Reapply "Implement NSDate as a small object (tagged pointer) - clang/…

…libobjc2 only (#451)" because of GUI breakage: apps hang when loading NSMenu

This reverts commit cac43f7.

ChangeLog

@@ -15,7 +15,22 @@
 	* Source/NSFileManager.m: Create an NSError object when we fail to
 	copy because the destination item already exists.
 
-2024-09-23: Hugo Melder <[email protected]>
+2024-10-10: Hugo Melder <[email protected]>
+
+	* Source/NSDate.m:
+	* Source/NSDatePrivate.h:
+	NSDate is now a small object in slot 6, when configuring GNUstep with the
+	clang/libobjc2 toolchain.  This is done by compressing the binary64 fp
+	holding the seconds since reference date (because someone at Apple thought
+	it would be a good idea to represent a time interval as a fp). Note that
+	this assumes that IEEE 754 is used.
+	* Source/NSCalendarDate.m:
+	Remove access to the NSDate private concrete Class
+	and implement -timeIntervalSinceReferenceDate instead.
+	Previously, all methods of the concrete date class were
+	added to NSCalendarDate via GSObjCAddClassBehavior.
+
+2024-23-09: Hugo Melder <[email protected]>
 
 	* Headers/Foundation/NSThread.h:
 	* Source/NSString.m:

Source/NSCalendarDate.m

@@ -58,9 +58,6 @@ @interface	GSTimeZone : NSObject	// Help the compiler
 @class	GSAbsTimeZone;
 @interface	GSAbsTimeZone : NSObject	// Help the compiler
 @end
-@class	NSGDate;
-@interface	NSGDate : NSObject	// Help the compiler
-@end
 
 
 #define DISTANT_FUTURE	63113990400.0
@@ -396,7 +393,6 @@ + (void) initialize
       absAbrIMP = (NSString* (*)(id,SEL,id))
 	[absClass instanceMethodForSelector: abrSEL];
 
-      GSObjCAddClassBehavior(self, [NSGDate class]);
       [pool release];
     }
 }
@@ -463,6 +459,11 @@ + (id) dateWithYear: (NSInteger)year
   return AUTORELEASE(d);
 }
 
+- (NSTimeInterval) timeIntervalSinceReferenceDate
+{
+  return _seconds_since_ref;
+}
+
 /**
  * Creates and returns a new NSCalendarDate object by taking the
  * value of the receiver and adding the interval in seconds specified.