What is the proper way of defining visibility/import/export macros in meson?

[MehradN]

I'm developing a cross-platform library for Linux and Windows, which should be built and linked as a shared library. (But I want to allow building and linking as static library as well.)

I'm trying to follow this guide (more specifically the "Step-by-step guide" section). But it requires a macro like FOX_DLL that is defined when the library is built and linked as a shared library, and a macro like FOX_DLL_EXPORTS that is defined when the library is only being built as a shared library.

I have some ideas on how to achieve this with Meson, but I'm not sure if I'm doing it correctly or if there is a better way to do it.

I know that the solution most likely revolves around library() <lang>_shared_args, declare_dependency() compile_args/link_args, add_project_arguments and get_option('default_library'). But I'm really confused, and I'm not sure which macros should be defined with which methods.

How should I define those macros? Should I follow other solutions for defining visibility macros, instead of the one mentioned in that guide?

[bruchar1]

With that example, you need to define FOX_DLL if you compile a shared library, and FOX_DLL_EXPORTS when you compile the actual DLL.

I will suppose default_library is either static or shared, as both would add more complexity... And I suppose language is cpp (but it could be c as well)

if get_option('default_library') == 'shared'
    add_project_arguments('-DFOX_DLL', language: 'cpp')
endif

foxlib = library(
    ...
    cpp_args: ['-DFOX_DLL_EXPORTS']  # not needed for static, but not harmful in that context
)

foxlib_dep = declare_dependency(
    link_with: foxlib,
)

[dcbaker]

ah, that's true. This really gets back to the whole "we need to have shared vs static libs in declare_dependency so you could just put it there. So many interesting ways that both libs don't work right yet :/

[MehradN]

So when I add an argument with add_project_arguments, all projects that will use my library as their subproject dependency will be forced to use those arguments as well?

[MehradN]

Can the both library problem be fixed with checking get_option('default_library') == 'both' and not get_option('prefer_static')?

[MehradN]

So when I add an argument with add_project_arguments, all projects that will use my library as their subproject dependency will be forced to use those arguments as well?

I tested it, and add_project_arguments doesn't force the dependents to define the macro.

[bruchar1]

add_project_arguments will add the args to all targets in your project. For targets outside your project, you are better to use the compile_args argument of declare_dependency