🚀 go-pugleaf

I'm having a curious problem with Objective C under AIX 4.1.  Well, I
was told that there was a bug in the current version of gcc we have
installed here (2.6.0) which prevented ObjC programs from linking
properly.  I was also given a sample program that supposedly exemplifies
the problem, but unfortunately, I don't know ObjC.  I thought I'd try
installing the gcc 2.7.0 to see if that would work, but it started to
look like it would be a lot of work, so I opted to try the test code
on my Linux system at home.  And, well... it didn't work.  It managed
to compile ok, but the program just seg-faulted around the
*ptr=strdup("hello world") call.  Replacing it with *ptr="hello
world" worked fine, however.  As far as I can tell (unless I'm just
missing something so incredibly obvious that I can't see it), there's
no reason the strdup shouldn't work.  Maybe there's some objective-c
thing about it that I don't know, or maybe there's really a bug.
Anyway, I'd greatly appreciate any help you have to offer.  Here's the
code:

-----------------------------------------------------------
// This is a simple hello-world style program for Objective C.
// Compile as "gcc -g objc-helloworld.m -lobjc"
// It's useful to test whether Objective C is working at all, in particular
// if the static constructors are being called.

// Another test of the linker can be tried by splitting this into three
// files: "HelloWorld.h", "HelloWorld.m" and "main.m" (following the
// comments) and try linking the two .o files together.
// "gcc -c -g main.m; gcc -c -g HelloWorld.m; gcc main.o HelloWorld.o -lobjc"
// this won't identify all possible objc-related linker problems, but might
// get one or two.

#import <objc/Object.h>

// HelloWorld.h
// #import <objc/Object.h>

@interface HelloWorld : Object {
  char *output;
}

-init;
-print;
@end

// HelloWorld.m
// #import "HelloWorld.h"
@implementation HelloWorld

-init {
  //output = (char *)strdup("Hello World!");
  output = (char *)malloc(1024);
  strcpy(output, "Hello World!");
}

-print {
  puts(output);
}

@end

// main.m
// #import "HelloWorld.h"
int
main() {
  id test;
  test = [[HelloWorld alloc] init];
  [test print];
  return 0;
}
-----------------------------------------------------------

Here's a message regarding this that was forwarded through several
other people before it got to me, so I have no idea who the original
sender was:

> Unpack the patch, you'll see it's a patch to gcc itself - expr.c,
> the md, etc. I don't have high hopes that this patch will work, either.
>
> The fundamental problem with the AIX support can be traced down to the
> __builtin_apply stuff. If you're willing to get your hands dirty, you
> should read up on how gcc does that and see if you can make it work
> under AIX. It involves stack frame manipulation. As far as I
> understand, the AIX patch I gave you just kludges things to give some
> extra slop space to take care of not understood problems.
>
> If you're not willing to get your hands dirty, then you're going to
> have to wait until someone fixes it (indeterminate time), or else pay
> someone like Cygnus to make it work.


Thanks,
Danny Sung
dannys@ucla.edu