>>> What is the failure behaviour of package.el for this at the moment?
>>
>> Package.el will signal an error during installation if it's not a
>> valid sexp. The error itself will depend on what the problem is.
>> Here's what you get if you miss a closing paren for instance:
>> package-read-from-string: End of file during parsing
>
> My issue with this is that, iff I see this error, my first port of call
> is going to be check-parens, and generally look for unbalanced parens in
> the relevant file. And there are not going to be any, because in the
> file, there is no invalid sexp. There is a commented out, pseudo sexp.
> [...]
> Just my thoughts, I will leave the issue in your hands from there.
Thanks for the thoughts. I do think package.el could do better error
reporting in these situations (and I might take that up too).
That said, I don't think the proposed patch makes this situation any worse.