'From Squeak3.1alpha of 5 February 2001 [latest update: #3579] on 12 February 2001 at 10:07:06 pm'!
"Change Set:		MutateFixNot
Date:			12 February 2001
Author:			Dan Ingalls

Reverts 3569 in case anyone received it.
"!


!ClassBuilder methodsFor: 'private' stamp: 'di 2/12/2001 22:06'!
fixGlobalReferences 
	"Fix all the references to globals which are now outdated.
	Care must be taken that we do not accidentally 'fix' dangerous stuff."
	| oldClasses newClasses condition any |
	classMap == nil ifTrue:[^self].
	(self retryWithGC: [condition _ classMap anySatisfy: [:any0 | any _ any0. any0 _ nil. any notNil and:[any
isObsolete]]. any_nil. condition]
		until:[:obsRef| obsRef = false])
		ifFalse:[^self]. "GC cleaned up the remaining refs"
	"Collect the old and the new refs"
	oldClasses _ OrderedCollection new.
	newClasses _ OrderedCollection new.
	classMap keysAndValuesDo:[:new :old|
		old == nil ifFalse:[
			newClasses add: new.
			oldClasses add: old]].
	oldClasses isEmpty ifTrue:[^self]. "GC cleaned up the rest"

	"Now fix all the known dangerous pointers to old classes by creating
	copies of those still needed. Dangerous pointers should come only
	from obsolete subclasses (where the superclass must be preserved)."
	self fixObsoleteReferencesTo: oldClasses.

	"After this has been done fix the remaining references"
	progress == nil ifFalse:[progress value: 'Fixing references to
globals'].
	"Forward all old refs to the new ones"
	(oldClasses asArray) elementsForwardIdentityTo: (newClasses asArray).
	"Done"! !


!ClassDescription methodsFor: 'initialize-release' stamp: 'di 2/12/2001 22:06'!
updateInstancesFrom: oldClass
	"Recreate any existing instances of the argument, oldClass, as instances of 
	the receiver, which is a newly changed class. Permute variables as 
	necessary."
	"ar 7/15/1999: The updating below is possibly dangerous. If there are any
	contexts having an old instance as receiver it might crash the system if
	the new receiver in which the context is executed has a different layout.
	See bottom below for a simple example:"
	| oldInstances |

	Smalltalk garbageCollect.	"ensure that allInstances is correct"
	oldInstances _ oldClass allInstances asArray.
	self updateInstances: oldInstances from: oldClass isMeta: self isMeta.
	"Now fix up instances in segments that are out on the disk."
	ImageSegment allSubInstancesDo: [:seg |
		seg segUpdateInstancesOf: oldClass toBe: self isMeta: self isMeta].
	oldInstances _ nil.
	Smalltalk garbageCollect.	"ensure that old instances are gone"


"	| crashingBlock class |
	class _ Object subclass: #CrashTestDummy
		instanceVariableNames: 'instVar'
		classVariableNames: ''
		poolDictionaries: ''
		category: 'Crash-Test'.
	class compile:'instVar: value instVar _ value'.
	class compile:'crashingBlock ^[instVar]'.
	crashingBlock _ (class new) instVar: 42; crashingBlock.
	Object subclass: #CrashTestDummy
		instanceVariableNames: ''
		classVariableNames: ''
		poolDictionaries: ''
		category: 'Crash-Test'.
	crashingBlock.
	crashingBlock value.
	"
! !