Re: Commit r28657

[Wolfgang Lux]

David Chisnall wrote:

> On 22 Sep 2009, at 17:17, Wolfgang Lux wrote:
>
> > David Chisnall wrote:
> >
> > > On 22 Sep 2009, at 13:43, Nicola Pero wrote:
> > >
> > > > IIRC objc/runtime.h is a private header used internally while  
> > > > compiling libobjc.  It is not for users and so it is not installed.
> > >
> > > Very odd; looking at the Makefile, you seem to be correct, but  
> > > it's installed on FreeBSD anyway.  Could someone who understands  
> > > how the configure script works add a check for the existence of  
> > > runtime.h?
> >
> > Given Nicola's comment may I suggest you change libobjc2 instead  
> > and move the relevant definitions to a publicly visible header,  
> > probably <objc/objc-api.h>.
>
> The runtime.h header in libobjc2 contains the same function  
> definitions as runtime.h on Apple's libobjc.  It is there for  
> source compatibility with the Apple runtime.
>
> > I think you will then be able to copy configure.ac's already  
> > existing logic that tests for the presence of objc_msg_forward2  
> > and check for the availability of objc_msg_forward3 and/or  
> > objc_proxy_lookup and don't have to include non-portable headers.
>
> runtime.h is the (only recommended) public header on OS X.

So then here is my take on the autoconf macros. I assume that you  
really want to test the presence of libobjc2 and take objc/runtime.h  
for granted (only) if using libobjc2. The following recipe therefore  
defines HAVE_LIBOBJC2 when it detects the new runtime.

Add the file config.forward3.m to the config directory (there are  
already config.forward.m and config.forward2.m):

#include <objc/runtime.h>

int main (void)
{
  struct objc_slot *(*__objc_msg_forward1)(id,SEL) = objc_msg_forward3;
  return 0;
}

Then add the following to configure.ac (e.g. below the test for  
objc_sync_enter):

AC_MSG_CHECKING(for libobjc2)
AC_COMPILE_IFELSE([#include "$srcdir/config/config.forward3.m"],
        have_libobjc2=yes, have_libobjc2=no)
if test $have_libobjc2 = yes; then
  AC_DEFINE(HAVE_LIBOBJC2,1,[Define if using libobjc2])
fi
AC_MSG_RESULT($have_libobjc2)

Finally update configure by running autoconf and autoheader and then  
test everything. Beware that I don't have libobjc2 installed at  
present, so I can't test it, and that its early in the morning :-)

Wolfgang