[PATCH vkd3d 4/4] build: Make the default symbol visibility "hidden".

[Henri Verbeet]

On Thu, 5 Aug 2021 at 03:01, Zebediah Figura (she/her)
<zfigura at codeweavers.com> wrote:
>
> On 8/4/21 7:48 AM, Henri Verbeet wrote:
> > On Wed, 4 Aug 2021 at 05:53, Zebediah Figura <zfigura at codeweavers.com> wrote:
> >> +#if defined(__GNUC__) && !defined(__MINGW32__)
> >> +# define VKD3D_API __attribute__((visibility("default")))
> >> +#else
> >> +# define VKD3D_API
> >> +#endif
> >> +
> > Arguably this is more about _WIN32 than about __MINGW32__. On _WIN32
> > we'd want to add dllimport/dllexport instead, perhaps as a followup.
>
> I was following the current code here (so one could argue that
> s/__MINGW32__/_WIN32/ deserves a followup anyway).
>
> That said, it's not obvious to me why this should be _WIN32. My
> understanding is that mingw doesn't support visibility attributes at
> all, hence the empty definition, but presumably we'd still want to mark
> visibility on ELF win32 targets (which I guess means winelib).

True, it's perhaps more about the executable format than the platform,
but I'd argue those are tied together a bit stronger than the compiler
and the platform. E.g., in the hypothetical case of compiling with
MSVC we'd want to use dllimport/dllexport there as well. In any case,
the way I'd imagine this eventually looking for e.g. vkd3d-shader
would be something like this:

#if defined(_WIN32)
# if defined(LIBVKD3D_SHADER_SOURCE)
#  define VKD3D_API __declspec(dllexport)
# else
#  define VKD3D_API __declspec(dllimport)
# endif
#elif defined(__GNUC__)
# define VKD3D_API __attribute__((visibility("default")))
#else
# define VKD3D_API
#endif

It's certainly fine to keep using __MINGW32__ here if you prefer
though; we don't really support compilers other than gcc (although
Chip has been adding some Clang support lately), and this would hardly
be the only place where we take __MINGW32__ and _WIN32 to essentially
mean the same thing.