Every time I get a different source directory, and I have a fixed build directory. Every time I will run cmake /path/to/project and run ninja. It will report an error : Make Error: The source "/path1/to/project/CMakeLists.txt" does not match the source "/path2/to/project/CMakeLists.txt" used to generate cache. Re-run cmake with a different source directory.
So what I did was manually change the options related to the path of project in the CMakeCache.txt. The result is that it will compile the project from scratch every time instead of incrementally compiling, So is there any feasible way to achieve incremental compilation or in this case it is impossible to achieve incremental compilation ？
Mount the source directory always to a same constant absolute location. On Linux, you could use mount namespaces, for example use proot.
proot -b /path/to/project:/work -w /work cmake -B builddir -S .
proot -b /path/to/project:/work -w /work cmake --build builddir
I'm trying to build the azure storage sdk and have hit a build failure. Looking at the build commands, I see that it is trying to use an old CXXFLAGS value (not sure if this is the reason for the failure but would like to clean this up).
My steps were essentially:
export CXXFLAGS="-fPIC"
run cmake3 and make on cpprestsdk
unset CXXFLAGS
run cmake3 on azure-storage-cpp
Then when I look at my compile_commands.json file, I still see the -fPIC option being used. I tried deleting the directory and cloning again but it is still there.
CXXFLAGS is not set anymore, even tried using a new shell but still no luck:
$ echo $CXXFLAGS
Any ideas what is going on?
Edit:
I'm using the following command:
cmake3 .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
and am following CentOS instructions from https://github.com/Azure/azure-storage-cpp
I have a cmake project which produces several executables. I want to package each executable in seperate Docker containers, so inside the Dockefile, I only built the target that I need:
RUN mkdir build \
&& cd build \
&& cmake /app/project -DCMAKE_BUILD_TYPE=Release
&& make -j 2 myExecutable \
&& make install/fast
This works as expected, but I run into an issue with the conan cmake integration. The installation is done when cmake is called, not during the actual build - this means that no matter which target I want to actually build, all the conan installation calls present in my cmake files are called - so way more packages are installed than necessary.
# for every target
# include conan dependencies (each target has its own conanfile.txt)
conan_cmake_run(CONANFILE conanfile.txt
BASIC_SETUP CMAKE_TARGETS
BUILD_TYPE "${CMAKE_BUILD_TYPE}"
BUILD outdated
${update_conan}
)
conan_target_link_libraries(${PROJECT_NAME})
Is there a way to make the cmake calls dependend on which target I actually want to build?
Unfortunately not, the macro conan_cmake_run has no distinction about which target is involved or even it was executed before. You could use CMake options to run or not conan_cmake_run.
Also, you could comment/vote your request thorough the issue https://github.com/conan-io/cmake-conan/issues/105
Regards!
I have been using autotools for a few years, and I'm learning CMake now for new projects.
Here is what I have:
myfirstrecipe.bb:
inherit pkgconfig cmake
...
do_install() {
install -d ${D}${datadir}/folder1/folder2
install -m 0755 ${S}/files/file.txt ${D}${datadir}/folder1/folder2
}
mysecondrecipe.bb:
...
DEPENDS = "myfirstrecipe"
...
This works fine. The second recipe can find the file.txt installed by the first recipe, which I see it is installed in the secondrecipe sysroot:
build/tmp/work/armv7ahf-vfp-os-linux-musleabi/mysecondrecipe/510-r0/mysecondrecipe-sysroot/usr/share/folder1/folder2/file.txt
However I want CMake to install the file instead. So when I try this:
myfirstrecipe.bb:
inherit pkgconfig cmake
...
OECMAKE_TARGET_INSTALL = "file-install"
CMakeLists.txt:
add_custom_target(file-install)
add_custom_command(TARGET file-install POST_BUILD
COMMAND ${CMAKE_COMMAND} -E make_directory ${CMAKE_INSTALL_DATADIR}/folder1/folder2
COMMAND ${CMAKE_COMMAND} -E copy_if_different
${CMAKE_SOURCE_DIR}/files/file.txt
${CMAKE_INSTALL_DATADIR}/folder1/folder2/)
Then I get a build error from mysecondrecipe.bb saying it could not find the file since it is not installed. I see it installed here:
build/tmp/work/armv7ahf-vfp-os-linux-musleabi/myfirstrecipe/1.0-r0/myfirstrecipe-1.0/share/folder1/folder2/file.txt
But not in the path above. Anyone can see what I am missing? If I were to use Autotools I could easily get this working with this:
Automake.am:
file-install: $(shell find files/ -type f -name '*.txt')
mkdir -p ${DESTDIR}${datadir}/folder1/folder2
cp -u $^ -t ${DESTDIR}${datadir}/folder1/folder2
Basically you do not use the standard way of installing files.
CMake has an install directive install, wich is commonly used and powerfull.
Doing so, leads to the nice situation, that Within myfirstrecipe.bb an own do_install task is not necessary. The cmake.bbclass, you already inherit, is adding a do_install task and relies on the install directive within your CMakeLists.txt
You can take a look at the cmake.bbclass to see how it is implemented. It's at poky/meta/classes/cmake.bbclass
I guess that switching to install will make life easier
I do cmake . && make all install. This works, but installs to /usr/local.
I need to install to a different prefix (for example, to /usr).
What is the cmake and make command line to install to /usr instead of /usr/local?
You can pass in any CMake variable on the command line, or edit cached variables using ccmake/cmake-gui. On the command line,
cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr . && make all install
Would configure the project, build all targets and install to the /usr prefix. The type (PATH) is not strictly necessary, but would cause the Qt based cmake-gui to present the directory chooser dialog.
