Sometimes I wish I could get a list of the imported targets that belong to a package. Is there a variable that holds them?
This would allow me to write something like this
find_package(Qt5 CONFIG REQUIRED)
message("Imported Qt5 targets: ${Qt5_IMPORTED_TARGETS}") # speculative code
With my current knowledge I have to rely on the documentation of the package to give me the names of all imported targets. Reading them from a variable or property would be easier.
CMake 3.21 introduced the directory property IMPORTED_TARGETS that can be used to get a list of all imported targets. This can be used to derive a list of targets that were imported by a single find_package() call when it is queried before and after the call to find_package(). The code could look something like this:
...
get_property(importTargets DIRECTORY "${CMAKE_SOURCE_DIR}" PROPERTY IMPORTED_TARGETS)
find_package(Qt5 COMPONENTS Core Widgets REQUIRED)
get_property(importTargetsAfter DIRECTORY "${CMAKE_SOURCE_DIR}" PROPERTY IMPORTED_TARGETS)
list(REMOVE_ITEM importTargetsAfter ${importTargets})
message("${importTargetsAfter}")
...
Usually it is good enough to only print the list of all imported targets and guess from the names which of them were imported by the package of interest.
Not precisely what you asked for, but for Qt5, one can do:
cmake_minimum_required(VERSION 3.14)
project(so)
find_package(Qt5 COMPONENTS Core Widgets REQUIRED)
get_cmake_property(_variableNames VARIABLES)
foreach(_variableName ${_variableNames})
if(_variableName MATCHES "^Qt5.*LIBRARIES")
message(STATUS "${_variableName}")
message(STATUS "\t${${_variableName}}")
endif()
endforeach()
Example output:
-- Qt5Core_LIBRARIES
-- Qt5::Core
-- Qt5Gui_EGL_LIBRARIES
-- Qt5::Gui_EGL
-- Qt5Gui_LIBRARIES
-- Qt5::Gui
-- Qt5Gui_OPENGL_LIBRARIES
-- Qt5::Gui_GL
-- Qt5Widgets_LIBRARIES
-- Qt5::Widgets
-- Configuring done
-- Generating done
-- Build files have been written to: /path/to/build
Caveat with approach: One needs to know the component names.
Related
we are working on an embedded project in C/C++ and currently some special needs appeared. Background is there are two compiled libraries which define the same symbols. The compiler allows to create relocatable output modules (with partial linking) and to hide symbols for other compilation units when linking. This also means the output module does not need to have all the symbols defined, this will be done in the final linking. Compiler used is TI LTS1.3.0. I will link directly to the relocatable-section of the manual: https://software-dl.ti.com/codegen/docs/tiarmclang/rel1_3_0_LTS/compiler_manual/linker_description/04_linker_options/linker-output-options.html#stdz0756429
The other part of the project is hardly built on CMake with static libraries which are linked against each other via target_link_libraries.
To get this working I created an "add_executable"-target for each of those both output modules with the same symbols. To those I pass the static-libraries by CMake and get the linked with target_link_libraries.
But now I have a problem. All contents of the static libraries are compiled in each of those output modules. This is unwanted behaviour since as said the final linking does the job of linking the missing stuff - so the static-libraries - to it. This should be done with another add_executable command via CMake as well.
using the target include directories property is not suitable since it only adds the include directories of the given target itself but not of the target the target will include and link against.
So e.g. if you have (pseudo code):
#library A
function( create_libA )
add_library( libA src/A.c )
target_include_directories( libA PUBLIC /inc ) #contains A.h
endfunction()
#library B. different location
function( create_libB LIBA )
add_library( libB src/B.c )
target_link_libraries( libB PUBLIC ${LIBA} )
target_include_directories( libB PUBLIC /inc ) #contains B.h
endfunction()
#target output module with partial linking. Only should link and compile LIBTOBELINKEDIN, not libB. different location.
function( build_part_module LIBB LIBTOBELINKEDIN )
add_executable( outputModuleA src/func.c ) #func.c does include A.h
#following would cause libA and libB also to be compiled and linked in the output due to transitive stuff as I understood, which is unwanted.
target_link_libraries( outputModuleA PUBLIC ${LIBB} ${LIBTOBELINKEDIN} )
#trying this
get_target_property(libBInc ${LIBB} INTERFACE_INCLUDE_DIRECTORIES)
#will only include B.h but not A.h. compilation will fail.
target_include_directories(outputModuleA /inc ${libBInc})
I did not find any solution in Cmake itself to solve this problem. It's confusing me since all the include-directories must be known when the libraries are passed transitive, which is stated in the documentation. But I understand that getting the target include directories of just the passed lib does not include the other ones.
