Using weak symbols rather than __attribute__((constructor)) preserves the
linking order as on other platforms.
--- src/Vendor.c.orig	2024-03-10 21:39:48
+++ src/Vendor.c	2024-05-22 23:44:47
@@ -111,20 +111,12 @@
  *
  ***************************************************************************/
 
-#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__APPLE__)
+#if defined(__CYGWIN__) || defined(__MINGW32__)
 /* to fix the EditRes problem because of wrong linker semantics */
 extern WidgetClass vendorShellWidgetClass; /* from Xt/Vendor.c */
 extern VendorShellClassRec _XawVendorShellClassRec;
 extern void _XawFixupVendorShell();
 
-#if defined(__APPLE__)
-__attribute__((constructor))
-static void __VendorShellHack(void)
-{
-    vendorShellWidgetClass = (WidgetClass)(&_XawVendorShellClassRec);
-    _XawFixupVendorShell();
-}
-#else
 int __stdcall
 DllMain(unsigned long mod_handle, unsigned long flag, void *routine)
 {
@@ -139,7 +131,6 @@
     }
   return 1;
 }
-#endif
 
 #define vendorShellClassRec _XawVendorShellClassRec
 
@@ -155,6 +146,9 @@
 };
 
 #define SuperClass (&wmShellClassRec)
+#if defined(__APPLE__)
+__attribute__((weak))
+#endif
 externaldef(vendorshellclassrec) VendorShellClassRec vendorShellClassRec = {
   {
     /* superclass	  */	(WidgetClass)SuperClass,
@@ -204,10 +198,11 @@
   }
 };
 
-#if !defined(__APPLE__)
+#if defined(__APPLE__)
+__attribute__((weak))
+#endif
 externaldef(vendorshellwidgetclass) WidgetClass vendorShellWidgetClass =
 	(WidgetClass) (&vendorShellClassRec);
-#endif
 
 /***************************************************************************
  *
@@ -348,7 +343,7 @@
     }
 }
 
-#if defined(__CYGWIN__) || defined(__MINGW32__) || defined(__APPLE__)
+#if defined(__CYGWIN__) || defined(__MINGW32__)
 /* shared libraries on these platforms have the wrong semantics */
 /* symbols do not get resolved external to the shared library */
 void _XawFixupVendorShell()