Can't include an external library in another header with Cmake - c++

I have a project setup with the following folder structure:
External
Boost
Poco
Libraries
Lib1
src
lib1.cpp
CMakeLists.txt
Lib2
src
CMakeLists.txt
Projects
Project1
src
CMakeLists.txt
Project
src
CMakeLists.txt
Public
Lib1
lib1.h
Lib2
Basically I have a folder for external libraries like Poco or Boost. Next to that I have a projects folder. Each project has it own independent source files and have the possibility to include/link one or more of the libs in the Libraries folder. Each library has also a private src folder and a public header folder.
The CMakeLists.txt file of a library looks something like this (${PUBLIC_DIRECTORY} is set to the correct public folder)
set(Sources
"${PUBLIC_DIRECTORY}/lib1.h"
"src/lib1.cpp"
)
include_directories("../../External/Boost")
add_library(Lib1 ${Sources})
link_directories("${CMAKE_CURRENT_BINARY_DIR}/Lib1")
The problem happens when I try to include a boost header like boost/lexical_cast.hpp.
When I include this in lib1.cpp, everything compiles. But when I do the same in lib1.h, I get the error: boost/lexical_cast.hpp: No such file or directory.
Does anyone know how to fix this problem?
thanks in advance

Turning my comments into an answer
When you #include "boost/..." in a .h file, make sure that all projects which use that .h file are correctly configured to use Boost. Bear in mind that from a compiler's point of view, .h files don't really exist - their content is textually pasted into the .cpp file, so only the .cpp file's settings (such as include paths) apply.

Related

CMake: Can we specify include directories for a specific set of files not forming an executable or lib?

If I have this source tree:
C:\app:
src:
CMakeLists.txt
main.cpp --> #include "acme/header_only_lib/api.h"
D:\3rdparty\acme\header_only_lib:
api.h --> #include "detail.h"
detail.h
Without using symlink tricks, and without adding files to the 3rdparty folders, if I must retain #include "acme/header_only_lib/api.h" in main.cpp, how should I specify the include directories in CMake such that api.h can see detail.h, without adding global include directory of D:\3rdparty\acme\header_only_lib? The header-only-lib is not an executable nor library target, and its code is not modifiable by me. I also don't want to pollute my global include directories by adding D:\3rdparty\acme\header_only_lib because the filenames inside there are too common and will easily clash with other libraries/future code.
Is there a CMake mechanism where I can say:
Only for D:\3rdparty\acme\header_only_lib\api.h, add D:\3rdparty\acme\header_only_lib as the include directory?
To add a directory to the global list of include directories, you use e.g.
include_directories( ${CMAKE_SOURCE_DIR}/3rdparty )
Note that you should not hardcode absolute paths (like D:\) into your CMakeLists.txt as that makes it impossible to build your project in any other location. CMake offers variables like ${CMAKE_SOURCE_DIR} and ${CMAKE_BINARY_DIR} for just that purpose.
If you want to add a directory to the list of include directories for a specific part of your build only, you use e.g.
target_include_directories( app PRIVATE ${CMAKE_SOURCE_DIR}/3rdparty )
This adds the directory only for the target (executable / library) app.
Note that, if your acme/header_only_lib is supposed to be installed alongside with the app binaries, this approach won't work, as your acme headers would need to "see" each other on the client's machine, which is unlikely if they reside in the acme/header_only_lib subdirectory but address each other without subdirs. That would require your client (who isn't using your CMakeLists.txt for his builds) to add acme/header_only_lib to the include paths for your header lib to work -- you should not do that.
Use include_directories or target_include_directories:
include_directories("D:\3rdparty")
OR with target_include_directories if you want to make this change only for the main target:
add_executable(main main.cpp)
target_include_directories(main PUBLIC "D:\3rdparty")
Then you can just #include "acme/header_only_lib/api.h" or #include <acme/header_only_lib/api.h>
Header only lib
If you want to do this for header-only-lib only, you need to do this in it's CMake file. First add the library as INTERFACE with no source files:
add_library(header-only INTERFACE)
Then include directories for it:
target_include_directories(header-only INTERFACE include-dir-for-header-only)
Then link it to the main target
find_library(HeaderOnly
NAMES header-only
HINTS "D:\3rdparty\path-to-lib"
)
target_link_libraries(main header-only)

Trying to use Boost with CMake in CLion [duplicate]