Since target_link_libraries does also not work this way I can only think of a maybe recursive solution? But for that my knowledge is just non-existent.
target_link_libraries with something like HEADERS_ONLY would be helpfull for this job.
Also one can say: if the output module contains all the definitions it won't be a problem, since the linker then knows them and will do its magic.
But this is also unwanted, since we use the generated static-libraries to place them into sections in different regions of the RAM directly. This would then mean to create another linker-script for partial linking which defines sections which then can be again moved. But the more we go this direction, the less we need CMake for it.
Instead of get_target_property use $<TARGET_PROPERTY> generator expression: the property's value, extracted by that expression, already includes transitive propagation:
target_include_directories(outputModuleA PRIVATE
$<TARGET_PROPERTY:libB,INTERFACE_INCLUDE_DIRECTORIES>
)
Note, that generator expressions has limited usage: not all functions expects them. Documentation for target_include_directories clearly states that the command supports generator expressions.
I have a project which is structured like this
project:
-- CMakeLists.txt
-- toolchain.cmake
-- source
-- includes
-- tools
-- arm-toolchain
-- arm-gnueabihf-gcc
-- ...
-- libraries
-- lib1
-- ...
-- CMakeLists.txt
-- lib2
-- ...
-- CMakeLists.txt
I would like to set the compiler for another architecture inside the toolchain.cmake like this:
...
set (CMAKE_C_COMPILER "${CMAKE_SOURCE_DIR}/tools/arm-toolchain/arm-gnueabihf-gcc")
...
Unfortunately the variable ${CMAKE_SOURCE_DIR} does change while compiling the project, at first it is:
CMAKE_SOURCE_DIR=/home/username/project
That's exactly what I expected. Unfortunately, it changes then to
CMAKE_SOURCE_DIR=/home/username/project/build/CMakeFiles/CMakeTmp
Therefore I cannot use ${CMAKE_SOURCE_DIR} as the root of my project-folder, is there another variable which does not change? Or, can I store the first value somehow? The problem is that the toolchain is invoked more than once, therefore a variable in which I store the initial value of ${CMAKE_SOURCE_DIR} is overwritten on the second run.
I found an answer here: https://gitlab.kitware.com/cmake/cmake/issues/16744
CMAKE_CURRENT_LIST_DIR does indeed work in this case.
I would like to create two separate executable from the same source files but with different linker parameters.
With the lines above, I can generate one executable without problem:
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} --specs=nano.specs -T libs.ld -T mem.ld -T sections.ld -L\"${CMAKE_CURRENT_SOURCE_DIR}/script\" -Wl,-Map,${MAP_NAME}")
add_executable(${ELF_NAME} ${PRJ1_SOURCE_FILES} ${PRJ1_HEADER_FILES})
target_link_libraries(${ELF_NAME} PRIVATE liba libb libc)
When I add the following two lines at the end of the code above, I can very well generate the second executable (with the same linker flags) besides the first one without problem:
add_executable(${ELF2_NAME} ${PRJ1_SOURCE_FILES} ${PRJ1_HEADER_FILES})
target_link_libraries(${ELF2_NAME} PRIVATE liba libb libc)
But my problem is that I have to generate the second executable (at the same time with the first one) with different linker parameters. I don't want to use conditional statements to generate one after another. My goal is to automate the process.
How can achieve this?
Use set_target_properties with LINK_FLAGS property. From set_target_properties manual:
set_target_properties(target1 target2 ...
PROPERTIES prop1 value1
prop2 value2 ...)
Set properties on a target.
...
See Properties on Targets for the list of properties known to CMake.
In the link properties on targets we can find LINK_FLAGS:
Additional flags to use when linking this target.
The LINK_FLAGS property can be used to add extra flags to the link step of a target. LINK_FLAGS_ will add to the configuration , for example, DEBUG, RELEASE, MINSIZEREL, RELWITHDEBINFO.
