1 files changed, 9 insertions, 1 deletions

diff --git a/src/doc.c b/src/doc.c
index 7792fcb25ca..beff68b3e5a 100644
--- a/src/doc.c
+++ b/src/doc.c
@@ -41,7 +41,7 @@ Boston, MA 02111-1307, USA.  */
 #include "keyboard.h"
 #include "charset.h"
 
-Lisp_Object Vdoc_file_name;
+Lisp_Object Vdoc_file_name, Vhelp_manyarg_func_alist;
 
 extern char *index ();
 
@@ -319,6 +319,8 @@ string is passed through `substitute-command-keys'.")
       else
         doc = get_doc_string (make_number (- (EMACS_INT) XSUBR (fun)->doc),
                               0, 0);
+      if (! NILP (tem = Fassq (function, Vhelp_manyarg_func_alist)))
+        doc = concat3 (doc, build_string ("\n"), Fcdr (tem));
     }
   else if (COMPILEDP (fun))
     {
@@ -781,6 +783,12 @@ syms_of_doc ()
   DEFVAR_LISP ("internal-doc-file-name", &Vdoc_file_name,
     "Name of file containing documentation strings of built-in symbols.");
   Vdoc_file_name = Qnil;
+  DEFVAR_LISP ("help-manyarg-func-alist", &Vhelp_manyarg_func_alist,
+    "Alist of primitive functions and descriptions of their arg lists.\n\
+All special forms and primitives which effectively have &rest args\n\
+should have an entry here so that `documentation' can provide their\n\
+arg list.");
+  Vhelp_manyarg_func_alist = Qnil;
 
   defsubr (&Sdocumentation);
   defsubr (&Sdocumentation_property);