I have a custom build cmake v3.10.0 which was compiled with a gcc_4.8.3. I am using this custom build cmake to compile a cmake project that must use gcc _4.1.2 because of legacy code.
Executing cmake promted me with an error because it needs to use the libstdc++-IFX.so.6 provided by gcc_4.8.3 which I fixed by adding the path to the correct library in my LD_LIBRARY_PATH before the path to the libraries provided by gcc_4.1.2.
Compiling my project and linking an executable (which is done by c++) results in the linker taking the gcc_4.8.3 stdlibs over the gcc_4.1.2 libs. Is there any way to tell cmake to not use the libraries it needs for himself for my cmake project preferably without touching LD_LIBRARY_PATH?
Edits:
#squareskittles comment: I did read and try everything this post suggest but without any changes. The libstdc++-IFX.so.6 is still taken from gcc_4.8.3
I am building the Poco libraries from source code using cmake, following the instructions from the official website, on OSX High Sierra.
From that I get a bunch of files representing the dynamic libraries with extension *.dylib for example libPocoJSON.23.dylib.
However an external application is looking (in the same path locations), apart from the files created with the build, for other files of the library with a similar name such as to the created ones (they are different only for a d appended to the first part of the name). One example of such file is:
libPocoJSONd.23.dylib
I have found that these files are created with the debug build (while the release build creates only the files without the d extension).
How to perform the build of the debug? Should I look for a flag to active in any of the cmake file or it is a complete different source code?
How to perform the build of the debug?
Use cmake -DCMAKE_BUILD_TYPE=Debug
See CMAKE_BUILD_TYPE for details.
I use find_package(HDF5 COMPONENTS CXX REQUIRED) in my CMAKE script to load the include directories and libraries of HDF5. Cmake tells me
Found HDF5: C:/Program Files/HDF_Group/HDF5/1.10.0/bin/hdf5_cpp.dll (found version "1.10.0") found components: CXX
And generates my visual studio solution.
I also use the library stored in ${HDF5_LIBRARIES} ${HDF5_CXX_LIBRARIES} for my target, but when I try to build it, I get a Linker Error LNK1107 saying that for file hdf5_cpp.dll:
invalid or corrupt file: cannot read at 0x380
which I think is due to the fact that visual studio is trying to directly link against the dll file instead of against the lib file which is in another folder, namely in:
C:\Program Files\HDF_Group\HDF5\1.10.0\lib
Question: Is this a bug in FindHDF or did I configure something wrong?
I have not used hdf5 on windows for some time, but I do recall there being a bug that causes it to link against the dll instead of the lib.
you should manually set (either via the command line cmake -D method, or via the cmake gui)
HDF5_hdf5_LIBRARY=C:\Program Files\HDF_Group\HDF5\1.10.0\lib\libhdf5.lib
HDF5_hdf5_cpp_LIBRARY=C:\Program Files\HDF_Group\HDF5\1.10.0\lib\libhdf5_cpp.lib
etc. - or just
HDF5_LIBRARY=C:\Program Files\HDF_Group\HDF5\1.10.0\lib\libhdf5.lib
HDF5_cpp_LIBRARY=C:\Program Files\HDF_Group\HDF5\1.10.0\lib\libhdf5_cpp.lib
depending on whether you have an older or newer version of FindHDF5 (they change the library var names in newer versions - check the ones used to make sure you get them right - I'm doing this from memory so might have made a mistake)
EDIT:
If the option of manaully specifying the libs is a problem, then there is the option of using FindPackage(HDF5 NO_MODULE) if your hdf5 library was compiled using cmake generated makefilesetc.
When using NO_MODULE, the find package scripts will bypass the findhdf5.cmake script and look for the HDF5Config.cmake or hdf5-config.cmake file that is placed in the relevant subdir of the hdf5 build/install folfer.
This is cross platform friendly and is supported by all newer hdf5 versions - provided they were built using cmake and not ./configure ...
I'm creating a very small project that depends on the following library: https://github.com/CopernicaMarketingSoftware/AMQP-CPP
I'm doing what i always do with third-party libraries: i add their git repo as a submodule, and build them along with my code:
option(COOL_LIBRARY_OPTION ON)
add_subdirectory(deps/cool-library)
include_directories(deps/cool-library/include)
target_link_libraries(${PROJECT_NAME} coollib)
This has worked perfectly for libraries like Bullet, GLFW and others. However, this AMQP library does quite an ugly hack. Their include directory is called include, but in their CMake install() command, they rename it to amqpcpp. And their main header, deps/cool-library/amqpcpp.h, is referencing all other headers using that "fake" directory.
What happens is: when CMake tries to compile my sources which depend on deps/cool-library/amqpcpp.h, it fails because it's not finding deps/cool-library/amqpcpp/*.h, only deps/cool-library/include.
