I am trying to build Gstreamer from source using Meson as a subproject of another big project. (Building from source using Meson)
The big Project`s meson contains:
gst_dep = subproject('gstreamer')
because the code of the original gstreamer project contains another subprojects folder that includes another gstreamer directory I am getting the next error:
subprojects/gstreamer/meson.build:155:4: ERROR: Recursive include of subprojects: gstreamer => gstreamer.
The directories structure:
-BigProject
-meson.build
-subprojects
-gstreamer #The original gstreamer code folder
-meson.build
-subprojects
-gstreamer
-gst-plugins-good
-gst-plugins-bad
etc.
What can I do to fix that?
Renaming GStreamer source repo will work.
Meson Subproject won't accept a recursive include of GStreamer repo as a subproject to add its GStreamer subproject.
That said, renaming your GStreamer repo to gstreamer-something and making your top meson.build's Subproject call to:
gst_dep = subproject('gstreamer-something')
Will work.
Moreover, for this renaming, you can specify the GStreamer repo name when cloning, this way:
git clone -b <branch> <src uri> gstreamer-something
Nonetheless, in case you are using a Meson Wrap , you can have the Wrap file with that name and should be enough.
You can follow this issue about this issue of GStreamer that doesn't considers itself to be added as a Subproject. Hopefully they come with a rename solution or similar, soon.
Related
I am confused on the right way to get an external library integrated into my own Cmake project (This external project needs to be built along with my project, it's not installed separately, so we can't use find_library, or so I think)
Let's assume we have a project structure like this (simplified for this post):
my_proj/
--CMakeLists.txt
--src/
+---CMakeLists.txt
+---my_server.cpp
That is, we have a master CMakeLists.txt that basically sits at root and invokes CMakeLists for sub directories. Obviously, in this example, because its simplified, I'm not showing all the other files/directories.
I now want to include another C++ GitHub project in my build, which happens to be this C++ bycrypt implementation: https://github.com/trusch/libbcrypt
My goal:
While building my_server.cpp via its make process, I'd like to include the header files for bcrypt and link with its library.
What I've done so far:
- I added a git module for this external library at my project root:
[submodule "third_party/bcrypt"]
path = third_party/bcrypt
url = https://github.com/trusch/libbcrypt
So now, when I checkout my project and do a submodule update, it pulls down bcrypt to ${PROJ_ROOT}/third_party
Next up, I added this to my ROOT CMakeLists.txt
# Process subdirectories
add_subdirectory(third_party/bcrypt)
add_subdirectory(src/)
Great. I know see when I invoke cmake from root, it builds bcrypt inside third_party. And then it builds my src/ directory. The reason I do this is I assume this is the best way to make sure the bcrypt library is ready before my src directory is built.
Questions:
a) Now how do I correctly get the include header path and the library location of this built library into the CMakeLists.txt file inside src/ ? Should I be hardcoding #include "../third_party/bcrypt/include/bcrypt/bcrypt.h" into my_server.cpp and -L ../third_party/libcrypt.so into src/CMakeLists.txt or is there a better way? This is what I've done today and it works, but it looks odd
I have, in src/CMakeLists.txt
set(BCRYPT_LIB,"../third_party/bcrypt/libbcrypt.so")
target_link_libraries(my app ${MY_OTHERLIBS} ${BCRYPT_LIB})
b) Is my approach of relying on sequence of add_directory correct?
Thank you.
The best approach depends on what the bcrypt CMake files are providing you, but it sounds like you want to use find_package, rather than hard-coding the paths. Check out this answer, but there are a few different configurations for find_package: MODULE and CONFIG mode.
If bcrypt builds, and one of the following files gets created for you:
FindBcrypt.cmake
bcrypt-config.cmake
BcryptConfig.cmake
that might give you an idea for which find_package configuration to use. I suggest you check out the documentation for find_package, and look closely at how the search procedure is set up to determine how CMake is searching for bcrypt.
I cannot make local include paths work in the Meson build system.
