I can't figure out how to import my source files, which are in a different directory. The structure of my project looks like this:
root
- src
- core
App.h
App.cpp
CMakelist.txt
CMakelist.txt
main.cpp
CMakelist.txt
My main CMakelist under root looks like this:
cmake_minimum_required(VERSION 3.17)
project(edu)
set(CMAKE_CXX_STANDARD 17)
## add subdirectory with source files
add_subdirectory(src)
add_executable(edu main.cpp)
My CMakelist under src looks like this:
add_subdirectory(core)
And finaly my CMakelist under core looks like this:
set(all_src
App.h
App.cpp
)
target_sources(core ${all_src})
But it doesn't work, I get an error:
Cannot specify sources for target "core" which is not built by this project
How do I fix it? My project is getting quite large and it would be convenient to put all the files in different directories instead of stacking them in add_executable
Thx!
The main issue here is that you never created a target called core. You need to either use either add_executable or add_library to create a target to add files to. You never created a target named core, so you're trying to add these files to something that doesn't exist.
What might help here is implementing Modern CMake, which is an approach to CMake looking at it more akin to a language than a tool. Here's a good beginners guide to structuring your project that should make it far easier to use CMake. If you want to separate your project into modules, I'd recommend making this it's own confined library within your project that will then be included into your main executable as a library. IF you just want to organize your source code, then try the method keeping separate src and include directories. It makes it far easier to organize and sort your code~
Here's some references for Modern CMake:
https://cliutils.gitlab.io/modern-cmake/
https://hsf-training.github.io/hsf-training-cmake-webpage/aio/index.html
https://gist.github.com/mbinna/c61dbb39bca0e4fb7d1f73b0d66a4fd1
If you do not want to use a separate library for core, you can use the following structure in src/CMakeLists.txt:
# core sources
set(core_srcs core/App.cpp core/App.h)
# aux sources
set(aux_srcs aux/stuff.cpp aux/stuff.h)
add_executable(edu main.cpp ${core_srcs} ${aux_srcs})
This lets you organize your CMakeLists.txt by module and keep your sources in different directories, without exploding the number of CMakeLists and sublibraries.
Related
I want to use the following library
https://github.com/gmeuli/caterpillar
It's documentation says that it's a header-only library, and that I should "directly integrate it into my source files with #include <caterpillar/caterpillar.h>." It also depends on a few other libraries, one of which I need to use directly as well.
So far I have done the following:
create cmake project to make an 'executable' (with the vscode extension)
created a 'lib' folder, inside which I did
git clone https://github.com/gmeuli/caterpillar
Then, I did include_directories(lib) in my cmake file.
But #include <caterpillar/caterpillar.h> doesn't quite work in my singular main.cpp file.
I played around with various CMake functions, and it either gave the error "No such file or directory" regarding caterpillar/caterpillar.h itself, or it gave "cannot open source file... dependent of caterpillar/caterpillar.h" depending on how I messed with the cmake file.
For reference:
cat ~/project/main.cpp
#include <caterpillar/caterpillar.hpp>
#include <lorina/lorina.hpp> //how do I include this ? it's in the lib folder of caterpillar itself, or do I need to have a copy of it in my lib folder too
int main()
{
// stuff in lorina:: namespace
// stuff in caterpillar:: namespace
return 0;
}
cat ~/project/CMakeLists.txt
include_directories(lib)
//... rest is stuff like CXX standard, etc etc
tree ~/project
main.cpp
lib/
caterpillar/
build/
cmake generated stuff
CMakeLists.txt
Firstly, modern cmake recommends target_include_directories() instead of old include_directories() for better scope management.
Actually <caterpillar/caterpillar.hpp> is not in $PROJECT_SOURCE_DIR/lib directory. That's why your code not works.
CMakeLists example:
cmake_minimum_required(VERSION 3.22)
project(myproject)
set(CMAKE_CXX_STANDARD 17)
add_executable(my_project main.cpp)
target_include_directories(my_project PRIVATE ${PROJECT_SOURCE_DIR}/lib/caterpillar/include)
# project_src_dir/lib/catepillar/include/ is the directory where you find the headers like <catepillar/catepillar.hpp>
target_include_directories(my_project PRIVATE ${PROJECT_SOURCE_DIR}/lib/caterpillar/lib/lorina)
caterpillar's document describes how to include their headers in a traditional style, assuming the readers could understand this and decide where to put the headers themselves. (which means you don't need the whole git repo but only the "include" dir.)
