Re: Recent change in master breaks async package update using paradox

[Lars Brinkhoff]

Eli Zaretskii wrote:
>> The first lambda is executed in a subprocess emacs and throws the error
>> (wrong-type-argument sequencep #s(package-desc swiper ... ))
>
> What is package-desc?  If its value and/or its semantics are only
> valid in the parent Emacs process, then it might not work to use it in
> the subprocess.

It's a defstruct in package.el.

I interpret the error message as something probably creating a
package-desc instance as a record.  But then something else expects this
instance to be a sequence.  Possibly because it's compiled with the old
cl-defstruct, or maybe it's using a function that worked with vector
structures but now doesn't work with record structures.  (If it's the
latter, we should probably add something to cl-old-struct-compat-mode to
make it work.)

I think there are only a few functions that wants a sequence but not a
record: elt, copy-sequence, concat, reverse, and sort.  In the context
of structure operations, the most likely function would be copy-sequence.

The problem is finding this function call which is made in an async
subprocess emacs.  The backtrace we have only shows what's going in in
the parent emacs.