This C++ inclusion works correctly:
#include </cygdrive/c/Users/user/project/Third-Party/eigen/Eigen/Dense>
This one does not:
#include "Third-Party/eigen/Eigen/Dense"
fatal error: Eigen/Dense: No such file or directory
In the Meson build file, I tried to add Eigen's path, without success:
# '.' will refer to current build directory
include_dirs = include_directories('include', '.', '../project/Third-Party/eigen')
This is the project tree structure:
project
meson.build
src
meson.build
example.h
example.cpp
Third-Party
eigen (headers only lib)
Eigen
Note: with CMake I do not have this issue.
For dependency management, meson allows you to manually declare include_directories() in your build files. However, there is another way do handle dependencies: using dependency() command.
dependency() is a much better way to handle dependencies, because meson will build it if necessary (if dependency is a shared or a static library) and safely allows you to use includes. That means that you don't have to know where includes for dependency are located physically or care about their paths ever after. The only downside is that this kind of dependency needs it's own meson.build file.
Using dependency() command:
To actually use it, you have to write a wrap file for dependency. Or, if you are lucky enough, there is already a wrap file for you in the Wrap DB -- a community-driven database for meson wrap files. Wrap file is a config of some kind that declare where you can get a dependency and in what form. Wrap file can wrap around zip archives and git repositories.
For your given dependency, there is wrap file in Wrap DB: eigen. All you have to do is download it and place it in the subprojects directory near your meson.build. For example:
$ cd project
$ mkdir subprojects
$ wget "https://wrapdb.mesonbuild.com/v1/projects/eigen/3.3.4/1/get_wrap" \
-O subprojects/eigen.wrap
Now, not every project builds with meson. For the ones that don't, wrap file also specify a patch. Patch is used to just copy appropriate meson.build file into dependency directory (as well as any other files that would be needed for building that particular dependency with meson). Eigen wrap file contains a patch.
To find out how any particular dependency declare itself as a dependency (using declare_dependency() command), you need to investigate meson.build file in dependency source directory (although it's often just name of the dependency plus _dep, e.g. "eigen_dep"). For me, eigen directory was subprojects/eigen-eigen-5a0156e40feb. So, you search for the declare_dependency() command:
$ grep declare_dependency subprojects/eigen-eigen-5a0156e40feb/meson.build
eigen_dep = declare_dependency(
As you can see, eigen declare dependency as eigen_dep. If you want to know what exactly is declared, just scroll down the dependency meson.build file.
Now, to use that eigen_dep in your project, create a dependency object with a dependency() command. Here is a sample project that I used to compile "A simple first program" from Eigen: Getting Started:
project('example', 'cpp')
eigen_dependency = dependency('eigen', fallback: ['eigen', 'eigen_dep'])
executable('example', 'example.cpp', dependencies: eigen_dependency)
Notice arguments for the dependency() command. The first one is system-wide dependency that meson is searching for. If there is no eigen for development installed in your system, then meson uses fallback: first item in fallback is basename of the wrap file, second item is a name of declared dependency.
Then use eigen_dependency variable in whatever you build, passing it to the dependencies argument.
Using include_directories() command:
If you want to just include some files from external directory (such as your "Third-Party" directory) using include_directories() command, that directory has to be relative to the meson.build file where you use it.
To use manually declared includes, you need to call include_directories() command to get the include_directories object. Pass that object to include_directories argument in whatever you build.
Given your example, I assume that root meson.build file is a project build file. Then in that root meson.build, for example, you can write:
# File: project/meson.build
project('example', 'cpp')
eigen_includes = include_directories('Third-Parties/eigen')
executable('example', 'example.cpp', include_directories: eigen_includes)
But if you want to get eigen includes from src/meson.build, then you need to change include_directories to:
# File: project/src/meson.build
eigen_includes = include_directories('../Third-Parties/eigen')
...
I am trying to integrate Google Test into the subproject of bigger project and I cannot find the solution that would be satisfying for me.
I have two constraints:
the source code of Google Test is already somewhere in the project structure (thus using URL to download it from git repository is not an option)
the source code of Google Test is not a subdirectory of my subproject (and never will)
So when I tried to do something like this:
add_subdirectory( ${GOOGLETEST_PROJECT_LOCATION})
I received:
CMake Error at unit_tests/CMakeLists.txt:10 (add_subdirectory):
add_subdirectory not given a binary directory but the given source
directory "${GOOGLETEST_PROJECT_LOCATION}" is not a subdirectory of
"${UNIT_TEST_DIRECTORY}". When
specifying an out-of-tree source a binary directory must be explicitly
specified.