For this specific problem, the library has provided a detailed CMakeLists.txt for users to include:
cmake_minimum_required(VERSION 3.22)
project(my_project)
set(CMAKE_CXX_STANDARD 17)
add_subdirectory(lib/caterpillar)
# this works because "project_src_dir/lib/catepillar/CMakeLists.txt" exists.
add_executable(my_project main.cpp)
target_link_libraries(my_project PRIVATE caterpillar)
# you need to tell cmake to add all catepillar settings into your project
I have a directory with c++ source and header files. I want to create a CMakeLists.txt to build this as a library for use in other CMake projects that include it as a sub directory.
Structure:
example/
foo.h
foo.cpp
CMakeLists.txt
The problem I run into is CMake doesn't seem to put foo.h anywhere, so getting the parent CMake to know how to find the header file is beguiling me.
Here's my current CMakeLists.txt:
cmake_minimum_required(VERSION 3.8.2)
project(example)
set (CMAKE_CXX_STANDARD 11)
# add library target foo
add_library(foo STATIC foo.cpp)
# tell cmake where to find headers for it
target_include_directories(foo PUBLIC .)
# sad attempt to get it to output the header
set_target_properties(foo PROPERTIES PUBLIC_HEADER foo.h)
I DON'T want to have to do install. The idea here is that the library would be used by other CMake projects, not by the entire system.
Ideally, the foo.h would show up next to libfoo.a in the build directory.
I've tried calling it a "FRAMEWORK", no luck; that only makes is a macOs framework.
I believe I can jury rig this, but methinks there's a best practice out there.
Open to an answer that says "here's a better way", too...
UPDATE
It might help to clarify how I think I want to pull this project into another. I've seen other projects use something like this:
add_subdirectory(<path_to_foo>/foo foo_build)
which causes the foo build to happen in a subdirectory. This allows me to refer to the library using 'foo_build', which is nice and clean. However, I still have to point at the original include directory to get the .h file, which makes me feel like I'm missing something.
It seems like cmake would have a clean solution for this.
I am fairly new to CMake but what I think you want is a 'add_custom_command'.
add_custom_command(TARGET foo.a POST_BUILD COMMAND copy foo.h ${CMAKE_LIBRARY_OUTPUT_DIRECTORY})
That might work.
What you are looking for is the following structure:
example/
- CMakeLists.txt
- src/
- main.c
- sub/
- foo/
- CMakeLists.txt
- src/
- foo/
- foo.c
- foo.h
Your CMakeLists will look like the following
example/CMakeLists.txt
# use modern target-based cmake features
cmake_minimum_required (VERSION 3.0)
# projectname
project (ff1_selfcheck)
add_subdirectory (sub/foo)
# executable to create
add_executable(${PROJECT_NAME}
src/main.c
)
# link libraries
target_link_libraries(${PROJECT_NAME}
PRIVATE
foo # imported target
)
example/sub/foo/CMakeLists.txt
# use modern target-based cmake features
cmake_minimum_required (VERSION 3.0)
# projectname
project (foo)
# executable to create
add_library(${PROJECT_NAME}
src/foo.c
)
# directories where to search for header files
target_include_directories(${PROJECT_NAME}
PUBLIC
source # the headerfiles in source are the includes
)
By using the project name foo in target_link_libraries(...) you refer to the foo library target
Furthermore, by using the PUBLIC keyword in the foo library, your headers (your include directory) is automatically propagated to every CMake project that adds this library via add_subdirectory(...).
Therefore you don't need to copy your headers! CMake >= 2.8.12 is beautiful, isn't it?
If you really want to copy files via CMake, the following would work:
file(COPY srcDir
DESTINATION dstDir
FILES_MATCHING
PATTERN .h
)
Take a look here: https://cmake.org/cmake/help/v3.2/command/file.html
As a general rule for CMake, sources are kept in the source directory and binaries and other generated files are within the build directory. So you wish is not very CMake-ish.
CMake would put headers and libraries according to your wishes when you install the project. Then you can specify what to copy where.
As you don't want to install this module, the best way is to create a package by providing a CMake config file for your project. This means that your project Foo would generate a file FooConfig.cmake which contains the paths to includes and libraries. The other CMake project would use find_package(Foo) to look for the file. By adding a hint to Foo_DIR you can make CMake find your project in a non-standard directory.
Further reading:
CMake documentation about packages
About how to use your library
Note, that configure_file is unrelated to what you wish, the confusing name has historic reasons. You can use this command, but per se it is unrelated.
UPDATE: after the update, I think that you want to use an external project. Behaves like an internal library, but pretty separated. See https://cmake.org/cmake/help/latest/module/ExternalProject.html
you should use generator expression for your "foo" include directory:
target_include_directories(foo PUBLIC
$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR})
And since you don't want install rules not need to also add a $<INSTALL_INTERFACE:include>...
