I am trying to organize libs and targets in separate (parallel) dirs. This seems to be a natural way to organize files to me, but I am really new and not sure. I was able to replicate the on-line CMake tutorials but it includes libs in a sub directory rather than a parallel one.
In the coding below, I try to define variables for the lib sources /headers with parent scope, then try to add a library in the root directory and make a custom target depend on it. I then link the lib to the target in sub dir. Obviously I missed something and I can't figure it out.
Below is my directory structure:
root/
root/lib/test.cpp, test.h
root/app1/app.cpp, app.h
In the root/CMakeLists.txt:
...
add_subdirectory(lib)
add_library (lib_test STATIC
${lib_test_sources}
${lib_test_headers}
)
add_custom_target(test DEPENDS lib_test)
In the root/lib/CMakeLists.txt
set(lib_test_sources
${lib_test_sources}
${CMAKE_CURRENT_SOURCE_DIR}/test.cpp
PARENT_SCOPE
)
set(lib_test_headers
${lib_test_headers}
${CMAKE_CURRENT_SOURCE_DIR}/test.h
PARENT_SCOPE
)
In the root/app1/CMakeLists.txt:
add_executable(test_app app.cpp)
target_link_libraries(test_app lib_test)
Normally the library definition is put in the subdir as well as the source definitions, i.e. move the
add_library (lib_test STATIC
${lib_test_sources}
${lib_test_headers}
)
into the root/lib/CMakeLists.txt. Then you would not need the PARENT_SCOPE and it should work as well.
Note that you might also need to add
include_directories("lib")
in case the app.cpp includes test.h, to find the headers located in the subdir.
Related
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 have a CMake project that looks like this:
project/
CMakeLists.txt
subprojectA/
CMakeLists.txt
include/
headerA.hpp
src/
libraryA.cpp
subprojectB/
CMakeLists.txt
src/
mainB.cpp
The "library" subproject, A, is compiled as a static library, becoming libsubprojectA.a. The "main" project, B, is compiled as a binary and depends on the library. mainB.cpp includes a reference to headerA.hpp.
Here is subprojectA/CMakeLists.txt:
project(SubProjectA)
include_directories(include)
add_library(subprojectA STATIC src/libraryA.cpp)
set(${PROJECT_NAME}_INCLUDE_DIRS
${PROJECT_SOURCE_DIR}/include
CACHE INTERNAL "${PROJECT_NAME}: Include Directories" FORCE)
And here is subprojectB/CMakeLists.txt:
project(SubProjectB)
include_directories(${SubProjectA_INCLUDE_DIRS})
add_executable(mainBinary src/mainB.cpp)
target_link_libraries(mainBinary subprojectA)
The main Project CMakeLists.txt looks like:
project(Project)
add_subdirectory(subprojectB)
add_subdirectory(subprojectA)
Note that subprojectB, the main project, is listed before subprojectA.
Here's the problem. When I first run "cmake" on this project, ${SubProjectA_INCLUDE_DIRS} is not set within SubProjectB.
What I think is happening is that the CMakeLists for SubProjectB loads first, when ${SubProjectA_INCLUDE_DIRS} has not yet been set. It sets its own include path to an empty string as a result. However, even though libsubprojectA.a gets built successfully before mainBinary, the include path was already set empty beforehand. As a result, I get this error when trying to make mainBinary:
subprojectB/src/mainB.cpp:1:23: fatal error: headerA.hpp: No such file or directory
#include "headerA.hpp"
^
It's a workaround to put subprojectA before subprojectB in the main Project CMakeLists in the declarative world of CMake. What I really want is to know the proper way to indicate to CMake that the include_directories(${SubProjectA_INCLUDE_DIRS}) line depends on the definitions that exist inside SubProjectA's CMakeLists. Is there a better way to do this?
If you want to express that include directory subprojectA/include is an interface of the library subprojectA, attach this property to the target with target_include_directories command:
subprojectA/CMakeLists.txt:
project(SubProjectA)
add_library(subprojectA STATIC src/libraryA.cpp)
# PUBLIC adds both:
# 1) include directories for compile library and
# 2) include directories for library's interface
target_include_directories(subprojectA PUBLIC include)
So any executable(or other library) which linked with subprojectA will have this include directory automatically:
subprojectB/CMakeLists.txt:
project(SubProjectB)
add_executable(mainBinary src/mainB.cpp)
target_link_libraries(mainBinary subprojectA)
Of course, for use last command properly you need to process directory with library before one with executable:
CMakeLists.txt:
project(Project)
add_subdirectory(subprojectA)
add_subdirectory(subprojectB)
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.
I have a folder net like:
main
headers
cls1.hpp cls2.hpp ...
sources
cls1.cpp cls2.cpp ...
resources
r1.hpp r2.hpp ...
I have tried more cmake methods to link the files, like
set(SRC ${SRC})
in parent dir and
set(SRC ${SRC} ${CMAKE_CURRENT_SOURCE_DIR}/cls1.cpp PARENT_SCOPE)
in subdir
OR
file(GLOB_RECURSE SRC_FILES ${PROJECT_SOURCE_DIR}/*.cpp)
file(GLOB_RECURSE HDR_FILES ${PROJECT_SOURCE_DIR}/*.hpp)
to get the .cpp and .hpp files, but when I do
#include "resources/r1.hpp"
I get error like "resources/r1.hpp" No such a file or directory
Can anyone help me pleas? How can I do linking between files in folders in my case?
To solve this specific problem, in your main CMakeLists.txt add this line before adding subfolders:
include_directories(".")
This will allow the compiler to see the file located in resources/r1.hpp starting from the root path.
However, I suggest you take a look to some CMake projects examples, because it doesn't seem you are doing things in the standard way (e.g. usually a good way is to add a sub directory that creates its own library, that then you link to your main executable)