Linking c/c++ executable to shared libs

[ericgtkb]

I have a project where I am building python extensions as well as some other c/c++ executables.
The build script is roughly as follows.

project('myproj', 'c', version: '1.0')

py = import('python').find_installation(pure: false)

# Shared lib
mylib = library('mylib', 'my_source.c', install: true)

# Python extension module
py.extension_module('_pyext', 'pyext.c', link_with: mylib, install: true, subdir: 'pyext')
py.install_sources('__init__.py', subdir: 'pyext')

# C executable
executable('myexe', 'main.c', link_with: mylib, install: true)

When running pip install mesonpy maps bindir to python's script directory (venv/bin in my case), and libdir to .myproj.mesonpy.libs (venv/lib/python.X.Y/site-packages/.myproj.mesonpy.libs in my case). For the python extension this is all fine and it is able to correctly link to libmylib.so in venv/lib/python.X.Y/site-packages/.myproj.mesonpy.libs, but the C executable myexe (in venv/bin) is not correctly linked.

Is there anyway, to correct the rpath for the C executable so it links to libmylib.so correctly in venv/lib/python.X.Y/site-packages/.myproj.mesonpy.libs? I've tried using the install_rpath option with libdir, but it still not able to set the correct rpath.

[rgommers]

Hi @ericgtkb, thanks for the clear example.

My first thought is that it's probably better to do one of two things:

1. make mylib a static library and link it into the executable
2. install both the shared library and the executable inside site-packages/myproj in the same subdirectory. Then add a [project.scripts] entrypoint in pyproject.toml to call the executable

(1) is an easier and smaller change than (2) if that's acceptable. If you do need the shared library installed, then you need (2). Both are portable also to Windows, while setting an RPATH is not. I'm also not even sure if the relative path from {bindir} to site-packages is constant for all possible install schemes.

[rgommers]

Note that to install a shared library in a different location inside site-packages/myproj, you need to add install_dir: py3.get_install_dir() / 'myproj',

[ericgtkb]

Thanks for the suggestions! Making mylib static is probably the best option for my project.

[Yashdate10]

Will you please suggest me some resources to learn DSA in C++?