BTW you should don't care to copy the include file in the build directory (supposing you are building out of the source).
ps: if you also generate headers files simply add $<BUILD_INTERFACE:${PROJECT_BINARY_DIR}>
TL;DR
Using CMake, how can I include subdirectories into a library such that they can be included without referencing the directories they reside?
End TL;DR
In attempt to be brief and speak in higher level ideas of what and how, I have removed everything that I consider to be unnecessary details. I will make edits if need be. As such, this is a brief synopsis of my project structure.
ParentDir
--src
----source.cpp
----source.h
----entities_dir
------entity.cpp
------entity.h
------CMakeLists.txt
----CMakeLists.txt
--CMakeLists.txt
--main.cpp
as it currently stands, I have a library defined by the CMakeLists in the src directory. As such, I can include src files in main by #include as apposed to #include "src/file.h" I would like to be able to do the same for my headers that exist within the subdirectories of src.
CMakeLists.txt
cmake_minimum_required(VERSION 3.6)
project(Project)
add_executable(Project ${SOURCE_FILES} main.cpp)
include_directories(src)
add_subdirectory(src)
target_link_libraries(Project Library) # Engine Libraries
src/CMakeLists.txt
file(GLOB SOURCE_FILES *.cpp)
file(GLOB HEADER_FILES *.h)
add_library(Library STATIC ${SOURCE_FILES} ${HEADER_FILES})
main.cpp
#include <source.h> // this works
#include <entity.h> // this does not work but I want it to
#include <entities/entity.h> // this works but I don't want this
int main() {}
I am not sure how to do this exactly. I have tried to GLOB_RECURSE, add_subdirectory(entities), etc. I have also tried creating a library called Entities inside the src/entities/CMakeLists.txt and linking that with link_libraries. None of these have been successful. What is the proper way to accomplish this, because I think I am probably approaching this completely wrong.
You need that path in your compilers header search path, which is achieved with include_directories() call. You can amend your existing include_directories(src) call to be:
include_directories(src src/entities)
Also, this SO post is related and worth reading: Recursive CMake search for header and source files. There is an excerpt there from the CMake website itself recommending against the usage of file(GLOB ...), which lends to recommending against recursive solutions in general. As a heavy user of CMake, I agree with the arguments made against it.
You just need to add:
include_directories(${CMAKE_CURRENT_LIST_DIR})
In each CMakeLists.txt in your your hierarchy.
CMake in itself doesn't compile your project, it only calls your toolchain and passes parameters to it, and your toolchain doesn't 'know' that it is being called by CMake, or the structure of your project. As such, you need to tell the toolchain where to locate include files.
While it is commonplace to have a CMakeLists.txt in every subdirectory, this is by no means a requirement. The CMakeLists.txt in your src directory could contain all instructions necessary to generate a build. Generally, CMakeLists.txt are put at each level to make the structure easier to manage, eg. each directory only needs to know what it needs to do (presumably, with the files in that directory).
I just want to make sure that my understanding about CMakeLists.txt is correct. My dummy project structure:
|-+ dummy
|-+ CMakeLists.txt
|-+ src
|-- CMakeLists.txt
|-- Converter.cpp
|-- Converter.hpp
|-- main.cpp
|-+ tests
|-- CMakeLists.txt
|-- Converter_ut.cpp
|-+ thirdparty
|-+ gmock-1.7.0
My goal is to create build process with CMake. This is my first attempt so I assume that there are some mistakes. It works but I am not sure if I understand everything correctly and I would be thankful if you could share with some comments / suggestions.
dummy/CMakeLists.txt
cmake_minimum_required (VERSION 2.8.11)
project (SUB)
add_subdirectory (src)
add_subdirectory (tests)
cmake_minimum_required is pretty self-explanatory,
project (SUB) sets project variables like ${SUB_SOURCE_DIR} and ${SUB_BINARY_DIR},
add_subdirectory, tells CMake to go and process CMakeLists.txt in the following directories
src/CMakeLists.txt
add_library (Sub
main.cpp
Converter.cpp)
target_include_directories (Sub PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
# Executable
add_executable (converter
Converter.cpp)
target_link_libraries (converter Sub)
add_library, creates library called "Sub" from two source files,
target_include_directories, tells the compiler where are the header files for "Sub" library (is that "PUBLIC" really needed here?),
add_executable, creates "converter" executable from Converter.cpp (why main.cpp is not needed here?),
target_link_libraries, links "Sub" library with "converter" executable
tests/CMakeLists.txt
# GMOCK
set (GMOCK_DIR "../thirdparty/gmock-1.7.0")
add_subdirectory(${GMOCK_DIR} ${CMAKE_BINARY_DIR}/gmock)
include_directories(SYSTEM ${GMOCK_DIR}/include ${GMOCK_DIR}/gtest/include)
# Executable
add_executable (tests
Converter_ut.cpp)
target_link_libraries (tests gmock_main Sub)
set (GMOCK_DIR ...), sets local variable "GMOCK_DIR" with my gmock folder location,
add_subdirectory, tells CMake to jump into gmock location and run their CMakeLists.txt, what is the second argument? {CMAKE_BINARY_DIR}/gmock?
