Possible bug: Empty magic word list in pathspec is handled differently in short vs. long form

From: Anselm Schüler <mail@anselmschueler.com>
Date: Feb 19, 2025, 10:49 UTC
Message-ID: <216a7288-b599-4333-ba62-10665d6a94d8@anselmschueler.com>

If you run git diff for a pathspec with an empty magic word/symbol list 
in short form (prefixed by ::) and in long form (prefixed by :():), you 
get different results.

Here’s an example use of git that illustrates this:

~☭ mkdir gittest
~☭ y gittest/
~/gittest☭ git init
Initialized empty Git repository in /home/anselmschueler/gittest/.git/
~/gittest (b0)☭ uuidgen >file
~/gittest (b0)☭ git add file && git commit -m "$(read)"
read> initial commit
[b0 (root-commit) cd3bd43] initial commit
  1 file changed, 1 insertion(+)
  create mode 100644 file
~/gittest (b0)☭ uuidgen >file
~/gittest (b0)☭ git diff -- "::file"

file ──────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────

───┐ 1: │ ───┘ 66d18ffa-1128-42a5-8d4e-f9d75eb86b92 9acea2b5-50a6-4f87-ae1a-64019a93e55e ~/gittest (b0)☭ git diff -- ":():file" ~/gittest (b0)☭

Is there a reason for this? I couldn’t find it documented in the git glossary <https://git-scm.com/docs/gitglossary>.

I’m running git 2.47.2, built with Nix (nixpkgs commit 2ff53fe) from the kernel.org source tarball.

~Anselm Schüler ⚙️