Fix .asd finding function

1 files changed, 7 insertions, 3 deletions

diff --git a/tw/home/files/emacs-init.el b/tw/home/files/emacs-init.el
index 72c75799..a924db56 100644
--- a/tw/home/files/emacs-init.el
+++ b/tw/home/files/emacs-init.el
@@ -873,9 +873,13 @@ For use in `org-latex-classes'."
 (defun tw/find-asd-systems (directory)
   "Return a list of Common Lisp .asd systems found in DIRECTORY."
   (let ((asd-rx (rx ".asd" eos)))
-    (mapcar (lambda (file)
-              (string-trim-right file asd-rx))
-            (directory-files directory nil asd-rx))))
+    ;; `locate-dominating-file' will call this function once with the original
+    ;; file name as DIRECTORY, but `directory-files' fails if its argument is
+    ;; a regular file, so protect against this.
+    (and (directory-name-p directory)
+         (mapcar (lambda (file)
+                   (string-trim-right file asd-rx))
+                 (directory-files directory nil asd-rx)))))
 
 (defun tw/lisp-project-setup ()
   "Set up a Lisp REPL for the current project."