On the other hand maybe ExternalProject_Add could be a solution but I do not know how shall I use it when I do not want to download sources at all and use sources from specific location in the project.
Project structure looks more or like like this:
3rdparty
|--googletest
...
subproject
|--module1
|--file1.cpp
|--CMakeLists.txt
|--module2
|--file2.cpp
|--CMakeLists.txt
|--include
|--module1
|--file1.h
|--module2
|--file2.h
|--unit_test
|--module1
|--file1test.cpp
|--module2
|--file2test.cpp
|--CMakeLists.txt
|--CMakeLists.txt
CMakeLists.txt
The error message is clear - you should also specify build directory for googletest.
# This will build googletest under build/ subdirectory in the project's build tree
add_subdirectory( ${GOOGLETEST_PROJECT_LOCATION} build)
When you give relative path (as a source directory) to add_subdirectory call, CMake automatically uses the same relative path for the build directory.
But in case of absolute source path (and when this path isn't in your source tree), CMake cannot guess build directory, and you need to provide it explicitly:
See also documentation for add_subdirectory command.
I feel obligated to comment on this because this was the top search result when I was googling this error.
For me, I'm apparently an idiot: I had modified the CMakeLists.txt file in the src directory of my project, but I didn't realize the file was locked and VS Code wasn't actually saving even when I hit Ctrl+S. Check the file tab in VS Code and see if there's a white dot there, indicating the file isn't saved. Hit Ctrl+S and see if you get a pop-up in the lower-right corner prompting you to try again as superuser.
I've still got errors, but they're new errors that make sense for my project.
I'm trying to compile a libpng library. The thing is that I need a specific version of this library - 1.2.37 - because the project I'm using it in is written with this version.
I've found the source code of this version here (GnuWin32 project).
But the folder structure looks something like this:
libpng-1.2.37-src/
contrib/
projects/
scripts/
CMakeLists.txt
png.h
pngread.c
pngwrite.c
...
See, the CMakeLists.txt is one level deeper than the source files.
I've tried:
source directory libpng-1.2.37-src/ -> resulted in error: The source directory does not appear to contain CMakeLists.txt
source directory libpng-1.2.37-src/scripts -> resulted in multiple errors: File libpng-1.2.37-src/scripts/scripts/libpng.pc.in does not exist.
copy CMakeLists.txt from /scripts to /libpng-1.2.37-src and set source directory to /libpng-1.2.37-src -> resulted in error: The source "/libpng-1.2.37-src/CMakeLists.txt" does not match the source "/libpng-1.2.37-src/scripts/CMakeLists.txt" used to generate cache.
What should I do to make it work? I don't know why the CMakeLists.txt file would be included if it can't be used.
The INSTALL file explicitely says:
If you want to use "cmake" (see www.cmake.org), copy CMakeLists.txt
from the "scripts" directory to this directory and type
cmake . [-DPNG_MMX=YES] -DCMAKE_INSTALL_PREFIX=/path
make
make install
And as a side note, before this it says that the classic way to install it is:
On Unix/Linux and similar systems, you can simply type
./configure [--prefix=/path]
make check
make install
It sounds like you did right with 3), however you forgot to cleanup the build dir before trying again.
If it's library which you use in your project you can build it automatically via technique called 'superbuild' (use ExternalProject_Add).
By specifying SOURCE_SUBDIR as is described here to subdirectory with CMakeLists.txt you can do something like this
ExternalProject_Add(libpng
GIT_REPOSITORY url-to-your-repository.git
GIT_TAG v1.2.37
SOURCE_SUBDIR "scripts"
I have been struggling with this for quite a while, and my adventures with cmake have only resulted in hackish solutions that I am pretty sure are not correct.
I created a library that consists of several files, as follows:
-libfolder
-codepart1folder
-CMakeLists.txt
-codepart1.cpp
-codepart1.hpp
-codepart2folder
-codepart3folder
-lib.cpp
-lib.hpp
-CMakeLists.txt
I wrote a CMakeLists file to compile the library (after some experimentation), and I can generate a lib.a file. Now I would like to include this code as a library in other projects, and access it through the interface in lib.hpp. What is the best way to do this, in terms of directory structure, and what I need to put into CMakeLists.txt in my root project?
