CMP0002 error when compiling different subproject with same target - cmake

I've many sub-folders
home
|
|-library1
|-library2
|
|-libraryn
Every subfolder contains a complete library that can compile by itself (every library has a different mantainer). Until now it works correctly and I compile them using a script.
Now I need to create another library, that depends on existing one. In order to do so, I've created a CMakeLists.txt under home folder, using add_subdirectory command that allows me to compile all libraries.
I've something like
cmake_minimum_required (VERSION 2.8)
add_subdirectory(library1)
add_subdirectory(library2)
...
add_subdirectory(libraryn)
When I try to execute cmake I obtain following error for various libraries:
CMake Error at libraryY/CMakeLists.txt:63 (add_custom_target):
add_custom_target cannot create target "doc" because another target with
the same name already exists. The existing target is a custom target
created in source directory
"/path/to/libraryX". See
documentation for policy CMP0002 for more details.
This happens because in every library we create a doc target in order to compile the Doxygen documentation of the library itself. It works fine when libraryes are compiled one by one, but with the master CMakeLists.txt it seems that I cannot do it.
# Create doc target for doxygen documentation compilation.
find_package (Doxygen)
if (DOXYGEN_FOUND)
set (Doxygen_Dir ${CMAKE_BINARY_DIR}/export/${Library_Version}/doc)
# Copy images folder
file (GLOB IMAGES_SRC "images/*")
file (COPY ${IMAGES_SRC} DESTINATION ${CMAKE_CURRENT_BINARY_DIR}/images)
configure_file (${CMAKE_CURRENT_SOURCE_DIR}/Doxyfile ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile #ONLY)
add_custom_target (doc
${DOXYGEN_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile
WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
COMMENT "Generating doxygen documentation" VERBATIM
)
else (DOXYGEN_FOUND)
message (STATUS "Doxygen must be installed in order to compile doc")
endif (DOXYGEN_FOUND)
Is there a way to compile these project at once without modify this target?

If you don't want to modify anything so you can build all this projects as subprojects, then you can use ExternalProject_Add to build and install dependencies.
option
Alternatively you can use option command to exclude doc target from build:
# Foo/CMakeLists.txt
option(FOO_BUILD_DOCS "Build doc target for Foo project" OFF)
# ...
if(DOXYGEN_FOUND AND FOO_BUILD_DOCS)
add_custom_target(doc ...)
endif()
# Boo/CMakeLists.txt
option(BOO_BUILD_DOCS "Build doc target for Boo project" OFF)
# ...
if(DOXYGEN_FOUND AND BOO_BUILD_DOCS)
add_custom_target(doc ...)
endif()

if (NOT (TARGET DOCUMENTATION))
add_custom_target(DOCUMENTATION COMMENT "workaround for multi-dependencies project")
add_dependencies(DOCUMENTATION DOCUMENTATION_${PROJECT_NAME})
endif()