add_executable, creates second executable file
target_link_libraries, links gmock_main library with second executable, "Sub" library is needed here because Converter_ut.cpp
needs to include "Converter.hpp" from src directory
Thank you in advance. I have read plenty of sites / tutorials already but I am still not sure about that.
One more thing - I cannot really imagine project with plenty of source files. Isn't there a better way to add source files to add_library and add_executable functions than listing it manually? Something like "take all *.cpp files from current directory"?
Thanks.
Cmake is not properly a programming language supporting a full paradigm, so use it, but if possible never start creating "a framework with it" (it would be cumbersome without proper syntactic sugar), it is intended to make small scripts not to write thousand lines of code (and despite few good frameworks exists, I tend to not use them: "If I cannot code it in few lines, then it's not job for CMAKE").
The important parts are (not that it is slightly different, I copy-pasted the improved version i still have to commit):
cmake_minimum_required( VERSION 2.8)
project( Infectorpp2)
# find additional cmake scripts (I'm driving away from this)
set( CMAKE_MODULE_PATH "${CMAKE_SOURCE_DIR}/cmake")
# create list of files from a glob
file( GLOB INFECTOR_SOURCE_FILES
"include/Infectorpp/priv/*.cpp")
# create list of files from a glob
file( GLOB INFECTOR_HEADER_FILES
"include/Infectorpp/priv/*.hpp"
"include/Infectorpp/*.hpp")
# or just "add_executable" the dollar "${}" just expand the list
add_library( libInfectorpp2 STATIC
${INFECTOR_SOURCE_FILES}
${INFECTOR_HEADER_FILES})
If you are not using 3rd party libraries, then you do not need to add target_include_directories because for your own application relative paths suffice.
For the testing part you are mostly ok to me, but I would do:
enable_testing()
## details omitted...
# create list of files from a glob
file( GLOB GMOCK_TESTS_SOURCE_FILES
"locationToTestFiles/*.cpp")
# Executable
add_executable (tests
${GMOCK_TESTS_SOURCE_FILES})
target_link_libraries (tests gmock_main Sub)
add_test(tests tests)
Also note that CMAKE is the only reason why I find useful having different extensions for C++ files, because of GLOBS, if you want to exclude some file you have to change its extension (to cc, c++, cxx or what your prefer).
You can do mostly anything following the same pattern, note that with GLOB you have to re-configure CMake to detect newly added files, however still better than adding them manually to build script (and anyway that will not cause a whole recompilation, CMake keep track of data and will avoid to re-compile old files)
Some people find useful adding files manually to CMake scripts because "I can keep old file there". Don't do that, move old files into an "old" folder, or just let your subversion system keep memory of them for you.
You will catch most errors earlier, and you will have a "ready to ship" project (you won't accidentally left wrong files that users will attempt to compile)
Another important point:
Do out of source builds, from your script I guess you are still not doing that.
Till date I still do not really understand what the 'best practice' is for doing this for a CMake project with many subdirectories.
Say I have a project hierarchy as such and each subdirectory has source files in it...
--CMake Project Source dir
|-- SubD1
|-- SubSubD1
|-- SubD2
What I would usually do is to do add_subdirectory(SubD1) and respectively for D2 in the CMakeLists.txt of the root directory and recursively for the subdirectory in the CMakeLists.txt of the SubD1 directory, while declaring variables in each subdirectory and making them visible in the root directory with PARENT_SCOPE.
That means if a file Source2.cpp exists in `SubSubD1', I'd simply do
set(SUBSUBD1_SOURCES Source2.cpp PARENT_SCOPE)
and expect to be able to use SUBSUBD1_SOURCE in my SubD1 directory.
Subsequently, say Source.cpp exists in SubD1, I would do
set(SUBD1_SOURCES ${SUBSUBD1_SOURCES} Source.cpp PARENT_SCOPE)
so that all sources would be visible in root dir.
