bug#40692: 28.0.50; Constant list modified inside function

[Ivan Andrus]

On Apr 17, 2020, at 5:45 PM, Ivan Andrus <darthandrus@gmail.com> wrote:
> 
> I believe this is the root cause of a bug in magit/forge 
> https://github.com/magit/forge/issues/267 in which all subsequent pull 
> requests created have the same name.  The maintainer of magit/forge (tarsius) 
> was unable to reproduce that bug, so I tried my hand at creating a minimal 
> test case, and I was able to get it down to this.
> 
> Now, I understand reference semantics of lists in general, but it seems like 
> this should be different.  If this behavior is intentional, what's the best 
> way to for creation of a new list every time so that functions using the 
> alist don't have to worry about not changing the list?

I tracked down the function doing the actual changing: json-encode-alist.  I 
filed https://debbugs.gnu.org/cgi/bugreport.cgi?bug=40693   

I still find the behavior here confusing, but I expect it will be considered 
expected behavior.

-Ivan