The following code fragment at the end of the method is not entirely correct:

     "And check if the immediate subclasses of oldClass can keep its layout"
     oldClass subclassesDo:[:sub|
          oldType _ sub typeOfClass.
          oldType == newType ifFalse:[
               self error: sub name,' cannot be recompiled'.
               ^false]].

Why should the subclasses of oldClass have the same type as the new type of
oldClass (their superclass) ? Perhaps they never had the same type, in which
case this will fail for any refactoring. A small testcase follows:

Object subclass: #A
     instanceVariableNames: ''
     classVariableNames: ''
     poolDictionaries: ''
     category: 'Kernel-Objects'.

Object subclass: #B
     instanceVariableNames: ''
     classVariableNames: ''
     poolDictionaries: ''
     category: 'Kernel-Objects'.

B variableSubclass: #Sub
     instanceVariableNames: ''
     classVariableNames: ''
     poolDictionaries: ''
     category: 'Kernel-Objects'.

Now the innocent refactoring ...

A subclass: #B
     instanceVariableNames: ''
     classVariableNames: ''
     poolDictionaries: ''
     category: 'Kernel-Objects'.

.... will fail.


The types only need to be the same if the new type of oldClass is variable,
therefore the easy fix:

     newType ~~ #normal ifTrue:
          "Check if the immediate subclasses of oldClass can keep its layout"
          [oldClass subclassesDo:[:sub|
               oldType _ sub typeOfClass.
               oldType == newType ifFalse:[
                    self error: sub name,' cannot be recompiled'.
                    ^false]]].

Florin