[git] Why should I use core.autocrlf=true in Git?

I have a Git repository that is accessed from both Windows and OS X, and that I know already contains some files with CRLF line-endings. As far as I can tell, there are two ways to deal with this:

1. Set core.autocrlf to false everywhere,

2. Follow the instructions here (echoed on GitHub's help pages) to convert the repository to contain only LF line-endings, and thereafter set core.autocrlf to true on Windows and input on OS X. The problem with doing this is that if I have any binary files in the repository that:

   1. are not correctly marked as binary in gitattributes, and
   2. happen to contain both CRLFs and LFs,

   they will be corrupted. It is possible my repository contains such files.

So why shouldn't I just turn off Git's line-ending conversion? There are a lot of vague warnings on the web about having core.autocrlf switched off causing problems, but very few specific ones; the only that I've found so far are that kdiff3 cannot handle CRLF endings (not a problem for me), and that some text editors have line-ending issues (also not a problem for me).

The repository is internal to my company, and so I don't need to worry about sharing it with people with different autocrlf settings or line-ending requirements.

Are there any other problems with just leaving line-endings as-is that I am unaware of?

I am a .NET developer, and have used Git and Visual Studio for years. My strong recommendation is set line endings to true. And do it as early as you can in the lifetime of your Repository.

That being said, I HATE that Git changes my line endings. A source control should only save and retrieve the work I do, it should NOT modify it. Ever. But it does.

What will happen if you don't have every developer set to true, is ONE developer eventually will set to true. This will begin to change the line endings of all of your files to LF in your repo. And when users set to false check those out, Visual Studio will warn you, and ask you to change them. You will have 2 things happen very quickly. One, you will get more and more of those warnings, the bigger your team the more you get. The second, and worse thing, is that it will show that every line of every modified file was changed(because the line endings of every line will be changed by the true guy). Eventually you won't be able to track changes in your repo reliably anymore. It is MUCH easier and cleaner to make everyone keep to true, than to try to keep everyone false. As horrible as it is to live with the fact that your trusted source control is doing something it should not. Ever.

Update 2:

Xcode 9 appears to have a "feature" where it will ignore the file's current line endings, and instead just use your default line-ending setting when inserting lines into a file, resulting in files with mixed line endings.

I'm pretty sure this bug didn't exist in Xcode 7; not sure about Xcode 8. The good news is that it appears to be fixed in Xcode 10.

For the time it existed, this bug caused a small amount of hilarity in the codebase I refer to in the question (which to this day uses autocrlf=false), and led to many "EOL" commit messages and eventually to my writing a git pre-commit hook to check for/prevent introducing mixed line endings.

Update:

Note: As noted by VonC, starting from Git 2.8, merge markers will not introduce Unix-style line-endings to a Windows-style file.

Original:

One little hiccup that I've noticed with this setup is that when there are merge conflicts, the lines git adds to mark up the differences do not have Windows line-endings, even when the rest of the file does, and you can end up with a file with mixed line endings, e.g.:

// Some code<CR><LF>
<<<<<<< Updated upstream<LF>
// Change A<CR><LF>
=======<LF>
// Change B<CR><LF>
>>>>>>> Stashed changes<LF>
// More code<CR><LF>

This doesn't cause us any problems (I imagine any tool that can handle both types of line-endings will also deal sensible with mixed line-endings--certainly all the ones we use do), but it's something to be aware of.

The other thing^* we've found, is that when using git diff to view changes to a file that has Windows line-endings, lines that have been added display their carriage returns, thus:

    // Not changed

+   // New line added in^M
+^M
    // Not changed
    // Not changed

_{* It doesn't really merit the term: "issue".}

For me.

Edit .gitattributes file.

add

*.dll binary

Then everything goes well.