From 0ea670366183723a96fcb18aa25d9766c3649b83 Mon Sep 17 00:00:00 2001
From: Fabian Boehm <FHomborg@gmail.com>
Date: Tue, 7 Jun 2022 20:10:13 +0200
Subject: [PATCH] completions/git: Terminate pathspec magic

Git's pathspec system is kind of annoying:

>  A pathspec that begins with a colon : has special meaning. In the short form, the leading colon : is followed by zero or more "magic signature" letters (which optionally is terminated by another colon :), and the remainder is the pattern to match against the path. The "magic signature" consists of ASCII symbols that are neither alphanumeric, glob, regex special characters nor colon. The optional colon that terminates the "magic signature" can be omitted if the pattern begins with a character that does not belong to "magic signature" symbol set and is not a colon.

So if we complete `:/foo`, that "works" because "f" is alphanumeric
and so the "/" is the only magic character here.

If, however the filename starts with a magic character, that's used as
a magic signature.

So we do what the docs say and terminate the magic signature after the
"/" (which means "from the repo root").

Fixes #9004
---
 share/completions/git.fish | 10 +++++++---
 tests/checks/git.fish      |  3 +++
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/share/completions/git.fish b/share/completions/git.fish
index 95dc605e9..35cd87faa 100644
--- a/share/completions/git.fish
+++ b/share/completions/git.fish
@@ -342,7 +342,11 @@ function __fish_git_files
                     if string match -q '../*' -- $file
                         or string match -q ':*' -- (commandline -ct)
                         set -l fromroot (builtin realpath -- $file 2>/dev/null)
-                        and set fromroot (string replace -- "$root/" ":/" "$fromroot")
+                        # `:` starts pathspec "magic", and the second `:` terminates it.
+                        # `/` is the magic letter for "from repo root".
+                        # If we didn't terminate it we'd have to escape any special chars
+                        # (non-alphanumeric, glob or regex special characters, in whatever dialect git uses)
+                        and set fromroot (string replace -- "$root/" ":/:" "$fromroot")
                         and printf '%s\t%s\n' "$fromroot" $d
                     end
                 end
@@ -476,10 +480,10 @@ function __fish_git_files
                 end
                 set -a file (string join / -- $previous)
 
-                # The filename with ":/" prepended.
+                # The filename with ":/:" prepended.
                 if string match -q '../*' -- $file
                     or string match -q ':*' -- (commandline -ct)
-                    set file (string replace -- "$root/" ":/" "$root/$relfile")
+                    set file (string replace -- "$root/" ":/:" "$root/$relfile")
                 end
 
                 if test "$root/$relfile" = (pwd -P)/$relfile
diff --git a/tests/checks/git.fish b/tests/checks/git.fish
index de7403baf..324c5ce28 100644
--- a/tests/checks/git.fish
+++ b/tests/checks/git.fish
@@ -40,6 +40,9 @@ touch foo
 complete -C'git add '
 #CHECK: foo	Untracked file
 
+complete -C'git add :'
+#CHECK: :/:foo	Untracked file
+
 git config alias.s status
 complete 'git s --s'
 # CHECK --short