Does anyone have any idea how i can fix this without having to bundle the library into my codebase?
This is not how CMake is supposed to work.
CMake usually builds an entire distributive package of a library once and then installs it to some prefix path. It is then accessible for every other build process on the system by saying "find_package()". This command finds the installed distibution, and all the libs, includes etc. automagically. Whatever weird stuff library implementers did, the resulting distros are more or less alike.
So, in this case you do a lot of unnecessary work by adding includes manually. As you see it can also be unreliable.
What you can do is:
to still have all the dependencies source distributions in submodules (usually people don't bother doing this though)
build and install each dependency package into another (.gitignored) folder within the project or outside by using their own CMakeLists.txt. Let's say with a custom build step in your CMakeLists.txt
use "find_package()" in your CMakeLists.txt when build your application
Two small addition to Drop's answer: If the library set up their install routines correctly, you can use find_package directly on the library's binary tree, skipping the install step. This is mostly useful when you make changes to both the library and the dependent project, as you don't have to run the INSTALL target everytime to make library changes available downstream.
Also, check out the ExternalProject module of CMake which is very convenient for having external dependencies being built automatically as part of your project. The general idea is that you still pull in the library's source as a submodule, but instead of using add_subdirectory to pull the source into your project, you use ExternalProject_Add to build it on its own and then just link against it from your project.
I have the following situation:
I'm working on an application that depends on a number of third party libs, among them wxwidgets
I build the application for multiple target configurations (x86, arm, Linux, Windows) using Linux as my build host system
Due to the above mentioned multiple target configurations, I have chosen to build those third-party libs from source, using CMake's ExternalProject_Add function.
The third-party libs are built 'on-demand' at a location separate from my application's CMAKE_BINARY_DIR so that I can wipe the build tree for my application without having to rebuild the third-party libs (takes a looooong time).
The location of the third-party libs is different depending on what target configuration I build them for (obviously).
I'm quite new to CMake and the problem I currently face is this:
The source files in my application can't find the wx include files and I need to set the correct linker flags to be able to link my application against wxwidgets.
This seems to be handled by a utility 'wx-config' that provides exactly that info as output when run with either the --cppflags or --libs flag. I can not however, figure out how to catch that output and append it to the include dirs and linked libraries I setup from my CMakeLists.txt files.
So basically what I want is.
Build wxwidgets (if it doesn't exist) for the current target configuration
Run wx-config --cppflags and --libs to find out the correct include dirs and linker flags for the current target configuration
Use the info from step 2 when building targets that are my own application
So far I've tried something like this:
# Set a target-configuration-specific location
set(wxwidgetsTop ${MYPROJECT_EXTERNAL_DIR}/wxwidgets/wxwidgets_${MYPROJECT_CURRENT_TARGET_CFG})
# Build the project
ExternalProject_Add( wxWidgetsExternal
PREFIX ${wxwidgetsTop}
URL ${MYPROJECT_EXTERNAL_DIR}/tarballs/wxWidgets-3.0.2.tar.bz2
SOURCE_DIR ${wxwidgetsTop}/src/wxwidgets
CONFIGURE_COMMAND ${configure_cmdline}
BUILD_COMMAND make -j${MYPROJECT_NCPU}
INSTALL_COMMAND make install
)
# Create a wxwidgets target to be used as a dependency from other code
add_library(wxWidgets IMPORTED STATIC GLOBAL)
add_dependencies(wxWidgets wxWidgetsExternal)
# (non-working) attempt to get the correct include dirs and linker
# flags for wxwidgets
add_custom_command(TARGET wxWidgetsExternal
POST_BUILD
COMMAND ${INSTALL_DIR}/bin/wx-config ARGS --cppflags
COMMENT "Running wx-config"
)
but the above does not provide a way to actually use the result from the custom command to append the cppflags and linker options when building the targets that make up my application.
What is a good way to achieve what I want?
I see three different ways of doing this:
Method 1: use find_package
Use wxWidgets as a standalone requirement for your project, and expect the devs to install it before building your project. In your CMakeLists.txt you will need to call find_package(wxWidgets), like this:
find_package(wxWidgets COMPONENTS net gl core base)
if(wxWidgets_FOUND)
include(${wxWidgets_USE_FILE})
# and for each of your dependent executable/library targets:
target_link_libraries(<YourTarget> ${wxWidgets_LIBRARIES})
endif()
This has the advantage of not rebuilding the lib if you rebuild your project, however it requires some work for your user (they need to handle the installation of wxWidgets by hand) and for you (you need to setup include paths / compile definitions / ... by hand).