Some minor additions as comments make it clear that providing a simple equivalence is not enough for some. Best practice would be to use an external build directory, i.e. not the source directly. Also to use more generic CMake syntax abstracting the generator.
mkdir build && cd build && cmake -DCMAKE_INSTALL_PREFIX:PATH=/usr .. && cmake --build . --target install --config Release
You can see it gets quite a bit longer, and isn't directly equivalent anymore, but is closer to best practices in a fairly concise form... The --config is only used by multi-configuration generators (i.e. MSVC), ignored by others.
The ":PATH" part in the accepted answer can be omitted. This syntax may be more memorable:
cmake -DCMAKE_INSTALL_PREFIX=/usr . && make all install
...as used in the answers here.
Note that in both CMake and Autotools you don't always have to set the installation path at configure time. You can use DESTDIR at install time (see also here) instead as in:
make DESTDIR=<installhere> install
See also this question which explains the subtle difference between DESTDIR and PREFIX.
This is intended for staged installs and to allow for storing programs in a different location from where they are run e.g. /etc/alternatives via symbolic links.
However, if your package is relocatable and doesn't need any hard-coded (prefix) paths set via the configure stage you may be able to skip it.
So instead of:
cmake -DCMAKE_INSTALL_PREFIX=/usr . && make all install
you would run:
cmake . && make DESTDIR=/usr all install
Note that, as user7498341 points out, this is not appropriate for cases where you really should be using PREFIX.
The way I build CMake projects cross platform is the following:
/project-root> mkdir build
/project-root> cd build
/project-root/build> cmake -G "<generator>" -DCMAKE_INSTALL_PREFIX=stage ..
/project-root/build> cmake --build . --target=install --config=Release
The first two lines create the out-of-source build directory
The third line generates the build system specifying where to put the installation result (which I always place in ./project-root/build/stage - the path is always considered relative to the current directory if it is not absolute)
The fourth line builds the project configured in . with the buildsystem configured in the line before. It will execute the install target which also builds all necessary dependent targets if they need to be built and then copies the files into the CMAKE_INSTALL_PREFIX (which in this case is ./project-root/build/stage. For multi-configuration builds, like in Visual Studio, you can also specify the configuration with the optional --config <config> flag.
The good part when using the cmake --build command is that it works for all generators (i.e. makefiles and Visual Studio) without needing different commands.
Afterwards I use the installed files to create packages or include them in other projects...
Starting with CMake 3.15, the correct way of achieving this would be using:
cmake --install <dir> --prefix "/usr"
Official Documentation
Starting with CMake 3.21 you can use the --install-prefix option instead of manually setting CMAKE_INSTALL_PREFIX.
The modern equivalent of configure --prefix=DIR && make all install would now be:
cmake -B build --install-prefix=DIR
cmake --build build
cmake --install build
Regarding Bruce Adams answer:
Your answer creates dangerous confusion. DESTDIR is intended for
installs out of the root tree. It allows one to see what would be
installed in the root tree if one did not specify DESTDIR.
PREFIX is the base directory upon which the real installation is
based.
For example, PREFIX=/usr/local indicates that the final destination
of a package is /usr/local. Using DESTDIR=$HOME will install the files
as if $HOME was the root (/). If, say DESTDIR, was /tmp/destdir, one
could see what 'make install' would affect. In that spirit, DESTDIR
should never affect the built objects.
A makefile segment to explain it:
install:
cp program $DESTDIR$PREFIX/bin/program
Programs must assume that PREFIX is the base directory of the final
(i.e. production) directory. The possibility of symlinking a program
installed in DESTDIR=/something only means that the program does not
access files based upon PREFIX as it would simply not work. cat(1)
is a program that (in its simplest form) can run from anywhere.
Here is an example that won't:
prog.pseudo.in:
open("#prefix#/share/prog.db")
...
prog:
sed -e "s/#prefix#/$PREFIX/" prog.pseudo.in > prog.pseudo
compile prog.pseudo
install:
cp prog $DESTDIR$PREFIX/bin/prog
cp prog.db $DESTDIR$PREFIX/share/prog.db
If you tried to run prog from elsewhere than $PREFIX/bin/prog,
prog.db would never be found as it is not in its expected location.
Finally, /etc/alternatives really does not work this way. There are
symlinks to programs installed in the root tree (e.g. vi -> /usr/bin/nvi,
vi -> /usr/bin/vim, etc.).
It is considered bad practice to invoke the actual build system (e.g. via the make command) if using CMake. It is highly recommended to do it like this:
Configure + Generation stages:
cmake -S foo -B _builds/foo/debug -G "Unix Makefiles" -D CMAKE_BUILD_TYPE:STRING=Debug -D CMAKE_DEBUG_POSTFIX:STRING=d -D CMAKE_INSTALL_PREFIX:PATH=/usr
Build and Install stages:
cmake --build _builds/foo/debug --config Debug --target install
When following this approach, the generator can be easily switched (e.g. -G Ninja for Ninja) without having to remember any generator-specific commands.
Note that the CMAKE_BUILD_TYPE variable is only used by single-config generators and the --config argument of the build command is only used by multi-config generators.
Lots of answer, but I figured I'd do a summary to properly group them and explain the differences.
First of all, you can define that prefix one of two ways: during configuration time, or when installing, and that's really up to your needs.
During configuration time
Two options:
cmake -S $src_dir -B $build_dir -D CMAKE_INSTALL_PREFIX=$install_dir
cmake -S $src_dir -B $build_dir --install-prefix=$install_dir # Since CMake 3.21
During install time
Advantage: no need to reconfigure if you want to change it.
Two options:
cmake DESTDIR=$install_dir --build $build_dir --target=install # Makefile only
cmake --install $build_dir --prefix=$install_dir