I am new to cmake and know this question has been asked before, but still cannot find what I am doing wrong. I have an external library with folders /include and lib. The /include folder contains all the headers (.h) and the /lib folder contains all the source (.c) files.
In my project I have this CMakeList.txt file:
cmake_minimum_required(VERSION 3.7)
project(FirstAttempt)
set(CMAKE_CXX_STANDARD 11)
set (EXTRA_LIBS "D:\\libtrading")
include_directories(${EXTRA_LIBS}/include)
link_directories(${EXTRA_LIBS}/include)
set(SOURCE_FILES main.cpp)
add_executable(FirstAttempt ${SOURCE_FILES})
target_link_libraries (FirstAttempt ${EXTRA_LIBS}/lib)
I know that I have to use target_link_libraries to link the source files of the library to my project, but certainly something is missing, but what? I am still receiving the error undefined reference to xxxxxx.
The library I am trying to include in my project is https://github.com/libtrading/libtrading.
Well, I'll try.
First, seems that you are calling link_directories() on the folder which contains header files, while it should be used in order to specify the path where to search libraries for.
Second, target_link_libraries() takes the absolute path of the shared/static library file as the second argument, while you are passing the directory path (well, it seems so).
target_link_libraries() doesn't link to the "source files of the library", - it links to the compiled shared/static library blob.
And, I would also recommend you to save the name of the executable to the variable so that you wouldn't be able to mistype the target name, like so:
set(TARGET FirstAttempt)
add_executable(${TARGET})
As you know, we need all source files to compile. So we need to point out Cmake know where/what are source files.
I think you should add all sources files like this
file(GLOB SOURCES_FILES "lib/*.c" main.cpp)
to add all .c files.
Or, you can add all lib/*.c files separately
file(SOURCES_FILES_LIBS "lib/*.c")
set(SOURCES_FILES main.cpp)
add_executable(FirstAttempt ${SOURCES_FILES_LIBS} ${SOURCES_FILES})

cmake - undefined reference to

I am new to cmake and know this question has been asked before, but still cannot find what I am doing wrong. I have an external library with folders /include and lib. The /include folder contains all the headers (.h) and the /lib folder contains all the source (.c) files.
In my project I have this CMakeList.txt file:
cmake_minimum_required(VERSION 3.7)
project(FirstAttempt)
set(CMAKE_CXX_STANDARD 11)
set (EXTRA_LIBS "D:\\libtrading")
include_directories(${EXTRA_LIBS}/include)
link_directories(${EXTRA_LIBS}/include)
set(SOURCE_FILES main.cpp)
add_executable(FirstAttempt ${SOURCE_FILES})
target_link_libraries (FirstAttempt ${EXTRA_LIBS}/lib)
I know that I have to use target_link_libraries to link the source files of the library to my project, but certainly something is missing, but what? I am still receiving the error undefined reference to xxxxxx.
The library I am trying to include in my project is https://github.com/libtrading/libtrading.
Well, I'll try.
First, seems that you are calling link_directories() on the folder which contains header files, while it should be used in order to specify the path where to search libraries for.
Second, target_link_libraries() takes the absolute path of the shared/static library file as the second argument, while you are passing the directory path (well, it seems so).
target_link_libraries() doesn't link to the "source files of the library", - it links to the compiled shared/static library blob.
And, I would also recommend you to save the name of the executable to the variable so that you wouldn't be able to mistype the target name, like so:
set(TARGET FirstAttempt)
add_executable(${TARGET})
As you know, we need all source files to compile. So we need to point out Cmake know where/what are source files.
I think you should add all sources files like this
file(GLOB SOURCES_FILES "lib/*.c" main.cpp)
to add all .c files.
Or, you can add all lib/*.c files separately
file(SOURCES_FILES_LIBS "lib/*.c")
set(SOURCES_FILES main.cpp)
add_executable(FirstAttempt ${SOURCES_FILES_LIBS} ${SOURCES_FILES})

