I have 2 folders "inc" and "lib" in my project which have headers and static libs respectively. How do I tell cmake to use those 2 directories for include and linking respectively?
The simplest way of doing this would be to add
include_directories(${CMAKE_SOURCE_DIR}/inc)
link_directories(${CMAKE_SOURCE_DIR}/lib)
add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # libbar.so is found in ${CMAKE_SOURCE_DIR}/lib
The modern CMake version that doesn't add the -I and -L flags to every compiler invocation would be to use imported libraries:
add_library(bar SHARED IMPORTED) # or STATIC instead of SHARED
set_target_properties(bar PROPERTIES
IMPORTED_LOCATION "${CMAKE_SOURCE_DIR}/lib/libbar.so"
INTERFACE_INCLUDE_DIRECTORIES "${CMAKE_SOURCE_DIR}/include/libbar"
)
set(FOO_SRCS "foo.cpp")
add_executable(foo ${FOO_SRCS})
target_link_libraries(foo bar) # also adds the required include path
If setting the INTERFACE_INCLUDE_DIRECTORIES doesn't add the path, older versions of CMake also allow you to use target_include_directories(bar PUBLIC /path/to/include). However, this no longer works with CMake 3.6 or newer.
You had better use find_library command instead of link_directories. Concretely speaking there are two ways:
designate the path within the command
find_library(NAMES gtest PATHS path1 path2 ... pathN)
set the variable CMAKE_LIBRARY_PATH
set(CMAKE_LIBRARY_PATH path1 path2)
find_library(NAMES gtest)
the reason is as flowings:
Note This command is rarely necessary and should be avoided where there are other choices. Prefer to pass full absolute paths to
libraries where possible, since this ensures the correct library will
always be linked. The find_library() command provides the full path,
which can generally be used directly in calls to
target_link_libraries(). Situations where a library search path may be
needed include: Project generators like Xcode where the user can
switch target architecture at build time, but a full path to a library
cannot be used because it only provides one architecture (i.e. it is
not a universal binary).
Libraries may themselves have other private library dependencies that
expect to be found via RPATH mechanisms, but some linkers are not able
to fully decode those paths (e.g. due to the presence of things like
$ORIGIN).
If a library search path must be provided, prefer to localize the
effect where possible by using the target_link_directories() command
rather than link_directories(). The target-specific command can also
control how the search directories propagate to other dependent
targets.
might fail working with link_directories, then add each static library like following:
target_link_libraries(foo /path_to_static_library/libbar.a)
Related
I'm new(ish) to CMake (meaning off and on over a few years I've been forced to use it even though it's something that's made me question my career path).
I have a folder with an include folder, and a lib folder containing .lib files and their corresponding .dlls for a dependency I'll call "mydep". I need to provide the infrastructure files, mydep-config.cmake, mydep-target.cmake, etc, which will add the includes folders and .lib files to the command line for compiling and linking and then move the .dlls to a specific location.
Can anyone point me to a simple example anywhere on the net that illustrates the way to do this? The CMake documentation is utterly useless.
Thanks!
There are basically 2 files you need to put in the correct location on the file system. Let's assume the library is to import is called ExternLib with version 1.2.3 and compiled for 64 bit. With the and you've got it stored in your repo as
external_dependencies/lib/ExternLib.lib
external_dependencies/bin/ExternLib.dll
external_dependencies/include/ExternLib/ExternHeader.hpp
external_dependencies/include/ExternLib/...
