* lisp/help-fns.el (describe-function-1):

Handle builtins with advertised calling conventions.  (Bug#20479)

1 files changed, 4 insertions, 1 deletions

diff --git a/lisp/help-fns.el b/lisp/help-fns.el
index 90200377428..4982ee54f46 100644
--- a/lisp/help-fns.el
+++ b/lisp/help-fns.el
@@ -495,6 +495,9 @@ FILE is the file where FUNCTION was probably defined."
                                f))
                     ((subrp def) (intern (subr-name def)))
                     (t def)))
+         (sig-key (if (subrp def)
+                      (indirect-function real-def)
+                    real-def))
          (file-name (find-lisp-object-file-name function def))
          (pt1 (with-current-buffer (help-buffer) (point)))
          (beg (if (and (or (byte-code-function-p def)
@@ -586,7 +589,7 @@ FILE is the file where FUNCTION was probably defined."
 
         (help-fns--key-bindings function)
         (with-current-buffer standard-output
-          (setq doc (help-fns--signature function doc real-def real-function))
+          (setq doc (help-fns--signature function doc sig-key real-function))
           (run-hook-with-args 'help-fns-describe-function-functions function)
           (insert "\n"
                   (or doc "Not documented.")))))))