bug#49118: 28.0.50; Error: File error Opening output file

[Eli Zaretskii <eliz@gnu.org>]

> Cc: 49118@debbugs.gnu.org
> From: Manuel Uberti <manuel.uberti@inventati.org>
> Date: Sat, 19 Jun 2021 16:34:41 +0200
> 
> On 19/06/21 16:32, Eli Zaretskii wrote:
> > What happens if you invoke the native-compilation like this:
> > 
> >    $ emacs -batch -l comp -f batch-native-compile /usr/local/share/emacs/28.0.50/lisp/time.el.gz
> > 
> > Does this also fail, and if so, what error message(s) do you see?
> 
> This is what I get:
> 
> manuel@hathaway:~$ emacs -batch -l comp -f batch-native-compile 
> /usr/local/share/emacs/28.0.50/lisp/time.el.gz
> uncompressing time.el.gz...
> uncompressing time.el.gz...done
> Debugger entered--Lisp error: (file-error 
> "/usr/local/share/emacs/28.0.50/lisp/time.el.gz" "Opening output file" "Cannot 
> overwrite file" "/usr/local/share/emacs/28.0.50/lisp/time.elc")
>    signal(file-error ("/usr/local/share/emacs/28.0.50/lisp/time.el.gz" "Opening 
> output file" "Cannot overwrite file" 
> "/usr/local/share/emacs/28.0.50/lisp/time.elc"))
>    comp--native-compile("/usr/local/share/emacs/28.0.50/lisp/time.el.gz")
>    batch-native-compile()
>    command-line-1(("-l" "comp" "-f" "batch-native-compile" 
> "/usr/local/share/emacs/28.0.50/lisp/time.el.gz"))
>    command-line()
>    normal-top-level()

Thanks.

Andrea, this means bug#48978 was not entirely fixed: we are still
trying to write the *.elc files when native-compiling.  Your last
change prevented Emacs from trying to create a temporary file under
/usr/share/emacs, but it didn't prevent the rest of byte-compile-file
from trying to overwrite the original .elc file, which here causes us
to signal an error.  We need to avoid writing the .elc file entirely
in this case, I think.