The `-pthread` flag tells the compiler/linker to link to additional
libraries needed for thread support (e.g. libatomic on riscv64). The
flag therefore should be used if requested using
`THREADS_PREFER_PTHREAD_FLAG` also when the pthread functions are
found in libc.
When a CMake based project fails, users start looking at
CMakeError.log and think that the FindThread output is
the problem, but it is a false positive.
Now FindThreads only logs to `CMakeError.log` when it fails
to find a suitable flag, reducing the amount of false positives in `CMakeError.log`.
Fixes#16540, Fixes#19344
When CMAKE_C_FLAGS contains '-Werror -Wmissing-prototypes'
the pthread test code check fails with error:
"src.c:3:7: error: no previous prototype for 'test_func' [-Werror=missing-prototypes]".
Adding 'static' keyword to 'test_func' fixes it.
Currently CMake passes `-Xcompiler -pthread` flags to CUDA compilers
irrespective of the actual CUDA compiler ID. This makes sure the
additional `-Xcompiler` flag is only used with nvcc.
When using ThreadSanitizer our existing CMAKE_HAVE_LIBC_PTHREAD test
program links using symbols from the tsan library. Among the symbols
not provided by that library, `pthread_cancel()` seems to be the less
risky symbol to add to the check.
Fixes: #19981
Revert commit de5f123d3a (FindThreads: Do not hard-code '-l' flag on
library name, 2019-09-23, v3.16.0-rc1~71^2). Some clients depend
on the value of `CMAKE_THREAD_LIBS_INIT` to contain a valid flag.
Fixes: #20061, #20065
When not using the `-pthread` flag we instead return a library to link
by name. Previously we hard-coded the `-l` flag before the library
name. When used with `target_link_libraries`, the hard-coded `-l` flag
is preserved rather than transformed into the link option preferred by
the toolchain in use. Drop the explicit `-l` part to let CMake's
generators produce the proper way to link the threads library for the
current toolchain.
Fixes: #19747
Drop the sentence added by commit 5a5a1d90f0 (Help: FindThreads not
needed with modern C++., 2019-01-09, v3.14.0-rc1~186^2) about not
needing the module with modern C++. The module is often still needed.
Fixes: #19297
Our check for just `pthread_create` is not sufficient because there are
cases where that symbol may be found in libc but not all of pthreads.
We first tried to address this in commit e9a1ddc594 (FindThreads:
Replace the pthread symbol checking in libc., 2018-11-18,
v3.14.0-rc1~292^2) by switching to `pthread_kill`, but that had to be
reverted by commit 18320230ec (FindThreads: Revert libc symbol check to
pthread_create, 2019-02-27, v3.14.0-rc3~6^2) because there are other
cases where `pthread_kill` is in libc but the rest of pthreads is not.
Update our check to try a complete program using pthreads as an actual
application might.
Fixes: #18994
Since commit e9a1ddc594 (FindThreads: Replace the pthread symbol
checking in libc., 2018-11-18, v3.14.0-rc1~292^2) we check libc for
`pthread_kill` instead of `pthread_create`. However, on FreeBSD
`pthread_kill` is in libc but not `pthread_create`. Discussion in the
original merge request for the above commit also considered
`pthread_key_create`, `pthread_self`, and `pthread_attr_init`. Every
symbol seems to have some reason it is not an appropriate choice.
Revert to the pre-3.14 behavior of using `pthread_create` pending
further investigation.
In commit e9a1ddc594 (FindThreads: Replace the pthread symbol checking
in libc., 2018-11-18, v3.14.0-rc1~292^2) we switched to checking for
`pthread_kill` in libc but did not update the symbol check's header file
to match. Add `signal.h` to get `pthread_kill`. Keep `pthread.h`
anyway since the purpose of the check is to verify that the pthread API
works.
Fixes: #18984
We do not need to support IRIX anymore, so drop relevant parts. In
particular, the `CMAKE_THREAD_PREFER_PTHREAD` is frequently confused
with `THREADS_PREFER_PTHREAD_FLAG`.