...
and you want the include paths used in your project to be
#include "ExternLib/ExternHeader.hpp"
First of all we'll use the file names externlib-config.cmake and externlib-version-config.cmake to allow the user to use arbitrary case when using find_package.
externlib-version-config.cmake
This file is used to check, if the version of the config script is compatible with the cmake configuration trying to find the package. Adding this file allows you to place multiple versions of the library to be found for different target architectures (e.g. Windows x64, Win32, linux x86_64, ...). find_package won't read the externlib-config.cmake in the same directory, if the version is marked as non-compatible via the version file.
set(PACKAGE_VERSION "1.2.3")
# basically ignore the version passed
set(PACKAGE_VERSION_COMPATIBLE TRUE) # consider every version compatible
#usually you'd add logic for ignoring any unspecified parts of the version here instead of treating unspecified version parts as 0
# we'll keep it simple though
if(PACKAGE_FIND_VERSION VERSION_EQUAL PACKAGE_VERSION)
set(PACKAGE_VERSION_EXACT TRUE) # make version as exact match
endif()
if(NOT WIN32)
set(PACKAGE_VERSION_COMPATIBLE FALSE) # disallow older version
else()
if (NOT CMAKE_SYSTEM_NAME STREQUAL "Windows") # note: we'll ignore the possibility of find_package before the first project() command
set(PACKAGE_VERSION_UNSUITABLE TRUE)
endif()
if(NOT CMAKE_SIZEOF_VOID_P STREQUAL "8") # check for 64 bit
set(PACKAGE_VERSION_UNSUITABLE TRUE)
endif()
externlib-config.cmake
Here we'll put the creation of the actual library in addition to providing any functions/macros/variables the user should have access to. We'll use ExternLib::ExternLib as target name, but you can simply replace this by any name of your choosing unique in your project.
if(NOT TARGET ExternLib::ExternLib) # prevent recreation on multiple uses of find_package
add_library(ExternLib::ExternLib SHARED IMPORTED)
get_filename_component(EXTERNLIB_BASE_DIR ${CMAKE_CURRENT_LISTS_DIR}/../../.. ABSOLUTE)
set(EXTERNLIB_BINARY_DIR ${EXTERNLIB_BASE_DIR} CACHE INTERNAL "Directory containing the dlls for ExternLib")
# add info about locations of the dll/lib files
set_target_properties(ExternLib::ExternLib PROPERTIES
IMPORTED_LOCATION "$CACHE{EXTERNLIB_BINARY_DIR}/ExternLib.dll"
IMPORTED_IMPLIB "${EXTERNLIB_BASE_DIR}/lib/ExternLib.lib"
)
# add include directory information
target_include_directories(ExternLib::ExternLib INTERFACE "${EXTERNLIB_BASE_DIR}/include")
# add dependencies, if required; you may need to use find_package to locate those
# target_link_libraries(ExternLib::ExternLib INTERFACE ...)
endif()
# any helper function/macro definitions should go here, since they may need to get reintroduced
Note: I did ignore the possibility of components of a package being specified here. Any components specifying components for find_package are simply ignored for the script above.
Placement of the files
You'll need to place the files in one of some possible paths below one of the directories mentioned in CMAKE_PREFIX_PATH or in one of the default dirs, see find_package Config Mode Search Procedure.
Note: we'll use a path that isn't documented for windows, since this path would also work for linux. (Boost is doing this too.)
lib/cmake/ExternLib-x64-1.2.3
(You could choose a different suffix to lib/cmake/ExternLib or just use lib/cmake/ExternLib. The search procedure picks up on any directory names which starts with the package name ignoring case, if it expects the lib name.)
Place both the files in this directory. externlib-config.cmake assumes lib is external_dependencies/lib here. Otherwise you may need to adjust EXTERNLIB_BASE_DIR accordingly.
Usage
We'll assume the CMakeLists.txt file is placed in the same directory as external_dependencies
project(...)
...
add_executable(my_exe ...)
...