Related

Create CMake/CPack <Library>Config.cmake for shared library

I have the simplest possible c-library which builds and is packed using the following CMakeLists.txt:
cmake_minimum_required(VERSION 3.5)
project (libfoo C)
add_library(foo SHARED impl.c)
target_link_libraries(foo)
install(TARGETS foo LIBRARY DESTINATION lib/)
install(FILES public_header.h DESTINATION include/libfoo)
set(CPACK_GENERATOR "TGZ")
include(CPack)
Working example is located here: https://github.com/bjarkef/cmake-simple/tree/master/libfoo
I execute mkdir -p build; (cd build/; cmake ../; make all package;) to build a .tar.gz package with the compiled shared library along with its public header file. This is all working fine.
Now I wish to modify the CMakeLists.txt to create the FooConfig.cmake and FooConfigVersion.cmake files needed for CMake find_package in a different project to find the foo library. How do I do this?
I have discovered I should used the CMakePackageConfigHelpers: configure_package_config_file and write_basic_package_version_file, and I should create a FooLibraryConfig.cmake.in file. However I cannot figure out how to put it all together.
Note that it is important the the resulting .cmake files only contains relative paths.
I have cmake module included in the top level CmakeList.txt:
# Generate and install package config files
include(PackageConfigInstall)
Within the generic PackageConfigInstall.cmake file, the config files are created from the cmake.in files, and installed. This module can be reused for other packages.
include(CMakePackageConfigHelpers)
# Generate package config cmake files
set(${PACKAGE_NAME}_LIBRARY_NAME ${CMAKE_SHARED_LIBRARY_PREFIX}${PACKAGE_NAME}${CMAKE_STATIC_LIBRARY_SUFFIX})
configure_package_config_file(${PACKAGE_NAME}-config.cmake.in
${CMAKE_CURRENT_BINARY_DIR}/${PACKAGE_NAME}-config.cmake
INSTALL_DESTINATION ${CMAKE_INSTALL_DIR}/${PACKAGE_NAME}
PATH_VARS LIB_INSTALL_DIR INCLUDE_INSTALL_DIR APP_INCLUDE_INSTALL_DIR )
configure_file(${PACKAGE_NAME}-config-version.cmake.in ${CMAKE_CURRENT_BINARY_DIR}/${PACKAGE_NAME}-config-version.cmake #ONLY)
# Install package config cmake files
install(
FILES
${CMAKE_CURRENT_BINARY_DIR}/${PACKAGE_NAME}-config.cmake
${CMAKE_CURRENT_BINARY_DIR}/${PACKAGE_NAME}-config-version.cmake
DESTINATION
${CMAKE_INSTALL_DIR}/${PACKAGE_NAME}
COMPONENT
devel
)
You'll need a package file for your library, such as your_lib-config.cmake.in, which will become your_lib-config.cmake. This will contain the include and library variables that can be used.
get_filename_component(YOUR_LIB_CMAKE_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
# flag required by CMakePackageConfigHelpers
#PACKAGE_INIT#
set_and_check(YOUR_LIB_INCLUDE_DIR #PACKAGE_YOUR_LIB_INCLUDE_INSTALL_DIR#/hal)
set_and_check(YOUR_LIB_LIBRARY #PACKAGE_LIB_INSTALL_DIR#/#CMAKE_STATIC_LIBRARY_PREFIX##PROJECT_NAME_LIB##CMAKE_STATIC_LIBRARY_SUFFIX#)
set_and_check(YOUR_LIB_LIBRARIES #PACKAGE_LIB_INSTALL_DIR#/#CMAKE_STATIC_LIBRARY_PREFIX##PROJECT_NAME_LIB##CMAKE_STATIC_LIBRARY_SUFFIX#)
You'll also want a config-version.cmake.in file like this:
set(PACKAGE_VERSION #PACKAGE_VERSION#)
# Check whether the requested PACKAGE_FIND_VERSION is compatible
if("${PACKAGE_VERSION}" VERSION_LESS "${PACKAGE_FIND_VERSION}")
set(PACKAGE_VERSION_COMPATIBLE FALSE)
else()
set(PACKAGE_VERSION_COMPATIBLE TRUE)
if ("${PACKAGE_VERSION}" VERSION_EQUAL "${PACKAGE_FIND_VERSION}")
set(PACKAGE_VERSION_EXACT TRUE)
endif()
endif()
There's quite a bit to the packaging scripts to get it all to work just right. I went through a lot of trial and error to finally get something that works on different targets (both linux server and embedded target). I might have left something out, so please just comment and I'll update answer.

