How to separate my project into multiple parts

[FranciscoOssian]

Hello, can anyone help, please?
I have this Premake file:

workspace "MyProject"
    configurations { "Debug", "Release" }
    location "build"

project "MyProject"
    kind "ConsoleApp"
    language "C++"
    targetdir "build/bin/%{cfg.buildcfg}"
    objdir "build/obj/%{cfg.buildcfg}"

    files { "src/*.cpp", "include/*.hpp" }
    includedirs { "include", "vendor/eigen", "vendor/viennaCL", "vendor/viennaCL/CL" }

    defines { "VIENNACL_WITH_OPENCL" }

    filter "configurations:Debug"
        symbols "On"
        optimize "Off"

    filter "configurations:Release"
        symbols "Off"
        optimize "On"

    filter {}

    links { "OpenCL" }

And I want to create a premake.lua file in vendor/eigen and in vendor/viennaCL, but all attempts fail.

Even if I try to do it together and create it in the same file:

project "Eigen"
    kind "StaticLib"
    language "C++"
    includedirs { "vendor/eigen" }

and call it in the project "MyProject":

links { "OpenCL", "Eigen" }

The result is:

../src/main.cpp:1:10: fatal error: Eigen/Dense: No such file or directory
    1 | #include <Eigen/Dense>
      |          ^~~~~~~~~~~~~

Edit:

The project structure of this issue is here https://github.com/FranciscoOssian/cpp-template

@:~/repos/cpp-template$ tree -L 2
.
├── include
│   └── test.hpp
├── premake.lua
├── src
│   ├── main.cpp
│   └── test.cpp
└── vendor
    ├── eigen
    └── viennaCL

The idea is simply to call the premake of the "X" dependency (creating file in "vendor/eigen") and configure it in the main premake, without writing details in the main premake.

[nickclark2016]

Have you tried using absolute paths? You can get the workspace location from the wks token. https://premake.github.io/docs/Tokens

[FranciscoOssian]

I tried using it for testing here, but I couldn't. For example, wks returns nil if I print it. And I'm not sure if I did it right because it gives the same error even if I don't use it. The biggest issue is that I imagine I shouldn't even need this because initially I'm trying to separate it in the same file, and yet it still gives the mentioned error.

How could I split it? Or how would I use this token if it did work? I really couldn't figure it out, sorry. Any help or suggestions would be greatly appreciated. Thank you in advance!

[samsinsane]

includedirs is for #include "Header.h"
externalincludedirs is for #include <Header.h>

You might find that includedirs works for #include <> and externalincludedirs works for #include "" for some systems/actions/compilers/whatever, but I would use the above as a rule of thumb when wanting to specify include directories. I thought this was covered in the "Write Premake Scripts" section of the documentation, but I can't see anything that covers it, we should definitely improve that. Similarly, includedirs should reference externalincludedirs so that users are able to find this related API.

[FranciscoOssian]

I just discovered that there's -isystem in compiler options; it might help because it suppresses some warnings related to third-party libraries. I tested using it in the context of my issue, but I'm still facing the same error.

[samsinsane]

externalincludedirs should map to -isystem for you.

So, to confirm, this is your directory structure:

premake5.lua
main.cpp
vendors/eigen/Eigen/Dense

and you've got this in your premake5.lua:

...
project "MyProject"
  ...
  externalincludedirs { "vendors/eigen" }
  ...

and in main.cpp:

#include <Eigen/Dense>
...

[FranciscoOssian]

The idea is to create some way of separating configurations into different files. Changing to externalincludedirs may alter the priority and warnings of this library, from what I researched. I updated my question to make it clearer.

[FranciscoOssian]

I found an example of premake that deals with GLFW and OpenGL, and the approach used is different from what I was trying, maybe that's why I always made mistakes. For now, the way I managed to solve it was simply by creating a function in the separate file with the configurations I wanted. For third parties static dependencies, this will be useful. It raised other questions for me, but I'll save them to research, and if I can't find answers, I'll ask another question. Thanks to those who were willing to help.

function useEigen()
    includedirs { "vendor/eigen" }
end

dofile "vendor/eigen/premake.lua"
project "Project"
    useEigen()