Re: Breakage by commit "779bc886f9 * Improve detection of Git submodules"

[Dmitry Gutov <dgutov@yandex.ru>]

On 15.05.2020 22:45, Tassilo Horn wrote:
> I've edebugged, and the problem is that
> 
> (let ((default-directory "~/Repos/el/emacs/lisp/net"))
>    (vc-root-dir)) ;=> nil
> 
> That's because `vc-deduce-backend' returns nil.  It only looks at
> default-directory when in dired-mode, shell-mode, or compilation-mode...

Oh, okay. Sorry about that.

Does this patch fix the situation?

diff --git a/lisp/progmodes/project.el b/lisp/progmodes/project.el
index faa60d123f..0ce2786a4d 100644
--- a/lisp/progmodes/project.el
+++ b/lisp/progmodes/project.el
@@ -274,8 +274,7 @@ project-try-vc
              ('Git
               ;; Don't stop at submodule boundary.
               (or (vc-file-getprop dir 'project-git-root)
-                 (let* ((default-directory dir)
-                        (root (vc-root-dir))
+                 (let* ((root (vc-call-backend backend 'root dir))
                          (gitfile (expand-file-name ".git" root)))
                     (vc-file-setprop
                      dir 'project-git-root
@@ -287,9 +286,8 @@ project-try-vc
                          (goto-char (point-min))
                          (looking-at "gitdir: [./]+/\.git/modules/"))
                        (let* ((parent (file-name-directory
-                                      (directory-file-name root)))
-                             (default-directory parent))
-                        (vc-root-dir)))
+                                      (directory-file-name root))))
+                        (vc-call-backend backend 'root parent)))
                       (t root)))
                     )))
              ('nil nil)