Re: What's all this about Swarm modifying the runtime?

[Alex Lancaster]

>>>>> "W" == W Northcott <address@hidden> writes:

W> Hi Alex
>> Actually I am trying to hack the gcc code merging the
>> powerpc-netbsd-gcc with darwin-powerpc-gcc, since the netbsd has
>> not the Next-objc inside him, while Darwin has netbsd code inside
>> him.

W> I don't want to rain on your parade, but I hate to see people
W> wasting time which is so valuable.

W> The gcc sources have all the code to compile Obj-C source into C
W> calls into either the GNU runtime or the Apple one.  Indeed
W> Darwin/MacOS X sources contain both runtimes!  By default, the gcc
W> sources built on Darwin will not build the GNU libobjc and will
W> produce a compiler which defaults to the Apple style runtime calls.
W> However you can change this easily enough with some very small mods
W> to the build scripts.  Which runtime you use in any given code is
W> determined at link time not by the compiler.  The Apple linker is
W> opensource, but it is NOT the GNU ld.

W> Even that much would be a waste of time however, because Swarm does
W> not even use the GNU runtime.  It uses a modified version which is
W> in the Swarm source tree.  This runtime uses GNU style calls, hence
W> the need for the -fgnu-runtime flag with the compiler, but you
W> still need to link Swarm code against this modified libobjc not the
W> GNU one.

Marcus Daniel's post on the historical reasons for libobjc in Swarm is
useful here.  We are at a stage where we could definitely merge any
substantive changes in libobjc back into the mainline GNU runtime, and
switch out our dependence on our (locally modified version of) libobjc
(and use the GNU one).  

One caveat would be to test that the ObjC package version they use in
Cygwin would work with Swarm, because as Marcus notes, historically
Cygwin didn't include the ObjC compiler or runtime as part of Cygwin,
and supporting MacOS X can't be at the expense of support under
Windows (since probably half our installation base is probably on
Windoze).

I have updated the relevant MacOS X task with the information from
Marcus' post:

http://savannah.nongnu.org/pm/task.php?func=detailtask&project_task_id=1132&group_id=1837&group_project_id=495

It's a task!  Somebody with more knowledge of GNUStep/ObjC issues
could take it up!  (Scott, Bill? ;-))

-- 
      Alex Lancaster |  Swarm Development Group  |  http://www.swarm.org


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