# this allows the user to pass directories to be searched first via -D option during configuration
list(APPEND CMAKE_PREFIX_PATH ${CMAKE_CURRENT_SOURCE_DIR}/external_dependencies)
find_package(ExternLib REQUIRED)
target_link_libraries(my_exe PRIVATE ExternLib::ExternLib)
# allow vs debugger to find the dll without copying the dlls around
set_target_properties(my_exe PROPERTIES
VS_DEBUGGER_ENVIRONMENT "PATH=${EXTERNLIB_BINARY_DIR};$ENV{PATH}"
)
Looking around on the net I have seen a lot of code like this:
include(FindPkgConfig)
pkg_search_module(SDL2 REQUIRED sdl2)
target_include_directories(app SYSTEM PUBLIC ${SDL2_INCLUDE_DIRS})
target_link_libraries(app ${SDL2_LIBRARIES})
However that seems to be the wrong way about doing it, as it only uses the include directories and libraries, but ignored defines, library paths and other flags that might be returned by pkg-config.
What would be the correct way to do this and ensure that all compile and link flags returned by pkg-config are used by the compiled app? And is there a single command to accomplish this, i.e. something like target_use(app SDL2)?
ref:
include()
FindPkgConfig
First of, the call:
include(FindPkgConfig)
should be replaced with:
find_package(PkgConfig)
The find_package() call is more flexible and allows options such as REQUIRED, that do things automatically that one would have to do manually with include().
Secondly, manually calling pkg-config should be avoid when possible. CMake comes with a rich set of package definitions, found in Linux under /usr/share/cmake-3.0/Modules/Find*cmake. These provide more options and choice for the user than a raw call to pkg_search_module().
As for the mentioned hypothetical target_use() command, CMake already has that built-in in a way with PUBLIC|PRIVATE|INTERFACE. A call like target_include_directories(mytarget PUBLIC ...) will cause the include directories to be automatically used in every target that uses mytarget, e.g. target_link_libraries(myapp mytarget). However this mechanism seems to be only for libraries created within the CMakeLists.txt file and does not work for libraries acquired with pkg_search_module(). The call add_library(bar SHARED IMPORTED) might be used for that, but I haven't yet looked into that.
As for the main question, this here works in most cases:
find_package(PkgConfig REQUIRED)
pkg_check_modules(SDL2 REQUIRED sdl2)
...
target_link_libraries(testapp ${SDL2_LIBRARIES})
target_include_directories(testapp PUBLIC ${SDL2_INCLUDE_DIRS})
target_compile_options(testapp PUBLIC ${SDL2_CFLAGS_OTHER})
The SDL2_CFLAGS_OTHER contains defines and other flags necessary for a successful compile. The flags SDL2_LIBRARY_DIRS and SDL2_LDFLAGS_OTHER are however still ignored, no idea how often that would become a problem.
More documentation here http://www.cmake.org/cmake/help/latest/module/FindPkgConfig.html
If you're using cmake and pkg-config in a pretty normal way, this solution works.
If, however, you have a library that exists in some development directory (such as /home/me/hack/lib), then using other methods seen here fail to configure the linker paths. Libraries that are not found under the typical install locations would result in linker errors, like /usr/bin/ld: cannot find -lmy-hacking-library-1.0. This solution fixes the linker error for that case.
Another issue could be that the pkg-config files are not installed in the normal place, and the pkg-config paths for the project need to be added using the PKG_CONFIG_PATH environment variable while cmake is running (see other Stack Overflow questions regarding this). This solution also works well when you use the correct pkg-config path.
Using IMPORTED_TARGET is key to solving the issues above. This solution is an improvement on this earlier answer and boils down to this final version of a working CMakeLists.txt:
cmake_minimum_required(VERSION 3.14)
project(ya-project C)
# the `pkg_check_modules` function is created with this call
find_package(PkgConfig REQUIRED)
# these calls create special `PkgConfig::<MODULE>` variables
pkg_check_modules(MY_PKG REQUIRED IMPORTED_TARGET any-package)
pkg_check_modules(YOUR_PKG REQUIRED IMPORTED_TARGET ya-package)
add_executable(program-name file.c ya.c)
target_link_libraries(program-name PUBLIC
PkgConfig::MY_PKG
PkgConfig::YOUR_PKG)
Note that target_link_libraries does more than change the linker commands. It also propagates other PUBLIC properties of specified targets like compiler flags, compiler defines, include paths, etc., so, use the PUBLIC keyword with caution.
