(Minibuffer History): Update add-to-history.

diff --git a/lispref/minibuf.texi b/lispref/minibuf.texi
index b5bcc3a77dc289fc90c0d5e04618c873ba889d74..73cc0817d9bc7eb3d20722c7a67a6ca6be5922dc 100644 (file)
--- a/lispref/minibuf.texi
+++ b/lispref/minibuf.texi
@@ -449,17 +449,20 @@ list, put the length in the @code{history-length} property of the
 history list symbol.  The variable @code{history-delete-duplicates}
 specifies whether to delete duplicates in history.
 
-@defun add-to-history history-var newelt &optional maxelt
-This function adds a new element @var{newelt} to the history list
-stored in the variable @var{history-var}, and returns the updated
-history list.  By default, the list length is limited by the value
-specified by @code{history-length} (described below), but the optional
-argument @var{maxelt} overrides that.  The possible values of
+@defun add-to-history history-var newelt &optional maxelt keep-all
+This function adds a new element @var{newelt}, if non-empty, to the
+history list stored in the variable @var{history-var}, and returns the
+updated history list.  By default, the list length is limited by the
+value specified by @code{history-length} (described below), but the
+optional argument @var{maxelt} overrides that.  The possible values of
 @var{maxelt} have the same meaning as the values of
 @code{history-length}.
 
-Duplicate members are removed from the history list, unless
-@code{history-delete-duplicates} is @code{nil}.
+Duplicate members are removed from the history list, if
+@code{history-delete-duplicates} is non-@code{nil}.
+
+If @var{keep-all} is non-@code{nil}, even an empty or duplicate
+@var{newelt} element is added to the history list.
 @end defun
 
 @defvar history-length