Ok, I have looked into this one in detail. The issue was triggered by
"NS" (Nathanael?) in update 5700 (which Ken was unsure if it ever got
properly reviewed btw) were he changed "self selectionAsStream" to "self
selection string" in #evaluateSelection.

The result of that change is that instead of passing a ReadStream with a
position into the full text, it passes only the selected code into the
Parser. That works fine until the Compiler starts to try to givinng
feedback using instvar requestor.

Those methods, like for example when it tries to correct a selector
(this one was caught by Frank's patch) or when it reports a compilation
error  (not caught by Frank's patch) then thinks that the position it
has are absolute and can be used in messages to requestor. But they are
now relative.

Also, I note that there is still a sender of #selectionAsStream, namely
when you choose "debug it". Given Frank's patch that case is now instead
broken.

My conclusion:
1. Nathanael just did this little change as a side thought, otherwise he
wouldn't have missed the other sender of #selectionAsStream.
2. If we indeed want the Parser to work like this then we need to fix
quite a few places more - Frank's patch just isn't enough.

Recommendation:

Unless someone stands up and fixes this thoroughly so that there are no
more senders of selectionAsStream ("debug it" works too), and syntax
errrors are also fixed to work etcetc, I think we should back this
change out and revert back to "self selectionAsStream".

regards, Gšran