It's rare that one would only need to link with SDL2. The currently popular answer uses pkg_search_module() which checks for given modules and uses the first working one.
It is more likely that you want to link with SDL2 and SDL2_Mixer and SDL2_TTF, etc... pkg_check_modules() checks for all the given modules.
# sdl2 linking variables
find_package(PkgConfig REQUIRED)
pkg_check_modules(SDL2 REQUIRED sdl2 SDL2_ttf SDL2_mixer SDL2_image)
# your app
file(GLOB SRC "my_app/*.c")
add_executable(my_app ${SRC})
target_link_libraries(my_app ${SDL2_LIBRARIES})
target_include_directories(my_app PUBLIC ${SDL2_INCLUDE_DIRS})
target_compile_options(my_app PUBLIC ${SDL2_CFLAGS_OTHER})
Disclaimer: I would have simply commented on Grumbel's self answer if I had enough street creds with stackoverflow.
Most of the available answers fail to configure the headers for the pkg-config library. After meditating on the Documentation for FindPkgConfig I came up with a solution that provides those also:
include(FindPkgConfig)
if(NOT PKG_CONFIG_FOUND)
message(FATAL_ERROR "pkg-config not found!" )
endif()
pkg_check_modules(<some-lib> REQUIRED IMPORTED_TARGET <some-lib>)
target_link_libraries(<my-target> PkgConfig::<some-lib>)
(Substitute your target in place of <my-target> and whatever library in place of <some-lib>, accordingly.)
The IMPORTED_TARGET option seems to be key and makes everything then available under the PkgConfig:: namespace. This was all that was required and also all that should be required.
There is no such command as target_use. But I know several projects that have written such a command for their internal use. But every project want to pass additional flags or defines, thus it does not make sense to have it in general CMake. Another reason not to have it are C++ templated libraries like Eigen, there is no library but you only have a bunch of include files.
The described way is often correct. It might differ for some libraries, then you'll have to add _LDFLAGS or _CFLAGS. One more reason for not having target_use. If it does not work for you, ask a new question specific about SDL2 or whatever library you want use.
If you are looking to add definitions from the library as well, the add_definitions instruction is there for that. Documentation can be found here, along with more ways to add compiler flags.
The following code snippet uses this instruction to add GTKGL to the project:
pkg_check_modules(GTKGL REQUIRED gtkglext-1.0)
include_directories(${GTKGL_INCLUDE_DIRS})
link_directories(${GTKGL_LIBRARY_DIRS})
add_definitions(${GTKGL_CFLAGS_OTHER})
set(LIBS ${LIBS} ${GTKGL_LIBRARIES})
target_link_libraries([insert name of program] ${LIBS})
Looking around on the net I have seen a lot of code like this:
include(FindPkgConfig)
pkg_search_module(SDL2 REQUIRED sdl2)
target_include_directories(app SYSTEM PUBLIC ${SDL2_INCLUDE_DIRS})
target_link_libraries(app ${SDL2_LIBRARIES})
However that seems to be the wrong way about doing it, as it only uses the include directories and libraries, but ignored defines, library paths and other flags that might be returned by pkg-config.
What would be the correct way to do this and ensure that all compile and link flags returned by pkg-config are used by the compiled app? And is there a single command to accomplish this, i.e. something like target_use(app SDL2)?
ref:
include()
FindPkgConfig
First of, the call:
include(FindPkgConfig)
should be replaced with:
find_package(PkgConfig)
The find_package() call is more flexible and allows options such as REQUIRED, that do things automatically that one would have to do manually with include().
