Merge pull request #248 from whhone/master

Fix `diff-hl-resolved-reference-revision` for Hg and Bzr with buffer-local `diff-hl-reference-revision`

Author: dgutov

diff-hl.el

@@ -1442,21 +1442,35 @@ CONTEXT-LINES is the size of the unified diff context, defaults to 0."
    ((eq backend 'Git)
     (vc-git--rev-parse diff-hl-reference-revision))
    ((eq backend 'Hg)
-    (with-temp-buffer
-      (vc-hg-command (current-buffer) 0 nil
-                     "identify" "-r" diff-hl-reference-revision
-                     "-i")
-      (goto-char (point-min))
-      (buffer-substring-no-properties (point) (line-end-position))))
+    ;;  Preserve the potentially buffer-local variables (e.g.,
+    ;;  `diff-hl-reference-revision`, `vc-hg-program`) by not switching buffer
+    ;;  until the vc-hg-command is done.
+    (let ((temp-buffer (generate-new-buffer " *temp*")))
+      (unwind-protect
+          (progn
+            (vc-hg-command temp-buffer 0 nil
+                           "identify" "-r" diff-hl-reference-revision "-i")
+            (with-current-buffer temp-buffer
+              (goto-char (point-min))
+              (buffer-substring-no-properties (point) (line-end-position))))
+        (kill-buffer temp-buffer))))
    ((eq backend 'Bzr)
-    (with-temp-buffer
-      (vc-bzr-command (current-buffer) 0 nil
-                      "log" "--log-format=template" "--template-str='{revno}'"
-                      "-r" diff-hl-reference-revision)
-      (goto-char (point-min))
-      (buffer-substring-no-properties (point) (line-end-position))))
-   (t
-    diff-hl-reference-revision)))
+    ;;  Preserve the potentially buffer-local variables (e.g.,
+    ;;  `diff-hl-reference-revision`, `vc-bzr-program`) by not switching buffer
+    ;;  until the vc-bzr-command is done.
+    (let ((temp-buffer (generate-new-buffer " *temp*")))
+      (unwind-protect
+          (progn
+            (vc-bzr-command temp-buffer 0 nil
+                            "log" "--log-format=template"
+                            "--template-str='{revno}'"
+                            "-r" diff-hl-reference-revision)
+            (with-current-buffer temp-buffer
+              (goto-char (point-min))
+              (buffer-substring-no-properties (point) (line-end-position))))
+        (kill-buffer temp-buffer))))
+    (t
+     diff-hl-reference-revision)))
 
 ;; TODO: Cache based on .git/index's mtime, maybe.
 (defun diff-hl-git-index-object-name (file)

test/diff-hl-test.el

@@ -223,6 +223,21 @@
 Diff finished."
                  (buffer-substring (point) (point-max))))))))
 
+(diff-hl-deftest diff-hl-resolved-reference-revision-buffer-local-hg ()
+  (diff-hl-test-in-source
+   (setq-local diff-hl-reference-revision "test-rev")
+   (setq-local vc-hg-program "chg")
+   (condition-case err
+       (progn
+         (diff-hl-resolved-reference-revision 'Hg)
+         (ert-fail "Expected an error to be signaled but none was."))
+     ;; We don't have a hg repo, but we can use the error message to verify the
+     ;; underlying command.
+     (error
+      (should (string-match-p
+               "chg .*identify -r test-rev -i"
+               (error-message-string err)))))))
+
 (provide 'diff-hl-test)
 
 ;;; diff-hl-test.el ends here