Method 2: embed wxWidgets
The second option is to bundle wxWidgets in your repo (svn external or git submodule) and usually (re)write the CMakeLists.txt of this lib to be target-oriented. Then, in your top-most CMakeLists.txt, you can do the following:
# for example, if you just need core and net:
target_link_librairies(my_app PUBLIC wxWidgetsCore wxWidgetsNet)
# No need to manually setup include dirs, etc...
To make a CMakeLists.txt target-oriented, you define include directories and other compilation properties for a target, not a directory. Example:
# When defining wxWidgetsCore, for example
add_library(wxWidgetsCore ...)
target_include_directories(wxWidgetsCore PUBLIC someDir)
target_compile_definitions(wxWidgetsCore PUBLIC -pedantic)
target_link_libraries(wxWidgetsCore PUBLIC someLib)
The drawback of this approach is that rebuilding your project will trigger a rebuild of wxWidgets. However, it is possible to trick this by not using "rebuild" but "clean just my app, then build". Here is some insight on how to achieve this.
Method 3: some sort of hybrid
The big drawback of method 2 leads to the third approach: don't put wxWidgets in your project, but create a CMakeLists.txt that will "import" the lib. The idea: you ask your user for the directory where wxWidgets is installed, then this script will setup everything for your project. First, put the CMakeLists.txt here:
/your-project-root
/thirdparty
/wxWidgets
CMakeLists.txt
/dir-where-wxwidgets-is-installed
...
Now, you define an imported target:
# When defining wxWidgetsCore, for example
set(WX_INCLUDE_DIR ${USER_SPECIFIED_WX_ROOT}/include)
add_library(wxWidgetsCore IMPORTED GLOBAL)
set_property(TARGET wxWidgetsCore APPEND PROPERTY
INTERFACE_INCLUDE_DIRECTORIES ${WX_INCLUDE_DIR})
See INTERFACE_INCLUDE_DIRECTORIES and INTERFACE_LINK_LIBRARIES. You need your user to have build wxWidgets somewhere in his system, but from your point of view you just do target_link_libraries(your_app PUBLIC wxWidgets...), as in method 2. The advantage is that this approach is interchangeable with method 2 transparently, and you don't put the whole dependency in your project.
Setting cppflags and linker flags has to be done at CMake time, but you are trying to run wx-config at build time and you are not capturing its output anyway, so your add_custom_command() isn't doing anything useful other than printing things to the build tool's output.
Ideally, you would use the FindwxWidgets module CMake already provides. It requires wxWidgets to already be built (but see further below). Have a look at the CMake documentation for it and see if that at least sounds like what you are trying to achieve manually by using wx-config. If you can get FindwxWidgets to do the job for you, that would be a much cleaner approach.
Getting something to build at configure time so you can use it later on in your CMakeLists.txt file is a bit more tricky. ExternalProject_Add() downloads and builds things at build time, but you need wxWidgets to be built earlier at configure time. I wrote an article recently for how to do at least the downloading part at configure time and you should be able to adapt it to do the whole build at configure time instead. The article uses Google Test as its example and can be found here:
https://crascit.com/2015/07/25/cmake-gtest/
It would be trivial to make it put the wxWidgets build wherever you like, not just in the CMAKE_BINARY_DIR area. That would allow you to have different wxWidgets builds for each build configuration and to be able to wipe out your application's build tree independently of the wxWidgets builds.
Hope that points you in the right direction.
The solution I use checks for wxWidgets installation in the system using find_package, if it's not found, then the script downloads wxWidgets from github and links the program against downloaded library. The lib is installed in the build directory, so only the first build is slow - subsequent builds do not even check wxWidgets sources timestamps, so the process is as fast as building using preinstalled wxWidgets library.
Here's how my script does it:
It quietly checks for wxWidgets installation using find_package(wxWidgets QUIET),
If it's found, the script adds a dummy library wxWidgets_external,
If it's not, then it creates an ExternalProject named wxWidgets_external which downloads, builds and installs the library in the build dir, setting wxWidgets_ROOT_DIR to point to the wxWidgets installation dir,
Then we add another ExternalProject pointing to a folder with the main program's source files and CMakeLists.txt build script. This external projects depends on wxWidgets_external which is either a dummy library in case wxWidgets is preinstalled in the system, or an external project set up to download the library from github,
In the aforementioned CMakeLists.txt we again call find_package, this time with REQUIRED parameter and use the library the standard way (https://docs.wxwidgets.org/trunk/overview_cmake.html). Because we set up the dependencies and variables correctly, this call will use either preinstalled wxWidgets (if it's available) or the one downloaded from github.
There are more quirks to it, but that's the gist of it. The full sample code (tested on Linux, Windows and Mac) is available on github (https://github.com/lszl84/wx_cmake_template).
Also see full blog post which explains this in more detail: https://justdevtutorials.medium.com/wxwidgets-cmake-multiplatform-superbuild-4ea86c4e6eda