Secondly, manually calling pkg-config should be avoid when possible. CMake comes with a rich set of package definitions, found in Linux under /usr/share/cmake-3.0/Modules/Find*cmake. These provide more options and choice for the user than a raw call to pkg_search_module().
As for the mentioned hypothetical target_use() command, CMake already has that built-in in a way with PUBLIC|PRIVATE|INTERFACE. A call like target_include_directories(mytarget PUBLIC ...) will cause the include directories to be automatically used in every target that uses mytarget, e.g. target_link_libraries(myapp mytarget). However this mechanism seems to be only for libraries created within the CMakeLists.txt file and does not work for libraries acquired with pkg_search_module(). The call add_library(bar SHARED IMPORTED) might be used for that, but I haven't yet looked into that.
As for the main question, this here works in most cases:
find_package(PkgConfig REQUIRED)
pkg_check_modules(SDL2 REQUIRED sdl2)
...
target_link_libraries(testapp ${SDL2_LIBRARIES})
target_include_directories(testapp PUBLIC ${SDL2_INCLUDE_DIRS})
target_compile_options(testapp PUBLIC ${SDL2_CFLAGS_OTHER})
The SDL2_CFLAGS_OTHER contains defines and other flags necessary for a successful compile. The flags SDL2_LIBRARY_DIRS and SDL2_LDFLAGS_OTHER are however still ignored, no idea how often that would become a problem.
More documentation here http://www.cmake.org/cmake/help/latest/module/FindPkgConfig.html
If you're using cmake and pkg-config in a pretty normal way, this solution works.
If, however, you have a library that exists in some development directory (such as /home/me/hack/lib), then using other methods seen here fail to configure the linker paths. Libraries that are not found under the typical install locations would result in linker errors, like /usr/bin/ld: cannot find -lmy-hacking-library-1.0. This solution fixes the linker error for that case.
Another issue could be that the pkg-config files are not installed in the normal place, and the pkg-config paths for the project need to be added using the PKG_CONFIG_PATH environment variable while cmake is running (see other Stack Overflow questions regarding this). This solution also works well when you use the correct pkg-config path.
Using IMPORTED_TARGET is key to solving the issues above. This solution is an improvement on this earlier answer and boils down to this final version of a working CMakeLists.txt:
cmake_minimum_required(VERSION 3.14)
project(ya-project C)
# the `pkg_check_modules` function is created with this call
find_package(PkgConfig REQUIRED)
# these calls create special `PkgConfig::<MODULE>` variables
pkg_check_modules(MY_PKG REQUIRED IMPORTED_TARGET any-package)
pkg_check_modules(YOUR_PKG REQUIRED IMPORTED_TARGET ya-package)
add_executable(program-name file.c ya.c)
target_link_libraries(program-name PUBLIC
PkgConfig::MY_PKG
PkgConfig::YOUR_PKG)
Note that target_link_libraries does more than change the linker commands. It also propagates other PUBLIC properties of specified targets like compiler flags, compiler defines, include paths, etc., so, use the PUBLIC keyword with caution.
It's rare that one would only need to link with SDL2. The currently popular answer uses pkg_search_module() which checks for given modules and uses the first working one.
It is more likely that you want to link with SDL2 and SDL2_Mixer and SDL2_TTF, etc... pkg_check_modules() checks for all the given modules.
# sdl2 linking variables
find_package(PkgConfig REQUIRED)
pkg_check_modules(SDL2 REQUIRED sdl2 SDL2_ttf SDL2_mixer SDL2_image)
# your app
file(GLOB SRC "my_app/*.c")
add_executable(my_app ${SRC})
target_link_libraries(my_app ${SDL2_LIBRARIES})
target_include_directories(my_app PUBLIC ${SDL2_INCLUDE_DIRS})
target_compile_options(my_app PUBLIC ${SDL2_CFLAGS_OTHER})
Disclaimer: I would have simply commented on Grumbel's self answer if I had enough street creds with stackoverflow.