So use something similar to:
set_target_properties(${ELF_NAME} PROPERTIES LINK_FLAGS " --specs=rdimon.specs")
While Kamil answer is good for now, I believe question you're asking for is properly addressed in upcoming CMake v3.13.
target_link_options was introduced for that purpose,
"Specify link options to use when linking a given target. The named must have been created by a command such as add_executable() or add_library() and must not be an ALIAS target."
https://cmake.org/cmake/help/v3.13/command/target_link_options.html#command:target_link_options
At the beginning I had a bunch of CMake projects handled separately: each one had its own target for generating documentation called doc. Now I need to wrap all these projects with a super-project: the problem is that super-project compilation fails complaining that exist multiple targets with the same name doc.
The simple solution I thought is to prepend each doc target with the name of the project, but it does not satisfy me.
I would like not to have to use make projectX_doc when compiling a single sub-project and to have a global target make doc for generating the documentation of all projects when compiling super-project.
Are my requests possible? Is there any mechanism to handle target collision?
well each subproject could verify if there are inside a super project with:
if("^${CMAKE_SOURCE_DIR}$" STREQUAL "^${PROJECT_SOURCE_DIR}$")
set(IS_SUBPROJECT FALSE)
else()
set(IS_SUBPROJECT TRUE)
endif()
Thus in your projects CMakeLists.txt you can do:
if (NOT IS_SUBPROJECT)
set(DOC_TGT doc)
else()
set(DOC_TGT ${PROJECT_NAME}_doc)
endif()
add_custom_target(${DOC_TGT} EXCLUDE_FROM_ALL ...
note: you can merge both snippets to avoid IS_SUBPROJECT variable
In your super project CMakeLists.txt:
add_custom_target(doc EXCLUDE_FROM_ALL
DEPENDS projectX_doc projectY_doc...
So when configuring/building each sub project standalone you have
make doc otherwise when you are in your super project target doc become a meta target...
note: You can also use this trick to modify default options etc...
e.g. gflags:
https://github.com/gflags/gflags/blob/master/CMakeLists.txt#L126
https://github.com/gflags/gflags/blob/master/cmake/utils.cmake#L61
https://github.com/gflags/gflags/blob/master/CMakeLists.txt#L163
I'm trying to call add_library for all files with certain endings.
The dir structure is:
src
| - CMakeLists.txt (1)
| - main.cpp
| - gui
| - CMakeLists.txt (2)
| - some source and header files
So currently all cc files are in the gui directory.
(1) CMakeLists.txt:
file( GLOB_RECURSE my_sources *.cc )
message(STATUS "my_sources = ${my_sources}")
add_subdirectory( gui )
add_library( my_src ${my_SOURCES} )
target_link_libraries( my_src
my_gui
)
qt5_use_modules( my_src Core Gui Widgets)
(2) CMakeLists.txt:
file( GLOB my_gui_sources *.cc)
add_library( my_gui ${my_gui_sources} )
qt5_use_modules( my_gui Core Gui Widgets)
But I keep getting this output:
You have called ADD_LIBRARY for library my_src without any source files. This typically indicates a problem with your CMakeLists.txt file
-- my_sources = /home/bla/bla/src/gui/BorderLayout.cc;...;/home/bla/bla/my/src/gui/MainWindow.cc
-- my_gui_sources = /home/bla/bla/my/src/gui/BorderLayout.cc;...;/home/bla/bla/my/src/gui/MainWindow.cc
-- Configuring done
-- Generating done
-- Build files have been written to: /home/bla/bla/my/build
I know that I currently don't need the add_library in the first CMakeLists.txt, but later I will. I changed the first GLOB to GLOB_RECURSE, so that it finds at least anything.
For some reason your
file( GLOB my_gui_sources *.cc *.h)
Is not finding any file. To debug, you can print:
message(STATUS "my_gui_sources = ${my_gui_sources}")
Probably you want to use GLOB_RECURSE, which search in sub-directories:
file( GLOB_RECURSE my_gui_sources *.cc *.h)
Note that you don't need to add headers files to the source list.
Take care that you will have to rerun cmake every time you add a file to your project (cmake won't be called automatically, thing that instead happens if you touch one of the cmake files).
Link to documentation of command "file"
Edit:
The actual problem is that in your first CMakeLists.txt file you are using inconsistent naming for your variable (note that casing is important), therefore you have to change your add_library command to:
add_library( my_src ${my_sources} )
Note (off the records :-) ): the fact that casing is important for variable names might be confusing because, on the other hand, in cmake command names are case insensitive. It's also sometimes weird to notice that the character - (minus) might be used as part of the variable name: using _ (underscore) is most of the time preferable.