Don't put trailing optional nil values into `command-history'

* src/callint.c (fix_command): Don't put trailing optional nil
values into `command-history' (bug#45333).

1 files changed, 33 insertions, 2 deletions

diff --git a/src/callint.c b/src/callint.c
index 92bfaf8d397..8283c61da67 100644
--- a/src/callint.c
+++ b/src/callint.c
@@ -170,7 +170,7 @@ check_mark (bool for_region)
    of VALUES to do its job.  */
 
 static void
-fix_command (Lisp_Object input, Lisp_Object values)
+fix_command (Lisp_Object input, Lisp_Object function, Lisp_Object values)
 {
   /* FIXME: Instead of this ugly hack, we should provide a way for an
      interactive spec to return an expression/function that will re-build the
@@ -230,6 +230,37 @@ fix_command (Lisp_Object input, Lisp_Object values)
             }
         }
     }
+
+  /* If the list contains a bunch of trailing nil values, and they are
+     optional, remove them from the list.  This makes navigating the
+     history less confusing, since it doesn't contain a lot of
+     parameters that aren't used.  */
+  if (CONSP (values))
+    {
+      Lisp_Object arity = Ffunc_arity (function);
+      /* We don't want to do this simplification if we have an &rest
+         function, because (cl-defun foo (a &optional (b 'zot)) ..)
+         etc.  */
+      if (FIXNUMP (XCAR (arity)) && FIXNUMP (XCDR (arity)))
+        {
+          Lisp_Object final = Qnil;
+          ptrdiff_t final_i = 0, i = 0;
+          for (Lisp_Object tail = values;
+               CONSP (tail);
+               tail = XCDR (tail), ++i)
+            {
+              if (!NILP (XCAR (tail)))
+                {
+                  final = tail;
+                  final_i = i;
+                }
+            }
+
+          /* Chop the trailing optional values.  */
+          if (final_i > 0 && final_i >= XFIXNUM (XCAR (arity)) - 1)
+            XSETCDR (final,  Qnil);
+        }
+    }
 }
 
 /* Helper function to call `read-file-name' from C.  */
@@ -340,7 +371,7 @@ invoke it (via an `interactive' spec that contains, for instance, an
              Make a copy of the list of values, for the command history,
              and turn them into things we can eval.  */
           Lisp_Object values = quotify_args (Fcopy_sequence (specs));
-          fix_command (input, values);
+          fix_command (input, function, values);
           call4 (intern ("add-to-history"), intern ("command-history"),
                  Fcons (function, values), Qnil, Qt);
         }