Making a CMake library accessible by other CMake packages automatically

I have one project that produces a library:
project (myCoolLibrary)
ADD_LIBRARY(my_cool_library SHARED ${mysources_SRC})
And another project that should be using this library:
find_package (myCoolLibrary REQUIRED)
INCLUDE_DIRECTORIES("${myCoolLibrary_INCLUDE_DIRS}" )
add_executable(myCoolExe ${my_sources_SRC} )
TARGET_LINK_LIBRARIES(myCoolExe ${myCoolLibrary_LIBRARIES} )
Is there a way that I can change the first file so that the second file works automatically? That by running CMake on the first file and then running make on the output, then running CMake on the second file, CMake is able to find the package?
An answer where I just give the address of where the first project is built to the second package is also acceptable.
Taking the code found in a blog post by #daniperez - Use CMake-enabled libraries in your CMake project (III) - I've come up with the following minimal solution:
myCoolLibrary/CMakeLists.txt
cmake_minimum_required(VERSION 3.3)
project(myCoolLibrary)
function(my_export_target _target _include_dir)
file(
WRITE "${CMAKE_CURRENT_BINARY_DIR}/${_target}Config.cmake"
"
include(\"\$\{CMAKE_CURRENT_LIST_DIR\}/${_target}Targets.cmake\")
set_property(
TARGET ${_target}
APPEND PROPERTY
INTERFACE_INCLUDE_DIRECTORIES \"${_include_dir}\"
)
"
)
export(TARGETS ${_target} FILE "${CMAKE_CURRENT_BINARY_DIR}/${_target}Targets.cmake")
# NOTE: The following call can pollute your PC's CMake package registry
# See comments/alternatives below
export(PACKAGE ${_target})
endfunction(my_export_target)
...
add_library(${PROJECT_NAME} SHARED ${mysources_SRC})
my_export_target(${PROJECT_NAME} "${CMAKE_CURRENT_SOURCE_DIR}")
myCoolExe/CMakeLists.txt
cmake_minimum_required(VERSION 3.3)
project(myCoolExe)
find_package(myCoolLibrary REQUIRED)
...
add_executable(${PROJECT_NAME} ${my_sources_SRC})
target_link_libraries(${PROJECT_NAME} myCoolLibrary)
To make it reusable I have packed everything into my_export_target(). And I'm friend of self-propagating properties like INTERFACE_INCLUDE_DIRECTORIES.
As commented by #ruslo, using export(PACKAGE ...) can pollute your package registry. So alternatively you can:
Write the target configuration files directly to some dedicated place specific for a certain toolchain
See e.g. How to install your custom CMake-Find module and 0003659: FIND_PACKAGE command improvements.
Set CMAKE_MODULE_PATH via the second project's CMake command line (injecting the search path(s) from the outside). If you are building the two projects anyway with a build script, then this is the most direct way to propagate the module search path(s).
Additional References
export()
CMake/Tutorials/Package Registry
Unable to find Eigen3 with CMake
How to instruct CMake to use the build architecture compiler

