Activate extra and major modes first

This prevents snippets from a parent mode from overriding those of the
major-mode's (or yas--extra-modes).  Snippets of ancestor modes may
still override snippets of some other ancestor modes, but hopefully this
won't cause much trouble in practice.

See [1] and subsequent comments.

[1]: https://github.com/capitaomorte/yasnippet/issues/619#issuecomment-149127150

* yasnippet.el (yas--modes-to-activate): Reverse result, so that parents
  of yas--extra-modes and major are later in the list.
* yasnippet-tests.el (loading-with-cyclic-parenthood)
(extra-modes-parenthood): Test it.

Close #626.

diff --git a/yasnippet-tests.el b/yasnippet-tests.el
index 47565718a9a12afa1d0714af3d713e11a3634554..52f0c3975ac5d2ee2693c69e28e8ff44b5d6166a 100644 (file)
--- a/yasnippet-tests.el
+++ b/yasnippet-tests.el
@@ -497,6 +497,7 @@ TODO: correct this bug!"
                           emacs-lisp-mode
                           lisp-interaction-mode))
               (observed (yas--modes-to-activate)))
+         (should (equal major-mode (car observed)))
          (should (equal (sort expected #'string<) (sort observed #'string<))))))))
 
 (ert-deftest extra-modes-parenthood ()
@@ -505,26 +506,29 @@ TODO: correct this bug!"
    (yas-with-snippet-dirs '((".emacs.d/snippets"
                              ("c-mode"
                               (".yas-parents" . "cc-mode"))
-                             ("cc-mode"
-                              (".yas-parents" . "yet-another-c-mode and-that-one"))
                              ("yet-another-c-mode"
                               (".yas-parents" . "c-mode and-also-this-one lisp-interaction-mode"))))
      (yas-reload-all)
      (with-temp-buffer
-       (let* ((_ (yas-activate-extra-mode 'c-mode))
-              (expected `(,major-mode
-                          c-mode
-                          cc-mode
-                          yet-another-c-mode
-                          and-also-this-one
-                          and-that-one
-                          ;; prog-mode doesn't exist in emacs 24.3
-                          ,@(if (fboundp 'prog-mode)
-                                '(prog-mode))
-                          emacs-lisp-mode
-                          lisp-interaction-mode))
+       (yas-activate-extra-mode 'c-mode)
+       (yas-activate-extra-mode 'yet-another-c-mode)
+       (yas-activate-extra-mode 'and-that-one)
+       (let* ((expected-first `(and-that-one
+                                yet-another-c-mode
+                                c-mode
+                                ,major-mode))
+              (expected-rest `(cc-mode
+                               ;; prog-mode doesn't exist in emacs 24.3
+                               ,@(if (fboundp 'prog-mode)
+                                     '(prog-mode))
+                               emacs-lisp-mode
+                               and-also-this-one
+                               lisp-interaction-mode))
               (observed (yas--modes-to-activate)))
-         (should (equal (sort expected #'string<) (sort observed #'string<))))))))
+         (should (equal expected-first
+                        (cl-subseq observed 0 (length expected-first))))
+         (should (equal (sort expected-rest #'string<)
+                        (sort (cl-subseq observed (length expected-first)) #'string<))))))))
 
 (ert-deftest issue-492-and-494 ()
   (defalias 'yas--phony-c-mode 'c-mode)

diff --git a/yasnippet.el b/yasnippet.el
index facb2b66e48ddce8a0c3913fce61343321ccf204..4f06a48e5d6230c1a0b66f6ceb135fa663e73027 100644 (file)
--- a/yasnippet.el
+++ b/yasnippet.el
@@ -728,22 +728,21 @@ defined direct keybindings to the command
 (defun yas--modes-to-activate (&optional mode)
   "Compute list of mode symbols that are active for `yas-expand'
 and friends."
-  (let (dfs explored)
-    (setq dfs (lambda (mode)
-                (unless (memq mode explored)
-                  (push mode explored)
-                  (loop for neighbour
-                        in (cl-list* (get mode 'derived-mode-parent)
-                                     (ignore-errors (symbol-function mode))
-                                     (gethash mode yas--parents))
-                        when (and neighbour
-                                  (not (memq neighbour explored))
-                                  (symbolp neighbour))
-                        do (funcall dfs neighbour)))))
-    (if mode
-        (funcall dfs mode)
-      (mapcar dfs (cons major-mode yas--extra-modes)))
-    explored))
+  (let* ((explored (if mode (list mode) ; Building up list in reverse.
+                     (cons major-mode (reverse yas--extra-modes))))
+         (dfs
+          (lambda (mode)
+            (cl-loop for neighbour
+                     in (cl-list* (get mode 'derived-mode-parent)
+                                  (ignore-errors (symbol-function mode))
+                                  (gethash mode yas--parents))
+                     when (and neighbour
+                               (not (memq neighbour explored))
+                               (symbolp neighbour))
+                     do (push neighbour explored)
+                     (funcall dfs neighbour)))))
+    (mapcar dfs explored)
+    (nreverse explored)))
 
 (defvar yas-minor-mode-hook nil
   "Hook run when `yas-minor-mode' is turned on.")