Re: Use -fvisibility=hidden for shared libraries

Hi,

On 2022-01-10 23:44:06 -0500, Tom Lane wrote:
> Andres Freund <andres@anarazel.de> writes:
> > On 2022-01-10 21:11:07 -0600, Justin Pryzby wrote:
> >> Without the patch, it fails under windows like:
> 
> > Ah, yea. It's about matching the declarations in ltree.h with the
> > PG_FUNCTION_INFO_V1() one.
> 
> > What is bugging me is that I am fairly sure that my local compilers at some
> > point complained about such mismatches on linux as well. But I can't reproduce
> > that right now :/

Now I wonder if I just saw it when cross compiling locally...


> Ah, I wondered about that.  I'd sort of expected warnings from
> mismatched declarations, but I didn't see any on Linux or macOS.

There are warnings when the declarations "explicitly" mismatch, e.g. one with
__attribute__((visibility("hidden"))) and one with
__attribute__((visibility("default"))). But -fvisibility=hidden isn't
sufficient.

Which makes sense to some degree, because of -fvisibility not applying to
extern declarations... But it's still annoying.

Greetings,

Andres Freund