Ooh, that's me! As in the comment, please don't do this.
It's been a while since I worked at a place doing this, and I'm on my phone, so some details may be fuzzy or wrong, but when I was figuring all this out, I remember this SO comment being really helpful:
Basically, there's two different APIs, and neither of them are designed for ignoring config files (but both of them happen to do things that look like ignoring config files, therefore get misused).
`assume-unchanged` is an optimisation tool that tells git that it shouldn't both checking files and folders that are expensive to check but never changed. If changes do ever happen, and git realises this, then git will remove the assume-unchanged flag - because clearly it wasn't true!
`skip-worktree` is a more aggressive version of this that tells git never to touch certain files or folders at all. But now it changes do happen to those files, it's not clear what git should do. Overwriting the files would cause data loss, but ignoring the files completely means that you miss out on upstream changes. And because you're telling git that these files should never be checked, there's no good way to handle merging and conflicts.
What typically happens with both of these flags is that they work well about 80% of the time, and then cause a lot of confusion that last 20% of the time.
The alternative is almost always some sort of configuration file that is directly referenced in .gitignore, and that therefore never gets checked in. (In addition, it's often useful to have a (e.g.) config.json.default file for getting new developers up and running quickly.) Any system that needs to be configured (database connections, API URLs, IP addresses, etc) should use this configuration file. Alternatively, I find environment variables, along with .env files for local development, to be really effective, because most things can already be configured that way.
This typically takes sightly longer to set up the first time, but will work very reliably from then on.
See also these changes in git's official documentation, and the commit message that explains why it was necessary:
For a long time I have been wishing that Git had a capability of "track this file locally, but don't transfer it when pushing or cloning". Such files would be listed using the same syntax as .gitignore, but in a different file, say .gitlocal or something.
Git kind of has some "local tracking" already: if I am not mistaken, lightweight tags behave like this. It would be cool if it could track files in the same way.
Under the hood it could be done via a separate database, stored not in .git but in .gitl directory or some such. The database in .git would behave as if both .gitignore and .gitlocal contribute to ignoring, and .gitl as if .gitlocal was .gitignore in reverse: it would ignore anything not covered in .gitlocal (and also ignore what's in .gitignore). Or something along these lines.
It's been a while since I worked at a place doing this, and I'm on my phone, so some details may be fuzzy or wrong, but when I was figuring all this out, I remember this SO comment being really helpful:
https://stackoverflow.com/a/23806990
Basically, there's two different APIs, and neither of them are designed for ignoring config files (but both of them happen to do things that look like ignoring config files, therefore get misused).
`assume-unchanged` is an optimisation tool that tells git that it shouldn't both checking files and folders that are expensive to check but never changed. If changes do ever happen, and git realises this, then git will remove the assume-unchanged flag - because clearly it wasn't true!
`skip-worktree` is a more aggressive version of this that tells git never to touch certain files or folders at all. But now it changes do happen to those files, it's not clear what git should do. Overwriting the files would cause data loss, but ignoring the files completely means that you miss out on upstream changes. And because you're telling git that these files should never be checked, there's no good way to handle merging and conflicts.
What typically happens with both of these flags is that they work well about 80% of the time, and then cause a lot of confusion that last 20% of the time.
The alternative is almost always some sort of configuration file that is directly referenced in .gitignore, and that therefore never gets checked in. (In addition, it's often useful to have a (e.g.) config.json.default file for getting new developers up and running quickly.) Any system that needs to be configured (database connections, API URLs, IP addresses, etc) should use this configuration file. Alternatively, I find environment variables, along with .env files for local development, to be really effective, because most things can already be configured that way.
This typically takes sightly longer to set up the first time, but will work very reliably from then on.
See also these changes in git's official documentation, and the commit message that explains why it was necessary:
https://github.com/git/git/commit/1b13e9032f039c8cdb1994dd09...