bug#62847: 29.0.90; Propertized space in Org Agenda's mode-name

[Mattias Engdegård]

16 apr. 2023 kl. 13.29 skrev Ihor Radchenko <yantar92@posteo.net>:

> I am wondering if there is any relevant warning raised by the byte
> compiler when doing something like
> (let ((str " ")) (add-text-properties 0 1 '(foo bar) str))

No, but it wouldn't be very hard to add one, but it would miss a lot of code 
that has no idea whether it is working on a string literal or not.

Counter to my usual preference for static checks I'd prefer a dynamic warning 
in this case because it would be precise and the run-time cost would likely be 
acceptable.

That requires a 'literal' flag for string objects and there's no obvious space 
for one, but perhaps we can grab the LSB of the `intervals` pointer.

Even if such a check defaults to off, it could be enabled selectively to root 
out bugs like this one. I'll see what I can do.