Re: Default lexical-binding to t

[Jim Porter]

On 11/5/2024 12:24 PM, Stefan Monnier wrote:
> > What bothers me is how do I know whether a given Lisp file of mine
> > will have problems under lexical-binding.  Do we have any tools which
> > will help me determine that?
>
> It's generally impossible to do that reliably (it can be reduced to
> a variant of the halting problem), but the problem is exactly the same
> as that of converting from dynbind to lexbind (which we do describe in
> the manual).

How about a less-reliable tool that catches some easy-to-detect 
problems? For example, look in every defun and see if the macro-expanded 
form of the function body refers to a variable that is neither 1) 
declared with 'defvar' or 2) let-bound in that function. This logic 
might not be exactly what we want since I haven't thought very long 
about it, but something along these lines could hopefully catch many errors.

Even if we can't catch 100% of issues, catching 80% of them would make 
users' lives easier.