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Comment by Elucalidavah | Hacker News Reader

> directory tree entry names

But... git doesn't really store directories, does it?

I wrote a longer comment saying this (deleted now since I was wrong).

Turns out that Git does somewhat store dirs (in form of trees). See https://git-scm.com/book/en/v2/Git-Internals-Git-Objects (section "Tree Objects").

To understand op's repro look at the last two lines (objects in the tree) in each of their command outputs, not the files shown in the first few lines.

What I think op means is that the `testing` tree pointed in their first example is sorted after `testing.md` even though it's only called `testing` because it's being sorted as `testing/` and `/` is > `.` bytewise.

I'm not at a computer right now but it would be nice to test it with files named `testing.` and `testing0` since they are adjacent bytewise and would show the implicit forward slash more clearly with the tree object sitting between them.

This makes me wonder why Git can't just store an empty tree for empty dirs.

EDIT: did the Gist https://gist.github.com/alvaro-cuesta/bd0234e3e1a66819c7e9e9...

Notice the `git cat-file -p HEAD^{tree}` outputs.

> This makes me wonder why Git can't just store an empty tree for empty dirs.

tl;dr: it can (see my other comment) and the empty tree is hardcoded. But since the index works with file paths and blobs, having no file means that there's no entry in the index

Yes it does, it just doesn't store empty directories.

You can perfectly easily put the empty tree object as a tree object's child, this just isn't supported and some parts of Git will break.

It can store empty directories (actually, trees). It can't do normally because the index maps paths to blobs, an empty directory doesn't have a file to map to a blob and then `git add` will have no effect. Given that normally we write commits from the index content, then normally we won't find an empty tree.

You can run `git commit --allow-empty` with an empty index and the root tree will be the empty tree:

   $ git init
   $ git commit --allow-empty -m foo
   $ git rev-parse @^{tree}
   4b825dc642cb6eb9a060e54bf8d69288fbee4904

4b825dc is the empty tree. And a funny thing about it is that it is hardcoded in Git, and you can use it without having this object:

   $ git init
   $ git commit-tree -m foo 4b825dc642cb6eb9a060e54bf8d69288fbee4904
   $ tree .git/objects # you'll see that there's no file for the empty tree

This is a good reading about that weird object: https://matheustavares.dev/posts/empty-tree

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