Most of the available answers fail to configure the headers for the pkg-config library. After meditating on the Documentation for FindPkgConfig I came up with a solution that provides those also:
include(FindPkgConfig)
if(NOT PKG_CONFIG_FOUND)
message(FATAL_ERROR "pkg-config not found!" )
endif()
pkg_check_modules(<some-lib> REQUIRED IMPORTED_TARGET <some-lib>)
target_link_libraries(<my-target> PkgConfig::<some-lib>)
(Substitute your target in place of <my-target> and whatever library in place of <some-lib>, accordingly.)
The IMPORTED_TARGET option seems to be key and makes everything then available under the PkgConfig:: namespace. This was all that was required and also all that should be required.
There is no such command as target_use. But I know several projects that have written such a command for their internal use. But every project want to pass additional flags or defines, thus it does not make sense to have it in general CMake. Another reason not to have it are C++ templated libraries like Eigen, there is no library but you only have a bunch of include files.
The described way is often correct. It might differ for some libraries, then you'll have to add _LDFLAGS or _CFLAGS. One more reason for not having target_use. If it does not work for you, ask a new question specific about SDL2 or whatever library you want use.
If you are looking to add definitions from the library as well, the add_definitions instruction is there for that. Documentation can be found here, along with more ways to add compiler flags.
The following code snippet uses this instruction to add GTKGL to the project:
pkg_check_modules(GTKGL REQUIRED gtkglext-1.0)
include_directories(${GTKGL_INCLUDE_DIRS})
link_directories(${GTKGL_LIBRARY_DIRS})
add_definitions(${GTKGL_CFLAGS_OTHER})
set(LIBS ${LIBS} ${GTKGL_LIBRARIES})
target_link_libraries([insert name of program] ${LIBS})
Is it possible to tell cmake to link against a static library instead of shared?
At the top of my CMakeLists.txt I have the following configured:
set(CMAKE_FIND_LIBRARY_SUFFIXES .a ${CMAKE_FIND_LIBRARY_SUFFIXES})
Later, I add a binary, and tell it to link against tcmalloc in release mode:
target_link_libraries(${BIN_NAME} optimized tcmalloc_minimal)
The resulting makefile links aginst the shared version of tcmalloc:
$ make VERBOSE=1 | grep tcmalloc
/usr/bin/c++ ... -Wl,-Bdynamic ltcmalloc_minimal
Further proof:
$ ldd app
...
libtcmalloc_minimal.so.4 => /usr/local/lib/libtcmalloc_minimal.so.4 (0x00007eff89733000)
...
Both static and shared versions of tcmalloc exist:
$ ls -1 /usr/local/lib/libtcmalloc_minimal*
/usr/local/lib/libtcmalloc_minimal.a
/usr/local/lib/libtcmalloc_minimal_debug.a
/usr/local/lib/libtcmalloc_minimal_debug.la
/usr/local/lib/libtcmalloc_minimal_debug.so
/usr/local/lib/libtcmalloc_minimal_debug.so.4
/usr/local/lib/libtcmalloc_minimal_debug.so.4.2.6
/usr/local/lib/libtcmalloc_minimal.la
/usr/local/lib/libtcmalloc_minimal.so
/usr/local/lib/libtcmalloc_minimal.so.4
/usr/local/lib/libtcmalloc_minimal.so.4.2.6
Question:
How can I configure cmake to link against the static version of tcmalloc?
You can create a helper function which sets CMAKE_FIND_LIBRARY_SUFFIXES at function scope (so therefore doesn't affect the parent scope) which searches for the library in question and sets an output variable with the result
function(find_static_library LIB_NAME OUT)
if (WIN32 OR MSVC)
set(CMAKE_FIND_LIBRARY_SUFFIXES ".lib")
elseif (UNIX)
set(CMAKE_FIND_LIBRARY_SUFFIXES ".a")
endif()
find_library(
FOUND_${LIB_NAME}_STATIC
${LIB_NAME}
)
if (FOUND_${LIB_NAME}_STATIC)
get_filename_component(ABS_FILE ${FOUND_${LIB_NAME}_STATIC} ABSOLUTE)
else()
message(SEND_ERROR "Unable to find library ${LIB_NAME}")
endif()
set(${OUT} ${ABS_FILE} PARENT_SCOPE)
endfunction()
You can then call this function from somewhere in your CMakeLists.txt to populate a variable with the location of the library.
