Define JNIEXPORT as visibility default with GCC? (original) (raw)

David Holmes david.holmes at oracle.com
Fri Feb 15 10:20:07 UTC 2013

On 15/02/2013 5:26 PM, Jeremy Manson wrote:

a) I don't know what's going on behind the scenes, but if this sounds like a good idea to folks, can we open a bug and get the process otherwise rolling?

b) Martin, where did the 4.2 restriction come from? Both Apple's site and the gcc wiki say that visibility support arrived in 4.0:

From the original push for 6588413 in linux gcc.make:

+# version 4 and above support fvisibility=hidden (matches jni_x86.h file) +# except 4.1.2 gives pointless warnings that can't be disabled (afaik)

So it was limited on x86 to >2 (which I think was a typo: intended to be

=2 or >1 ?)

Of course the bsd port copied the linux file.

David

http://gcc.gnu.org/wiki/Visibility https://developer.apple.com/library/mac/#documentation/DeveloperTools/Conceptual/CppRuntimeEnv/Articles/SymbolVisibility.html

On Thu, Feb 14, 2013 at 3:01 PM, David DeHaven <david.dehaven at oracle.com_ _<mailto:david.dehaven at oracle.com>> wrote: >>>> +#if defined(GNUC) && (GNUC > 4) || (GNUC == 4) && >>>> (GNUCMINOR > 2) >>>> + #define JNIEXPORT attribute((visibility("default"))) >>>> + #define JNIIMPORT attribute((visibility("default"))) >>> >>> The default compiler in Xcode 4.1 is llvm-gcc 4.2, it seems. The conditional above excludes that. Is this intentional? >> >> It's is gcc, with a LLVM backend. > > Yes, but it identifies itself as GCC 4.2, so the conditional doesn't fire. I assume this was not the intent and the version check is just wrong. It may be that they deliberately stayed with gcc 4.2 to keep parity with clang, which only supports 4.2 (or it may not, because clang supports lots of 4.3+ features).

> If Xcode is fine with the #define, I suggest to drop the version check completely. We already do not support compiling with GCC versions which are so old that they lack visibility support. If it were Mac only, I'd agree. The same header is currently used for all "unix-like" OS's (which may change, if I have my way), so Solaris and Linux would also be affected. Most Linux distros have used gcc 4 for quite a while now, I've no idea what Solaris uses and embedded targets are a wild mishmash of whatever someone manages to cobble together, so the simpler GNUC check may still be appropriate. -DrD-

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