Eli Zaretskii <eliz@gnu.org> writes:

>> Ehmm...  I see that test/src/buffer-tests now have 5 failures that
>> were not there before:
>> 
>>   5 unexpected results:
>>      FAILED  test-buffer-modifications
>>      FAILED  test-kill-buffer-auto-save-default
>>      FAILED  test-kill-buffer-auto-save-delete-no
>>      FAILED  test-kill-buffer-auto-save-delete-yes
>>      FAILED  test-restore-buffer-modified-p
>> 
>> Also, 7 of the lisp/files-test fail:
>> 
>>   7 unexpected results:
>>      FAILED  files-tests-bug-18141
>>      FAILED  files-tests-file-name-non-special-make-auto-save-file-name
>>      FAILED  files-tests-file-name-non-special-set-visited-file-modtime
>>      FAILED  files-tests-no-file-write-contents
>>      FAILED  files-tests-revert-buffer
>>      FAILED  files-tests-revert-buffer-with-fine-grain
>>      FAILED  files-tests-zzdont-rewrite-precious-files
>> 
>> Could you please look into these?  (Interestingly, those 5+7 don't
>> fail for me on MS-Windows, only on GNU/Linux...)

FYI, all the tests are passing on my side (GNU/Linux):

cd test
make src/buffer-tests

Ran 406 tests, 406 results as expected, 0 unexpected (2023-12-30 11:24:04+0100, 0.464788 sec)

> I think at least part of the problem is in this fragment from
> find-file-noselect:
>
> 	     ;; Find any buffer for a file that has same truename.
> 	     (other (and (not buf)
>                          (find-buffer-visiting
>                           filename
>                           ;; We want to filter out buffers that we've
>                           ;; visited via symlinks and the like, where
>                           ;; the symlink no longer exists.
>                           (lambda (buffer)
>                             (let ((file (buffer-local-value
>                                          'buffer-file-name buffer)))
>                               (and file (file-exists-p file))))))))

Not this one - (and file ...) will never trigger when file is nil.

>   Test test-buffer-modifications backtrace:
>     file-exists-p(nil)
>     find-buffer-visiting("/tmp/emacs-test-MzitxT-buffer" #f(compiled-fun
>     find-file-noselect("/tmp/emacs-test-MzitxT-buffer" nil nil nil)
>     find-file("/tmp/emacs-test-MzitxT-buffer")
>
> Please attend to this as soon as you can, because I think this same
> problem will break many other use cases.

I think I found the problem - it is rather silly.
See the attached patch.