On Tue, Aug 23, 2016 at 11:21 AM, marcel.taeumel <Marcel.Taeumel at hpi.de>
wrote:

>
> Hi, there.
>
> It is, unfortunately, not possible to turn back time and rewrite history.
> ;-)
>

... unless we're dealing with software. Oh wait, we are ;)

There is several important code that makes excessive use of instVar
> accesses such as in SystemProgressMorph or HandMorph. Making any change in
> their class layout while using some of their methods will provoke a strange
> error. This could only be changed by a VM that keeps old class
> layouts/schemata around for some longer time until there is no old compiled
> method on any stack anymore.


Class layout changes and instance migration is handled fully in the image
by class ClassBuilder. The VM is not at fault here.


> Usually, restarting the update process helps here. There is no way to fix
> that in order to interactively update from 5.0 to 5.1 without any errors.
>

We can retroactively change the config map that introduced the problem. I'm
certain it would be possible to fix, but I am not entirely sure it's worth
the trouble.

- Bert -
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