Automatic C++26 Module Interface Propagation from Required Packages to Consumer Targets

[ziaratban]

I'm a beginner with xmake. It's really enjoyable. Mr. @waruqi , your work is super valuable 🙏.

To put it simply, I don't need to mount the engine (compiler) onto a body anymore. xmake has already built that body, and I can use the engine at full power. That's awesome. In my opinion, xmake is on the right track.

For writing a highly scalable project, I need the following feature:
I need to be able to access a module from a remote package without having to do anything special.

I think I've realized that this feature isn't supported in xmake. Did I get that right?

mathlib/                        # Library repository (git)
├── xmake.lua
└── source/
    ├── math.ixx                # Module interface
    └── math.cpp                # Module implementation (class Math {...})

myrepo/                         # Package repository (git)
└── packages/
    └── m/
        └── mathlib/
            └── xmake.lua       # Package definition

calc/                           # Consumer project
├── xmake.lua                   #add_repositories('myrepo')  add_requires('mathlib')  add_packages('mathlib')
└── source/
    └── main.cpp                # uses import Math;

When I try to use the Math class in main.cpp, I get an error like: error: <target> missing Math dependency for module source/main.cpp

What should we do?

[waruqi]

see https://xmake.io/examples/cpp/cxx-modules.html#module-package-distribution
https://xmake.io/examples/cpp/cxx-modules.html#module-package-integration
https://github.com/xmake-io/xmake/tree/dev/tests/projects/c%2B%2B/modules/packages

[ziaratban]

Oops, it's so cold in here. But thanks @waruqi for taking the time to reply. It's obvious you're super busy.

That was great, simple, everything got solved. I think I trusted AIs too much and should go back to more traditional methods. :)

But one thing hasn't been resolved for me here.
After setting public = true, I was able to achieve my goal and get the build to pass successfully.
However, at runtime I ran into the error: error while loading shared libraries: [libtest.so](https://libtest.so/), which I fixed with the code below in the source package.

    on_load(function (target)
        local pkg = target:pkg("testlib")
        if pkg then
            target:add("rpathdirs", path.join(pkg:installdir(), "lib"))
        end
    end)

But I think I'm making a mistake somewhere, because in your example no special setting was done.

How can I avoid even doing this setting? (It's not ideal for every package)

[waruqi]

did you ser shared for testlib package? add_requres("testlib", {configs = {shared = true}})

it will add lib path to LD_LIBRARY_PATH when you can xmake run.

if you call xmake install, it will also add rpath.

[ziaratban]

add_requres("testlib", {configs = {shared = true}}) worked.

thanks.