custom target as a target library in cmake

I have a custom target that is in fact an externally generated library that I want to integrate in my build.
add_custom_command(
OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/liblib2.a
COMMAND make -f ${CMAKE_CURRENT_SOURCE_DIR}/makefile liblib2.a)
add_custom_target(lib2
DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/liblib2.a)
How can I tell cmake that this target is in fact a library, where it can be found and where are the headers ?
To be clear : I don't want the upper CMakeList using this library having to manually specify include folders and the library location folder It must be done automatically (from the target properties).
On a standard cmake library I would just have to add the INTERFACE_INCLUDE_DIRECTORIES property in the library CMakeLists to make cmake link my app with the relevant -I and -L gcc parameters :
set_target_properties(lib1
PROPERTIES
INTERFACE_INCLUDE_DIRECTORIES
${CMAKE_CURRENT_SOURCE_DIR})
But in the case of a custom target I don't know how to to it.
Any clue ?
Thanks for your help.
Thanks to zaufi it works!
For others who may be interested in embedded externally build target inside cmake here is what I did :
cmake_minimum_required(VERSION 2.8)
SET(LIB_FILE ${CMAKE_CURRENT_SOURCE_DIR}/bin/liblib2.a)
SET(LIB_HEADER_FOLDER ${CMAKE_CURRENT_SOURCE_DIR}/include)
# how to build the result of the library
add_custom_command(OUTPUT ${LIB_FILE}
COMMAND make
WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
# create a target out of the library compilation result
add_custom_target(lib2_target DEPENDS ${LIB_FILE})
# create an library target out of the library compilation result
add_library(lib2 STATIC IMPORTED GLOBAL)
add_dependencies(lib2 lib2_target)
# specify where the library is and where to find the headers
set_target_properties(lib2
PROPERTIES
IMPORTED_LOCATION ${LIB_FILE}
INTERFACE_INCLUDE_DIRECTORIES ${LIB_HEADER_FOLDER})
Now in a CMakeLists.txt I can do somthing like
add_subdirectory(${ROOT_DIR}/lib1 bin/lib1)
add_subdirectory(${ROOT_DIR}/lib2 bin/lib2)
add_executable(app app.c )
target_link_libraries(app lib1 lib2)
No need to specify where the .a and the .h are.
You can use add_library() and tell that it actually imported. Then, using set_target_properties() you can set required INTERFACE_XXX properties for it. After that, you can use it as an ordinal target like every other built by your project.
Thank you for posting the solution. I have wrapped your snippet in a function:
function(add_external_library)
set(options)
set(oneValueArgs TARGET WORKING_DIRECTORY OUTPUT COMMENT)
set(multiValueArgs COMMAND INCLUDE_DIRS)
cmake_parse_arguments(ARGS "${options}" "${oneValueArgs}" ${multiValueArgs}" ${ARGN})
# Specify how to build the result of the library
add_custom_command(OUTPUT "${ARGS_OUTPUT}"
COMMAND ${ARGS_COMMAND}
WORKING_DIRECTORY "${ARGS_WORKING_DIRECTORY}"
COMMENT "${ARGS_COMMENT}")
# Create a target out of the library compilation result
add_custom_target(${ARGS_TARGET}_target DEPENDS ${ARGS_OUTPUT})
# Create an library target out of the library compilation result
add_library(${ARGS_TARGET} STATIC IMPORTED GLOBAL)
add_dependencies(${ARGS_TARGET} ${ARGS_TARGET}_target)
# Specify where the library is and where to find the headers
set_target_properties(${ARGS_TARGET}
PROPERTIES
IMPORTED_LOCATION "${ARGS_OUTPUT}"
INTERFACE_INCLUDE_DIRECTORIES "${ARGS_INCLUDE_DIRS}")
endfunction()
# Example
add_external_library(TARGET YourLib
COMMAND /bin/bash compile_your_lib.sh
WORKING_DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}"
OUTPUT "output/yourlib.a"
INCLUDE_DIRS "include/a" "include/b"
COMMENT "Building YourLib")
add_executable(YourExe)
target_link_libraries(YourExe YourLib)

How to make cMake use Debug compilation mode for only a subset of directories in a project?