The problem is of course that the file paths aren't kept when the variables arrive at the root directory. What I'm currently doing is for all source files that I set, I include a ${CMAKE_CURRENT_LIST_DIR}, making it
set(SUBSUBD1_SOURCES ${CMAKE_CURRENT_LIST_DIR}/Source2.cpp PARENT_SCOPE)
and
set(SUBD1_SOURCES ${SUBSUBD1_SOURCES} ${CMAKE_CURRENT_LIST_DIR}/Source.cpp PARENT_SCOPE)
In this case, I could then say, do add_executable(myProg SUBSUBD1_SOURCES) in the root directory of my CMake project.
Are there any better ways of doing this then having to always include a CMake variable in front of all source files?
There is a fourth way if you're using newer versions of CMake.
Take a look at target_sources() command of CMake.
It seems like you are declaring your target in your CMakeLists.txt
add_executable(my_target "subd1/CMakeLists.txt" "subd2/CMakeLists.txt")
add_subdirectory(subd1)
add_subdirectory(subd2)
Instead of propagating your Source files up to the root you can depend on the target you have defined in the root CMakeLists.txt. That means subd1/CMakeLists.txt may look like:
target_sources(my_target PRIVATE "subd1/Source.cpp" "subd1/Source2.cpp")
[EDIT]
As stated in the comments you must give the relative path of the source-files to target_sources(). I use target_sources() because I do not want the explicit source file listing to pollute the targets CMakeLists.txt. Another use case is that target_sources() can be invoked with the PUBLIC or INTERFACE keyword to propagate source files to depending targets. Well I never used target_sources() that way.
[/EDIT]
If you're using IDEs like Visual Studio that support folders you make want to also declare a source_group() in the CMakeLists.txt that contains your target. So the root CMakeLists.txt may look like:
add_executable(my_target "subd1/CMakeLists.txt" "subd2/CMakeLists.txt")
add_subdirectory(subd1)
add_subdirectory(subd2)
...
source_group(subd1 REGULAR_EXPRESSION "subd1/*")
source_group(subd2 REGULAR_EXPRESSION "subd2/*")
I'm using this approach because it leads to much cleaner CMakeLists.txt files, its lesser work and I think the introduction of not needed variables only raises the complexity of your CMakeLists.txt files.
CMakeLists.txt as target sources
I currently use the CMakeLists.txt of the sub folders as source files of the target because otherwise CMake will complain that the add_executable command has no source files given.
There are 3 ways I have used before. I normally prefer the 1st way, but have already used all 3 depending on the use case:
1. You directly name the sources in your root CMakeLists.txt file
set(
SUBD1_SOURCES
"SubD1/SubSubD1/Source2.cpp"
"SubD1/Source.cpp"
)
set(
SUBD2_SOURCES
"SubD2/Source3.cpp"
)
add_executable(myProg ${SUBD1_SOURCES} ${SUBD2_SOURCES})
2. You use OBJECT intermediate libraries to collect/group your sources
SubD1/SubSubD1/CMakeLists.txt:
add_library(SubSubD1Objs OBJECT Source2.cpp)
SubD1/CMakeLists.txt:
add_subdirectory(SubSubD1)
add_library(SubD1Objs OBJECT Source.cpp)
CMakeLists.txt:
add_executable(myProg $<TARGET_OBJECTS:SubSubD1Objs> $<TARGET_OBJECTS:SubD1Objs>)
3. You write your own function() to collect the data (and do the prefixing)
CMakeLists.txt:
function(my_collect_sources)
foreach(_source IN ITEMS ${ARGN})
if (IS_ABSOLUTE "${_source}")
set(source_abs "${_source}")
else()
get_filename_component(_source_abs "${_source}" ABSOLUTE)
endif()
set_property(GLOBAL APPEND PROPERTY GlobalSourceList "${_source_abs}")
endforeach()
endfunction(my_collect_sources)
add_subdirectory(SubD1)
#add_subdirectory(SubD2)
get_property(MY_SOURCES GLOBAL PROPERTY GlobalSourceList)
add_executable(myProg ${MY_SOURCES})
SubD1/CMakeLists.txt:
add_subdirectory(SubSubD1)
my_collect_sources(Source.cpp)
SubD1/SubSubD1/CMakeLists.txt:
my_collect_sources(Source2.cpp)
In your case there's no need to use add_subdirectory since you have only one target which is created in the root CMakeLists.txt. You can simply write this:
add_executable(myProg
SubD1/Source.cpp
SubD1/SubSubD1/Source2.cpp)
Use add_subdirectory for subdirectories creating their own targets so there's no information to pass upwards.