On 05/12/2016 04:16 PM, Emil Velikov wrote:
On 10 May 2016 at 13:00, Yury Gribov <[email protected]> wrote:
On 05/06/2016 07:25 PM, Alan Coopersmith wrote:
On 05/ 6/16 04:18 AM, Yury Gribov wrote:
Unfortunately I don't see any good approach. We could move definitions of
_X_EXPORT and friends to configure.ac but this would need to be done
for all X11 packages (not just libICE) which just does not scale.
And then you'd require any package that #includes an X11 header to use
autoconf and add those to configure.ac and that really doesn't scale.
There is a way around this: you can strip internal defines from public
headers and replace it with e.g. extern. This is how visibility was enabled
for acl and libattr some time ago
(http://lists.nongnu.org/archive/html/acl-devel/2016-02/msg00020.html).
If you're suggesting that we should remove all the internal prototypes
(declarations) from the exported headers, yes that would be great. If
you're thinking about defining _X_EXPORT via extern that won't work,
as it will break way too many applications that set
-fvisibility=hidden or alike.
The libacl way is to use proper _X_EXPORT (actually they have
ACL_PUBLIC_API or something like that) when building X11 libraries but
replace it with 'extern' in installed devel headers. Funny enough, this
works with -fvisibility=hidden (if you declare some function extern and
it's not defined in the application code, the linker will resolve the
call to PLT).
> Or perhaps you're thinking about nuking
the macro all together ? Sadly that won't work either, as it will
break way too many other (sub)projects that depend on it.
On the WIN32 (original?) topic
- _X_EXPORT implemented via __declspec dllimport/dllexport
Works fine on mingw-w64 - and the resulting binary has only the
annotated symbols as exported.
- fvisibility=hidden
Does nothing on mingw64, although it does not cause any warning/errors.
So in general something like the following should work
Note: mingw and cygwin will need to drop fvisibility and/or alike and
set the BUILDING_DLL define
--- a/Xfuncproto.h.orig
+++ b/Xfuncproto.h.new
@@ -89,8 +89,15 @@ in this Software without prior written
authorization from The Open Group.
#endif /* GNUC >= 4 */
/* Added in X11R6.9, so available in any version of modular xproto */
-#if (__has_attribute(visibility) || (defined(__GNUC__) && (__GNUC__ >= 4))) \
- && !defined(__CYGWIN__) && !defined(__MINGW32__)
+#if defined(_WIN32) || defined(__CYGWIN__) && defined(__MINGW32__)
+# ifdef BUILDING_DLL // should we prefix this with _X_ ?
+# define _X_EXPORT __declspec(dllexport)
+# else
+# define _X_EXPORT __declspec(dllimport)
+# endif
+# define _X_HIDDEN
+# define _X_INTERNAL
+#elif __has_attribute(visibility) || (defined(__GNUC__) && (__GNUC__ >= 4))
# define _X_EXPORT __attribute__((visibility("default")))
# define _X_HIDDEN __attribute__((visibility("hidden")))
# define _X_INTERNAL __attribute__((visibility("internal")))
Jon, have I lost the plot with any of the above ? Please don't be shy
to say "yes you have" ;-)
Can you give it a quick test on your end ?
Thanks
Emil
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