bug#69930: 29.1; onedrive

[Stephen Vavasis]

Thanks for getting back to me so quickly!  I just did some quick testing: the 
problem persists even with emacs -Q.  However, changing the variable 
backup-by-copying seems to fix the problem.  Thanks!  I will let a few 
colleagues know about this setting.

-- Steve Vavasis

P.S.  For your future reference, I also have attached screenshots showing how 
this issue appears in the cloud.   There are four screen shots for test.tex 
(before changing the variable backup-by-copying) and four for x.log (after I 
changed the variable).   The first screenshot for each file is taken before I 
edited it; the second taken is after I edited it but before I saved it; the 
third is after emacs auto-saved it, and the fourth is after I saved it with 
CTRL-X CTRL-S and opened the file's the version history.   As you can see, the 
version history is lost for test.tex but not for x.log.
  

-----Original Message-----
From: Eli Zaretskii <eliz@gnu.org> 
Sent: Thursday, March 21, 2024 12:56 PM
To: Stephen Vavasis <vavasis@uwaterloo.ca>
Cc: 69930@debbugs.gnu.org
Subject: Re: bug#69930: 29.1; onedrive

> From: Stephen Vavasis <vavasis@uwaterloo.ca>
> Date: Thu, 21 Mar 2024 12:45:46 +0000
> 
> Emacs does not work properly with the version-history feature of 
> Microsoft's OneDrive cloud file system.  The situation arises for a 
> file on the C: drive of my Windows machine that sits inside the 
> OneDrive cloud-sync'd folder.  When I edit a file like this on my 
> Windows machine with emacs, the OneDrive version-history shows only the 
> latest version.
> It seems that the Emacs save-button CTRL-X CTRL-S causes OneDrive to 
> discard older versions.  Older versions of the file can still be found 
> in the Recycled folder in the cloud.  This is not an ideal place for 
> them because Recycled is not easily searched, file names can collide, 
> and Recycled is periodically purged.

Does this happen in "emacs -Q"?  If this doesn't happen in "emacs -Q", you 
should look for some customization of yours that causes this; in particular, 
Emacs by default never writes old versions of files to the Recycled directory.

If "emacs -Q" also shows this behavior, my suggestion is to try setting the 
option backup-by-copying to a non-nil value.

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