Thank you for working on this! I will personally find this very useful, e.g. when dealing with virtual disk images that are huge in size and change often, making the current versioning approach not feasible and forcing to disable file versioning for the whole folder.

Just a comment, as I haven't tested the code at all yet. I don't think we actually use the word "archive" in the GUI when talking about versioning. I understand that it is present in the code, but in the GUI, we just talk about "Versions Path" and "versions being stored" there (i.e. not "archived"). Wouldn't it be better and more understandable if we stick to the current wording?

Basically, what I want to say that "archive" is a vague term, which can mean different things depending on the context.

Also, are you planning to enable this by default? If not, then I think it should be just ref #6164 instead of fixes #6164.

Thank you for working on this! I will personally find this very useful, e.g. when dealing with virtual disk images that are huge in size and change often, making the current versioning approach not feasible and forcing to disable file versioning for the whole folder.

Glad that this change is helpful to you!

Just a comment, as I haven't tested the code at all yet. I don't think we actually use the word "archive" in the GUI when talking about versioning. I understand that it is present in the code, but in the GUI, we just talk about "Versions Path" and "versions being stored" there (i.e. not "archived"). Wouldn't it be better and more understandable if we stick to the current wording?

Basically, what I want to say that "archive" is a vague term, which can mean different things depending on the context.

I have made changes to UI code. Do you think we need similar renaming across backend changes?

Also, are you planning to enable this by default? If not, then I think it should be just ref #6164 instead of fixes #6164.

Going through #6164 discussion, I don't see a clear majority for any behavior. Let's use this PR to invigorate the dead discussion 🙈

I've quickly glanced over the code changes and in general, the feature seems sensible. The extra interface for checking whether the versioner supports the flag seems a little specific and could possibly be integrated more elegantly / with broader scope. Though I can't give you a counter-proposal now, would need to invest more time understanding the relevant bits first. So let's hear an opinion on that from the other maintainers.

Thank you for the review. My motivation behind this was to avoid modifying the core Versioner interface and only the versioners that support this feature need to implement the interface. But I am open for suggestions.

The change to the man page is however definitely out of place, because it is generated from the docs repo and should be adjusted there.

Removed man changes as they are tracked via syncthing/docs#930

Sorry for the late feedback, but the word "archive" is used several times in
https://github.com/syncthing/docs/blob/main/users/versioning.rst
Also, the word "version", when used as a verb (it's 99% of the time a noun, according to here) describes creating a new copy of something that is then used. Whereas the verb "archive" (it's 90% of the time a noun) describes creating a copy for historical purposes. So, I would suggest we stick with "archive" when describing creating a trash can backup.

I've now looked a bit more closely at the PR.

@rasa is right about the word "archive" already used in the Docs, I think it could also be used here, just make the wording more clear and easily understandable to the user. I'll try suggesting some fixes directly in the code in this regard.

Thank you for the review. My motivation behind this was to avoid modifying the core Versioner interface and only the versioners that support this feature need to implement the interface. But I am open for suggestions.

Is there any difficulty with applying this universally to all versioning types (except external, of course)? Simple and staggered versioning would greatly benefit from the feature as well.

Going through #6164 discussion, I don't see a clear majority for any behavior. Let's use this PR to invigorate the dead discussion 🙈

On the one hand, there are different opinions, but on the other, the issue was created by @calmh himself and requests "enabling by default" right in the title, so I think to actually "fix" the issue, the option does need to come enabled. Otherwise you can just ref #6164 instead and leave the "enabling by default" part for a later discussion 😉.