Constraints on variables in pure procedures

[Brooks Moses]

Paul Thomas wrote:
> Brooks,
>>Has a PR been filed for this?
> 
> No.  The correspondence arose out of PR20863, where one of the genuinely 
> illegal cases does not cause an error.  I was looking at the code, in 
> place, that tries to apply purity and it made no sense to me whatsoever.
> 
> It might be best to add this to PR20863, refer to the thread and change 
> the title of the PR.

Done.

> This would make a very nice tyro front-end project. :-)

Indeed.  Had I but time, and no dissertation to finish.  :)

- Brooks