Failure to find it results in a hard failure
find_static_library(tcmalloc_minimal TCMALLOC)
You can then use this variable in your call to target_link_libraries and be sure you're linking against the static version
target_link_libraries(${BIN_NAME} optimized ${TCMALLOC})
Here you can see the result:
$ make VERBOSE=1 | grep tcmalloc
/usr/bin/c++ ... /usr/local/lib/libtcmalloc_minimal.a ...
If you only need to support non-Windows platforms, then this old email from the CMake mailing list from one of the Kitware developers gives the simplest method. In essence, use find_library() to find the location of the actual library, favouring static libraries over shared ones by listing them first in the names to look for. i.e.
find_library(TCMALLOC_LIB NAMES libtcmalloc_minimal.a tcmalloc_minimal)
You would then link to the library found in the usual way:
target_link_libraries(${BIN_NAME} ${TCMALLOC_LIB})
You could get smarter about how you define the static library name if you need to support platforms where a static library is named something other than lib???.a. You would use CMAKE_STATIC_LIBRARY_PREFIX and CMAKE_STATIC_LIBRARY_SUFFIX variables for that.
On Windows, the problem is that you cannot distinguish between a static library and the import library for a DLL, as discussed in this old issue in the Kitware bug tracker. Both have the file extension .lib, so you can't use the extension to work out if a particular file is a static library or not, unlike Unix-based platforms where you can.
You have to set your CMAKE_FIND_LIBRARY_SUFFIXES variable in this manner:
set(CMAKE_FIND_LIBRARY_SUFFIXES .a)
because in default CMAKE_FIND_LIBRARY_SUFFIXES there is also .so suffix (and it seems not searching in order of insertion). In order to allow portability other suffixes should be added (see here for default values of CMAKE_FIND_LIBRARY_SUFFIXES on different platforms).
I'm currently trying to get CMake running for my project (on windows). I want to use a custom location where all libraries are installed. To inform CMake about that path I tried to do that:
set(CMAKE_PREFIX_PATH D:/develop/cmake/libs)
But when I try to find the library with
find_library(CURL_LIBRARY NAMES curl curllib libcurl_imp curllib_static)
CMake can't find it.
When I set my prefix path to
set(CMAKE_PREFIX_PATH D:/develop/cmake/libs/curl)
... the library is located.
So my question is:
How can I configure CMake properly to work with a directory structore at a custom location which looks like that:
D:/develop/cmake/libs/
-> libA
-> include
-> lib
-> libB
-> include
-> lib
-> ...
-> include
-> lib
In "include" lie the public headers and in "lib" are the compiled libraries.
edit:
The current workaround for me is, to do this before i search for libraries:
set(CUSTOM_LIBRARY_PATH D:/develop/cmake/libs)
file(GLOB sub-dir ${CUSTOM_LIBRARY_PATH}/*)
foreach(dir ${sub-dir})
if(IS_DIRECTORY ${dir})
set(CMAKE_PREFIX_PATH ${CMAKE_PREFIX_PATH};${dir})
endif()
endforeach()
But that way the default module for boost wont find it until it because the directory structore of boost is a bit different.
boost -> include -> boost-1_50 -> *.hpp
When I move the content if "boost-1_50" to "include" the library can be found but that way it's not possible to handle multiple versions right?
The simplest solution may be to add HINTS to each find_* request.