Rephrased the question.
I have the following problem:
My project has several binaries and libraries that reside in distinct sub-directories under the main project folder.
It is useful to be able to debug only a subset of them, without recompiling the whole project in Debug mode.
I want to be able to only change the compilation mode for this subset in a semi-automatic fashion.
How can I accomplish this using CMake?
If you change the build type, the whole project will be recompiled from scratch. Usually you keep 2 separated build tree, one configured debug and one configured release.
Note that CMAKE_BUILD_TYPE can be set from command line or from cmake-gui, you shouldn't set it in the CMakeLists.txt file.
To compile only some part of your project in debug mode, you can proceed as follow. In your main CMakeLists.txt, before including any subdirectory, define the following macro:
macro (CHECK_IF_DEBUG)
if (NOT (CMAKE_BUILD_TYPE MATCHES Debug))
get_filename_component(THIS_DIR ${CMAKE_CURRENT_SOURCE_DIR} NAME)
STRING(REGEX REPLACE " " "_" THIS_DIR ${THIS_DIR}) #Replace spaces with underscores
if (DEFINED DEBUG_${THIS_DIR})
message(STATUS "Note: Targets in directory ${THIS_DIR} will be built Debug") #A reminder
set (CMAKE_BUILD_TYPE Debug)
endif()
endif()
endmacro()
Then, in each subdirectory add (at the beginning of the CMakelists.txt) the macro call
CHECK_IF_DEBUG()
When you need to temporarily debug a part (subdirectory) of your project, open your project in cmake-gui, and define a variable ("Add Entry") with name DEBUG_<DirectoryName>. You can define multiple ones. If your directory name contains spaces, in the variable name replace them with underscores. Don't forget to click Configure and Generate from cmake-gui to make the change effective. The value assigned to the variable is not important, it can be left empty.
When you are finished debugging, go back to cmake-gui and remove the corresponding entries. Don't forget to Configure and Generate.
I have tested it in a small project and it seems to work properly.
Note: If you create more than one target (add_library or add_executable) in the same CMakeLists.txt (=in the same subdirectory), I haven't found a way to have one target built in one way and one target in another: the only thing that seems to count is the value of the CMAKE_BUILD_TYPE directory when CMake is finished parsing the file.
In answer to your comment, you can have a reminder printed at build time by adding in the block the following line:
add_custom_target(info_${THIS_DIR} ALL COMMAND echo Targets in directory ${THIS_DIR} are built Debug)
See add_custom_target.
The solution I came with is as follows:
I created a macro that will read a config file in the binary directory and set the compilation type based on its content.
When this file changes, cMake will rerun on that directory only and it will recompile it also, because its dependencies changed. This is exactly what I needed.
The macro follows:
macro(set_buildmode _local_app_name)
if(NOT EXISTS ${CMAKE_CURRENT_BINARY_DIR}/BUILDMODE)
file(WRITE ${CMAKE_CURRENT_BINARY_DIR}/BUILDMODE ${CMAKE_BUILD_TYPE})
message(" *** Creating file 'BUILDMODE' with type '${CMAKE_BUILD_TYPE}' for '${_local_app_name}'")
endif()
configure_file( ${CMAKE_CURRENT_BINARY_DIR}/BUILDMODE
${CMAKE_CURRENT_BINARY_DIR}/BUILDMODE.junk)
file(READ ${CMAKE_CURRENT_BINARY_DIR}/BUILDMODE CMAKE_BUILD_TYPE)
string(STRIP ${CMAKE_BUILD_TYPE} CMAKE_BUILD_TYPE)
endmacro()
To make sure I always know if I have compiled in any other mode other than release, I also have this macro:
macro(add_buildmode_message _local_app_name_full)
get_filename_component(_local_app_name ${_local_app_name_full} NAME)
add_custom_target(Checking_BUILDMODE_for_${_local_app_name} ALL
COMMAND bash -c "if [ \"${CMAKE_BUILD_TYPE}\" != \"Release\" ] ; then echo -e \" ${BoldRed}${_local_app_name} was built with type '${CMAKE_BUILD_TYPE}'${ColourReset}\" ; fi"
VERBATIM)
endmacro()
Here is an example of its usage:
set(appname example)
###### Call set_buildmode here
set_buildmode(${appname})
set(${appname}_SRCS
example.cpp
main.cpp)
set(${appname}_HDRS
example.h)
set(${appname}_LIBS)
set(BUILD_SHARED_LIBS ON)
execute_process(COMMAND ln -frs ${${appname}_HDRS} ${CMAKE_BINARY_DIR}/include/
WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
set(MYLIB_VERSION_MAJOR 2)
set(MYLIB_VERSION_MINOR 1)
set(MYLIB_VERSION_PATCH 0)
set(MYLIB_VERSION_STRING
${MYLIB_VERSION_MAJOR}.${MYLIB_VERSION_MINOR}.${MYLIB_VERSION_PATCH})
add_library(${appname} ${${appname}_SRCS})
target_link_libraries (${appname} ${${appname}_LIBS} ${CMAKE_THREAD_LIBS_INIT})
##### Add the fake target for checking the build mode
add_buildmode_message(${appname})
set_target_properties(${appname} PROPERTIES VERSION ${MYLIB_VERSION_STRING}
SOVERSION ${MYLIB_VERSION_MAJOR})
install(TARGETS ${appname} DESTINATION lib)

