initialization of element is conditional (in the or: block).
I'm amazed, that's a new behavior, is it a consequence of using AST?

But a dumb compiler not knowing the semantic of or: (it is a message like others) could conclude that element may be used uninitialized in the whileFalse block...
A compiler that is inlining or: with a well known semantic has no excuse ;)

2016-08-16 22:12 GMT+02:00 stepharo <stepharo@free.fr>:

While browsing the system I saw that the following method raised a temp read before written...

It did not jump to my eyes. Working on something else....

PositionableStream>>upTo: anObject
�� "Answer a subcollection from the current access position to the
�� occurrence (if any, but not inclusive) of anObject in the receiver. If
�� anObject is not in the collection, answer the entire rest of the receiver."
�� | newStream element |
�� newStream := (collection species new: 100) writeStream.
�� [self atEnd or: [(element := self next) = anObject]]
�� whileFalse: [newStream nextPut: element].
�� ^newStream contents