Re: Bug report: objc classes linked in wrong order

[nicola at brainstorm dot co dot uk]

> > Anybody has any other idea about of how to have the NXConstantString class
> > from a shared library to be linked instead of the NXConstantString from a
> > shared libobjc when linking both libraries ?
>
> Make the non-preferred one weak.

Can I make an objective-C class weak ?

I found no evidence of this - because each module has a list of classes to
load, and loads them all - but I might be wrong - so please give me a hint
if I actually can in some way make a class weak.

But I liked your hint anyway, because using __attribute__((weak)) at least
can help to make the patch simpler.

--- ./init.c.orig	Mon May 15 10:34:03 2000
+++ init.c	Fri May 26 16:29:47 2000
@@ -26,6 +26,10 @@

 #include "runtime.h"

+/* Define this to 1 if you want to provide your own version of
+   NXConstantString in your library or user code */
+int __attribute__((weak)) _user_defined_NXConstantString = 0;
+
 /* The version number of this runtime.  This must match the number
    defined in gcc (objc-act.c) */
 #define OBJC_VERSION 8
@@ -469,7 +473,34 @@
   /* dummy counter */
   int i;

+  /* dummy pointer */
+  const char *p;
+
   DEBUG_PRINTF ("received module: %s\n", module->name);
+
+  if (_user_defined_NXConstantString == 1)
+    {
+      /* The user has overridden _user_defined_NXConstantString to
+	 tell us that he doesn't want us to load the library's
+	 NXConstantString implementation */
+      DEBUG_PRINTF ("Filtering out libobjc's NXConstantString at programmer's request:\n");
+
+      /* Search last occurrence of letter 'N' in the module name */
+      p = (char *)strrchr (module->name, 'N');
+      if (p)
+	{
+	  /* Found; compare string starting with this last 'N' to
+	     "NXConstStr.m" */
+	  if (strcmp (p, "NXConstStr.m") == 0)
+	    {
+	      /* it matches, so it is (should be) our NXConstantString
+                 module - don't load it */
+	      DEBUG_PRINTF ("Module not loaded\n");
+	      return;
+	    }
+	}
+      DEBUG_PRINTF ("Module loaded\n");
+    }

   /* check gcc version */
   init_check_module_version(module);


And then GNUstep can be patched as follows:

--- NSGCString.m	2000/03/17 13:13:07	1.77
+++ NSGCString.m	2000/05/26 15:26:11
@@ -23,6 +23,12 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111 USA.
 */

+/*
+ * Tell libobjc not to include its own implementation of NXConstantString
+ */
+
+int _user_defined_NXConstantString = 1;
+
 #include <config.h>
 #include <base/preface.h>
 #include <Foundation/NSString.h>


Please notice that I already talked to the other GNUstep developers and we
agreed this solution could be acceptable.