bug#52295: 28.0.90; Killing text results in coding system complaint

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Po Lu <luangruo@yahoo.com>
>> Cc: 52295@debbugs.gnu.org
>> Date: Sun, 05 Dec 2021 16:58:27 +0800
>> 
>> >> w32--set-selection: Coding system is invalid or doesn't have an eol
>> >> variant for dos line ends: nil [2 times]
>> >
>> > What are the values of the following variables on that system?
>> >
>> >   selection-coding-system
>> >   next-selection-coding-system
>> 
>> Both variables are nil.
>
> That's the problem.  But I don't understand why is that so.  The value
> of selection-coding-system is set in globals_of_w32select, which is
> called during startup, and where we have this code:
>
>   ANSICP = GetACP ();
>   OEMCP = GetOEMCP ();
>
>   QANSICP = coding_from_cp (ANSICP);
>   QOEMCP = coding_from_cp (OEMCP);
>
>   if (os_subtype == OS_SUBTYPE_NT)
>     Vselection_coding_system = Qutf_16le_dos;
>   else if (inhibit_window_system)
>     Vselection_coding_system = QOEMCP;
>   else
>     Vselection_coding_system = QANSICP;
>
> On Windows 9X, this should assign the ANSI codepage to
> selection-coding-system.  Since your codepage seems to be 1252, it
> should assign the symbol 'cp1252-dos' to selection-coding-system, see
> coding_from_cp.
>
> Why doesn't this happen in your case?

Maybe that variable is dumped during the build process, with a value
appropriate for NT, and when Emacs starts on a 9X system some other code
sees that it is invalid and sets it to nil?