I need to improve doc but this doc is about using clangd language server to provide support with completion validation etc in editors for c, h, files not for building application.

Building application can be interesting with codelldb to debug c application by using the dap server from LSP4IJ and codelldb template

Yes I know it's not about building the application. My question is "how do I tell clangd (and by extension LSP4IJ) about the header files in my project so that completion/validation/etc. works?"

Maybe it's more clear with an example: Let's say I have some dependency vendored into my project at ./vendored/some-dep. When I build my app I use -I./vendored/some-app/include to make sure the compiler knows where to find them. But my editor doesn't have completion for anything I'm using from some-dep because clangd doesn't know to look there. How do I tell clangd to look there?

@antonysouthworth-halter please share a simple project and tell me what you want to have. Thanks.

@antonysouthworth-halter could you try something:

Go the the Installer tab and click on Run Installation:

If the installation can be done, it should work.

For instance given this hello.ccp file:

#include <iostream>

int main() {
    std::cout << "Hello, world!" << std::endl;
    return 0;
}

If you open completion you should see