bug#53678: 29.0.50; Invalid read syntax: "#<" for package install in Windows

[Shuguang Sun via "Bug reports for GNU Emacs, the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>]

Alan Mackenzie <acm@muc.de> writes:

> Hello again, Shuguang.
>
> On Thu, Feb 03, 2022 at 10:55:02 +0800, Shuguang Sun wrote:
>> Thank you Stefan and Alan in another email.
>
>> With the hint, I find out the `async-bytecomp-package-mode` is turn on
>> by the package `helm-core`. So it is a bug of `async-bytecomp` maybe,
>> and I will report it the package author.
>
>> Sorry for the misleading information in the orignial email.
>
> A hypothesis for what is happening is that a symbol with position,
> looking like:
>
>     #<symbol foo at 666>
>
> , has somehow got into a .elc file.  The loader (contained within the
> file .../src/lread.c) chokes when it encounters such a symbol.
>
> If you have an idea which .elc file might be causing the trouble, could
> I suggest you visit this file within Emacs.  There is a mode for .elc
> files.  :-).  Then search the buffer for the string "#<symbol".  Or even
> just for the "#<" which the loader might have reported.

No "#<" in the elc.

A reproducible example is:
- Install package `async` which includes `async-bytecomp`
- M-x list-package
- M-x async-bytecomp-package-mode (make sure `async-bytecomp-package-mode` is enabled)
- M-x package-reinstall  <= `magit`

>
>
>
>> ------------------ Original --------------
>> Date: Wed,Feb 2,2022 11:32 AM
>
>
>> Eli Zaretskii [2022-02-01 17:00:34] wrote:
>> &gt;&gt; Date: Tue, 01 Feb 2022 13:32:11 +0800
>> &gt;&gt; From:&nbsp; Shuguang Sun via "Bug reports for GNU Emacs,
>> &gt;&gt;&nbsp; the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org&gt;
>> &gt;&gt; When I try to install packages from the Package Menu or the command of
>> &gt;&gt; package-install since about two weeks ago, it reports the error:
>> &gt;&gt; ```
>> &gt;&gt; error in process sentinel: async-when-done: Invalid read syntax: "#<"
>> &gt;&gt; error in process sentinel: Invalid read syntax: "#<"
>> &gt;&gt; ```
>> &gt; Stefan, any thoughts?
>
>> IIUC the above error involves some part of the `async` package.
>> Could you give a bit more information about how you hooked `async` with
>> `package`?
>
>
>> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; Stefan

-- 
Best Regards
Shuguang Sun