"make dist" equivalent in CMake

According to FAQ, CMake doesn't create a make dist target and source package can be created using CPack. But CPack just makes a tarball of the source directory with all files that don't match patterns in CPACK_SOURCE_IGNORE_FILES.
On the other hand, make dist generated by autotools bundles only files it knows about, mostly sources needed for compilation.
Anyone has a smart way of making a source package with only files that are specified in CMakeLists.txt (and its dependencies)?
I've been thinking about this for a while and I won't pretend I can simulate a make dist without having this directly supported by CMake itself.
The problem is that you can add a lot of file dependencies with CMake on the one side (e.g. to pre-build libraries) and on the other side CMake does not know about dependencies directly checked by the generated build environment itself (e.g. any header dependencies).
So here is a code that just collects all CMakeList.txt and source files given with any build targets:
function(make_dist_creator _variable _access _value _current_list_file _stack)
if (_access STREQUAL "MODIFIED_ACCESS")
# Check if we are finished (end of main CMakeLists.txt)
if (NOT _current_list_file)
get_property(_subdirs GLOBAL PROPERTY MAKE_DIST_DIRECTORIES)
list(REMOVE_DUPLICATES _subdirs)
foreach(_subdir IN LISTS _subdirs)
list(APPEND _make_dist_sources "${_subdir}/CMakeLists.txt")
get_property(_targets DIRECTORY "${_subdir}" PROPERTY BUILDSYSTEM_TARGETS)
foreach(_target IN LISTS _targets)
get_property(_sources TARGET "${_target}" PROPERTY SOURCES)
foreach(_source IN LISTS _sources)
list(APPEND _make_dist_sources "${_subdir}/${_source}")
endforeach()
endforeach()
endforeach()
add_custom_target(
dist
COMMAND "${CMAKE_COMMAND}" -E tar zcvf "${CMAKE_BINARY_DIR}/${PROJECT_NAME}.tar.gz" -- ${_make_dist_sources}
COMMENT "Make distribution ${PROJECT_NAME}.tar.gz"
WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}"
)
message("_make_dist_sources = ${_make_dist_sources}")
else()
# else collect subdirectories in my source dir
file(RELATIVE_PATH _dir_rel "${CMAKE_SOURCE_DIR}" "${_value}")
if (NOT _dir_rel MATCHES "\.\.")
set_property(GLOBAL APPEND PROPERTY MAKE_DIST_DIRECTORIES "${_value}")
endif()
endif()
endif()
endfunction()
variable_watch("CMAKE_CURRENT_LIST_DIR" make_dist_creator)
Note: The used BUILDSYSTEM_TARGETS property needs at least CMake version 3.7
I see the code above as an starting point and prove of concept. You could add libraries, headers, etc. on a need-by basis, but you should probably just tweak cpack to do your bidding.
As a starting point see e.g. the link #usr1234567 provided in the comments.
References
Get all source files a target depends on in CMake
Simon is correct above but does not give a full answer. With git you can generate a compatible tar ball archive with the git archive command.
This example with the version is compatible with make dist of yesteryear.
git archive --format=tar.gz -o my-repo-0.01.tar.gz --prefix=my-repo-0.01/ master
See: https://gist.github.com/simonw/a44af92b4b255981161eacc304417368