bug#54433: 29.0.50; Invalid read syntax: "#<" with async-bytecomp

[Michael Heerdegen <michael_heerdegen@web.de>]

Hello,

when updating packages with M-x package-list-packages, and using
async-bytecomp.el to compile, some users get an error like this one:

error in process sentinel: async-when-done: Invalid read syntax: "#<"
error in process sentinel: Invalid read syntax: "#<"

This seems to be related to the recent addition of symbols with
positions.

async uses `async-inject-variables' to collect variable bindings of
interest and deliver them to the other Emacs instance.  The return value
contains symbols with positions in some scenarios.

The root of the trouble seems to be the value of
`byte-optimize--dynamic-vars'.  As soon as I byte compile any file, I
see lots of symbols with positions in `byte-optimize--dynamic-vars'.

Is that expected?  What has to be done?

TIA,

Michael.


In GNU Emacs 29.0.50 (build 55, x86_64-pc-linux-gnu, GTK+ Version 3.24.24, cairo version 1.16.0)
 of 2022-03-17 built on drachen
Repository revision: 97e687006498490cca1e6dabc1ea7e692271c5ed
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12011000
System Description: Debian GNU/Linux 11 (bullseye)

Configured using:
 'configure --with-native-compilation --with-xwidgets'