mirror of
https://gitlab.kitware.com/cmake/cmake.git
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Matthew Woehlke
5abaf65154
The `CMAKE_REQUIRED_FLAGS` variable, used by the various entry points to
`cmake_check_source_{compiles,runs}`, specifies that flags shall not be
separated by semicolons. This is because the way in which it is passed
to the child `cmake` process means that, when considered as a list (with
semicolon separated items), only the first item is actually used as
compile flags, with any additional items actually seen as arguments to
the child `cmake` process. While this usage is unsupported, if invoked
accidentally, flags starting with `-W` were silently ignored by CMake.
However, CMake 4.4 newly complains about unrecognized warning
categories, which means that uses which were silently broken now result
in a hard error.
In the longer term, it would be helpful to introduce a policy to repair
improper use of semicolons in `CMAKE_REQUIRED_FLAGS` in order to do what
the user probably meant. However, for various reasons, we do not want to
introduce a policy to CMake 4.4 at this time, and anyway, the policy
won't help users that haven't enabled it. Therefore, alter the 'check
source' functions to detect arguments being passed to `cmake` rather
than the compiler, and remove any such that start with `-W`. This
removes any arguments that newly cause errors starting with CMake 4.4,
while not otherwise altering behavior in case any users were abusing
this implementation quirk.
Strictly speaking, this means that users can no longer abuse this quirk
to alter CMake's diagnostics. However, the only case in which this
should be observable is if the user is already abusing the quirk to
inject their own CMake logic into the CMake-provided test projects.
Since this was never supported, anyone doing that can keep the pieces.
Issue: #27901
Fixes: #27893
CMake
*****
Introduction
============
CMake is a cross-platform, open-source build system generator.
For full documentation visit the `CMake Home Page`_ and the
`CMake Documentation Page`_. The `CMake Community Wiki`_ also
references useful guides and recipes.
.. _`CMake Home Page`: https://cmake.org
.. _`CMake Documentation Page`: https://cmake.org/documentation
.. _`CMake Community Wiki`: https://gitlab.kitware.com/cmake/community/-/wikis/home
CMake is maintained and supported by `Kitware`_ and developed in
collaboration with a productive community of contributors.
.. _`Kitware`: https://www.kitware.com/cmake
License
=======
CMake is distributed under the OSI-approved BSD 3-clause License.
See `LICENSE.rst`_ for details.
.. _`LICENSE.rst`: LICENSE.rst
Building CMake
==============
Supported Platforms
-------------------
* Microsoft Windows
* Apple macOS
* Linux
* FreeBSD
* OpenBSD
* Solaris
* AIX
Other UNIX-like operating systems may work too out of the box, if not
it should not be a major problem to port CMake to this platform.
Please post to the `CMake Discourse Forum`_ to ask if others have
had experience with the platform.
.. _`CMake Discourse Forum`: https://discourse.cmake.org
Building CMake with CMake
-------------------------
You can build CMake as any other project with a CMake-based build system:
run an already-installed CMake on this source tree with your preferred
generator and options. Then build it and install it.
To build the documentation, install `Sphinx`_ and configure CMake with
``-DSPHINX_HTML=ON`` and/or ``-DSPHINX_MAN=ON`` to enable the "html" or
"man" builder. Add ``-DSPHINX_EXECUTABLE=/path/to/sphinx-build`` if the
tool is not found automatically.
To run the test suite, run ``ctest`` in the CMake build directory after
building. See the `CMake Testing Guide`_ for details.
.. _`Sphinx`: https://sphinx-doc.org
.. _`CMake Testing Guide`: Help/dev/testing.rst
Building CMake from Scratch
---------------------------
UNIX/Mac OSX/MinGW/MSYS/Cygwin
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
You need to have a C++ compiler (supporting C++11) and a ``make`` installed.
Run the ``bootstrap`` script you find in the source directory of CMake.
You can use the ``--help`` option to see the supported options.
You may use the ``--prefix=<install_prefix>`` option to specify a custom
installation directory for CMake. Once this has finished successfully,
run ``make`` and ``make install``.
For example, if you simply want to build and install CMake from source,
you can build directly in the source tree::
$ ./bootstrap && make && sudo make install
Or, if you plan to develop CMake or otherwise run the test suite, create
a separate build tree::
$ mkdir build && cd build
$ ../bootstrap && make
By default the ``bootstrap`` script configures CMake to build with vendored
dependencies. However, CMake does not vendor OpenSSL. To bootstrap in a
minimal environment, disable use of OpenSSL::
$ ./bootstrap -- -DCMAKE_USE_OPENSSL=OFF
Windows
^^^^^^^
There are two ways for building CMake under Windows:
1. Compile with MSVC from VS 2015 or later.
You need to download and install a binary release of CMake. You can get
these releases from the `CMake Download Page`_. Then proceed with the
instructions above for `Building CMake with CMake`_.
2. Bootstrap with MinGW under MSYS2.
Download and install `MSYS2`_. Then install the required build tools::
$ pacman -S --needed git base-devel mingw-w64-x86_64-gcc
and bootstrap as above.
.. _`CMake Download Page`: https://cmake.org/download
.. _`MSYS2`: https://www.msys2.org/
Reporting Bugs
==============
If you have found a bug:
1. If you have a patch, please read the `CONTRIBUTING.rst`_ document.
2. Otherwise, please post to the `CMake Discourse Forum`_ and ask about
the expected and observed behaviors to determine if it is really
a bug.
3. Finally, if the issue is not resolved by the above steps, open
an entry in the `CMake Issue Tracker`_.
.. _`CMake Issue Tracker`: https://gitlab.kitware.com/cmake/cmake/-/issues
Contributing
============
See `CONTRIBUTING.rst`_ for instructions to contribute.
.. _`CONTRIBUTING.rst`: CONTRIBUTING.rst