bug#55767: 29.0.50; tramp converts buffer of remote OSX file to utf-8-mac after save

[Michael Albinus]

Jake Nelson <jake.nelson@gmail.com> writes:

Hi Jake,

> 1. Visit remote file on an OSX system using
> /scp:hostname:/path/to/file
> 2. Modify buffer
> 3. Save
> 4. Note buffer-file-coding-system has updated to utf-8-mac (and (Mac)
> now listed
> in modeline).
> 5. Modify and Save again and the file line endings will be converted
> to
> carriage returns.

Well, I don't use macOS myself, neither locally nor on a remote
machine. So I hope you can help me to puzzle this out.

> I used git bisect to find commit
> 47fe7a5983a97c3e806e90340f3cd6ab3f0c49b2 introduced this behavior.
> Prior
> to 47fe7a59 emacs would not modify the line endings of the file.   I
> believe utf-8-mac is only for Mac Classic files.

Well, IIRC, 47fe7a59 was just a refactoring of code. It introduced the
new macro tramp-skeleton-write-region in order to simplify Tramp's
different write-region implementations.

Hmm, you are speaking about "Mac Classic files". How could Tramp
determine, whether a remote machine uses this? These days, Tramp calls
"uname -sr". If the result string contains "Darwin", Tramp assumes macOS
on the remote side. Is there something else Tramp shall distinguish for
remote macOS'es?

Best regards, Michael.