POSIX.1-2024.
* manual/signal.texi (Miscellaneous Signals): Mention that SIGWINCH was
added by POSIX-1.2024.
* manual/startup.texi (Environment Access): Mention that secure_getenv
was added by POSIX.1-2024.
* manual/string.texi (Truncating Strings): Mention that strlcpy,
strlcat, wcslcpy, and wslcat were added by POSIX-1.2024.
(Search Functions): Document that memmem was added by POSIX-1.2024.
* manual/terminal.texi (Allocation): Mention that ptsname_r was added by
POSIX-1.2024.
* manual/threads.texi (Waiting with Explicit Clocks): Move node under
POSIX Threads.  Mention pthread_cond_clockwait,
pthread_rwlock_clockrdlock, and pthread_rwlock_clockwrlock were added by
POSIX-1.2024.
(Joining Threads): New node under Non-POSIX Extensions.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
Signed-off-by: Collin Funk <collin.funk1@gmail.com>

The POSIX Semaphores functions are currently undocumented in our info
pages.  This commit adds links to the man-pages documentation for all
the `sem_*' functions (except `sem_clockwait') so that they refer to
some useful documentation instead of just being stubs.  `sem_clockwait'
isn't documented by man-pages but thankfully already has a small useful
blurb in our own docs.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

This commit moves the `sem_*' family of functions from the IPC chapter,
replacing them with a reference to their new location in the Threads
chapter.  `sem_clockwait' is also moved out of the Non-POSIX Extensions
subsection since it is now included in the standard since Issue 8:
https://pubs.opengroup.org/onlinepubs/9799919799/functions/sem_clockwait.html

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

The manual contained several instances of incorrect formatting
that were correct texinfo but produced incorrectly rendered manuals
or incorrect behaviour from the tooling.

The most important was incorrect quoting of function returns
by failing to use {} to quote the return.  The impact of this
mistake means that 'info libc func' does not jump to the function
in question but instead to the introductory page under the assumption
that func doesn't exist.  The function returns are now correctly
quoted.

The second issue was the use of a category specifier with
@deftypefun which doesn't accept a category specifier.  If a category
specifier is required then @deftypefn needs to be used. This is
corrected by changing the command to @deftypefn for such functions
that used {Deprecated function} as a category.

The last issue is a missing space between the function name and the
arguments which results in odd function names like "epoll_wait(int"
instead of "epoll_wait".  This also impacts the use of 'info libc'
and is corrected.

We additionally remove ';' from the end of function arguments and
add an 'int' return type for dprintf.

Lastly we add a new test check-deftype.sh which verifies the expected
formatting of @deftypefun, @deftypefunx, @deftypefn, and
@deftypefnx.  The new test is also run as the summary file is
generated to ensure we don't generate incorrect results.

The existing check-safety.sh is also run directly as a test to increase
coverage since the existing tests only ran on manual install.

The new tests now run as part of the standard "make check" that
pre-commit CI runs and developers should run.

No regressions on x86_64.

HTML and PDF rendering reviewed and looks correct for all changes.

Reviewed-by: H.J. Lu <hjl.tools@gmail.com>

The __rseq_size value is now the active area of struct rseq
(so 20 initially), not the full struct size including padding
at the end (32 initially).

Update misc/tst-rseq to print some additional diagnostics.

Reviewed-by: Michael Jeanson <mjeanson@efficios.com>
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>

The argument to @deftypefun must be on a single line.
Also add the missing @safety for sem_clockwait.

Reported-by: Nilgün Belma Bugüner <nillguine@gmail.com>