My current attempt has been to add -libfolder as a subfolder to my current project, and add the commands:
include_directories(${PROJECT_SOURCE_DIR}/libfolder)
link_directories(${PROJECT_BINARY_DIR}/libfolder)
add_subdirectory(libfolder)
target_link_libraries(project lib)
When I run make, the library compiles fine, but when project.cpp compiles, it complains that it cannot find codepart1.hpp (which is included in lib.hpp, included from project.cpp).
I suspect that this is the wrong way about doing this, but I cannot wade through the CMake documentation and find a good tutorial on setting up projects like this. Please help, CMake gurus!
The clean way to import one CMake project into another is via the find_package command. The package declaration is done by using the export command. An advantage of using find_package is that it eliminates the need to hard-code paths to the package's files.
Regarding the missing hpp file, you didn't include codepart1folder, so it's not on the include path.
Ok, so after consulting a coworker of mine who is a CMake guru, it seems CMake does not have support for what I am trying to do, leaving one with 3 options:
Add all of the dependencies to the parent projects CMakeLists.txt - not very clean, but it will get the thing to work. You'll have to do this for every project you add the code to, and go back and fix things if your library changes.
clean up your library headers. This is done through some compiler hackery. The idea is to forward-declare every class, and use only pointers or boost::shared_ptr, and then include the dependencies only in the cpp file. That way you can build the cpp file using all the findpackage stuff, and you get the bonus of being able to use the lib by only including the header and linking to the library.
Look into build systems. Having portable code and fast code compilation with complex dependencies is not a solved problem! From my investigations it turned out to be quite complicated. I ended up adopting my coworkers build system which he created himself in cmake, using things he picked up from Google.
Looking at your post you don't seem to add 'codepart1folder' to the includes anywhere. How are you including codepart1.hpp as:
#include <codepart1.hpp>
#include "codepart1folder/codepart1.hpp"
I don't think there is a standard accepted way to structure cmake projects. I've looked at a bunch of cmake repos and they tend to have differences. Personally I do the following:
-project
CMakeLists.txt
-build
-cmake
OptionalCmakeModule.cmake
-src
-Main
Main.cpp
Main.hpp
-DataStructs
SomeTree.hpp
SomeObject.hpp
-Debug
Debug.hpp
-UI
Window.hpp
Window.cpp
Basically that dumps all the source code into 1 directory, then you perform an out of source build with: 'mkdir build && cd build && cmake .. && make' in the projects root folder.
If you have separate libs as part of your project, then you might want a separate libs directory with another subfolder for your specific lib.
I have some of my repos on: https://github.com/dcbishop/ if you want to look at the CMakeLists.txt files.
The main problems with my project structure are that I use the FILE_GLOB which is apparently the 'wrong' way to do things (if you add files after running 'cmake ..' then they won't be picked up hen you do a 'make'). I haven't figured out what the 'right' way to do it is (from what I can see it involves keeping a separate list of files) I also only use 1 CMakeLists.txt file.
Some projects also choose to separate their cpp and hpp files into separate directories. So you would have an include and src folders (at least for the hpp files that are intended to be used externally). I think that would mainly be for projects that are mainly large libraries. Would also make installing header files much easier.
You are probably missing
include_directories(${PROJECT_SOURCE_DIR}/libfolder/codepart1folder)
In such a case you might want to set( CMAKE_INCLUDE_CURRENT_DIR on) to add all folders to the include directory path variable.
Check cmake's output on the command line whether the correct include folders are set or not. Additionally you can always use message() as "print debugging" for cmake variables.
In case of include directories however you need to read the directory property to see what is actually in the include directories.
get_property(inc_dirs DIRECTORY PROPERTY INCLUDE_DIRECTORIES)
message("inc_dirs = ${inc_dirs}")
I hope this helps you figuring out what is missing.
Edit
I just saw your comment about added codepart1folder in the libfolder. It is only available in the libfolder's include_directory path and not propagated to the root folder.
Since the include codepart1.hpp is present in the lib.hpp however you need to have it also available in the project path otherwise you will get missing declaration errors when you build your project.