Also remove references to the IRIX-specific options and results
from other modules and tests.
With asan build, we will have the pthread_create() symbol in libc. However,
libasan doesn't have full pthread implementation. We can't assume that we
have the pthread implementation in libc using pthread_create() symbol.
Replace the pthread_create() with pthread_kill() as a quick fix.
2cc050b53b CUDA: Add test for device linking when host linking uses threads
83c13ca44f FindThreads: Pass -pthread to CUDA compiler through -Xcompiler
cf92fd9ae9 Merge branch 'cuda-filter-device-link-items' into cuda-thread-flags
e768d96c74 CUDA: Filter out host link flags during device linking
Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Kelly (KT) Thompson <kgt@lanl.gov>
Merge-request: !2512
Use `try_compile` instead of `try_run`. It is not clear why `try_run`
was ever needed, and it does not work during cross-compiling.
Update the check's source file to remove code associated with actually
running things. Also remove the ancient `__CLASSIC_C__` code path and
use a simple `int main(void)` as in `Modules/CheckIncludeFile.c.in`.
Fixes: #16920
Per-source copyright/license notice headers that spell out copyright holder
names and years are hard to maintain and often out-of-date or plain wrong.
Precise contributor information is already maintained automatically by the
version control tool. Ultimately it is the receiver of a file who is
responsible for determining its licensing status, and per-source notices are
merely a convenience. Therefore it is simpler and more accurate for
each source to have a generic notice of the license name and references to
more detailed information on copyright holders and full license terms.
Our `Copyright.txt` file now contains a list of Contributors whose names
appeared source-level copyright notices. It also references version control
history for more precise information. Therefore we no longer need to spell
out the list of Contributors in each source file notice.
Replace CMake per-source copyright/license notice headers with a short
description of the license and links to `Copyright.txt` and online information
available from "https://cmake.org/licensing". The online URL also handles
cases of modules being copied out of our source into other projects, so we
can drop our notices about replacing links with full license text.
Run the `Utilities/Scripts/filter-notices.bash` script to perform the majority
of the replacements mechanically. Manually fix up shebang lines and trailing
newlines in a few files. Manually update the notices in a few files that the
script does not handle.
While at it, also add a branch using CheckIncludeFileCXX. Also give a better
error message if no supported language is enabled. C++ support isn't working
yet, but it has never worked.
This not only holds the library, but can also hold compiler flags needed, e.g.
the -pthread flag preferred by gcc on some platforms. There was no clean way
to get that compiler flag from the module until now.
This allows a following commit to introduce a switch to prefer that check over
searching for the explicit library names without breaking backward
compatibility.
Fixes issues #14812 and #14813 where find_package(OpenMP QUIET) and
find_package(Qt4 QUIET) would still print out messages when calling
check*() functions.
Also a partial fix for #14445 where building CMake
(without cmake-gui) when Qt5 is installed and Qt4 is not installed
and warnings come out of FindQt4.cmake.
Ancient versions of CMake required else(), endif(), and similar block
termination commands to have arguments matching the command starting the
block. This is no longer the preferred style.
Run the following shell code:
for c in else endif endforeach endfunction endmacro endwhile; do
echo 's/\b'"$c"'\(\s*\)(.\+)/'"$c"'\1()/'
done >convert.sed &&
git ls-files -z -- bootstrap '*.cmake' '*.cmake.in' '*CMakeLists.txt' |
egrep -z -v '^(Utilities/cm|Source/kwsys/)' |
egrep -z -v 'Tests/CMakeTests/While-Endwhile-' |
xargs -0 sed -i -f convert.sed &&
rm convert.sed
QNX has the phtread stuff in the standard library. The best way would
IMHO be to check if a program that uses pthread_* can be successfully
linked without specifying any linker option before trying out the
different flags.
QNX has the phtread stuff in the standard library. The best way would
IMHO be to check if a program that uses pthread_* can be successfully
linked without specifying any linker option before trying out the
different flags.
