Warn about key rebinds

init.el

@@ -40,6 +40,9 @@
 (load "frame-manip")
 (load "file-manip")
 (load "window-manip")
+(load "gpolonkai-misc")
+
+(advice-add 'define-key :before #'warn-key-rebind)
 
 ;; Define aliases
 (defalias 'yes-or-no-p 'y-or-n-p)

lisp/gpolonkai-misc.el

@@ -0,0 +1,27 @@
+(defun warn-key-rebind (keymap key new-def)
+  "Warn if a key is being rebound."
+  (let ((global-def (global-key-binding key))
+        (local-def (local-key-binding key))
+        (minor-defs (minor-mode-key-binding key))
+        (key-desc (key-description key)))
+    (when (and global-def
+               (not (numberp global-def))
+               (not (equal global-def new-def)))
+      (warn "'%s' from the global keymap is being rebound from '%s' to '%s'"
+            key-desc
+            global-def
+            new-def))
+    (when (and local-def
+               (not (numberp local-def))
+               (not (equal local-def new-def)))
+      (warn "'%s' from the local keymap is being rebound from '%s' to '%s'"
+            key-desc
+            local-def
+            new-def))
+    (when minor-defs
+      (dolist (binding minor-defs)
+        (warn "'%s' from '%s' keymap is being rebound from '%s' to '%s'"
+              key-desc
+              (car binding)
+              (cdr binding)
+              new-def)))))