bug#21930: emacs-repository-get-version fails on linked worktrees

[Juanma Barranquero <lekktu@gmail.com>]

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Package: emacs
Version: 25.0.50
Severity: minor

When run inside a linked worktree (created with "git worktree add ..."),
emacs-repository-get-version needs to ask the VCS to find the repository
version, which doesn't work during dumping.

I'd like to apply this patch to the release branch.


diff --git i/lisp/version.el w/lisp/version.el
index 43103fd..4207cb4 100644
--- i/lisp/version.el
+++ w/lisp/version.el
@@ -114,15 +114,15 @@ emacs-repository-version-git
    (match-string 0)))))

-(defun emacs-repository--version-git-1 (file)
+(defun emacs-repository--version-git-1 (file dir)
   "Internal subroutine of `emacs-repository-get-version'."
   (when (file-readable-p file)
-    (erase-buffer)
-    (insert-file-contents file)
-    (cond ((looking-at "[0-9a-fA-F]\\{40\\}")
-   (match-string 0))
-  ((looking-at "ref: \\(.*\\)")
-   (emacs-repository--version-git-1
-    (expand-file-name (match-string 1)
-      (file-name-directory file)))))))
+    (with-temp-buffer
+      (insert-file-contents file)
+      (cond ((looking-at "[0-9a-fA-F]\\{40\\}")
+             (match-string 0))
+            ((looking-at "ref: \\(.*\\)")
+             (emacs-repository--version-git-1
+              (expand-file-name (match-string 1) dir)
+              dir))))))

 (defun emacs-repository-get-version (&optional dir external)
@@ -139,18 +139,36 @@ emacs-repository-get-version
 the VCS if we cannot find any information ourselves."
   (or dir (setq dir source-directory))
-  (when (file-directory-p (expand-file-name ".git" dir))
-    (if external
- (emacs-repository-version-git dir)
-      (or (let ((files '("HEAD" "refs/heads/master"))
- file rev)
-    (with-temp-buffer
-      (while (and (not rev)
-  (setq file (car files)))
- (setq file (expand-file-name (format ".git/%s" file) dir)
-      files (cdr files)
-      rev (emacs-repository--version-git-1 file))))
-    rev)
-  ;; AFAICS this doesn't work during dumping (bug#20799).
-  (emacs-repository-version-git dir)))))
+  (let* ((base-dir (expand-file-name ".git" dir))
+         (in-main-worktree (file-directory-p base-dir))
+         (in-linked-worktree nil)
+         sub-dir)
+    ;; If the sources are in a linked worktree, .git is a file that points
to
+    ;; the location of the main worktree and the repo's administrative
files.
+    (when (and (not in-main-worktree)
+               (file-regular-p base-dir)
+               (file-readable-p base-dir))
+      (with-temp-buffer
+        (insert-file-contents base-dir)
+        (when (looking-at "gitdir: \\(.*\.git\\)\\(.*\\)$")
+          (setq base-dir (match-string 1)
+                sub-dir (concat base-dir (match-string 2))
+                in-linked-worktree t))))
+    ;; We've found a worktree, either main or linked.
+    (when (or in-main-worktree in-linked-worktree)
+      (if external
+          (emacs-repository-version-git dir)
+        (or (if in-linked-worktree
+                (emacs-repository--version-git-1
+                 (expand-file-name "HEAD" sub-dir) base-dir)
+              (let ((files '("HEAD" "refs/heads/master"))
+                    file rev)
+                (while (and (not rev)
+                            (setq file (car files)))
+                  (setq file (expand-file-name file base-dir)
+                        files (cdr files)
+                        rev (emacs-repository--version-git-1 file
base-dir)))
+                rev))
+            ;; AFAICS this doesn't work during dumping (bug#20799).
+            (emacs-repository-version-git dir))))))

 ;; We put version info into the executable in the form that `ident' uses.

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