Tell CLion to use header include path with prefix

I have a project layout as follows:
workspace
project_a
project_a -> .h files here
Root -> .cxx files here
project_b
project_b -> .h files here
Root -> .cxx files here
I cannot change the directory layout due to the build system that we're using.
Headers are included as
#include "project_a/some_header.h
also from the corresponding .cxx file.
I've created a CMakeLists.txt file in the root directory, that adds all my projects via include_directories(project_a project_b), which should be the path prefixed before the one given in the #include. CLion does not manage to find and index any of my files.
Additionally, I have an automatically generated directory of headers of structure
include
lib_a -> .h files
lib_b -> .h files
and I've set them up accordingly, but it also does not work.
Does CLion not manage to resolve the prefixed path in the #include or why is this not working?
In CMakeList.txt, which should be located in parent folder, "workspace" folder in that situation, add
set(INCLUDE_DIRECTORIES ./)
If, for example, there is a parent folder, that holds include files:
workspace
includes_folder
project_a
a.h
b.h:
#include <project_a/a.h>
Then CMakeList.txt should contain
set(INCLUDE_DIRECTORIES ./)
include_directories(includes_folder)
If the only thing that doesn't work is Clion's interpretation of your headers then you should check out the Clion FAQ. If Clion's not working the way you expect then your CMake project might not be set up correctly or you might be doing something unintentionally. You should show us your CMakeLists.txt.
From the Clion FAQ:
Q: CLion fails to find some of my headers. Where does it search for them?
A: CLion searches through the same places CMake does. Set the INCLUDE_DIRECTORIES variable in CMake to provide the headers path to the IDE.
By the way, in this wiki you can find a lot of useful CMake variables with descriptions that can be especially helpful if you are new to CMake.
Q: Refactorings are not working and highlighting is wrong, even though the project can be compiled correctly. What’s happened?
A: Most probably CLion is unaware of some files in your project (these files are grayed out in the project tree):
non-project-files
It gets this information from the CMakeLists.txt files in the following way:
set(SOURCE_FILES main.cpp)
add_executable(my_exec ${SOURCE_FILES})
This is how CLion now knows that main.cpp is included in your project. As for now, header files (in case their names differ from the appropriate .cpp files already added to the SOURCE_FILES variable) should also be included in the project in that way.

CMake and handling subfolder header files

I'm trying to set up my project to build several dynamic libraries that encompass its complete functionality. There are subfolders for each library. The subfolder libraries are dependent on each other, so they must reference functions from each other. I seem to have managed to get CMake to run without errors on the project, but when I go to build, I have trouble with my headers finding each other. It seems at build time, the include path isn't set up correctly. How can I fix this? Are there additional steps I need to take to set up the include path correctly?
The structure looks something like this
root
CMakeLists.txt
bin
lib
lib0
CMakeLists.txt
lib0.h
lib0.cpp
lib1
CMakeLists.txt
lib1.h
lib1.cpp
...
In the CMakeLists.txt for the root directory I have declarations like this:
set(ROOT /blah/blah/root)
include_directories(${ROOT}/lib0)
include_directories(${ROOT}/lib1)
add_subdirectory(lib0)
add_subdirectory(lib1)
In the CMakeLists.txt for the subfolders, I have:
set(lib0_SOURCES "")
list(APPEND lib0_SOURCES lib0.cpp)
add_library(lib0_lib ${lib0_SOURCES})
And my headers for the libraries look like (suppose this is lib0.h):
#include "lib1/lib1.h"
...
CMake runs fine with no errors, but when I go to compile, I get an error like:
In file included from /blah/blah/root/lib0/lib0.cpp:1:0:
/blah/blah/root/lib0/lib0.h:1:30: fatal error: lib1/lib1.h: No such file or directory
You told GCC to #include the file "lib1/lib1.h". When you build, CMake will ask to look for extra headers in "${ROOT}/lib0" and "${ROOT}/lib1"
So, GCC is trying "${ROOT}/lib0/lib1/lib1.h" and "${ROOT}/lib1/lib1/lib1.h" Yup, cant work.
To fix it:
you can use in your root CMakeLists.txt : include_directories(".")
keep your CMakeLists but #include the file "lib1.h"
remove the include_directories in CMakeLists and #include the file "../lib1/lib1.h"
IMO, I'd go for the first option!
You need to use the double naming scheme or specify the base directory as the include path:
root
CMakeLists.txt
bin
lib
lib0
CMakeLists.txt
lib0.cpp
lib0
lib0.h
lib1
CMakeLists.txt
lib1.cpp
lib1
lib1.h
...
I would ask CMake to just consider the ROOT directory for C/C++ include look-ups:
set(ROOT /blah/blah/root)
include_directories(${ROOT})
add_subdirectory(lib0)
add_subdirectory(lib1)
Then, in C/C++, use angle braquets ('<' and '>') rather than double quotes ('"'):
#include <lib1/lib1.h>