Weak pointer support fixes and use for notification observers.

ChangeLog

@@ -1,3 +1,27 @@
+2024-12-27 Richard Frith-Macdonald <rfm@gnu.org>
+
+	* Headers/GNUstepBase/GSIMap.h:
+	* Headers/GNUstepBase/GSObjCRuntime.h:
+	* Source/GSPrivate.h:
+	* Source/NSConcreteHashTable.m:
+	* Source/NSConcretePointerFunctions.h:
+	* Source/NSNotificationCenter.m:
+	* Source/NSObject.m:
+	* Source/ObjectiveC2/GNUmakefile:
+	* Source/ObjectiveC2/README:
+	* Source/ObjectiveC2/weak.m:
+	* Tests/base/Functions/runtime.m:
+	* Tests/base/NSHashTable/weakObjects.m:
+	* Tests/base/NSMapTable/weakObjects.m:
+	* Tests/base/NSNotification/general.m:
+	* Tests/base/NSPointerArray/weakObjects.m:
+	Implement weak objects API support for classic/gnu runtime.
+	Use it to implement weak reference support in NSPointerFunctions
+	(for NSMapTable, NSHashTable, NSP{ointerArray) and to implement
+	safe observer support for NSNotificationCenter (if an observer is
+	deallocated then it is removed from the notification center the
+	next time a notification woudl be posted to it).
+
 2024-11-29 Richard Frith-Macdonald <rfm@gnu.org>
 
 	* Source/NSURLProtocol.m: fix leaks due to retain loops.

Headers/GNUstepBase/GSObjCRuntime.h

@@ -63,6 +63,18 @@
  #endif
 #endif
 
+#if defined(OBJC_CAP_ARC)
+#  include <objc/objc-arc.h>
+#else
+GS_EXPORT void objc_copyWeak(id *dest, id *src);
+GS_EXPORT void objc_destroyWeak(id *obj);
+GS_EXPORT id objc_initWeak(id *addr, id obj);
+GS_EXPORT id objc_loadWeak(id *object);
+GS_EXPORT id objc_loadWeakRetained(id *addr);
+GS_EXPORT void objc_moveWeak(id *dest, id *src);
+GS_EXPORT id objc_storeWeak(id *addr, id obj);
+#endif
+
 /*
  * Hack for older compiler versions that don't have all defines
  * needed in  objc-api.h

Source/NSConcretePointerFunctions.h

@@ -28,17 +28,15 @@
 #  include <objc/capabilities.h>
 #endif
 
+#import	"GNUstepBase/GSObjCRuntime.h"
+
+#define WEAK_READ(x) objc_loadWeak((id*)x)
+#define WEAK_WRITE(addr, x) objc_storeWeak((id*)addr, (id)x)
+
 #if defined(OBJC_CAP_ARC)
-#  include <objc/objc-arc.h>
-#  define WEAK_READ(x) objc_loadWeak((id*)x)
-#  define WEAK_WRITE(addr, x) objc_storeWeak((id*)addr, (id)x)
 #  define STRONG_WRITE(addr, x) objc_storeStrong((id*)addr, (id)x)
 #  define STRONG_ACQUIRE(x) objc_retain(x)
 #else
-extern id objc_loadWeak(id *object);
-extern id objc_storeWeak(id *addr, id obj);
-#  define WEAK_READ(x) objc_loadWeak((id*)x)
-#  define WEAK_WRITE(addr, x) objc_storeWeak((id*)addr, (id)x)
 #  define STRONG_WRITE(addr, x) ASSIGN(*((id*)addr), ((id)x))
 #  define STRONG_ACQUIRE(x) RETAIN(((id)x))
 #endif