Drop unneeded definitions

1 files changed, 16 insertions, 0 deletions

diff --git a/compat-26.el b/compat-26.el
index bdfb6e9..ad080f5 100644
--- a/compat-26.el
+++ b/compat-26.el
@@ -83,6 +83,22 @@ see `region-noncontiguous-p' and `extract-rectangle-bounds'."
 
 ;;;; Defined in subr.el
 
+(compat-defun provided-mode-derived-p (mode &rest modes) ;; <compat-tests:provided-derived-mode-p>
+  "Non-nil if MODE is derived from one of MODES.
+Uses the `derived-mode-parent' property of the symbol to trace backwards.
+If you just want to check `major-mode', use `derived-mode-p'."
+  ;; If MODE is an alias, then look up the real mode function first.
+  (let ((alias (symbol-function mode)))
+    (when (and alias (symbolp alias))
+      (setq mode alias)))
+  (while
+      (and
+       (not (memq mode modes))
+       (let* ((parent (get mode 'derived-mode-parent))
+              (parentfn (symbol-function parent)))
+         (setq mode (if (and parentfn (symbolp parentfn)) parentfn parent)))))
+  mode)
+
 (compat-defun alist-get (key alist &optional default remove testfn) ;; <compat-tests:alist-get>
   "Handle optional argument TESTFN."
   :explicit t