For example:
find_library(CURL_LIBRARY
NAMES curl curllib libcurl_imp curllib_static
HINTS "${CMAKE_PREFIX_PATH}/curl/lib"
)
For Boost I would strongly recommend using the FindBoost standard module and setting the BOOST_DIR variable to point to your Boost libraries.
I saw that two people put that question to their favorites so I will try to answer the solution which works for me:
Instead of using find modules I'm writing configuration files for all libraries which are installed. Those files are extremly simple and can also be used to set non-standard variables. CMake will (at least on windows) search for those configuration files in
CMAKE_PREFIX_PATH/<<package_name>>-<<version>>/<<package_name>>-config.cmake
(which can be set through an environment variable).
So for example the boost configuration is in the path
CMAKE_PREFIX_PATH/boost-1_50/boost-config.cmake
In that configuration you can set variables. My config file for boost looks like that:
set(boost_INCLUDE_DIRS ${boost_DIR}/include)
set(boost_LIBRARY_DIR ${boost_DIR}/lib)
foreach(component ${boost_FIND_COMPONENTS})
set(boost_LIBRARIES ${boost_LIBRARIES} debug ${boost_LIBRARY_DIR}/libboost_${component}-vc110-mt-gd-1_50.lib)
set(boost_LIBRARIES ${boost_LIBRARIES} optimized ${boost_LIBRARY_DIR}/libboost_${component}-vc110-mt-1_50.lib)
endforeach()
add_definitions( -D_WIN32_WINNT=0x0501 )
Pretty straight forward + it's possible to shrink the size of the config files even more when you write some helper functions. The only issue I have with this setup is that I havn't found a way to give config files a priority over find modules - so you need to remove the find modules.
Hope this this is helpful for other people.
Use CMAKE_PREFIX_PATH by adding multiple paths (separated by semicolons and no white spaces). You can set it as an environmental variable to avoid having absolute paths in your cmake configuration files
Notice that cmake will look for config file in any of the following folders
where is any of the path in CMAKE_PREFIX_PATH and name is the name of the library you are looking for
<prefix>/ (W)
<prefix>/(cmake|CMake)/ (W)
<prefix>/<name>*/ (W)
<prefix>/<name>*/(cmake|CMake)/ (W)
<prefix>/(lib/<arch>|lib|share)/cmake/<name>*/ (U)
<prefix>/(lib/<arch>|lib|share)/<name>*/ (U)
<prefix>/(lib/<arch>|lib|share)/<name>*/(cmake|CMake)/ (U)
In your case you need to add to CMAKE_PREFIX_PATH the following two paths:
D:/develop/cmake/libs/libA;D:/develop/cmake/libB
There is no way to automatically set CMAKE_PREFIX_PATH in a way you want. I see following ways to solve this problem:
Put all libraries files in the same dir. That is, include/ would contain headers for all libs, lib/ - binaries, etc. FYI, this is common layout for most UNIX-like systems.
Set global environment variable CMAKE_PREFIX_PATH to D:/develop/cmake/libs/libA;D:/develop/cmake/libs/libB;.... When you run CMake, it would aautomatically pick up this env var and populate it's own CMAKE_PREFIX_PATH.
Write a wrapper .bat script, which would call cmake command with -D CMAKE_PREFIX_PATH=... argument.
You have one extra level of nesting.
CMAKE will search under $CMAKE_PREFIX_PATH/include for headers and $CMAKE_PREFIX_PATH/libs for libraries.
From CMAKE documentation:
For each path in the CMAKE_PREFIX_PATH list, CMake will check
"PATH/include" and "PATH" when FIND_PATH() is called, "PATH/bin" and
"PATH" when FIND_PROGRAM() is called, and "PATH/lib and "PATH" when
FIND_LIBRARY() is called.
I've encountered a similar scenario. I solved it by adding in this following code just before find_library():
set(CMAKE_PREFIX_PATH /the/custom/path/to/your/lib/)
then it can find the library location.